MatraSport Forum

Since I have had several enquiries in the last few months about the high fifth gear that I pioneered on the Murena, I thought it would be best to add a thread about it.

The Murena 2.2 was always under-geared from new, and since the CX 2.4 GTi Turbo 2 and the Diesel Turbo 2 had a better gear set with slightly higher third and fourth and a much higher fifth gear, I looked into the possibility of utilising some or all of this on the Murena.  You could replace the whole gear set for one of these at the time when they were available, but it was going to be expensive.  So I considered just changing the fifth gear, which would be much easier and far less costly, and it turned out to be almost ideal, and you didn't even have to take the gearbox out of the car!

However, it was not just a straight swap of fifth gear pairs, which could have been really easy and cheap.  The two Citroën cars mentioned above, obviously had problems with the original end case bearings and gears, and so they redesigned it and provided a kit for the dealers to repair the gearboxes when they were under warranty.  It is this kit that I used to buy, to uprate the Murena.  It consists of new bigger end case bearings and retaining plate, new spacers and bushes, new fifth gear pair, a new synchromesh unit and two shaft nuts.  The only thing they forgot to put in was a gasket.  At the time I could get these kits for around £175 which was not bad and you not only got a better fifth gear ratio but also uprated bearings too.  However, because of the redesign you could not fit just a new fifth gear pair.

I eventually ordered about 15 kits and did many of the upgrades but some owners did the conversions themselves or had them done by their own mechanic.  After that there was no more interest and I didn't buy any more.  I have no stock left.  I wish I had, but even five sets at £175 would have been £875 which was a lot in 1992 and I just could not afford to have bought that many without confirmed orders.

Now, after maybe fifteen years, there is suddenly a lot of interest in this conversion for some reason.  Possibly it is the new Murena owners who have bought the cars second hand, and find the gearbox needs some work and would like to do the mod. whilst they are overhauling the gearbox?  I don't know.  However, the problem now is that the CX is itself an old model which Citroën don't really want to hold or supply parts for any longer.  Like most manufacturers, once a car is ten years old (or less if they can) they no longer want to know!  It used to be they were obliged to provide backup up to ten years old, I don't know if that rule still applies, but we are talking twice that age anyway.

The result is that it is now very difficult to get hold of any parts for the CX transmission, let alone these fifth gear kits.  The synchro cones alone which you might expect to need as they are a wear item are bad enough at around £70 each.  About a year ago it took seven months to get two fifth gear kits, and they cost around £300 each.  The last price I was given was almost £400 a kit and god knows how long they would take to supply them.  Basically they are trying to put you off in the first place, in my opinion.

Since they have to come from France, maybe you could get them easier and or cheaper directly from someone in France?  However, if anyone really wants one of these high 5th ratios now, it will probably mean searching for an old CX box that has the correct gears in it.

My website, which has just had some updates in case you haven't looked in a while, has the part number for this fifth gear kit on one of the FAQ pages; and you are welcome to try Citroën parts directly yourself.  If anyone finds a better price or supply, then please let others here know as there are a number of others certainly interested.

I hope this explains the modification and current situation.

Roy

P.S. I've just remembered, these kits have fitted all the boxes that I've come across bar one - it was obviously an early box, and the synchro was different, and this was parts not included in the kit, so I had to change them for the other type.  So if you have an early car, please check with me first or bear in mind you may have to change a few other bits.  That may be no problem if you have access to a spare box, but could cause you trouble otherwise.

Roy,

Thank you for all your work and for your very exhaustive description of the matter! Perfect!

I will have a look at my car first because it's an early one (1981).

Jan

Thanks for info Roy.
I supose the gearbox of the cx is not a direct fit?

No.  There are a number of differences.  However, if you could find a complete Diesel turbo 2 or 2.4 GTi turbo 2 box with the correct ratios it would be easy to swap the parts over, so I would seriously consider buying it.  These, boxes are quite rare though, so there won't be many second hand ones around I think!

Roy

On the mainland I see them sometimes passing by.
I know what to look for now.
Thanks.

I phoned to Citroen CR and they told me the price 15700,-CZK = cca 600,-Eur but this part in no longer available  :(

Based on the above discussion I checked with my local car breaker, and much to my supprise they had in their store a gearbox from a 1989 CX 2.5 TD with 120.000 km on the counter. (remark: tall gearing)
So I purchased the gead box immidietly, even though I found it a little expensive at 375 EURO.

Hans

Here is one to, but not sure it is the right one.
http://cgi.ebay.de/Citroen-CX-II-Getriebe-2-5-GTi-gebr_W0QQitemZ280342199975QQcmdZViewItemQQptZAutoteile_Zubehör?hash=item4145b27ea7&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1229%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

Hi Roy.

I was wondering if, without opening the gearbox, there is a way to tell if a previous owner has installed the 5th. gear kit. It should be possible to tell if you know how fast the car should drive in 5th gear at a given RPM, and with the standard tire size. Do you know if that kind of information is available anywhere?

Yes, question is - how high the top speed than will be? And if we'll find an used CX gearbox, how we recognise that it is the right one?

I think topspeed wil not change if you not push some extra horsepower out of the engine itself.
Possible that topspeed is even lower.

Ussualy the information you are requesting is listed in the user manual...
Given as speed in highest gear at 1000rpm.

Otherwise I'm sure the gear ratios are listed in the workshop manual.

I have looked into the gear ratio of the 1.6, but can't help you with the 2.2 though.

You do not want to have a longer 5th gear (or at least I do not) in order to get a higher top speed. I want a longer 5th gear in order to get a more relaxed cruising speed with less engine noise at say at around 150 km/h. A side effect will maybe be lower fuel consumption. However for my own Murena I have an engine that is more powerful than standard ready to be installed.
In order to identify if a Citroën CX gearbox has the taller gearing I think you need to know in which version of the CX the box has been used (i.e. a GTi or a Turbo diesel). But remember that you will need to installed the internal parts from the CX gearbox in the Murena gearbox housing.

Hans

I think that "S" engine has enough power for top speed let's say 225km/h? I don't know how it is at your cars, but my Murena shows 200km/h (and it isn't its top speed ;) ) when GPS says 203km/h and tacho in Skoda Octavia driven by my friend behind me shows 215km/h. Than 225km/h in Murena could be something about 240km/h in other cars - muhehe  8)

even though the Murena is fairly low, it is very wide, so the frontal area is about the same as any other car, - which means it runs into a wall of air-resistance at high speed (proportional to the v³ ), so I doubt any standard S will do much over 210 or 220 on a very good day (in tail wind?).

My 136hp 1.9i (B3 gearbox) has a terminal velocity of 205km/h on GPS  (tested in Germany of course :-)  )  - however thats very close to running out of revs (it's and 8valve engine, remember).  For most practical purposes, I'd say 200k - and frankly top speed is not very practical to start with.

My 406Coupe (V6 24V)  easily hits 230km/h and given enough road, it does 243km/h - thats 212hp with the about the same frontal area and AFAIK about the same Cw.

The rule-of-thumb formula I recall says:
    HP needed = 1/1200 * A * Cw * v³
where A is the frontal area, v is the velocity, and Cw the air resistance coefficieant (Murena: 0.32)

I believe the frontal area of the Murena is about 2.5m2 - which makes the theoretical topspeed look like this:

A=2.5 m²


HP      Vmax (m/s)   (km/h)
      
   95      52            188
 118      56            202
 136      58            212
 143      59            215
 150      60            219
(212      67            246)

which sounds reasonable for a rule-of-thumb formula.

/Lennart

188........No License for 6 weeks.
215........No license for 3months.
246........Probably dead penalty over here.

It is nice that it is possible, but my car wil never run at that speeds, even not at a circuit.
In the first place it is 27 years old, and 2nd I don't want the fun of something breaking down at those speeds.
Not that I didn't try it out, but that was only one time to see if it is in the car.
(http://img156.imageshack.us/img156/6168/p1000661.jpg)

With this speed you have to watch out for the special equipment of the police.
(http://i32.tinypic.com/25r1slw.jpg)

Nice one. :-)

Just for clarification I did 243k (GPS) in my Peugeot 406 Coupe, north of Essen a quiet evening last summer, on a derestricted stretch of German Autobahn - this is on the way back (my son driving me taking the picture, we're not that dumb :-) ) where we only nudged 240k (149mph - surprisingly precise comparing to GPS) - we found an apparently quite new stretch of Autobahn in the middle of the Ruhr district :
  (http://www.sorth.dk/d2c_6698sml.jpg)
And I have to say, as fun the Murena is, the 406 Coupe is much better suited for those speeds, larger car, larger wheels, nice big Brembo brakes etc etc.

The Murena I'm quite happy to keep well below 200k and even 80k can be fun on the right roads.


mind you, I have calculated that at the above speed, my V6 drinks 1.1 liter of petrol per minute :-)


/Lennart

 :D :D :D

Are your policemen really so hard? Here the top speed on highway is 130km/h but when you're driving 130k, you have all the time someone 30cm behind you trying to push you out of the street. As my average is 400km/day (in a company car) I am also using highways in 150 - 180 km/h commonly. The stationary radars are only in cities and everybody knows where, so the trafic goes fast - than slowly passing the radar - than fast  :D and on highways there are only few Passat R36 and Mondeo ST - so when you see this car, you drive slowly, that's all. And also all GPS navi systems are informing about radars, the same all radio stations are informing about places where police is maesuring the speed. I say, that, in this situation, if somebody is measured, he has to be so dumb that he can kill somebody driving so reckless, so good that he is punished. If I had to drive max 130k on highway I had to be thinking that I'm sleeping behind the steering wheel...

 Quote Michael.
-------------------
I am also using highways in 150 - 180 km/h commonly.
And also all GPS navi systems are informing about radars.
If I had to drive max 130k on highway I had to be thinking that I'm sleeping behind the steering wheel...
====================================================================

Driving in the Netherlands with those speeds, and you loose your'e license in a few days for sure, or at least give you speeding tickets that wil make you feel a poor man that month.

My last ticket was in april.
I drove 86 km/h, where 80 was alowed :o
I know it, I am a speedpirat :P

GPS don't know about laserguns and we have a lot of unrecognisable flying policecars on the road.

You get used to slow driving, the distance between the bigger places are not that much overhere.
If you do that long enough, 150 km/h gives the feeling that your'e flying.

100- 120km/h is max allowed overhere on the highways.
Sleeping with those speeds is impossible.
There are enough idiots on the road that keep you awake.

Wow, it's not good  :-[ fast driving is the best relax and I can't be every second day on the circuit, so it's fine that our cops are more benevolent. And true is, that those people, who think that speed is the biggest reason for crashes, are absolutely out, because when you drive fast, you are concentrating for it much more than people who are bored by traveling at 100km/h. If someone is stupid, he can kill himself or someone else at 30km/h  ::)

Quote Michael
---------------
And true is, that those people, who think that speed is the biggest reason for crashes, are absolutely out, because when you drive fast, you are concentrating for it much more than people who are bored by traveling at 100km/h
=====================================================================

Our country is small and very populated.
On a bad day we have 400km traffic jam on the roads.
Nobody expects someone driving 200 km/h behind him.
The only speedy driving we can do is in the night from 02.00 AM til 05.00 AM.

Its no problem.
The best fun driving the Murena, is on the smaller countryroads.

You are right. I searched the repair manual from Simon and found that on a 1.6 with 195/60 X 14 rear tires, at 1000 RPM the speed is 30.91 kmh. On the 2.2 with 195/60 X 14 tires, at 1000 RPM, the speed is 33,79 kph. So at 3000 rpm the speed shoulld be 101,37 kph.

That is interesting, because on my 2.2 I am pretty sure that at 3000 RPM it goes about 120 kph. ;D
I will verify that this weekend. Of course it also depends on how accurate the tachometer is.  Any ideas on how to check that? ???

I have just the same: 3000RPM at 120km/h. Seems to be rather usual, due to inaccurate tachometer.

Jan

You can check it very easily - go on highway and reach speed 120km/h on your tacho, than you have to make 1km (hope that you also have the signs in the middle of the highway each km as we have) in 30 seconds. If it will be more, than your tacho shows more than is real. For example if you need 33 sec for driving 1km than your real speed is 108km/h. BUT this experience (tacho shows more) I have from all Talbots and Simcas, but in all 2,2 Murenas AFAK the speedometer shows exactly the true (sometimes a little less - 200 when real is 203) but the rewmeter shows less than is real! So when it shows 3000 rpm, your engine has 3550 rpm real. And that's more dangerous ;)
You can check your real rews with stroboscope which is usually used for setting the pre-ignition.

First let me say that all the rev counters (tachometers) on Matra cars are inaccurate, whilst the speedometers are usually quite accurate, so you cannot use the standard instruments and compare them with the book figures.  The handbook and manual gives you the gearing for all the gears, but since we are only talking about a higher 5th gear we will only look at the 5th gear ratio.

Since there are many cars out there with non-standard wheels and tyres, I am only talking here about standard cars.  For anything different you will have to calculate for your differences.  The Murena 1.6 has a 62/13 (4.769:1) diff. ratio and 195/70 x 13 rear tyres and gives 31.65 kph per 1000 rpm in 5th (or 30.96 kph if on alloys with 60 profile tyres like the 2.2).  The 2.2 has a higher 61/14 (4.357:1) diff. ratio and 195/60 x 14 rear tyres and gives 33.89 kph at 1000 rpm in 5th.  (Please note the Murena hand book 3 for the 2.2 has mistakes in the gear speed calculations as they have used the wrong 1.6 diff. ratio!)

So at 3000 in top the 1.6 should be doing 94.95 kph  Let's call it 95 kph.  Because of the rev counter inaccuracy you will find that at 3000 rpm the speedo will read higher.  This is because the revs are actually higher.  Similarly the 2.2 at 3000 rpm should be doing 101.67 kph but it will often read more than 110 kph!  Again it is because the revs are actually higher.  When I first got my Murena 2.2 I noticed the power peak appeared to be at just over 5200 rpm, and it was best to change up around 5200 to get the best acceleration, but the engine peak according to the spec. is 5800 rpm.  Well that 5200 on the rev counter was actually 5800!  So don't ever take the engine to the red line (assuming you could get it there) on the tacho (6300 rpm on my 2.2) as you will actually be pulling about 7000 rpm - well over the rev limit!

The high 5th gear will add approx. 9 per cent to the top gear ratio, so for a given speed the revs will be lower.  So lets go back to my car as an example.  At 3000 rpm it was indicating 110 kph in standard set up.  With the high 5th gear it now shows 2700 rpm for the same speed.  The new 5th gear should now be giving 36.766 kph at 1000 rpm.  Therefore you can see that at 6000 rpm the original 5th gear gave 203.3 kph top speed and the new one should give 220.6 kph

It was reported in the press that the Murena 2.2 did indeed have a 200 kph top speed on test.  Now any car that can achieve top speed in top gear shows that it is under-geared.  Top gear should be a cruise gear (except in a racing car!) yet because of its good aerodynamics and under-gearing the Murena could pull the max. revs in top gear, which shows it is capable of more.  With my high fifth gear and extra power slightly above the 'S' (mine measured 145 bhp on a dyno) my car has pulled max. revs in 5th again (yes, it was showing off the clock on the speedo and a true 135 mph and when we checked another club members car we actually got 138 mph both cross checked for accuracy with GPS) and proved that it can actually cope with an even high ratio.  However, it is much more suitable than the standard and doesn't feel under-geared anymore, which it always did with the original.

Finally, to answer your question, can you tell without taking the box apart?  Well I could, because when you drive them, 4th and 5th are too close together, and if the high 5th is fitted, there is a bigger gap.  It is not too big a gap but it is noticeably better.

Roy

No this is not true in this case.  It would only be slower if it was over-geared as a true top gear should be.  Because the car is still not over-geared even with the high fifth, it will still pull well in top and give a higher speed.  I have fitted a 2.2 Murena that had a totally standard engine with this high 5th, and this performed better too.

The point though as Hans said is not to have a higher top speed, but to get more relaxed cruising, and it has worked out that on a long run where you spend more time in top, the fuel consumption does improve slightly.

Roy

Well, Roy confirmed my words ;) and I am really interested in it! It is really much more clever than some dirty (and often more expensive and complicated) conversions...
Wow Roy, thank You for sharing this genial improve! I have to find some CX 2,5 TD gearbox...
PS: and I was not so far with my imagine of reaching 225km/h. Well, 220km/h is very nice, because speedometers in all other cars are lying cca 7% so when they shows 240km/h the reality is 223km/h... BINGO!

Is this, what we see on the picture, the gear wheels which have to be changed?

(http://guillaume.derugy.free.fr/images/murena/refectionboite/carter5.JPG)

Yep, those are the 5th. gear wheels :)

Well it's not necessary to have them brand new, so used CX gearbox must be good too. Time to search one...  ;D

There's a man of action!

Exactly 45 minutes after having read Roys post on the high fifth gear, Michael has already taken his gearbox apart and is ready to do the mod!

Thats dedication, and I think you deserve the golden Matra palms :-)


/Lennart

 :D :D :D
Pic is from forum-auto.com but at night, i've made registration on Citroen forum, so i hope it won't take a lot of time to find some "fast five"  ;)

Yes Michael, those are the gears.  Standard set are 33 and 45 teeth, and the ones you want are 31 and 46 teeth.  As the gear is slightly larger in diameter, the fork and cover needs to be modified to clear it.  Even if you have a Citroën box then you can't swap the fork over, even though it will already be modified, because it is different where it mounts to the selector shaft and does not fit in the Murena version.  I have the full fitting instructions for anyone doing the job.  Just download www.matraclub.org.uk/files/Fifth.txt

Roy

Well Lennart, you are right Michael has been very determined stripping his gearbox so soon.
But on the other hand now he is not able to drive in his Murena until he (maybe) finds a CX TD gearbox
Hans

Roy: thank You once more very much!
 
Hans: it's not my gearbox!  :D my Murena sleeps at garage at knows nothing about what i am prepairing  ;D
But on weekend, we had a nice times with our Murenas:
http://michaltalbot.rajce.idnes.cz/Vyjizdka_210609/ (http://michaltalbot.rajce.idnes.cz/Vyjizdka_210609/)

Oh, didn't i told you, that me and Maria will have a child? Yes, she is in 4 month of pregnancy and i will be a proud dady  ;D

Congratulation.
Then it is good that you have a Murena with a middle (child) seat!

Hans

Thank You  ;)
Yes that's great, we could travel with our child between us - which car can offer this (except of ugly Multipla? :D )
Murena is the best  ;)

Congratulations to both of you !

Personally I never found the original (1998) Multipla ugly - it deserves a place in the world for being different - the high mounted ligts should also be a good idea in fog, - apart from the apparently rather poor NCAP rating, I think it was a great and original car, that should deserve being added to your growing signature :-)

However, the newest version of the Multipla has IMO lost all the charm, only retaining the seating arrangement - but trying to make the rest conform to an "ordinary" car - big shame.

To real original Multipla was even cooler - a "stretched limo" version of the Fiat 500 :
http://www.sorth.dk/p/20080920/Med/20080920_164030.html

/Lennart

Lennart, i have to say, that from outside the Multipla isn't so bad at all, but interior is really very chaotic, disharmonic and its designer surelly had a lot of grass  :D

Hey, we have a Multipla and love it!

 :D :D :D i have a Tagora and love it too ;) I think it is fine that everybody has a different taste ;)

If the 5th. gear speed at 1000 rpm normally is 33,79 kpm, as the repair manual states, then the new gears will result in a speed of 36,77 kph, or about 110 kph at 3000 rpm. That is closer to what I see when my tach shows 3000, so maybe I already have the 31/46 gears. But, not knowing the inaccuracy of the tach and the spedometer, the only way to tell for sure is when I count the teeth next week, when I take the gearbox apart.  :)

I can almost guarantee that you don't have the high fifth gear.  All Murena have an inaccurate tachometers that means they show 3000 rpm at around 110 kph.  The fact that you get those figures almost proves it is standard.  When the high fifth is fitted it will read approx. 2700 rpm at 110 kph.  With the high fifth and the inaccurate tachometer, you will see something like 120 kph at 3000 rpm and 160 kph at 4000 rpm.

Roy

Hi Roy.

A couple of posts ago, in this thread, I did write that my spedometer reads 120 kph when the tach is showing 3000 rpm. What I should have written above was "That is closer to the 120 kph I see when my tach shows 3000 rpm"
So I am still dreaming  8)  but I will have the tach calibrated and clock the speed from the markers on the interstate.

Jon.

Well, finally i've found a guy who has a lot of spare parts for CX incl.lot of gearboxs. He also said that surelly will have 5th speed gears for sale for very reasonable price. On wednesday i will go to his stock and will see how many of sets (used of course) he has, so - is someone else interested? I don't know the price now, but i will tell you asap on wednesday.

So last night, on my private road, very near the M25, I hit 160kph, which was actually very close to 100mph, according to my satnav, and the tacho was bang on 4000rpm, so I guess I have the high 5th gear? Do you recall supplying one to Phil Siddall, Roy?

Michel, congratulations on the imminent baby. I can highly recommend a Multipla for families and the interior chaos becomes quite charming after a while.

I hope for you that you have, but I'm afraid that there is a fair chance it is just a larger inaccuracy of your rev counter.

Jan

So, I'm back from the "CX guy" and situation is as follows - when he said that he has 5th gears, he though only one wheel (the right one on my picture) because it includes synchrons, the rest he allways puts into the trash  ::) BUT, he has some complete 2,5 Turbo gearboxes and price for one is cca 250,-Eur. So we've made a deal and next saturday, I will change all parts  ;D I will make videos before and after and put them on youtube, just give me 10 days  ;)
Anyone intersted? 8)

Ok Michael, I am looking forward for the tutorial.
What I am interested in is if the gearbox of a 2500 diesel (not turbo) has the same gearing.
I can buy one for €35.-

You can easy check it here:
http://www.globalcar.com/datasheet/Citroen/1974_Citroen_CX25_Diesel.htm (http://www.globalcar.com/datasheet/Citroen/1974_Citroen_CX25_Diesel.htm)

And it seems that 2,5 D isn't good one, because its top gear ratio is 0,8 what is more than at Murena (0,73) but we need less and than only one version of CX has it lower - 2,5 TurboInjection which has 0,67 and that's what Roy was speaking about - Vmax will be 225km/h.

Thanks for the info michael.
I start looking for the right one.
I take my time on this one, because several other jobs comes first.
Maybe I take off the complete gearbox, because the 2nd gear synchro is beatable.
It works wel, but if I do a trafficlight race the synchro is not fast enough.

No, he did not get a kit from me.  However, the details have been up on my website for many years, so it is possible that some owners may have read it, and then gone ahead with obtaining the parts and doing the modification without my knowledge.  Those figures certainly look correct.  You would have thought though, that if he did put the high fifth gear in, it would be such an attractive selling feature... so why was it not mentioned when you bought it from him?

Since we know the rev counters are inaccurate, and often I have found two cars will even read differently, so they are not even the same inaccuracy, which could also account for the figures.

There is another cross-check anyone can do - a 2.2 on standard wheels and tyres should be doing 26.38 kph per 1000 rpm in 4th gear.  So at 3000 rpm it should be doing 79.14 kph.  And at 33.89 kph per 1000 rpm in fifth it should be doing 101.67 kph at 3000 rpm.  If it actually reads approx. 110 kph in fifth at 3000 rpm then it is likely to be showing around 86 kph in fourth at 3000 rpm.

Even better, you can check the gap difference.  At 3000 rpm in 5th if you drop to 4th it should show about 3850 rpm.  If you have the high fifth gear the gap is going to be larger.  So at 3000 rpm in fifth, if you now change to fourth it will read something like 4170 rpm.  Any rev counter inaccuracy will be there all the time so the gap difference should really show whether the mod. has been done.

Roy

According to globalcar.com datasheet
The CX GTi prtrol has topgear reatio of  0.73 and final drive of 4.77
The Murena 1.6 has  topgear reatio of  0.73 and final drive of 4.77
The Murena 2.2 has  topgear reatio of  0.73 and final drive of 4.35

It seams that globalcar.com's datasheets are not accuarate. Or at least there are some confusion.

Hans

Thanks Roy,
Good tips.
Jan

Matra-Hans - but we don't need the final ratio! Important is only the 5th gear  ;) and when we know (thanks to Roy) the number of teeths, we can easily control it.

He was too busy trying to convince me it was a genuine "S"...


I tried this and changing into 4th at 3000rpm in fifth puts the revs at about 3750rpm, so it looks like the standard 5th.

After very very long rainy period, I've spent this day on my motorbike (2008 ZX6R Ninja) and not with my gearbox, but at the evening I took my Murena for test drive with standard 5th gear to make a video "Before". There was some trafic on the highway, so I've made only one short video in speed arround 180 - 190km/h. I will put it on youtube and put the link here later this evening. After some kilometers I reached the top speed 212km/h on my GPS and held it for long 5 seconds. My tachometer showed only 205km/h and rewmeter was close to 6000 rpm ( 212 km/h = 6280 rpm real) - so I was afraid of damaging the engine, because short overloading is O.K. but longer time overloading could be very dangerous and at 212km/h the rews are on the limit.
On video, I'm going to load in next minutes, can be seen that my tacho shows less than reality, at 184 km/h GPS it shows 180 km/h and rewmeter shows 5000 rpm, but reality is cca 5300 rpm.
So tomorrow morning I will change the 5th gear wheels (they are allready demounted from CX gearbox and prepared in my garage) and will make the test drive. Hope there will be less traffic so I'll try to make short video "After"  ;)

Better watch out. the police are watching U-tube too and your video is considered evidence and an admisiion of guilt.  ;D They nailed one dude, who posted a video of himself doing close to 300 (as far as I remember) on his motor bike. Took his license and fined him heavy. So be careful what you post there.  ;)

Thanks, but this video is not a prove that who was driving that fast and also where it was taken  ;) if that guy agreed with what police said, and if there wasn't filmed his face, than he is stupid. It's normal situation here, that you receive letter from police with your photo at for example 120km/h on 80km/h speed limit. So you go to police office and say that you don't agree that it's you on the picture, and that's all, police can't do nothing with it. Owner of the car mustn't be automaticaly responsible for violation made by his car and if owner say, that car was driven by someone from his family he don't  have to say his/her name. Or you can say that car was driven by Abraham Bush, living in New Zealand, who visited you and is looking same as you, and they know that only one thing they can do is - discard it. Police is only for fun, only stupid men with no education are doing this work...

And finally, here is the video:

http://www.youtube.com/watch?v=21kVxZMiMTo (http://www.youtube.com/watch?v=21kVxZMiMTo)

So today I started with changing the gears (picures are here: http://michaltalbot.rajce.idnes.cz/Gearbox/#album (http://michaltalbot.rajce.idnes.cz/Gearbox/#album) ), but there were some problems. Those two big nuts were tightened so hard, I think that somebody in past (there were silicon gasket under the cover) tightened it by air pistol. I used everything, all my power but it was impossible to turn it off. So I had to use very destructive way to get them out  :( (picture DSC07930 - the small "blue" strips is what I used to cut the nuts - terrible work) but after that "piggy work", I changed the gears and wanted to finish the operation with mounting the synchro-wheel with fork. And next problem is here. Roy wrote that original fork can't be used, so I prepaired the fork from CX gearbox and though that it solve the problem, but not - hole for securing screw is on a different place on CX fork  :( (piture DSC07933 left is CX right is Murena) so I must to fix this problem now, but how? :-[ Do I have to brush the original fork, or do I have to bore next hole into CX fork?

Interesting photos, Michal. I'm a little surprised you had to cut the nuts to get them off. I suppose you have spares from the CX box?


I'd go for machining the original. Drilling another hole in the CX fork could reduce strength a bit. They look to be quite close to each other.

/Anders

I know what you faced with the nuts. I took my gearbox apart today for the purpose of fixing the 1./2. shifting problem. The nuts are of the same type as on the wheel hub. You have to make a punch that will straighten the rim out, without damaging the threads. Even so the nuts would not budge. When I took off the wheels I used an angle grinder with a diamond blade to cut away the part of the nut that was bent unto the notch on the shaft. I did not want to do that on the gearbox and risk getting metal shavings into the box. So I went and cut off a 80 cm. piece of 3/4" water pipe to extend the socket wrench. After fastening the gearbox to the table and with the added leverage, the nuts came loose. I cannot imagine why it would be necessary to tighten them so hard, when you have the notch to secure them. (Photos are on their way.)

In the process I have counted the teeth on the 5. gear set. 33/45 standard  :'(  I also think I found the shifting problem, but that is a different post.

I think that mechanics in service, when they are tightening this nuts, are using air pistols, because it's easier and they don't have to fix the gearbox wheels against turning, but it's too strong.
If You want those fast 5th gears, there is a solution ;) Finally I bought only wheels + bearings + fork from CX for that 250,-EUR and leaved the rest at his garage (because - what I will do with CX gearbox? Nobody will buy it and I don't have enough space for saving it). Still it's much cheaper than new set from Citroen (cca 600,-E). So if You want, I can buy and demount all parts for You and send it by post. All You need is on the picture DSC07921. It is 31 x 46 teeths  ;)

I decided to brush the original fork, but question is, if 2mm (max. what is possible) is enough. Roy, do You have a picture of brushed fork? (hope that "fork" is right word)

It was a hard day today ;)
I picked up the brushed fork, than I completed the gearbox and went on the highway for test drive. I did more than 70 kms, but trafic was still so busy. But I've made some video as I promised. At speed 160km/h the rewmeter was bellow 4000 rpm. I've counted that for cca 230km/h I will need longer free road and on my way back there was one place, so I pressed the throttle and reached 220km/h GPS when rewmeter was a little above 5500rpm. Than I had to slow down because of traffic again :( but it works, so if it can reach 6280 rpm it must to make 231km/h GPS. So next time, maybe on sunday morning when roads are empty, but first I must repair my clutch, because 300m before my garage my clutch slave cylinder leaved its place! :o maybe because of weak old safety ring, I don't know... will check it on saturday.
I will load the video on youtube (but it takes nearly one hour with my internet connection  :( ).

Edit: video is here: http://www.youtube.com/watch?v=FGTe1mQRASQ (http://www.youtube.com/watch?v=FGTe1mQRASQ) and pictures are completed here: http://michaltalbot.rajce.idnes.cz/Gearbox/ (http://michaltalbot.rajce.idnes.cz/Gearbox/)
I forgot to write, that driving experiences are that acceleration from 160km/h is worse but from 170km/h it's much better and the car goes up very fast, reaching 210km/h is very easy and travel around 170km/h is like eating sunday dinner  ;) and I'm speaking about GPS values.

You must be eating fast food on Sundays  ;D ;D ;D

Congratulation with the well done "surgery" on the gearbox.

Hans

Yes, if people don't use the torque values when tightening nuts and bolts then others often have more trouble.  All those I have done came apart without using my impact wrench.  If the gearbox is locked in two gears, as per my instructions, you should be able to undo the nuts using a normal 18" breaker bar on a socket.


Not quite true.  What I said was the original fork has to be modified, and I described how to do that.  The problem with trying to use the fork from the Citroën box is, as you found, the mounting is different, certainly on the early ones, which from the photos I can see you have.  It is better to modify the Murena fork.


Yes, it can be machined either on a professional machine or by hand as I have done using a grindstone on a hand drill.


No because the boss for the hole is in the wrong place.  Citroën machined the fork to clear the larger gear but that fork is no longer available.  However, you can machine the original yourself, as you have done.


So now you know what a Murena can really do! :-)

Roy

Roy: yes, I know now ;) but what I still don't know is - how to thank You for sharing this with us. Lot of people modify their engines and spend a lot of money for same target - to be faster. The worst thing (from my point of view) is that when somebody who will see Murena for first time in his life, won't know how it looked like when it was made in Romorantin and with engine from Alfa Romeo, Ford, etc. everybody can say: "hm you had to use a different engine in this sports car, to be faster than average familly car, so original engine had to be a trash" :-\ But this modification stays hidden and if I will beat somebody at topspeed on highway, then I can proudly open the engine bay to show him what Talbot-Matra produced ;)

We'll have to have a 'High Five' Murena club with a badge! :-)

Roy

Congratulations Michal. The difference is quite clear.

Jan

Indeed, Roy! Indeed! :D

Nice job Michael, and defenitly wurth the trouble.
One thing I missed in youre tutorial.
a picture of the machined fork.

Oetker: no, no, it is there - http://michaltalbot.rajce.idnes.cz/Gearbox/ (http://michaltalbot.rajce.idnes.cz/Gearbox/) picture 16072009.

Ok, very clear to me.
This wil be on the to do list if I can find the right gearbox.
Thanks for sharing this info.

I found the gears, but only the gears.
31 and 46 tooth.
Is this enough to do the mod?
(https://lh6.googleusercontent.com/-XTJUdwnIIu4/VAyVC1V-UsI/AAAAAAAAFH0/xoYsIfXGaDc/s800/CX_25i_vijfbak_tandwielen.JPG)
(https://lh3.googleusercontent.com/-oGNKgS6CjwM/VAyVDD5OT_I/AAAAAAAAFH4/v2K7fuFHTaE/s800/CX_25i_vijfbak_tandwielen2%2520%25281%2529.JPG)

Come on, keep up at the back there  ;D
I refer you to Roy's original post.

If you look at my pics, there is a difference compared to the gears of Michael.
I think I have a pair of the Turbo type 1 (early models) and maybe no modification of the fork is needed.
Don't forget technical enghlish is also difficult for a foreigner.
You read the words but not all hits the brain.
What I am curious about, if Michael used all parts of what he bought.
I can buy the 2 gears but the rest of the things is the question.

I used these two gears + CX synchro wheel, in the end the fork was used the original one, but modified. I think that it's necessary, because the bigger CX wheel (46 teeth) is bigger than original one.

Thanks for the info.
To make it clear, I only need the the synchrowheel with this gears to complete the task.
It wil be my first gearbox job ;), so sorry to be a bit of a noob in this case.

Some additional info, for people looking for this sets.
It seems there are 2 types of CX2500 GTI turbo.
Type 1 has the gears on my pics.
Aldo the toothcount is 31-46, they have a different diameter ,and wil not fit the Murena gearbox.
Type 2 has the gears in Michaels pics.
This is what is needed.
I found a compleet set for €150.- and go for the badge ;D

That is a complication.
How do you know you have the good type 2 gearbox?

Jan

Ask for CX2500 GTI Turbo2.
If youre interested Jan, I maybe have found a second set.
I pulled all the strings I could find, and have now several reactions.

Yes, I am interested.

Jan

I wil PM you if I have things sorted out.
Wil be somewhere around next week, because I have to collect the set I bought, and see what I got.

First set is collected.
(http://img190.imageshack.us/img190/311/cxtndwmedium.jpg)
This Citroen guy wil inform me for more kits if he can put his hand on it.
Second set wil be collected in the coming week.

No, a modification to the selector fork will always be needed, since the 46 tooth gear is approx. 2 mm larger diameter than the original 45 tooth gear.

After seeing Micheal's picture of the two forks - it reminded me why the Citroën one doesn't fit and you need to modify the Murena one.  The bolt hole and boss are in the wrong place on the Citroën fork.  The Murena end casing is less deep and so there is less space inside, so the Murena fork has the end angled off and is mounted on the shaft in a different position to fit inside the smaller end case.

As for whether the early (type 1) Citroën gears will fit - I'm not sure, since I have never had any to measure accurately.  It is possible, but you would need to check not only the diameters, but the centre holes where they fit on the shafts, the width or thickness of the gears and the centre bosses, and the relationship to the other parts when fitted.  With the kits I obtained, since the bearings were bigger all the dimensions had to alter, and you were provided with new bushes, collars and spacers so that the new gears would line up correctly.

So please bear in mind that if you are taking parts from a Citroën box, you may need these bushes, collars or spacers as well as the gears.  The fork you won't want.

Roy

The Citroen garage where I ordered a set told me there was a difference in diameter.
I have to see for myself as I collect this set.
They opened a Turbo II box specialy for me.
I will compare myself when I am there to collect.

Hi
Have just opened my CX turbo diesel gearbox and inside it I found the gear wheels that I was looking for 46 & 31.
Information form Globalcar´s datasheet regarding the gearing of the various Citroën models made me a little nervous, and I have been thinking that may be I had wasted 380 Euro for the box.

As I am working abroad I purchased the gearbox over the Internet and asked my wife to collect it. I came home on holiday yesterday, but could not find a chance to go to the workshop until to day.

Hans

I think it is best to go and see for the gears, and not buy a compleet gearbox.
See the pics of differences I found in some 2500 turbo gearboxes.
Both have 31 tooth, but diameter is different.
(http://img248.imageshack.us/img248/8700/tandwielencxturbo2boven.jpg)

Today we started with the gearswitch.
(https://lh4.googleusercontent.com/-03DzrfZitdc/T2mWhlY8D6I/AAAAAAAABH0/KF9vnrYZTfY/s800/P1010251.JPG)

Last week I had lots of trouble to get the right wheelarm off, (had to saw it out) and of course it wasn't any better with the left one >:(
(https://lh3.googleusercontent.com/-2uFpi9j0sCg/T2mWhlor8GI/AAAAAAAABH4/aABhCDUVDC0/s800/P1010250.JPG)
(https://lh3.googleusercontent.com/-P3wi9btUrdM/T2mWit63zbI/AAAAAAAABIE/1kSv_Oj9s40/s800/P1010252.JPG)
After strugling for a few hours we had the bloody thing out and could get started with the gears.
(https://lh6.googleusercontent.com/-5t8Q101ZOuc/T2mWixXdKWI/AAAAAAAABIA/3SURJXSAUj8/s800/P1010254.JPG)
(https://lh3.googleusercontent.com/-bngfNRFnULg/T2mWj3y6dpI/AAAAAAAABIM/DPOyEtiSL8o/s800/P1010255.JPG)
Then grinding of almost 2mm off the fork to make it fit.
(https://lh5.googleusercontent.com/-VJ2F17PUdVM/T2mWkN-DY3I/AAAAAAAABIQ/l0waLU4Ogz4/s800/P1010258.JPG)
(https://lh6.googleusercontent.com/-yObditybRho/T2mWpN00jJI/AAAAAAAABIo/53tmkCVkIII/s800/P1010262.JPG)
(http://img401.imageshack.us/img401/6991/p1010263medium.jpg)
This was a piece of cake to do.
Everyrhing looks good and running free.
(https://lh3.googleusercontent.com/-mciUfksnMnA/T2mWrMzlGUI/AAAAAAAABIw/_3QAvXK-CAA/s800/P1010264.JPG)
(https://lh3.googleusercontent.com/-gDKhqtexheM/T2mWr9kaEJI/AAAAAAAABI4/E2VwW0Ugz24/s800/P1010265.JPG)
(https://lh5.googleusercontent.com/-WtrLUAUfpH8/T2mWsE2reZI/AAAAAAAABI8/2a6g6s03TAY/s800/P1010266.JPG)
We didn't manage to get the Job ready today, because we couldnt get the bolt out of the arm, and besided that I didn't have a replacemant bush.
Puted the arm in the car and drove over to Car-joy to get a new bush fitted.
They were so kind to help me out.
It took 3 man to get the bush out, but it is fixed.
(https://lh5.googleusercontent.com/-S2LrVLpDMdM/T2mWuBEjlVI/AAAAAAAABJQ/ShBUEB3sb0Y/s800/P1010269.JPG)
(https://lh3.googleusercontent.com/-rHAMWkmBNWw/T2mXuL6lCjI/AAAAAAAABJ4/iSp1HsU7c1E/s800/P1010268.JPG)
Tomorow I hope to complete the task.

Puted the things back together an made a testdrive.
Grinded a little of the housing.
(https://lh5.googleusercontent.com/-bRAK5TGPcds/T2mXxKy7BkI/AAAAAAAABKc/dl7NoswxhYU/s800/P1010276.JPG)
(https://lh3.googleusercontent.com/-8T5B7AFamWo/T2mXxn2LzAI/AAAAAAAABKg/MC3c0eKo9cg/s800/P1010277.JPG)
(https://lh4.googleusercontent.com/-f74ej0Mlp_c/T2mXyBF2tyI/AAAAAAAABKo/_0kfEcdtte4/s800/P1010278.JPG)

RPM before modification
http://www.youtube.com/watch?v=Huez4YZ7Zgo

120kmh = 3500 RPM
160kmh = 4700 RPM

After modification.
Driving 120kmh 3200RPM
http://www.youtube.com/watch?v=1N_I1Wd0-ek

Driving 160kmh 4400 RPM
http://www.youtube.com/watch?v=qZOTFz3bjoY

About 8-9% better.

I have to do the job again, because after modification a little noise is coming from the gearbox.
Have to find out what the problem is.

Edit:
After driving 2 seasons with the car the noise is almost gone.
I think the gears had to set.

Herman

Nice work. Why did you have to grind off the housing? To accomodate the larger gears? Nice videos too :) Maybe you should find a friend to hold the camera next time...? ;)


Ouch. Well now at least you know how to do the operation and won't have to spend hours taking the trailing arm off! I hope you will be able to spot the problem. Is it gear of bearing noise?

By the way: Your videos lead me to this one (Murena leading 1984 rally cross championship at Brands Hatch):
http://www.youtube.com/watch?v=Ng7i5eHx0VU

/Anders

The housing was very close to the gears, and I was not sure if it would hit it or not.
So to be sure I grinded a bit of.
The noise in the box sounds like defect clutch bearing but a bit louder.
Also I hear all the synchros work in all shifts.
When I puted in the last gear with the synchro, it falled appart.
I puted it back toghetter and have the feeling something is not right at that point.
Next week I will take a look if I can find a solution.

If anyone downloads my instructions, and reads them fully, you will note that there is no need to remove the trailing arm at all.  The job can be done with the arm in situ.  This can save a lot of additional work.

Roy

Yes I saw the instructions about the wheelarm, but they both needed servicework and oilfilling.
The holes on the top need to be welded to fill with oil.
The right one I replaced last week, and this was a combined job doing gearbox and arm.
(https://lh4.googleusercontent.com/-cHp-LbnZj4Q/T2mXv8pnKYI/AAAAAAAABKU/sR-ERH9p8pQ/s800/P1010274.JPG)
(https://lh4.googleusercontent.com/-3v2GADzGhlA/T2mX-llMBJI/AAAAAAAABLA/XfXQCuwjy64/s800/P1010281.JPG)
(https://lh5.googleusercontent.com/-FF3qDHiSVsE/T2mX_SP25gI/AAAAAAAABLM/-13TQcb84eQ/s800/P1010283.JPG)
(https://lh5.googleusercontent.com/-c69CFOBT5CM/T2mYAsDB42I/AAAAAAAABLY/lI2nEziZaFU/s800/P1010285.JPG)

Bolts with copper so next time no problem.
(https://lh5.googleusercontent.com/-moEecPjLkjg/T2mYBR4eARI/AAAAAAAABLw/tubrbK_9cVE/s800/P1010286.JPG)

The place where water can give problems closed with kit.
(https://lh6.googleusercontent.com/-pe4XyOzN8o4/T2mYBTrfyCI/AAAAAAAABLs/6qi8OC479KM/s800/P1010287.JPG)

Filled with oil.
This will stay rustfree forever.
(https://lh3.googleusercontent.com/-BIbbk_xsmmg/T2mYEfv4OKI/AAAAAAAABMI/pEhZVqv0XYk/s800/P1010290.JPG)

Job wel done.
(https://lh6.googleusercontent.com/-p9mvZhp6x6k/T2mYEuyaYFI/AAAAAAAABMU/kFPUcEqlb6o/s800/P1010291.JPG)

Herman

There seems to be differences in gearboxes on the Murena to.
Another Murena that is in the work for a modification is clearly different.
Other bushing
Other gears and smaller.
(https://lh3.googleusercontent.com/-50n0wMkChsY/T2wwwT4xxOI/AAAAAAAAB9k/AuduN_VObGU/s800/P1030310.JPG)
Also the fork is smaller and doesn't fit around the gearsurround.
Probably a older type gearbox??
They are preparing a set of spacers and another synchoring to make it work.
It is not in all cases a straight forward job, so be warned.

Herman

Thanks Herman, for the nice pictures.
I presume this is my gearbox.
It turns out to be the early type of the gearbox (from 1981) for which Roy already warned.
There has to be changed more than with the newer ones.

Jan

Yes, this is the earlier box, which I did say has differences so that the kit I listed does not fit.  The problem is that I have seen this type even on a late Murena so you can't tell from the cars age, and as I've never found a gearbox serial number, the only way to tell is when you remove the end casing and can see the fifth gear synchro.

Roy

I did look for a serialnumber on the box, and you are right.
Nowhere to find.
Ordering parts for this gearboxes is a shot in the dark ::)

Oetker: nice job  ;)

Only one question - I heard, that using of used engine oil for anticorro protection is a big mistake, because used engine oil includes particles of sulfur which causes the corrosion paradoxically  ??? Do You know about this?

Quote Michael.
-----------------
Do You know about this?
=================

No, it is that you mention it, but never tought about that.
On the other hand it needs oxygene to corode.
The oil is out the arm now.
There was to much leaking and you don't want that with the brakes near by.
Maybe fill it with something thicker, but I think I just put waxoil in it.

The other car has the gears also fitted with some spacers, and is on a testdrive to Corsica.
Also this car has secundair noises from the gearbox.
@ Michael.
Is there extra noise coming from youre gearbox after modification?

There was a little noise for first cca 100m, it was something like when You drive back on Reverse. But after short time it disappeared, so I think that it needed to be oiled properly. But some small problems came, like when Murena was saying: "So You want to try my patience with Your experiments?" ;D for ex. middle axle-shaft boot broke a little and vaseline went out right to the exhaust right in that moment, when Skoda SuperB 2,5 TDi was behind me in cca 217km/h. You can imagine that smoke and well-oiled front part of SuperB - it will never be corroded  ;D ;D ;D Next time I came to my garage and wanted to start it, but not even a "click" - the earth cabel leaved its place on starter... And I'm not speaking about 3 times repairing the clutch slave cylinder which fell of its place because of weak C ring  ::)
But I still love her  ;)

Hahaha poor guy! ;D

/Anders

The Badge ;D

(http://img529.imageshack.us/img529/5030/p1010369medium.jpg)
(http://img401.imageshack.us/img401/6230/p1010368medium.jpg)

Oetker: wow, that's smart and cool! ;D I like it very much

I have 5
If you want one I can send one.
Wil cost you a beer on a meeting in the future.
PM me the adres.

Herman,

Nice! I want one for my high-five Murena. Can you take it with you sunday, when we will meet in Reuver?




Yes, indeed. My wife and I went to Corsica with the Murena for a holiday. I experienced the high-five as an improvement: it feels more natural by the larger difference with the fourth gear (just as we are used to nowadays) and the five has become a real gear now. However, the gearbox has some singing noise that was not there before. May be it will diminish in course of the time.

Jan

Ok, Jan.
Will take one with me.
See you sunday

The French forum says that the gearbox of the Murena stems from Citroen / Lancia.
Among the early Murena's you have two types of gearboxes: in one type the assembly of the fifth gear is similar to those in Citroen, in the other type the assembly of the fifth gear is similar to those in Lancia. And those two are not interchangeable.

This will be the explanation, I presume.

I have tried to find out if it is actually necessary to replace the synchro parts as well. But if it is mentioned in any post, I have missed it.

I know to modify the shifter fork and bell casing to allow for the larger wheel, but since I don't see any modifications to the fork part, I am hoping it means that the original synchro slider ring and parts can be used. Is that true?

The reason I am looking at this again is that I have found a cross reference that say the Citroen 5. gear kit is the same as the one for a Fiat Scudo or Ducato, with either the 1.9 TD or 2.5 diesel engines. (around year 2000-2004) Those kits I have found for about €170-190.

If I don't want to wait I can actually go get one at my local Fiat dealer, though he wants a bit more money. >:(

On the newer type gearbox, the synchroring is the same, the rest I didn't fit to try out.

Well, I communicated with Roy bout this and though I am not 100% sure it will work, I decided to go for it. You see I found the Fiat kit, partnumber "9567493480", for £45 on eBay.  :D

There is one more kit on eBay (
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=130350451266 ), but it sells for €170, and the one I can get from the Danish Fiat dealer is DKr. 1589 +25% VAT (appx. £225)

I found the cross reference here and they sell it for €190:
http://www.axel-augustin.de/shop/product_info.php/products_id/10722/cPath///zahnradkit-5-gang-46-x-31.html
As you can see the Citroen number 2344CO is compared to the Fiat number 9567493480

I will keep you posted on what I find, once the kit arrives. It may offer hope for those of you still thinking about "changng gears"  ;D It will be a while though before I attempt the conversion, we have to get out of this feeezing cold weather, as I have no garage to work in. :(

Good info Jon.
The Fiat number makes it more easy to find.
'The Ducato/J5 is sold in great numbers, and yes, they had lots of trouble with the 5th gears.

Here is another one for 80€:
http://cgi.ebay.fr/1-KIT-PIGNONS-NEUF-FIAT-ULYSSE-SCUDO-DUCATO_W0QQitemZ360224161357QQcmdZViewItemQQimsxZ20100108?IMSfp=TL100108225001r10636

I bought this kit to find out if the noise from my gearbox that I have since replacing the gears, are coming from the bush and spacer.
If this is the solution, then I try to make the other kit complete.
I always can sell it if it doesn't lead to a solution.

Are you sure you made enough clearance in the shifter fork and the end case when you installed the new gear? The clearance may be ok when you move the gears by hand, but under load the gear may just touch. Perhaps you will see marks from that when you open it up again.

I am really curious to hear if the kit you bouoght will work. It sounds like you will get to try it before I do. :D

When I installed the set there was space between the ground plate and the gears, but very minimal.
I have the feeling that the bush/bearing is a bit taller, and the spacer is needed to bring the gears in line.
I will try to measure things out exactly this time.
Don't want to do this job 3 times.

The car is in his winter hide out 10 miles from home.
Another project is keeping me busy, so I hope somewhere next month to do the job.

The other project.
pics are missing now
Then we go on with the real car.

I once had the CRX version of that mark Civic.....only a 1.5 12valve, but the most fun car to drive I have ever owned... Murena included!  :)

The kit arrived this morning. It was sold by "digitechdirectuk" on eBay, who sold the item as "new". I would rather say it was "unused", because it displays a bit of oxidization on the surfaces and on the side, that was not shown on the photo, one of the gears has several rust spots with appx. 1mm thick scales.  >:( The teeth are ok though, so I expect no problems once the rust and oxidization has been cleared away.

My set came in today.
(http://img690.imageshack.us/img690/3310/p1010916medium.jpg)
There are some differences compared to the sets I bought some time ago.
If i jump to conclusions, the I think the gears will have a bit more distance from the groundplate as with the sets I bought before.
Maybe this month I find the time to try out.

Herman

That looks exactly like my set. I am really happy to hear that the synchro fits perfectly.  :D That was a big concern of mine.  :o
Did you check the splines in the large gear wheel? are they identical to the Murena gear wheel? ???
What do you mean with the bushing not fitting? If that turns out to be the only problem I believe I can turn a new one that does fit. Fortunately that is the simplest part to make.  ;D ;D ;D

The splines looks the same.
I am not correct with the bush, you need it to fit the gear in the box.
I hope the inner diameter  of the bush fits the gearbox.
Looks promising.

Let me explain again as this thread has become so long, some have forgotten why the Citröen kit was available.

They had a problem with these units, and the work that was decided was necessary to improve the reliability, was to upgrade the end case bearings.  Since these bearings are wider, the end retaining plate is modified to hold them, and all the other appropriate parts had to be modified to match, so if the bearings are wider, some parts had to be narrower.  Citröen of course were replacing like for like with respect to the gears - 31:46 to 31:46.  We were taking advantage of the higher ratio and replacing 33:45 with 31:46 so the fork and casing had to be modified slightly to fit the larger gear.

So you can fit a complete kit and it will all fit correctly.

However, if you strip and take parts from a transaxle with the old smaller bearings, or you buy new parts that were for that version, then you will have to make sure you check all the parts are the same in the relevant dimensions so that they fit correctly.  You cannot 'mix and fit' or you will be asking for trouble.  As I have only fitted complete new kits to the later more reliable spec. I cannot verify what parts you would need for the older spec. so you must make sure yourself.

I hope this clear things up.

Roy

Thanks Roy for clearing that up. Since I was not planning on replacing the bearings, I will make sure that the width of the gear and bushing parts are the same as the originals. If the new gears are narrower, it should be possible to add shim rings to make up for the difference.

quote Jon
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If the new gears are narrower, it should be possible to add shim rings to make up for the difference.
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That is exactly what they have done with the gearbox of JV.
Also this box is wining, but that is the older type gearbox witch have also extensive modifications to the fork.
We will see.

Exactly.

Although as I remember Roy said that they have used both types of gearboxes together.

Would the Fiat kit have been better for my gearbox?

Quote JV
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Would the Fiat kit have been better for my gearbox?
===================================

That is difficult to predict.
The older type gearbox was not suited to do the modification in the first place.
Lots of parts are different and at Car-joy I saw the differences when they were busy with the job.
I think you are the only one that has this mod in the world with this older type box.
Car-joy made extra spacers to make it work and changed the older type synchro to the newer type, and had some extra update work with the fork, because this didn't fit the switch gear.
Also youre box has a smaller groundplate.

Anyone knows all gear ratios (numbers o teeths) in Murenas?

Yes I have all the info on this subject!  Email me directly roy@matraclub.org.uk as I don't get in here often.

Roy

Now that I have the gear box apart, I will also replace the 5th gear with the new ratio set. But as Oetker's pictures show the gears are not formed the same.

I have set the gears side by side in the photo below, so you can see the differences.

The new gear with the synchro is 3,5 mm narower than the original, thus requiring a shim. The other gear wheel has a protrusion rather than a shallow indention. Therefore they cannot be fitted by just shimming. The shaft is not long enough and you would not be able to fasten the end nut. Besdes the end housing would not be deep enough to close as far as I can see. >:(

The solution will be to take this gear wheel to a machine shop (or my friend Jan) to be milled down and turned to a shape identical to hte original wheel. Not impossible, but a rather annoying delay.

But who knows, perhaps I will have this done by the time I figure out how to replace the 2. gear synchro ring.  ::) (see my Help needed topic on this matter)

Sorry Jon, my plan to do the the box earlyer this year didn't match with some other plans, so you are on your own for now.
Also I have a spare box, and the sound in my old box is more and more less, so I'm not realy in a hurry to do the job.
In stead of doing the box on the car I am planning to do the spare box with the Fiat gears., and make that box in tiptop shape.
In this case I hope to learn from you, because this is moved to a winterproject now.
Keep us informed.

Hi Jon

To machine these gears you might have to have them heat treated to soften them before they are worked on and then reharden them afterwards, some years ago I played around with Simca 1000 gearboxes and that was the only way we could machine the gears in those boxes.

Good luck.

Regards
John

Yes, I thought about that, but I will try with diamond tipped cutting tools first. I would hate to not get them back to the corect hardness if I soften them up.

Hi Jon
If you are unable to machine the gears normally, another thing you could try is something that I used to do on Simca gearboxes when I could not get the correct ratios. The teeth of the gear and part of the outer gear were ground off just leaving the centre of the gear; we then had another gear made which had a centre which was an interference fit on the old part of the gear that was left. The two pieces were then submerged arc welded together. With your situation you could remove the centre of the new gear and grind the teeth and part of the old gear and then combine the 2 pieces that would then fit your gearbox

I have attached a quick drawing to try and help my explanation.

The down side is that the gears do need heat treating after the machining but we never had a failure of the gears.

Regards
John

Well, the gear box is reassembled and back in the car, with its new 2. gear synchro ring. Its like having a new car.  :D
I have put off the 5. gear replacement until after the summer holidays. I will have the gear shaped to look like the original, such that it fits with the original bearings. I will also have a shim ring made to fit over the gear/synchro assembly, since this is 3,5 mm narrower than the originals. The shim will have to be hardened, I think.

Well it is almost time.

Jan has turned the Fiat gear for me so it now has the dimentions of the original Murena gear. It turns  ;D out that the gears, even though hardened, can be turned on a lathe with a tungsten-carbide bit.

If you look back to page 9 in the post, there is a photo of the two gear sets and the difference. Here you can see the modded gear.

Since the indention in the gear rests on the center ring of the bearing, it has no wear due to friction against other parts. The other side had to be turned 1mm down. It is held by the nut which turns with the shaft. Again no wear. I am therefore not worried about any reduction in hardness on the surfaces that were turned. The whole gear did not get hot enough to reduce the hardness of the teeth, which is what matters.

The other gear wheel, with the synchro, is not as wide as the original and requires a shim (3,5 mm thick). This gear turns on the inner bushing, which is a fraction wider than the gear. Thus when the nut is tightened against the shim, which tightens against the synchro, which tightens against the bushing, (I think that is the order  :D) the gear can still turn freely

I will bring the gears to the Danish meet on the island of Fyn this weekend (tomorrow). There is not enough time to fit them before that.  :( I would have loved to test the difference on the long haul there.

Super.
Now to find a shim that meet all sizes.
Think that has to be made seperately.

Already done. ;D
 Jan turned a couple that we will harden and grrind to the correct thickness.

If possible, I like one to.
That will save me work this winter.
Ofcourse payed for.