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Author Topic: Murena high fifth gear  (Read 50162 times)
roy4matra
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« on: June 17, 2009, 10:26:01 am »

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 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 CitroŽn 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 CitroŽn 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 £50 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 kits, I can place an order but I would want a deposit of say £200 first.  I am also warning you that it could take a long time to actually get the kit after placing the order, but I would keep you updated as I would be regularly chasing them about it.  Obviously if the order was for a number of these kits rather than just one, it might be considered more worth their while and maybe the order would be processed quicker, but I couldn't guarantee this as we are talking about the French here. :-)

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 CitroŽn 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.
« Last Edit: January 29, 2017, 01:08:22 am by roy4matra » Logged

JV
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« Reply #1 on: June 17, 2009, 05:14:32 pm »

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
« Last Edit: June 17, 2009, 05:16:03 pm by JV » Logged

Jan Verdam
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« Reply #2 on: June 17, 2009, 06:23:05 pm »

Thanks for info Roy.
I supose the gearbox of the cx is not a direct fit?
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I feel like Jonah, only my fish looks different.
Murena 2.2 Red 1982. Murena 1.6 black on places.
roy4matra
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« Reply #3 on: June 17, 2009, 08:44:48 pm »

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 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
« Last Edit: January 29, 2017, 01:14:31 am by roy4matra » Logged

Oetker
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« Reply #4 on: June 17, 2009, 08:47:47 pm »

On the mainland I see them sometimes passing by.
I know what to look for now.
Thanks.
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I feel like Jonah, only my fish looks different.
Murena 2.2 Red 1982. Murena 1.6 black on places.
michaltalbot
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« Reply #5 on: June 18, 2009, 12:45:14 pm »

I phoned to Citroen CR and they told me the price 15700,-CZK = cca 600,-Eur but this part in no longer available  Sad
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Matra_Hans
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« Reply #6 on: June 19, 2009, 10:41:11 am »

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

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Oetker
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« Reply #7 on: June 19, 2009, 10:46:58 am »

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_ZubehŲr?hash=item4145b27ea7&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1229%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50
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I feel like Jonah, only my fish looks different.
Murena 2.2 Red 1982. Murena 1.6 black on places.
Jon Weywadt
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« Reply #8 on: June 23, 2009, 10:31:29 am »

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?
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Matranaut par excellence Cool
michaltalbot
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« Reply #9 on: June 23, 2009, 11:55:08 am »

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?
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Oetker
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« Reply #10 on: June 23, 2009, 12:01:08 pm »

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.
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I feel like Jonah, only my fish looks different.
Murena 2.2 Red 1982. Murena 1.6 black on places.
Waldo
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Diesel power :o)


« Reply #11 on: June 23, 2009, 12:46:51 pm »

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.


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?
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Matra_Hans
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« Reply #12 on: June 23, 2009, 06:37:19 pm »

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 CitroŽn 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
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michaltalbot
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« Reply #13 on: June 23, 2009, 10:27:50 pm »

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 Wink ) 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  Cool
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Lennart Sorth
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« Reply #14 on: June 23, 2009, 11:39:39 pm »

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
« Last Edit: June 23, 2009, 11:48:31 pm by Lennart Sorth » Logged

Lennart.Sorth@matrasport.dk
Murena 1983 1.9i silver // Alfa Romeo Giulietta 2.0d 2012 white // Smart 4two cdi 2010 blue //
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