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Author Topic: Help needed replacing 2. gear synchro ring  (Read 17818 times)
Jon Weywadt
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« on: July 16, 2010, 11:48:19 am »

Hi guys.
I planned on using my vacation to replace the 2. gear synchro ring, but I am stuck. I have the gear box on the table. the 5th gears off, the bell housing off the main gears and looking at the gears. But I am unsure of how to proceed.

I have the shop manual, but either I don't understand the German or it is assuming that I know something bout gear boxes, that I don't. Angry

I would have thought that there was a retaining ring holding the gears onto the shafts. I can see that I have to remove the 3./4. idler assembly off the secondary shaft, in order to start removing the 3. and 4. gears and synchros. But I cannot move the ball bearing at the end of the secondary shaft and it has no retaining ring that I can see. I dare not use force with a gear puller unless I know that is what is required.

Is it possible to pull out the whole shaft with gears and all and then disassemble it from the 1./2. gear end?

Hope one of you can explain it better than the German shop manual.  Grin
« Last Edit: July 16, 2010, 12:01:35 pm by Jon Weywadt » Logged

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Jon Weywadt
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« Reply #1 on: July 16, 2010, 01:29:50 pm »

Update.
Looking at the way the gears and shafts inter lock, it appears that if I loosen the bolt, in the red circle on the photo below, I can pull out the selector shaft. That will allow the reverse selector assembly to be pulled out. Then it appears to be possible to lift out the idler shaft with all idler gears, while at the same time sliding the reverse idler gear off its shaft.

Of course that still leaves the main shaft with all the synchros. That does not appear to come out easy. Any feedback is appreciated.

Also, I am concerned about removing the selector shaft mentioned, because when moving it up and down, it is obvious that there is an indent and ball holding it in position. If I remove it the ball is likely to come out and the shaft cannot be put back in. There has got to be a place to remove the spring and ball, but I have not located it yet.
« Last Edit: July 16, 2010, 01:32:17 pm by Jon Weywadt » Logged

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suffolkpete
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« Reply #2 on: July 16, 2010, 03:25:39 pm »

On my 1.6 'box, the selector detent balls and springs are held in place by the left-hand mounting bracket.  If you have the usual Murena problem of no second gear synchro, you may have one of the gearboxes that was incorrectly machined, in which case you will have to replace the gear as well as the synchro.  There is a thread on it somewhere in the forum.
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Jon Weywadt
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« Reply #3 on: July 16, 2010, 03:47:43 pm »

On my 1.6 'box, the selector detent balls and springs are held in place by the left-hand mounting bracket.  If you have the usual Murena problem of no second gear synchro, you may have one of the gearboxes that was incorrectly machined, in which case you will have to replace the gear as well as the synchro.  There is a thread on it somewhere in the forum.

Since I have the bell housing off I also have the detent balls and springs you mention, out. But there must be anotehr detent on 5th gear selector shaft, because when I move it up and down it locks in place in the middle where the selector claws lign up.

I will search for the thread you mention. Thanks.

Update
OK I found a thread that talks about the synchros. From there I quote Anders:

"Because of this, the entire 1st and 2nd gear had to be replaced. But it was worth it:
Roy did a great job on the gearbox; it works like a "knife in butter" Wink now, and could even be better than it was when new? He also fitted the new 5th gear, which I think fits the car perfectly, especially on my engine which has max torque around 3500 rpm, where it is going about 130 km/h (speed limit on danish motorways)."


If the problem is not the synchro ring being worn, but rather that the cone on the gear wheel is worn, then one solution could be to mill off about 0,5 mm from the gear side of the synchro ring. This will allow it to seat deeper onto the gear without touching the side, thus fitting tighter onto the cone. I can see no ill side effects from trying that, if my new synchro ring also seats too close to the gear.

I still haven't found anything on how to take it apart, though. Sad
« Last Edit: July 16, 2010, 05:52:51 pm by Jon Weywadt » Logged

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Anders Dinsen
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« Reply #4 on: July 16, 2010, 08:00:31 pm »

... and it's still running knife-in-butter!  Cool

Here's Roys excellent photo of the gear wheel and the synchro (blurred somewhat) in the background:



Looking at that photo again, I think the problem was the gear being machined too small. Because of that the synchro was working on the side of gear, instead of on the cone's surface. Note how the cone is not worn at all. Unless you add material to the synchro, machining will not help Sad At least not in my case.

I hope you find out how to get it apart. Have you tried e-mailing Roy?

Cheers,
Anders
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suffolkpete
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« Reply #5 on: July 16, 2010, 08:08:34 pm »

Roy is currently chasing microcars round Europe so he may not reply quickly.  I have a Swiss (French language) version of the official manual with lots of sketches, but I assume yours is the same only in German, otherwise I'll scan the pictures and email them to you.  I've never taken one of these apart, my solution was to replace the gearbox with a second hand one but I still have the old one.  If I ever find myself in a position of having a lot of time on my hands, I might have a look inside.
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Jon Weywadt
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« Reply #6 on: July 16, 2010, 10:28:10 pm »

Thanks Anders and Pete.

The reason I am proceding so cautiously (and that is not like me with stuff like this) is that I have to be able to put it back into usable order again by the end of next week. If that is without the new synchro, so be it. I want it fixed right, so if the new synchro is not fiting any better, then I will take it to a chrome shop and have them lay some chrome on the cone. Adding a few tenths of a mm should make it work great. My other option, like I mention, is to mill off some thickness of the ring on the side that faces the gear. That will make the diameter of the ring's cone smaler where it fits aginst the gear cone.

The new fifth gear will have to wait until I, or my friend Jan, can put it on a lathe and make it look like the original. The original center bushing fits perfectly in the new gear, but a 3,5 mm shim will be needed, as mentioned. See my entry in the High 5th gear post (page 9 by now)
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« Reply #7 on: July 17, 2010, 10:12:03 am »

Well I may be slow, but I believe I have got it now Cheesy
I found the detent for the 5./R. shift rod and I now know how to remove and reinsert it.
I have also translated the German instructions as best as Google language tools can do.
Between that, my rudimentary knowledge of technical German, and what I know about gear boxes + mechanics in general, I should be able to get it disassembled. I am writing the steps I perform down in english.

I will also try to make a video of the work while I disassemble the gears. I hope it will turn out. At least I will have evidence of what I did (or did wrong  Wink ) so I can reverse the process.

I will also take lots of photos, so I can post the process, in case some of you find yourself needing to do the same work.
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« Reply #8 on: July 17, 2010, 10:45:56 am »

I like the idea of milling down the face of the synchro ring, it sounds lijke a very simple and economical way of solving the second gear problem.  If you go down this route, let us know how you get on.  Gearbox parts are not only very expensive, but it is a nightmare finding the coreect ones, with all the different variations, far better to put the old ones back if you can.  I might try this on my spare gearbox.  I'm not so interested in the high fifth, there are no motorways in the part of the country where I live and you can't go faster than 70 mph (112 kph) anywhere in the UK anyway.  The standard ratios are fine for my use.
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Jon Weywadt
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« Reply #9 on: July 17, 2010, 01:54:07 pm »

I like the idea of milling down the face of the synchro ring, it sounds lijke a very simple and economical way of solving the second gear problem.
---

I have talked to my friend Jan about this. With his knowledge of materials he recommend having it planed on a parallel sander. The ring is hardened and would be difficult to mill or turn.

I have made an English set of instructions and list of tools which I have attached as a word document.

I also include photos of the 2. gear with the old synchro and new synchro. You can see the clearance on the new and no clerance on the old ring.

Like on Anders' photo the 2. gear cone does not show any signs of wear. There are signs of wear on the side of the gear, consistent with the synchro ring resting flat against the side with no contact to the cone. I actually found that the ring had radial play on the cone when resting against teh gear. I canot believe this 2. gear worked for very long while new. Now a days there would have been a recall. Wonder if 29 years is too late for that  Grin

The link to the instructions is right above the first photo.
« Last Edit: July 19, 2010, 09:54:06 pm by Jon Weywadt » Logged

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« Reply #10 on: July 17, 2010, 04:29:54 pm »

Hi Jon

Hooray! Great to see you've got it apart!  Smiley

About the 2nd synchro - yes, it's very strange it ever passed any kind of quality control. Many must have been like this. Maybe the did realise, but only after production ended. Someone on the French forums might know?  Huh

You plan about documenting the procedure sounds very good. When you have the files ready, I'm sure Lennart will be more than willing to allocate a space for it here on the web site.

/Anders  Cool
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« Reply #11 on: July 17, 2010, 06:34:43 pm »

Hi Jon
--
You plan about documenting the procedure sounds very good. When you have the files ready, I'm sure Lennart will be more than willing to allocate a space for it here on the web site.

/Anders  Cool
Hi Anders.
there is actually already a link to the Word document above the photos. I will add photos in the document later, but that is it for now. I also have a video of the disassembly. I will make a WMI file of it and attach it.
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Jon Weywadt
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« Reply #12 on: July 19, 2010, 12:28:07 am »

Hi Jon
--
You plan about documenting the procedure sounds very good. When you have the files ready, I'm sure Lennart will be more than willing to allocate a space for it here on the web site.

/Anders  Cool
Hi Anders.
there is actually already a link to the Word document above the photos. I will add photos in the document later, but that is it for now. I also have a video of the disassembly. I will make a WMI file of it and attach it.

Sorry, I forgot to mention that the message from Philbert was actuallly writen by me, while I was visiting Jan.

Well the gear box is reassembled and waiting to be installed in the morning. Jan will swing by and give me a hand. I can't wait to try out the new synchro.  Grin

Assembly posed two challenges. The easy one was searching through the parts manual to see where the small diameter detent lockout pin should be inserted. I had not noticed that there is a small hole in the grove on the bottom of the 3./4. shifter rod. The more difficult was to get all the parts of the 5./R. shifter rod and reverse mechanism installed, while at the same time keeping the detent pin and spring from flying all over (more than the 3 times it did  Cheesy) I am sure an experienced mechanic knows a trick or two on how to manage this, but it was challenging. Grin

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« Reply #13 on: July 19, 2010, 08:50:11 pm »

Quote
--------
You can see the clearance on the new and no clerance on the old ring.
===================================================
Sorry for my late reaction, but did you measure the clearance between synchro and gear?
According to Citroen specialists I asked, the clearance need to be between 0.6-1mm to have good synchro.
1mm new
0.5 warned out.
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Jon Weywadt
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« Reply #14 on: July 19, 2010, 09:22:37 pm »

Quote
--------
You can see the clearance on the new and no clerance on the old ring.
===================================================
Sorry for my late reaction, but did you measure the clearance between synchro and gear?
According to Citroen specialists I asked, the clearance need to be between 0.6-1mm to have good synchro.
1mm new
0.5 warned out.

I measured the clerance before I reassembled the gear box. The clearance between the underside of the new synchro ring and the gear was 0,7 mm, so it is in the range that Citroen prescribes.

The old ring actually could move laterally while resting against the side of the gear. I cannot see how it could ever have worked properly. There was no sign of wear on the 2. gear cone. when looking on the other gears cones, they all had signs of wear. I would have expected the 2. gear to show more wear than any of the others. The only wear was to the side of the gear and face of the synchro ring.

In order to get 0,6 mm clearance under the old ring, I had to place a 1 mm feeler blade between it and the cone. This means that the ring was 1 mm  too big in diameter for proper fit. There is no way it wore down that much. It must have been too big from the start.

I also checked the clearance between the 1. gear and its synchro ring. It was 0,6 mm and if, as the manual says, the 1. and 2. gear synchro rings are identical, then the 2. gear cone must have been manufactured too small. I forgot to try to swap the rings, to see if they indeed were identical. But if you buy a new 2.  gear synchro ring it will work. I got mine off eBay for 14£, but I was lucky to find it there.

UPDATE.

With help from Jan we got the gear box installed and the car out for a test drive.
It runs like a new car.  Grin Grin Grin
What a difference driving and being able to shift through al the gears, up or down.
Also, this car likes the hot weather we are having. The engine runs much better and really pulls from 3500 rpm.
« Last Edit: July 19, 2010, 10:01:43 pm by Jon Weywadt » Logged

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