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Discussion Starter · #1 ·
Hi everyone,

over the last weeks I rebuilt a gearbox for the first time. I took a lot of time to check and clean and did it with as many good quality parts as I could find - means all the synchros are replaced with the Goetze ones and all the bearings have been replaced just to be sure I don't have to do the job again anytime soon.

However, while driving it the first time it made a grinding noise only when the clutch (also replaced) is engaged - means it has to be something in the gearbox.

What I found on the gearbox is that the synchros of 3. and 4. have almost no clearance to the sleeve (original sleeve of 5. gear with unused side now facing to 3. gear side). When turning it, the sleeve rubs on the opposite side of the synchro opening, which creates that grinding noise I could hear when driving. When turned by hand it can hardly be heard - pretty much only if you know it is there and pay attention to it. I guess this is why I did not spot it during the first assembly.
The clearance to the fork is within spec and the sleeve sits well centred, so the clearance to 3. is the same. Also the distance of the two dog gears is 42.2mm and already on allowed the maximum.

Comparing this to 1. and 2. gear and the new repro sleeve there, I see a lot more clearance between the sleeve teeth and the synchros. The distance of the dog rings is slightly less even and the sleeve has the same width as the original ones.

Did anyone face this issue as well or has any advice if this is just normal and the synchros just need to be worn in to stop the grinding?

I would really appreciate your opinion on this - Thanks a lot already : )


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The little internal clutches and "dogs" behind the large snap ring are pretty specific to each gear as I recall.. it's the only variable I can think of besides what you are checking along with wear on the forks.
 

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Hopefully you will be able to read from attached photos. My workshop manual described the process on page 75 and FIG 6:29.

However I’m also confused as there is a hole and thread on selector shaft where fork attaches.

 

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Discussion Starter · #6 ·
Hopefully you will be able to read from attached photos. My workshop manual described the process on page 75 and FIG 6:29.

However I’m also confused as there is a hole and thread on selector shaft where fork attaches.

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Interesting ... looks like the sleeve is pushed within it’s play range to the maximum and not concentric in the picture.

Looking at my picture again, it seems like the sleeve must be too far forward. Shouldn’t it sit pretty mich in the middle of the triangular sliding thing?

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Yep. There is wiggle room to move the fork fore and aft to get it centered. Use lock tire blue AND the fold-over tab on the fork bolt that holds it to the selector shaft
 

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Ps it is critical to line up the serrations on the keeper correctly with the fork. See Vintres “trans rebuild for dummies” post although mistitled, Vintre is no dummy!! I think he wrote it for me!
 
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Discussion Starter · #9 ·
Ps it is critical to line up the serrations on the keeper correctly with the fork. See Vintres “trans rebuild for dummies” post although mistitled, Vintre is no dummy!! I think he wrote it for me!
wow - this is excellent! Somehow, I missed that thread so far.

I guess there is not much that can go wrong, when I follow these steps on the second attempt of assembly.

Thanks goats for sharing and Vintre to put all the effort to write it down
 

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I think I read that your 3/4 is the problem area with an original slider. That is surprising.

The quality of recent past and current new aftermarket sliders are not good. They are dimensionally incorrect and they can ruin your expensive new synchros. Even with a properly positioned slider it can still drag on the synchros. Some don’t drag, some do. Ive observed this within batches of these new production parts.

If the aftermarket slider is the issue you could have the slider machined to correct the ramp height and prevent the dragging condition but the tooth shape/angle will still be wrong. My suggestion would be to find some NOS sliders, or good used units from 5/R position which are half new.

I hope the vendors are able to leverage their purchasing power with the manufacturer in the near future to correct these quality and design issues.
 

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Discussion Starter · #11 ·
I think I read that your 3/4 is the problem area with an original slider. That is surprising.

The quality of recent past and current new aftermarket sliders are not good. They are dimensionally incorrect and they can ruin your expensive new synchros. Even with a properly positioned slider it can still drag on the synchros. Some don’t drag, some do. Ive observed this within batches of these new production parts.

If the aftermarket slider is the issue you could have the slider machined to correct the ramp height and prevent the dragging condition but the tooth shape/angle will still be wrong. My suggestion would be to find some NOS sliders, or good used units from 5/R position which are half new.

I hope the vendors are able to leverage their purchasing power with the manufacturer in the near future to correct these quality and design issues.
 

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Discussion Starter · #12 ·
Actually the slider I got from OKP here in Germany looks decent to me - or at least a lot better than the used one. I’ll gonna check them back to back for 3./4. since they are easy to swap.

For my other issues - I just assembled everything with reasonable amounts of assembly grease and centred the sliders and for now everything works decent. I hope it will be the same on the car.

I had some issues with the shifter rods and gear selecting as well, but I guess I did not add enough lube on assembly.
 

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Discussion Starter · #13 ·
Hi there again,
today I‘ve assembled my gearbox once again and paid very close attention to center everything correctly and checked all other measurements are within the limits stated in the workshop manual.

It actually is a lot better than the first time. On the bench it pretty much shifts nicely. However, getting it out of 5th gear sometimes (not always) is a bit tricky and needs the gear lever to be pushed a bit to the right and then back. As it is somewhat difficult to shift it like sitting in the car, my question is if this is an issue or normal?

Could it also just be that the shimming of the lever/tower is a bit wrong? Shifting to 3 and 4 is easy and they go straight in.

I‘ve put a picture of the current shimming, as I did it in a test assembly with a fair bit of grease on everything

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you need to look down and make sure that when the stub is in neutral, that the bottom tang is in the center of the middle shift rod. Thats what the shims are for -- to center the shifter in the shift rod.
 
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Discussion Starter · #15 ·
Thanks for the instant reply, goats!
I will check this again tomorrow.

When I got it right from previous discussions and the different setup found on my two gearboxes, there is more than one way where to put the waved washers, correct?

Does the out of 5th resistance perhaps also have to do with the retainer plate that keeps it from going straight from 5th to reverse?
 

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your photo does not show the anti-reverse plate. Set up the shifter tower per the parts book you can find for the transmission. I dont recall where on-line the exploded parts diagrams are.....you will have to find them. You may need some additional shims, not sure. The important thing is to have the shifter nub centered in the shift rod.
 

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Discussion Starter · #17 ·
Ok, I will check this again.

The parts diagram I have. There are a lot of parts catalogues and manuals to download from one of the parts dealers here in Germany:

Does it sound like just a shimming exercise then or might there still be something wrong inside?
 

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impossible to say really without seeing it. Until its shimmed correctly there is no way to know
 

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Discussion Starter · #19 ·
Hi,

so, I checked the shimming and it turns out it was not centred properly - also not far off, so 3/4 could be shifted straight still.

After playing with my available shims, I think I got it right and now it shifts nicely through all gears and out of 5th as well - with and without retainer plate. It’s actually pretty simple to adjust once it is understood how it works :)

Picture of the centred mechanism in 3rd gear below.
The red stuff is some assembly lube.

Thank you for helping me out on this again!

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People get in trouble on shims when the shims STICK to a surface on disassembly and then fall off on the bench the next day.. then ...""where did that come from?"
 
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