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Old 12-06-2013, 08:27 PM   #31
SculptD OP
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Hmm, 3 hours, tech day, hmm.

You hopefully will be looking at three of these. Maybe not so chunky, maybe very thin. But IMO, the thickness you see here is unequivocally that which you want to base your shim choices on. Tell me how this technique could lead to an incorrect result.

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Old 12-06-2013, 08:29 PM   #32
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Well, Photobucket led to an incorrect result. That shows as a cropped image in my library...
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Old 12-06-2013, 09:03 PM   #33
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One caution that I can add regarding the epoxy method of shimming the gearbox. Do not beat the rear cover on to get the bearings to seat. It is often hard to get the cover hot enough for it to slip on without hang ups. Beating or tapping on the cover will cause the input shaft to bounce up and down and you will get a zero clearance. There is a warning about this in the Ed Korn video about trannie rebuilding which I think Cycle Works still sells.

Allow the trans to get hot enough to cure the epoxy. It is hard to measure if it is soft.
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Old 12-06-2013, 10:20 PM   #34
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The tech day was 4 hours to tear down and overhaul two boxes, then three hours of frustration not getting the shims right. Maddening.
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Old 12-06-2013, 10:54 PM   #35
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Originally Posted by DiabloADV View Post
The tech day was 4 hours to tear down and overhaul two boxes, then three hours of frustration not getting the shims right. Maddening.
Details of the shimming problem?

ScultpD i'm not infering anything towards your procedure in your gearbox rebuild. This is a recent gearbox thread you've done good work.- I wasn't going to start another one simply to find out what guys are using to measure for shims (other than palstiguage stuff) specifically the different tools & particularly from guys that do many of these boxes.

Disston, Anton, Rob (&anyone else I haven't mentioned)- what do you use?

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Old 12-06-2013, 11:24 PM   #36
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Using those depth gauges is tricky. We had no gage blocks or other references to use to test our results. We had calipers instead of micrometers. I was a rookie using pro tools and just could not get the measurements consistent. My box wouldn't shift. Start over. Did it again. Start over. Then too loose -- could push the output shaft axially back and forth. I gave up.

So, I've got all new bearings, a rebuilt shifting cassette and a shiny clean box. I just need to put it back together.
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'01 Z3 3.0 Coupe. The Clownshoe.
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Old 12-06-2013, 11:27 PM   #37
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Originally Posted by AntonLargiader View Post
Just upgrade that stuff. .
What is the minimum parts list to do that?

Or...find a new transmission...?
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Old 12-07-2013, 12:01 AM   #38
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Quote:
Originally Posted by DiabloADV View Post
Using those depth gauges is tricky. We had no gage blocks or other references to use to test our results. We had calipers instead of micrometers. I was a rookie using pro tools and just could not get the measurements consistent. My box wouldn't shift. Start over. Did it again. Start over. Then too loose -- could push the output shaft axially back and forth. I gave up.

So, I've got all new bearings, a rebuilt shifting cassette and a shiny clean box. I just need to put it back together.

One of the most difficult jobs is getting the shim stacks right. If you measure the shims they aren't a consistent thickness around the circumference, this leads to all kinds of issues when put two or more shims together. I tend to put the shims needed together, measure, turn the shims, measure again, turn again etc. Used and new Shims that have too big a variation go straight in the bin.

I have a micrometer depth gauge and a good digital calliper with a depth gauge attachment. I take all readings twice, once with each device. The shim stack is checked twice with a digital micrometer and the callipers. Everything gets written down and worked through in a methodical manner. Despite that I've still had a few that needed to be pulled down and done again and you will for some inexplicable reason get the odd gearbox that turns out to be a pain in the arse even when it's shimmed perfectly.
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Old 12-07-2013, 12:30 AM   #39
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I've mentioned this in another trans thread but I've gotten really good,consistent results using a dial indicator and a shim plate. I bolt the shim plate to the trans and measure how far the inner race sticks up and then transfer the shim plate to the cover and measure the depth of the bearing bore. The beauty is that I can remove and reinstall the plate on either the trans or the cover and get the same results.

The shim plate is exactly 10mm thick so the math is quite simple. to do the cover all I have to do is zero the dial indicator out in the bottom of the bore and then bring it up to the plate, measure and subtract 10mm.





For the box I zero it out on the shim plate, measure the height of the bearing and add 10mm.



To me the biggest advantage is repeatability of the measurement and being able to use the inner race as opposed to the outer race which can move quite a bit on a class 3 bearing.
I also don't have to worry about whether the cover warping throws off my results.
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Old 12-07-2013, 06:00 AM   #40
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To me, any measurement that is based on a cover that is hot enough to slide over bearings is useless. Covers change shape dramatically as they cool (which is happening during the measurements).

I use the traditional BMW method (cold parts) except the plate I use is an awesome 3/4" thick one that John Chay made me. That way I measure down to the bearing from the plate with a regular depth gauge; no need for a stand. Cycleworks rents that plate out, but I think it's aluminum (mine's steel).
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Old 12-07-2013, 06:05 AM   #41
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Originally Posted by DiabloADV View Post
What is the minimum parts list to do that?

Or...find a new transmission...?
Depends what you have, what you need and how much you want to spend to preserve its incompatibility with the future. '74s have the biggest compatibility issues, '75~'76 less so, '77-on much less so, '82-on is future proof.

What's your situation?
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Old 12-07-2013, 06:29 AM   #42
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Originally Posted by AntonLargiader View Post
Depends what you have, what you need and how much you want to spend to preserve its incompatibility with the future. '74s have the biggest compatibility issues, '75~'76 less so, '77-on much less so, '82-on is future proof.
That's a great explanation Anton. I've been thinking this exact thing recently but could not put it in words as you have provided.
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Old 12-07-2013, 07:12 AM   #43
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I'm not one of the Pros. I'm a vocal novice and I have acquired the tools to do transmissions. I have been learning to do transmissions for several years. I rebuilt my first trans about 5 years ago using the epoxy method of shimming. The big mistake I made was beating the cover on because I didn't get it hot enough. The epoxy method may work for you but for me it is not a favorite. I guess I am prejudiced about it. But part of that reason is also that all the pros use some form of a shim plate.

I tried the solder method and lost one of my brand new bearings because the solder in the out put shaft was hit momentarily by a raw flame. Molten solder went into the bearing and I had to say I can't use it. Would you? So I don't like the solder method either.

I have two micrometer depth gauges. They were bought cheap on Ebay. I think I like the Mitutoyo best but the Starrett is fine. They both work well. I bought a brand new Mitutoyo Gauge Block in 1/2" size. That small item cost as much as either depth gauge. I also have bought some cheap Chinese parallel sets. So I have done the measurement several times but it's turned too cold for me to normally spend much time in my small shop. I'm also busy working.

I have several damaged rear covers to make into shim plates and I think I may find some place to do this sometime soon. I have an old plate but it is so beat up I have filed the edges to take the dings out. I also have a Granite Flat Surface and several other measurement tools. These things are not cheap. If you are doing One Transmission it does not make sense. But if you are driven as I am to learn and do my own work and plan on doing more than one it may balance out.

I should be finished with my second rebuild in the Spring.
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Old 12-07-2013, 01:15 PM   #44
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Originally Posted by AntonLargiader View Post
Depends what you have, what you need and how much you want to spend to preserve its incompatibility with the future. '74s have the biggest compatibility issues, '75~'76 less so, '77-on much less so, '82-on is future proof.

What's your situation?
Except for the input shaft and its cush drive mod around '86? I think the late PFA input gear for earlier cush drive/input shafts is NLA?
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Old 12-07-2013, 02:44 PM   #45
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Yes, but that' a pretty small issue. So you may have to buy the coupler that matches your new input gear, no big deal.

Is the smaller coupler really NLA? Never noticed. I think I still have one or two. The new one is kind of ridiculously big.
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