I have a gsr transmission. The outer portion of the case had a crack so changed just the passenger side of the transmission casing to an ls housing. Will I need to re shim the main shaft? I have been searching and have yet to find a definite answer..

 

At a minimum you would want to check the clearance. We are talking about stacked tolerances here, it's not likely that your stack and case are the same exact dimensions as the ls case and the stack that came out of it. I would guess the clearance would be different, but out of spec is another question. (on a side note even if it was another gsr case you would want to check the clearance)

 

In most cases it should not need to be reshimmed but, it is always important to check anyway. You can do a quick bench check by installing the mainshaft by itself and closing the case. It should spin freely without any movement in and out.

 

It will need to be shimmed. Checking for in/out movement will not tell you anything unless the clearance is way out. You'll need the mainshaft base and holder. P/N's are in the Helms.

 

Of course doing it strictly to the service manual is the proper way and always recommended. Failed to add that into my last post. But, most of these guys do not have access to the Factory manual or specialized tools and probably not willing to spend the cash on them for a one time job. Especially in this economy. Should they be doing trans work without them then? Probably not. But, at the end of the day..they are going to anyway.

 

Access to the manual is as simple as buying it (pirated versions are available online if you don't want to spend the money on it). As for the tools you can get a ballpark idea with just feeler gauges and a straight edge (also in the Helms) but won't be able to verify without the specialty tools.

Clearances in the transmission are just as important as clearances in the engine.

 

Do not forget to check diff bearing clearance as well.

 

I have a short cut around the proper tooling that Aquafina has due to reverse engineering. Not as accurate but note he is working on a Liberty Billet case in his pics.

What is being measured is the crush of the mainshaft thrust washer, aka preload.

Then again I'm mostly doing SCCA IT builds and a little less preload means less friction loss in the tranny.

 

I check the mainshaft and diff shim clearance on every trans I build, whether its a 10k billet case trans or a stock D15 rebuild.

 

this thread is just in time for me to assembly my liberty faceplated gearset. I dont have that tool but i can make something on the mill. Am i understanding this correctly:

U want to clamp down on the mainshaft so u can apply a pulling force and so to speak pull it towards the crank? then u measure how much it moves before binding?

 

Yes. Don't recall who it was but I saw someone make their own tools with basic machinery (mill and lathe). The holder has a lip on it that you cannot see in the picture. You stop tightening the holder once the dial gauge stops moving.

 

makes perfect sense. I found a pretty good walk through

http://forums.clubrsx.com/showthread.php?t=638721

 

Same. You never know who was in them before, if that person checked after swapping things around, etc. I've only done a few $7k transmissions though. Damn $10k ballers. :p

I will say this year I found one with a differential that had .09" of thrust clearance, which then developed into .120" of thrust clearance after the speed gear on the diff machined the case out through 1000s of miles of driving. LOL The builder used B16/LS diff bearings on a GSR diff. Never spaced the diff higher to avoid the case, and never had a thick enough shim to even fill the top side either. The aluminum particles from the case cycled through the oil and ruined the surface of every single gear and bearing in the trans.

 

SCCA trannys are so easy, LOL!

 

I have done lots of reading here and appreciate the wealth of information you guys provide. I do lots of google searching but still sometimes am at a loss due to my lack of experience.

I am going to be ripping into a D series DX/LX transmission (P20/A000) to see about replacing the input shaft bearing and to learn.

I can get a bearing and seal set for about 200 Canadian shipped up from Ebay, 114 plus 70 bucks shipping/handling. It doesn't have any of the small needle bearings just mainly the caged and ball bearing replacements and the one needle bearing for the countershaft that should be staked.

Two questions about the process for you masters... Do the main and counter shafts need to be reshimmed when swapping in new main bearings?

The kit I'm looking at so that you can see all the bearings provided to be replaced:

http://www.ebay.ca/itm/200568938961?...84.m1438.l2649

The second and last question is, do the smaller needle bearings and I think sealed bearings on the shafts need replacing often or do they tend to out last the main bearings that tend to be in rebuild kits?

Sorry for hijacking an old thread but my question is about shimming the main shaft like the OP and I have googled a lot to get an idea of what I'm in for so not really sure if this warrants a thread of it's own or can supplement the OP's thread.

Thanks for all your great information. Please be gentle on my first post, I am most definitely a noob but enjoying the learning experience.

Cheers

 

I check the shim clearance on every transmission regardless of what is being done to it. It's not likely that just changing the ISB will put the clearance under/over the limit, but I set the clearance to a specific number based on a few factors.

The countershaft does not use a shim in your transmission.

The needle bearings (that the gears ride on) rarely need to be replaced if the transmission has been properly maintained.