TxPete20

Hello everyone. I'm in the process of rebuilding my T56 for my 01 C5Z. I've gotten to the shimming process. I've but the input, main, and counter shaft together and got the case on with no shims to check for end play. Right now I have .000in of end play without shims. I've replaced all bearings/races and I have a 8620 forged steel mainshaft. Everything is seated properly as well. Is this okay with the new bearings? This is my first time rebuilding a T56. I've gone through the manual to see of I might have messed up and I haven't. I even went as far as disassembling everything and put it back together.

Rick@RKT Performance

If you have replaced all the bearings and races, make sure the races on the main case are seated all the way. Of all the T56 I've done, I never had one that didn't have play on the main/counter shafts.

Supercharged111

I just reshimmed a box I'd previously. I was not happy with the inconsistency that I got in my readings before. I used this method to help draw the line where zero preload is.


I added .012" to the input/main and .007" to the cluster gear to get what feels by hand to be as close to 0 on the input/main as my shims allow and .001"ish preload on the cluster gear. There's no question my races were seated the first time I did this. The kicker? Prior to disassembly I had no perceptible endplay, so I have no idea where to begin to understand how I could be so far off and think I'm right.

TxPete20

I made sure all races were seated. I used a feeler gauge to check and make sure there was no gap.

Rick@RKT Performance

Also the race inside the input shaft?

TxPete20

Yes. I've inspected it to make sure there were no burrs. It sat flush against the lip inside.

Rick@RKT Performance

If everything checks out and input shaft have zero play, go with it and finish assembly.

Supercharged111

I'm incredibly suspicious that OP is encountering something similar to what I did. I HIGHLY recommend adding the thinnest shim you have and see if that induces preload. If it doesn't, keep going until it does so you can truly see where 0 is. Using this method, as I got a thou or 2 from 0, the shaft (either one) would have a noticeable amount of rotational resistance (which I initially mistook as preload) that would go away once you gave the shaft a few spins.

Vox Machina

Might be a silly question, but when you're measuring endplay, is the trans horizontal or vertical? When I rebuilt my t56 I saw a significant different in numbers based on where gravity was pulling the shaft.

Supercharged111

By the book it should be vertical with the input facing down. I have seen YouTube videos with folks laying them down and measuring. I wouldn't recommend that.

TxPete20

Not a silly question, but you want it standing vertical to measure for endplay