rogergm92

iTrader: (2)

Hi transmission gurus, hope you can help me finding out why this happened

Background
I've recently built a Camaro 99 with a 4.8 (not the original LS1), with a t56. Mated by a new McLeod RST and a new LUK slave cylinder. Properly gave it their break in miles in city traffic (Guatemala city has a lot of hills and ravines).

Later on, some months after, I did a sloppy combo (VS 7875, dekas, fuel pump, tune, etc.) and just shoot for 520whp (dynoed)

Just for fun installed a 2 step

No power shifting, no crazy slicks with sticky tracks (just slicks with crappy tracks). Just broke one U joint. Some weeks after, I got hard 2nd and reverse shifting after I got stuck in an inclined dirt road.

Problem
Two weeks after, coming back from some rolls, at the middle of the road with normal driving the transmission did heavy noises. In all in neutral, in all gears. Even more noise decelerating. It just wanted to be accelerating. With clutch applied it did less noises but the noises were in there.

Dissembled and the slave cylinder was cracked + Mainshaft and countershaft (but put attention to the teeth)

Images

















Question
Why did it ate those gears like that (at the middle, not all teeth length)?
Why it failed that part before my rearend, or before the outputshaft.
Any thoughts or recommendations for the moment of re assembly, or any important advise?

THANKS!

jmd

iTrader: (4)

That's a severe headset gear mis-alignment.
Second, the maindrive (Input) should not have been able to crack the slave cylinder without being loose. For it to be loose like that, the shimming at the front case adapter plate was probably not set up right at all. This can happen with improper procedure swapping a 94-97 LT1 T56 to LS1 T56.

rogergm92

iTrader: (2)

How do you set it up right? It is mostly bolt on for what I see. Or is there a specific order of torquing parts, lets say the bellhousing before the slave cylinder (for example)

And the transmission comes from the same car. It is a 99 z28 with the original t56, the only swapped part is the LR4 4.8 (not anymore an LS1)

stevieturbo

You have the parts in front of you...inspect.

What was, or is the endplay on the input shaft ?

Is the taper bearing that goes inside the input shaft in good condition ?

That input doesnt look standard, although you've only shown a small portion of it in the photo. So someone has been inside this trans before ?

stevieturbo

The misalignment referred to....presumably is just because the front cover is off...I cant see how it would ever go together and it be as bad as it looks...even if the damaged gears almost do look as if they had run like that.

Are the bearing shells installed in the front cover ok ? Surely they just be or it'd have been horrific to drive and making all sorts of noises ?

rogergm92

iTrader: (2)

Terrible terrible noises
inputshaft
the taper bearing was in good condition. BTW the new inputshaft comes with it
We suspect someone was inside the gearbox before.

BTW the pilot bearing was totaled.

The interesting part is that it was using the corvette style pilot bearing (the big one), and not the small needle pilot bearing. I think that the issue is comming from here