2002 Trans Am T56 6 Gear Question

[lastofthebreed_ws6]

Morning guys. T56 Question.
2002 WS6

I bought my car used in 2017, the guy who had it had just bought it to flip (he worked at a Gm store) - had his trans guy replace the following :

- After Market Clutch Kit NCF : 1104173 (Ideal Supply)
-12523250 - 5th/6th Gear Synchronizer
-24264182 - Slave Cylinder (Internal)
-12541299 - 5th / 6th / Reverse Shift Shaft Retaining Ring
-14058965 - 5th Gear Retaining ring
-12523253 - Multipurpose Retaining ring
-12523252 - Synchronizer blocking ring
-12523055 - Reverse Shift fork retaining ring

he issue I'm having (and it has never changed in ~40,000km and 5 years) is when its warm, it maybe 40% of the time will not engage 6th, no noise, just will feel like it went in but shifter just bounces and car revs (as its in Neutral), re attempting will allow it to go in. I've changed fluid to Syncromesh - no change. Now running MTF PN GM MT & TC Fluid - 88861800 - As per GM bulletin 04-07-30-037C (Replacement for Dexron III) - No change. When cold it is 100% fine, just intermittently does it when its warm. I plan on eventually replacing the oil pan, and rear plate cover, so while I had trans out to do that, I was going to entertain replacing whatever I suspected to be the issue.
Thanks!

 

[oil pan 4]

Probably the shift fork linkages. I had a problem like that. Ended up being a little spot of rust on the shift rod that wouldn't let the shift fork move far enough to engage the gear. Could be a burr or rough spot, doesn't have to be rust.
It was on a late 1990s t56.

 

[ArrestMeRedZ]

As a wild guess, I'd go with Oil Pan's theory. As a not so wild guess, I'll bet the problem was there when the seller had the transmission maintenance done, but it wasn't fixed. In the alternative, in the process of doing the maintenance the builder caused the problem.

Hopefully, the seller disclosed the problem to you before the purchase.

 

[clinebarger]

Does it have a aftermarket shifter with adjustable stops? If so....Adjust them out of the way & retest.

The Mainshaft is a common wear item, Wears where the 5th/6th driven gear presses on.....If the driven gear slides off without using a puller, The shaft is worn out.

Swap all the nylon fork pads to bronze & swap in a iron 3/4 shift fork.

People like to dog on these units in 5th/6th & they are NOT designed for it!