I finished swapping a '01 6.0L/4L80e/t-case into my 95 K1500. The trans had about 95k on it and I installed a shift kit and filter/fluid during the swap. It ran well for about 65mi with the only issue being a very hard 1-2 shift. Problems started and I changed the filter fluid again about 5mi ago. Now I have a few issues that I'm trying to sort out, see if they're related, etc. I'm really hoping it doesn't need a rebuild already.

1. At idle in R & N it will walk itself forward. If I give it some throttle, it'll back up but you can feel it overcoming internal resistance.

2. The harsh shift is gone. It doesn't slip or slow shift, but it also doesn't act like it has a shift kit or torque management removed.

3. The pressure fluctuates. I hooked up a gauge and shifting from R through 1 at idle the pressure will hover at about 30psi, sometimes dropping to 10, other times spiking to 60psi. Once I hit first, pressure will hold steady at about 60psi as I shift back up through the gears.

I dropped the pan again and the fluid is almost black (with about 5mi on it). I have never found any metal in the pan.

I'm thinking the fluid could explain #2 & 3. Would a full flush correct this and clear all contaminants out, including the torque converter?

What about #1? Everything I've seen suggests that welded directs won't allow it to back up at all.

 

What shift kit did you put in?

 

TransGo stage 2. Triple checked everything as I put it in. Dropped the pan to check it again when I found the 'black' ATF.

 

Low pressure killed the clutches? Sounds like you have a valve body leak somewhere.

I had similar clutch material right after my 80e build because of a stuck AFL valve, but I doubt very much thats your case.

I don't know much more than that.

 

I've seen burnt fluid, but never loaded up this bad. Is this clutch material?

 

Yup, clutch material. My pan looked exactly like that.

 

Welcome to the club!

 

That sucks. Not exactly suprised, but losing 3rd in the 60 is why i started the whole project. Thanks for the help. Guess its time for a rebuild

 

Think I found the problem. Forwards. Haven't gotten into the valvebody yet. Anything specific I should look for that would've caused this?

 

How does the trans go relief valve look? There has been problems reported with them in the past. Not saying it's your issue, but it's best to omit that assembly and use the self-regulating Sonnax valve instead.