My setup is a 05 Tahoe 5.3L swap with a 4L60E in to a 54 Chevy P/U.

Engine is stock with headers and a light tune with VATS delete, etc.

Trans was overhauled by an experienced builder. 3-4 clutch was done with 7 frictions, and corvette actuator was installed. The goal was to improve reliability and firm up sh

The truck is street driven, no track work at all. Currently in the middle of a 5000 mile road trip and am having occasional engagement, slipping issues in 3-4 shifts. Seems to only occur after the trans is warm.

Will shift out of third and not engage 4th, or
Shift to 4th and then begin to gradually slip (rpm will increase slowly and sometimes completely release).
Going back to third manually then shifting to OD will generally fix the issue, until I slow due to driving conditions and need to move back up thru the gears. Then it may happen again. I would estimate the slippage is only happening 5-10% of the time.

Fluid is not burnt, level is good.

I have a Lokar shifter installed and have double checked the linkage adjustment, believe it is ok.
I am using the factory neutral safety switch, could the wrong adjustment cause this kind of adjustment?

Any suggestions on this would be appreciated. Still have 2500 miles to drive and don't want to get stuck in the boonies...

 

What do you have for a rear differential gear ratio? I ask because I have a set of 2.73 gears and was advised to not use overdrive much around town in my 4L60E. Apparently, there's not much apply pressure to those 3-4 clutches when in OD and with a 2.73 "highway / higher speed" differential, that translates to a higher frictional load on those clutches. I was told that OD was OK at higher speeds with 2.73 gears such as interstate highway driving but to avoid it around town.

I'd also be curious what your pressures are in 3rd and 4th to rule out pump problems.

My two cents.

Rick