so i built my 4l80e with hd clutches and a trango shift kit last year and its been great using a b&M ratchet shifter. however a couple months ago 4th gear started to slip at cruising speeds with the converter locked. so i ran through a couple things. noticing the shift cable for the b&m shifter had stretched and was applying some pressure against selector when in 4th towards neutral. so i adjusted it properly and no issues for a couple weeks. but then it started again so i tested the line pressures in gear all around 190-200 psi with reverse higher i dont recall the number but it was good so i chocked it up to the mishap with the shifter so i just tuned out 4th gear because it was October and was nearing the end of the season here in ny anyway so i put 2 more track days on the trans just not using 4th at all and it performed flawlessly for the 4 hours of track time i had between both days.

now to today i tore the trans open quick since i knew 4th gear clutches are right behind the pump for a quick swap out for good ones and i found clutches that really didnt look to me (at least compared to some 4l60e 3-4 clutches ive seen) and measured out to be the same thickness as the new clutches and steels. only one of the frictions had a center wear mark which was weird. other than that even the steals arein good shape. could these small issues be causing my issues? i never do wot pulls in 4th either because with my gearing it shifts to 4th at like 150mph. also its hooked to a cammed 5.3 that put 350whp and 350 torque to the ground so not a super power house but a good runner


1 of 2 frictions only one side damaged

only heat mark on one steel

other friction that had damage

this is the vehicle btw

 

air check the 4th gear apply piston seals to about 40psi. you can do it on the bench, just make sure the clutch pack and pressure plate (and snap ring) are in place as the piston can overtravel without them in.

endplay is usually around .080 or .100 and ive not found a way to adjust it.

problems I look for are galled piston seal surfaces. if the piston ever cocked in the bore it'll chatter the hell out the sealing surfaces. since it's aluminum its pretty easy to mess it up