Originally posted by ronb
tech service info claims the 4L60`s have problems with fluctuating line pressure therefore requiring the use of the solid seals on the stator shaft as the revisions dictate! for example, the reverse input drum oil port is larger than the 700r4 drum and also the input clutch piston orifice is resized to 1/16in!
I see little pressure fluctuation in the 4L60E / 65E when setup correctly.
I resize ALL orifice holes in the reverse input drum aluminum piston to .060 regardless of feed hole size.
GM did have problems with reverse input frictions burning up since they tried to engineer a softer apply of the clutch through orifices that were too close to the same size of the feed and bleed holes
Weekly I build 5 to 7 4L60 , 4L60E & 65E units that range from 1987 to 2005 model years. None come back with a sealing ring problem. I use L cut rings only.
One area some DIY folks may screw up is the bushing replacement in this drum..... ie: they dont replace them. The reverse input drum bushungs are subject to high wear.