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Rebuilding my 4l60e. Is there ANY possible way of installing the low reverse piston into the drum without wreaking the rubber lip and ineer seals. I've gone through like 4 sets. Like how did they pull it off in the factory?

bbond105

Just to be sure, the low/reverse piston goes into the very bottom of the trans case. This piston does not use lip seals it uses three square cut seals, (1 inner seal and 2 out seals all square cut). You will need to use some type of trans lube on the seals and case. Then align the notch on the piston with the notch in the case and tap into place. I use a 3 foot long 3/8 extension to tape it in. It shouldn’t take a lot of force. Install the return spring and snap ring and air test.

mrvedit

^^^Good advice.
However I would call them "square shaped" seals, kind of like a square o-ring.
(I'm trying to distinguish them from the seals in the servo which are actually cut.)
I just tried it myself...
The key is good lubrication on both the seals and the sealing areas of the case. I found TransGel not slippery enough by itself and therefore mixed in some ATF to make a very slippery gel which I applied on the seals and case.
Tapping with a 3/8" extension did not work for me. However I was successful with a 2' piece of 3" PVC pipe, put a block of wood on it and hit it moderately with a hammer. The PVC pipe lets you apply even downward pressure, otherwise it may jam up crooked.
To be sure, I popped it back out (with air pressure) and confirmed that the seals were still in perfect condition. As mentioned by bbond105, it should be air tested.