After tranny disassembling the cause of "flare" on 2-3 gear become obvious - forward piston was cracked according to mechanic words. It was around 12k miles after full rebuild and 3k miles after LE2 HC (gear change set on 6200 rpms).
So, is it frequent failure or very rare? Is it enough to change all soft parts and this piston or is there any other recommended solution? What would you suggest - I consider of buying new tranny but there are so much goodies in the old one...

 

We offer a steel piston update for older 4L60E's. All late 4L60E's come with steel 4th, forward, and over-run pistons. You'll also have to replace the 3-4 and forward spring packs.

Usually, the forward piston breaks because of high line pressure. It's a fairly common problem.

Frank

 

Thanks for answer.
Do you think that I have old model of 4L60E? The car is 95'.

 

Yes....

Frank

 

The aluminum forward piston will crack once in awhile, that is why I send them out to be cryoed "cold stabilized" to -320F in liquid nitrogen. This will prevent them cracking in the vast majority of cases, (I have not had one crack yet). I use these "treated pistons" on all input drums requiring the HD steel sleeve, as the steel forward piston will not interchange. The aluminum overrun & 3-4 piston have never cracked in my experiences. I do not like to go above 235-240 psi. for maximum pressure at WOT.