I remembered the poll Wilwren started about 4t60e failures and their mileage when they failed. If at all possible, I would like to start another thread that builds on this, but with the cause of failure along with the mileage, if the cause is known. I would also like to have stated what hardparts, if any, needed to be replaced because of the failure.

For example: 1993 4t60e-hd, failed at approx 170k, torn down at approx. 178k. Initial cause of failure likely caused by lack of thrust washer at the 4th gear apply piston. Hard parts damaged were reverse reaction drum, driven sproket support, 2nd clutch drum, 4th clutch hub and shaft.

Any takers?

The highest normal wear component over 120k is normally the 2nd gear clutches on the 4T60, due to the relatively low peak RPM that the torque is delivered, and it'* proximity to the 2nd gear shift.

L67'* also have a unique habit of shearing the pin in the differential. The resulting debris can take out alot of other things, including the differential housing itself.

The reverse reaction drum (stovepipe) failure is also common at high miles, but typically doesn't take out the trans like the other two failures do.

If you're losing TCC lockup in overdrive, it'* normally caused by 2nd gear clutch material in the fluid, causing too much slip in the TC, forcing the PCM to unlock the TCC clutch.

differential failure at 108K - 93SSEi - destroyed the case of the trans, new trans had to be rebuilt then installed. Odd part about it as it was babied by an older driver.

I am seriously thinking that is what happened the first time with the 93 trans. The diff and cover look way too good to have 178k on them.

2nd gear was crappy on mine too, though I have not taken apart that pack yet. I'm thinking I will once I get real bored around the house though.