Some history. Swapped a '94 LT1/4L60-E into a '91 Firebird. Trans was rebuilt in donar car about 3000 miles ago. Got the swap done, and have 3-4 weeks of drive time on it, about 1000 miles or so trouble free.

The situation. I went for a full throttle blast on the way to a buddys house. from a stop to about 100 MPH or so with no problems(also not the first time it's been pushed hard), and continuted on to my friends house at 55 MPH and everything was fine. Parked the car, it sat for maybe 20 minutes. Went to leave, and suddenly have no 3rd or 4th.

Symptoms/diagnostics. No trans codes, only 1 engine code(see This Postfor details). Scanner says shift solinoids are working properly in all gears, and you can feel it shift, but it's slipping hardcore in 3/4. I know the pack is probably burned up, but what would cause it to go so suddenly like it did? I mean, it worked fine when I parked it, and didnt work when i got back in. Any other things I can check before pulling the trans(severe budget restrictions, so I'd rather not rebuild if I don't NEED to )Thanks for the info.

 

Most will agree that the 3-4 clutch pack going is probably the #1 cause of a 4l60 or 4l60e to die a mild death. There are kits available to upgrade the 3-4 pack. You may want to consider this if you rebuild and plan to keep the car for a while.

 

i agree with floor guy. i personally like the raybestos Z-pac.

 

Thanks for teh replys. I know it's the 3/4 clutch pack, I'm just wondering why it went suddenly with no warning. It was fine when i parked it, and didnt work when i drove it 20 minutes later. generally when a clutch pack goes, it goes gradually with increasing slippage and some forwarning. This went out suddenly.

 

most clutch packs do go out that way. but when my 3/4 pack went out on my original tranny, it went out on the highway with no warning at all. just gone! since then have used a couple of different setups and i like the raybestos one the best. plus, the factory settings on this clutch pack were loose to begin with. if a factory rebuild was done, it wouldn't take much.

on another note, it is possible that it could be a problem with hte valve body. the ecm says the shift solenoid is working, doesn't mean it really is. electrical shorts can do weird things to an electronically controlled tranny.

 

I agree. I have little experience with the 4l60e. I also agree that one would think that the 3-4 clutch pack would go slowly, but good one day and bad the next is how it usually seems to happen.