Z-28 Trans. Problem 4th Rebuild...HELP

**thinktwice** · 07-25-2010, 05:59 PM

hey guys new here, but have heard a lot of good things about LS1.com. I hope someone can point me in the right direction.I have a 1998 Z-28. Not a real "built" engine but do have a cam, headers, nitrous, vigilante stall, moser 12 bolt, computer tuning and some other small things done. My problem is with the transmission (4L60e) It has been rebuilt 4 times, and the same thing keeps happening. third and 4th gear just go out. the first and second time it was rebuilt by a guy that has been doing transmissions all his life, and he can't figure out the problem. The third time it was done by a reputable speed shop here, and the 4th time the same speed shop just replaced the transmission with one built with all the "heavy duty" parts. So the 4th trans. was a completely different trans and built. (still a 4L60e) No one seems to know what the problem could be. I have had one guy tell me it could be the computer. Now I need to decide what to do, but don't want to have it fixed again just to have the same thing happen. Can anyone help me out?? The last trans lasted about 9 months before it went out, and the car was not raced. Thanks

**98maro** · 07-25-2010, 06:03 PM

Welcome to ls1
I Don't knw what to say bout the trans bout I'm sure some1 else can help you

How many horses you got on the motor?

**Wesman** · 07-25-2010, 06:12 PM

The big question is -

Were the transmission lines and cooler flushed completely or replaced with each trans rebuild?? When the clutches burn out, they leave a ton of deposits in the fluid, which in turn clog up the lines and cooler. Once that happens, even a brand new trans will just overheat and burn out quickly.

**thinktwice** · 07-25-2010, 06:44 PM

The last time it was dynoed was before we put the bigger cam in. If I remember correctly it was 384 to the wheels on motor, no nitrous. Back then it ran 7.0 1/8 mile at 101 that was with the nitrous. the cam in it now is a bit bigger 232/234 112.
Back to the trans problem, I am not sure if everything was flushed out but on the 3rd rebuild they installed a new trans cooler, so I am pretty sure everything was flushed and checked then. This thing is a real mystery. It looks like the guys that worked on the car and do this for a living could figure this out, but so far no luck. Thanks for the replies so far.

**JaycenK** · 07-27-2010, 05:55 PM

you are making over 500 on NOS and you need to have it done by someone like preformabuilt and it needs to be built bulletproof. you will keep trashing that thing unless you get someone that really knows how to build the 4l60-e. anyone can throw parts at them. You are at the point where you need to make a decission to invest the money into the 4l60e or go th400.