1995 Z28 4L60e 207miles

Was rebuilt a few years and 35k miles ago and worked better than new. Smart but reasonable rebuild choices made for daily driver and ease of ordering with all in one kit.

Seems the transmission will slip going into 2nd gear with spirited acceleration and also in highway cruise kickdown into 2nd until the revs are reduced. Drives perfectly normal when driven reasonably.

Servo cover seems to move in when lightly forced in the 3/16 area, very hard to measure exactly, but seems in the begining to have problems area.
New band 35k miles ago but reused reverse input drum with now 207 miles.

The pump pressures are good/great and reverse makes 170-200+ psi just above 550 revs as in a safe backing up. Pressures measured with external guage.
Driving 1/2 150-180 and settles down 120 in 3/4 also see 60 with 0 throttle. Very quick pressure increase. Didn't find anything pump pressure concerning.

Fluid is 60% 35K, 30% 10k, condition good but obviously not brand new, level is full with slightly overfill.

Nothing else obviously or even when stressed concerning.


Q) Can a longer servo pin such as that sonnax work and buy time/mileage?
Q) Can the servo and pin come out with the transmission in the car and get put back in properly?
Q) Does the transmission need to have the cross member remove and lower the transmission somewhat to make is possible or just more pleasant?
Q) Any suggestions for pin length (new) to get the most out of this repair.
Q) How long can I still have 2nd and 4th use as wear continues unrepaired.
Q) How long will the TC last? Spring mod done during rebuild.

Many thanks.
Stephen

 

Can it be done with the transmission still in the car? YES, with a bit of straight forward work.

Thanks to buddy from Z Zone Motorsports.

 

Just a “heads up”……

There's virtually no one here any more. I'm trying to hold things together, and Shoebox stops by, along with about a 1/2-dozen LT1 diehards. Unfortunately it takes a while to get responses, if at all. Embarrassing!

 

Thanks for the update. What's embarrassing is my failure to really check this when the transmission was out of the car.

Do you know what length or ring/groove type the 1995 4L60e's from the Z28's came with?

Apparently the no groove servo 8680501 is marketed as "gets you back in the area that's good" or something similar.

Just wondering if a reasonable guess if the 8680501 which is 2.70-2.71 inches will get my estimated >3/16 servo cover play back in the 1/16 -1/8 range.

If I started with a 2 ring 8680571 2 ring at 2.61-2.62 it should be slightly above the mid range of 1/16-1/8 play.

Given the cost of the pin and a servo seal kit and ability to DIY while the transmission is in the car it's something to do and do before the snow comes.

Glad to see you're still following and providing your great advice and experiences.

Take care.
Stephen

 

Unfortunately, I never worked on a 4L60E.

 

Update.

Installed 8680501 the no groove pin 2.70-2.71 in length and longer than OEM and previous pin in this transmission the 8667571 2.61-2.62" 2 rings.

Also replaced the servo cover oring seal and used a new snap ring, the original snap ring and 5 year old servo seal would not seal properly.

So far everything is working as it should and more desirable for this application. The shifts from 1-2 and 2-3 according to a scanner are back in the .60 to .70 area during normal driving and drivability seems in indicate those shifts as well as perhaps others are occouring with less lag. Still smooth up and down shifts and more firmer when more throttle is used. Have yet to test the highway downshift from 4-3 or 4-2 with spirited acceleration for slippage.

Servo cover movement when forced with a pry bar externally seems much closer to 1/8 movement now.

Stephen