Help! '95 Riv. transmission problem

[Guest fowlintent]

I am at the end of my patience. I bought a '95 Riviera last July, and it has spent more time in the shop than on the road.

The car had a transmission problem that I can only describe as a mushy 1st gear, and not going into overdrive. One repair shop flushed the transmission system, replaced fluid, cleaned filter, and the mushy 1st gear problem improved. The transmission would also shift to overdrive UNTIL it had been on the road for 30 minutes or so, then it stopped shifting.

I took it to a transmission shop, and they told me the front seal had been compressed, was leaking and needed to be replaced, and that might take care of my problems. Nope. They then suggested replacing the torque converter, which they did, still no improvement. They then determined that the first torque converter may have been defective (something about stall codes, which was over my head), and replaced it a second time. Just picked the car up yesterday (after 8 weeks in the shop) It drove great for the first 30 minutes, then stopped shifting to overdrive.

Does anybody have any suggestions. I love the car, but I can't keep throwing good money after bad. Thanks for any help you might be able to give me.

[RivNut]

No suggestions from me except to ask the guys over on the Riviera Performance Forum for help. That era group does most of their exchanges there.

Riviera Performance - Dashboard

or the Riviera Performance Group

Buick Performance Group Forum

[steelman]

I think this is a computer controller transmission. Based on the description, something (likely computer) is getting too warm after 30 minutes and causing trouble. I think this is an electronic issue, not a mechanical one.

[tim63riv]

Fowl,

Sounds like you have an issue with your car and the repair shop! Your car has a 4T60-E transmission with most of the transmission being electronic except for the shift feel which is controlled by the vacuum modulator.

It is also a little difficult to tell if you have lost 4th gear or if you have lost TCC after 30 minutes. The way to tell this is too wait for the problem to occur at 45 mph or so and then manually shift the transmission into 3rd gear and see if the RPM's increase. If so, you still have 4th gear, if not you lost TCC (torque converter clutch).

"Mushy" 1st gear could also be a 2nd gear start that could be caused by a bad shift solenoid or a sticking valve in the valve body.

With any transmission issue, it is important to find out what you have still got working and what is not working.

There is NO reason for a shop to have a car for 8 weeks for a transmission repair. Buick dealers still work on the 4T60-E, might want to give the professionals a try!

Tim