Lockup Torque Converter Problems
Thread Starter
Safety Car
Joined: Jul 1999
Posts: 3,946
Likes: 63
From: Marianna FL
Lockup Torque Converter Problems
On my 95 the torque converter appears to be trying to lockup, but it does not. About 60 mph, you can hear the engine speed vary slightly, but it never drops and smooths out. The RPM's are higher than what I'd expect with 3.07 gears and a lockup converter. The fluid is clean and the filter/fluid has low miles. The car and trans itself has 225k miles. Other than the converter locking up, the trans appears to be in good shape. Anyone have guidance on diagnosing this problem?
Race Director
Joined: Apr 2003
Posts: 17,695
Likes: 1,666
From: moraga ca
Your symptoms and mileage suggest a worn torque converter. There is a chance it could be your lockup solenoid in the tranny not working properly, but I would guess it's the lockup lining in the converter that is worn. If the tranny seems ok and you don't want to spring for a rebuild, just change the converter.
Thread Starter
Safety Car
Joined: Jul 1999
Posts: 3,946
Likes: 63
From: Marianna FL
There was some wear material in the pan when I changed the fluid, but it did not appear to be excessive. Going through the factory manual, it pointed to the lockup solenoid but my experience with other types of solenoids is they work or they don't. I really think if I'm going through the trouble to pull the trans again that I will go ahead and rebuild it. Thanks for the help.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 7
From: Tampa Florida
You may want to check the adjustment/contacts on brake switch. An intermittent brake switch can cause your tranny to drop in and out of lockup. Here is a good thread that shows the switch in a little more detail: http://forums.corvetteforum.com/c4-t...-for-94-a.html
Pro
Joined: Aug 2004
Posts: 549
Likes: 13
From: Richmond VA
Had the same issue with my 94 but a lot less miles. I did a Datamaster log on the tranny and saw the ecu send the command but nothing returned to say it locked. Replaced the lockup solenoid and all was fine.
If the solenoid sends a lock confirmation back and converter still not locked look at the TC.
If the solenoid sends a lock confirmation back and converter still not locked look at the TC.
Last edited by blue94; Jan 22, 2010 at 01:14 PM.
Thread Starter
Safety Car
Joined: Jul 1999
Posts: 3,946
Likes: 63
From: Marianna FL
Thanks for the other two suggestions engle and blue. I was looking at the wiring schematic and wondered if the brake switch could cause a problem like that. Also a good idea to datalog and see what is happening.
Thanks again!
Thanks again!
