Reverse on ‘77 with 350 trans
Thread Starter
Instructor
Joined: Apr 2006
Posts: 233
Likes: 35
From: San Diego, CA
Reverse on ‘77 with 350 trans
When shifting into reverse, hesitates and slips (sometimes about a minute) before clunking into gear. Not low on fluid but that is what it acts like.
Just another Corvette guy
Joined: Feb 1999
Posts: 8,518
Likes: 3,865
From: Palm Springs, CA.
Hey Ron,
This is pretty common with the Turbo 350 and 400 if they've sat for a length of time. The rear piston seal dries up and when the car is fired up it doesn't seal well so fluid slips by before shifting into gear. Depending on how bad it is, I have had good luck using an automatic trans conditioner like Lucas, etc. to soften up that rear piston seal. It may take 200-300 miles of regular driving before it does the job but once it works, it works. Certainly worth a try before going to all the trouble of pulling the trans for an overhaul.
Cheers, Greg
This is pretty common with the Turbo 350 and 400 if they've sat for a length of time. The rear piston seal dries up and when the car is fired up it doesn't seal well so fluid slips by before shifting into gear. Depending on how bad it is, I have had good luck using an automatic trans conditioner like Lucas, etc. to soften up that rear piston seal. It may take 200-300 miles of regular driving before it does the job but once it works, it works. Certainly worth a try before going to all the trouble of pulling the trans for an overhaul.
Cheers, Greg
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Greg is right. And the amount of sitting time is unpredictable. Sometimes after a week, sometimes after a month. For my TH350 the outside temp effects operation too.
Its just a matter of idling a minute or two, then the tranny grabs. No further issues the rest of the day.
Its just a matter of idling a minute or two, then the tranny grabs. No further issues the rest of the day.
Last edited by HeadsU.P.; Aug 2, 2020 at 07:49 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Just a 'double-check'...
The auto trans fluid is checked hot with engine running and in drive range. If you fill it with engine OFF to the fill line, the trans will be low on fluid when running.
The auto trans fluid is checked hot with engine running and in drive range. If you fill it with engine OFF to the fill line, the trans will be low on fluid when running.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Not sure that's a good idea unless you trust your parking brake.
Every GM I have had says: running, on the level, warm, in park.
Every GM I have had says: running, on the level, warm, in park.
Last edited by HeadsU.P.; Aug 3, 2020 at 03:44 PM.
