c4 87 Auto Transmission Issues
Thread Starter
Drifting
Joined: Nov 2009
Posts: 1,341
Likes: 2
From: Perth Western Australia
St. Jude Donor '10
c4 87 Auto Transmission Issues
I just got my vette back from the shop with a freshened up engine and more freeflowing inlet and exhaust. However, on my first cruise to test out my newly released torque and horsepower it appears my transmission has died. I believe the transmission is a 4 speed turbo 700.
I only get drive in the 2 position and R position. The shifter has never gone into the 1 position. In the D or D overdrive positions the vehicle will get drive from a standing start but as the revs build up all drive is lost. If the throttle is depressed a long way whilst in D or D overdrive at speed it will shift down and get drive again (presumably in 2nd gear). There is no drive in cruise mode over about 40kmh (25 mph). Also I note that when I put the selector in the 2 position it feels like the car body moves relative to the driveline (very strange feeling).
Can anybody confirm that I am up for a major overhaul and what the likely cause is? Is it possible that it is something trivial like the throttle valve (TV) cable is out of adjustment due to the recent work on the engine?
I only get drive in the 2 position and R position. The shifter has never gone into the 1 position. In the D or D overdrive positions the vehicle will get drive from a standing start but as the revs build up all drive is lost. If the throttle is depressed a long way whilst in D or D overdrive at speed it will shift down and get drive again (presumably in 2nd gear). There is no drive in cruise mode over about 40kmh (25 mph). Also I note that when I put the selector in the 2 position it feels like the car body moves relative to the driveline (very strange feeling).
Can anybody confirm that I am up for a major overhaul and what the likely cause is? Is it possible that it is something trivial like the throttle valve (TV) cable is out of adjustment due to the recent work on the engine?
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
I just got my vette back from the shop with a freshened up engine and more freeflowing inlet and exhaust. However, on my first cruise to test out my newly released torque and horsepower it appears my transmission has died. I believe the transmission is a 4 speed turbo 700.
I only get drive in the 2 position and R position. The shifter has never gone into the 1 position. In the D or D overdrive positions the vehicle will get drive from a standing start but as the revs build up all drive is lost. If the throttle is depressed a long way whilst in D or D overdrive at speed it will shift down and get drive again (presumably in 2nd gear). There is no drive in cruise mode over about 40kmh (25 mph). Also I note that when I put the selector in the 2 position it feels like the car body moves relative to the driveline (very strange feeling).
Can anybody confirm that I am up for a major overhaul and what the likely cause is? Is it possible that it is something trivial like the throttle valve (TV) cable is out of adjustment due to the recent work on the engine?
I only get drive in the 2 position and R position. The shifter has never gone into the 1 position. In the D or D overdrive positions the vehicle will get drive from a standing start but as the revs build up all drive is lost. If the throttle is depressed a long way whilst in D or D overdrive at speed it will shift down and get drive again (presumably in 2nd gear). There is no drive in cruise mode over about 40kmh (25 mph). Also I note that when I put the selector in the 2 position it feels like the car body moves relative to the driveline (very strange feeling).
Can anybody confirm that I am up for a major overhaul and what the likely cause is? Is it possible that it is something trivial like the throttle valve (TV) cable is out of adjustment due to the recent work on the engine?
Have a Qualified & experienced ASE Master Mechanic check the transmission out for you in your 87 Vette.
If you have a 1987 Corvette Factory Issue GM Service manual, It shows you step by step diagnosing and repairing your 700R4 Transmission.
If your transmission has indeed failed, have your original rebuilt, preferably by a Veteran Auto trans mechanic.
Your original 1987 700R4 Corvette trans has a valvebody with specially calibrated componets unique to the Corvette Only.
BR
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
It sort of sounds like they took the torque converter out of the trans when they did the engine and lost some fluid. Check that first, other than that, you might just check the T.V. cable.
Just found a way to cheat there.
if you look at the throttle cable, the TV cable will have a white 3/4 circle button to push.
The proper way to check it is to push the button, slide the throttle sheath in , then with engine off, pull the throttle cable full travel. The TV cable should adjust.
The cheat way is to pull the sheath a little far, and look for a wear mark where it has ridden in the housing for a few thousand miles.
Push the button, and slide it back to the wear mark.
Give it a test drive to see that things changed or didn't change.
The other thing is that maybe the trans was removed with the engine, and they installed the linkage a little bit off.
It may need some adjusting.
Good luck
Just found a way to cheat there.
if you look at the throttle cable, the TV cable will have a white 3/4 circle button to push.
The proper way to check it is to push the button, slide the throttle sheath in , then with engine off, pull the throttle cable full travel. The TV cable should adjust.
The cheat way is to pull the sheath a little far, and look for a wear mark where it has ridden in the housing for a few thousand miles.
Push the button, and slide it back to the wear mark.
Give it a test drive to see that things changed or didn't change.
The other thing is that maybe the trans was removed with the engine, and they installed the linkage a little bit off.
It may need some adjusting.
Good luck
Thread Starter
Drifting
Joined: Nov 2009
Posts: 1,341
Likes: 2
From: Perth Western Australia
St. Jude Donor '10
The engine wasn't removed from the vehicle. The heads were removed for servicing only. So torque converter and oil weren't touched. I did have a play with the TV adjustmnent. Didn't seem to make any difference.
I have since spoken to the mechanic and he believes the transmission needs reconditioning due to the clutch issues mentioned by BR below.
The box is probably long overdue for this.
The mechanic has a specialist he uses who knows how to beef up the box and has suggested putting in a stage 2 shift kit whilst hes at it.
I have since spoken to the mechanic and he believes the transmission needs reconditioning due to the clutch issues mentioned by BR below.
The box is probably long overdue for this.
The mechanic has a specialist he uses who knows how to beef up the box and has suggested putting in a stage 2 shift kit whilst hes at it.
