RPM and shifting on 1984

[Walter F.]

I have seen several stock crossfire Corvette owners displaying 0 to 60 mph runs on their 1984 and other early C4 Corvettes. Their tach shift points are about 4500 RPMs in each gear at WOT. My 1984 is about 3500. I had the car cheched out at a transmission shop and they said the cars transmissions shifts fine? This transmission was rebuilt by the last owner who put a shift kit in it along with a upgraded spline. He also changed the compter to one coming out of a newer caprice. This was done I am told to program a chip. My knowledge is limited on cars so please bear with me if the questions I ask seem dumb. My first question is am I hurting the cars transmission with these early shifting points at WOT? Am I correct that the ECM has nothing to do with the cars shifting? The TV cable is all the back at it farest point. The car always shifts smooth with no noises or banging. Any infomation will be helpful.

[Mark E.]

Re: RPM and shifting on 1984

Walter,

Disclaimer: I'm not an automatic transmission expert. But I've owned an '87 C4 with a 700R4 and studied the manual a bit. The 700R4 in early C4s is not electronically controlled. Shift firmness and timing are mechanically controlled with a Throttle Valve (TV) Cable and Governor.

If you don't have them, I recommend getting the Chevrolet service manual and the C4 Corvette Sourcebook by Loughmiller, even if you don't intend to work on the car yourself. They will help you understand your car, speak intelligently with a technician, and verify they know what they're doing.

Proper TV cable adjustment is critical on these transmissions for part throttle shift timing and kick-down operation. The TV cable doesn't determine wide-open throttle shift points (the Governor does), but the Governor won't work properly unless the TV cable is adjusted properly. So, if your transmission "shifts fine" but the timing of the shifts is off, I would check the adjustment of the TV cable first. If that doesn't clear things up for you, then check the governor.

Adjusting the TV cable is simple, but it's critical to carefully follow the procedure in the manual. It's my experience that many transmission shops either don't know the proper adjustment procedure, or don't follow it.

Changing the governor is only a bit more challenging, and is certainly within the realm of the do-it-yourselfer.

I hope this helps.

Early WOT shifts won't hurt the transmission.