Transmission shifting back and forth at constant speed

[jeff in co]

Took the gears out and they actually don't look too bad. I'll give it a shot though to see if it fixes it. Found a local shop that may have some so we'll see what happens....

 

[Blue85]

Looks fine.

 

[chulisohombre]

i second that.those gears look fine as is.did you try spinning the cable with a drill?how did the speedo do?

 

[CherryK5]

^^^

I did disconnect the speedo cable last night and put it on a drill....results were no bouncing. I also drove around with the cable disconnected and I did not feel the converter going in and out. So hopefully, this is the problem.

I found this site for new gears:

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

A good write-up with gm part numbers:

http://www.73-87.com/7387garage/drivetrain/speedo.htm


Also, found some alternate sources as the transmissioncenter is falling out of stock on some of the gears:
http://atransmission.info/gm-transmissions-parts/700r4-parts/700r4-speedometer-kits-and-gears.html
http://www.performanceautomatic.com...ries/speedometer-gears/speedometer-gears.html
http://paceperformance.com/i-7134410-8640518-f-gear.html

 

[jeff in co]

Just to follow up on the fix.

I swapped out the cable speedo for an electric speedo and that fixed everything! Tranny stays in gear, no problem and no longer hunts up and down. Cruise is also much more steady as a result, too. So something was wrong either in the speedo head (changed out twice), cable (1 years old) or the speedo gears at the T-case.

Thanks all!