Coke Robot

Bad Speedometer Cable? Failing Transmission?

2 posts in this topic

I've been trying to hunt down the source of what could be causing my auto transmission to shift oddly for a while now. The ATF fluid never leaks or has ever leaked, it is at right levels, and doesn't get brown or smell burnt. For a LONG time, the transmission has shifted rather roughly between certain gears at certain speeds when the pedal is held at certain heights. I've hunted around all over and can't figure it out. Shifting from park to reverse and then drive and back up again causing the transmission to jerk. I can get the car to actually shift fairly smoothly if I keep the pedal depressed down in a sweet spot to make it go right. Even more odd, since I've had this car it's been an issue but it hasn't been so bad that it's warranted rebuilding or anything, nor has it gotten progressively worse. In fact, it's gotten slightly better over time from tinkering with the TPS sensor and switching to synthetic ATF. There aren't really specific gears that shift hard either. I can go from 1st to 2nd smoothly, then 3rd is rough. I can go from 1st to 2nd roughly, 3rd is smooth. 

Thinking about this lately, the speedometer doesn't show the right MPH that it should. If I check with my phone with GPS, going 60 MPH in the car reflects as about 54-55 MPH. Between two different gauge clusters, one analog and the other digital, both have reflected the same speed variance. I don't know if the vehicle speed sensor on the gauge cluster affects shifting for sure, but would an old speedo cable indirectly affect the transmission? I don't really want to go about throwing parts at it but I'm kind of at the point I probably will. 

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Have you checked your front and rear engine mounts??

The phone gps always shows different in my experience. Hate to say but these transmissions were probably one of the worst autos ever and I am surprised yours still works. They are notorious for hard shifting.

I bought a 88 626 gt with a auto that would not move the car. I since swapped the trans for a manual only to find the crank took a walk. I assume this was because of that auto transmission but cannot confirm. As a matter of fact I plan on dropping the oil pan tomorrow to see what the damage is. 

 I would start to look for a manual transmission swap for the future if you really like the car. I have a 626 n/a on its way out. Not sure if I'll be rebuilding the engine or parting it out as of yet I'll keep you in mind if I retire old Betsy 

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