Transmission suddenly switching gears at much different speeds.

Dear Car Talk

Dear Car Talk | May 01, 1993

Dear Tom and Ray:

I own a 1989 Jeep Cherokee with 60,000 miles on it. Just recently, the transmission started shifting at much different speeds than it always has. The change is most noticable at the shift points between second and third and between third and overdrive. Also, the transmission shifts more often than it used to. It seems as though the transmission is "hunting" for the correct gear while going back and forth a lot between gears. The transmission mechanic said there was nothing wrong with the transmission itself, it's just that the shift points have changed for one reason or another. I'm not satisfied with this explanation. Any idea what caused this to happen?

RAY: The shift points just changed "for one reason or another?" What is this guy, a car psychiatrist? He thinks this is being caused by hormonal changes?

TOM: The thing most likely to cause this sort of problem, Tony, is a downshift cable that's hung up. That could cause the car to stay in each gear longer, which would explain the harsher shifting (because it's shifting at higher rpm).

RAY: It could also cause what Dr. Ruth might call "premature downshifting." So that if you accelerated even lightly, you would cause the transmission to kick down into a lower gear. That could explain the "hunting" sensation, and more frequent shifting you describe.

TOM: So take it to another, more interested mechanic, and ask him to check the downshifting cable to see if it's stuck. Tell him the car's already had a full psychiatric evaluation, and it's ready for a mechanical work up.

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