c-6 shift problem
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New User
Joined: Aug 2003
Posts: 18
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c-6 shift problem
I have a 81 F-150 that I had the tranny rebuilt in. Now it shifts from 2nd to 3rd almost immediatly, and does not downshift back to second when pulling a hill or after slowing down and taking a turn. The rebuilder says that it is because I don't have the kick-down attached. My research says that the kick-down only controls hard throttles as in passing. Any advice?
Posting Guru
Joined: May 2003
Posts: 1,525
Likes: 3
c-6 shift problem
You are right, the kickdown will only affect shifting if it is pushed down like wideopen throttle. The shift points are controled by a balance of oil pressure between the vacumn modulator and the governor. It is possible you could also have a valve body problem with the shift valves. Mayby sticky valves or wrong springs behind the shift valves.
Posting Guru
Joined: May 2003
Posts: 1,525
Likes: 3
c-6 shift problem
Yes it could be a vacumn problem. You should have full manifold vacumn at the modulator. The bad news is if you have sticky valves it is caused by foriegn material getting into the valve. That material has to come from something inside the transmission. I would also be concerned that the valve body may not have been correctly assembled if it was cleaned.
