Powerglide problem
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Joined: Jan 2006
Posts: 63
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From: Havelock NC
Powerglide problem
I have a problem with the powerglide transmission "slamming" (engaging hard) into drive or reverse. What could cause this? The tranny shifts fine from 1st to second and downshifts OK. but it really slams into drive or reverse from park or neutral. Anyone?
Doug
Doug
Le Mans Master
Joined: Jun 2004
Posts: 9,018
Likes: 331
From: Southeast Missouri
How high is your idle speed? Did the problem just start, or has it come on gradually? Have you made any changes to the car recently? Too high an idle speed can cause harsh engagement. Does it creep excessively in Drive? Another sign of too high an idle speed. Lastly, I'd check the vacuum modulator for proper operation. Just a few . . .
Ron
Ron
Racer
Joined: Sep 2004
Posts: 473
Likes: 25
From: La Quinta CA
I've had the same problem with my 67 coupe - when I reset the idle speed to 750 to 800 RPM, it shifts into reverse or drive smoothly - above that, or when it's still in fast idle (about 1200 RPM) it slams into gear. I had my idle adjustment set a little higher since it has A/C, in very hot weather it won't idle smoothly with air on and in drive at 750 to 800 RPM idle . I found a good hot weather idle is about 900 RPM, cool weather is 750.
Intermediate
Joined: Jun 2006
Posts: 32
Likes: 0
From: San Francisco CA
hard shifting
I have just the opposite problem with a 64; when the car is cold it really hits hard downshifting from 2nd to 1st. When the car gets warm it goes away, but ocassionally will downshift hard again. Mechanic says the modulator seems OK; any other ideas?
Le Mans Master
Joined: Jun 2004
Posts: 9,018
Likes: 331
From: Southeast Missouri
Harsh closed throttle downshifts can be caused by improper low band adjustment; vacuum modulator stuck, diaphram leaking, or line broken; too high engine idle speed; or a couple other internal problems. I'd start with the ones you can check externally!! Good Luck!!
Ron
Ron
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