My '79 downshifts when it feels like it

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My '79 downshifts when it feels like it

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Corvette >> Corvette Models >> Corvette C3 Forum >> My '79 downshifts when it feels like it

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My '79 downshifts when it feels like it - 11/12/2007 3:36:36 AM

c.a.guyer

Posts: 11
Joined: 10/27/2007
Status: offline

Sometimes my '79 will downshift correctly and sometimes not at all-when I got the car some bozo had the cable adjusted up so tight that the throttle would only open half way-I've since adjusted it correctly but it only downshifts like it should once in a while-Is a valve damaged in the tranny or ?????????? How do I fix??????????
Thanx guys

Post #: 1

RE: My '79 downshifts when it feels like it - 11/12/2007 4:38:27 AM

DeeVeeEight

Posts: 502
Joined: 10/24/2007
From: South Jersey
Status: offline

There is a vacuum diaphragm located on the side of the transmission that controls the shifts. Often this diaphragm goes bad and throws off the shift points. It is easy to replace. You may also need to re-adjust the kick-down cable. Another factor is exhaust back-pressure. A low restriction exhaust may affect the shift points.

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1979 L-82, 383 Stroker, Edelbrock RPM Air Gap intake, Holley 750, Headers, Flowmasters, VB&P 400# rear monospring, Richmond 5 speed. American Racing Vector Wheels, Firestone Indy 500's

(in reply to c.a.guyer)

Post #: 2