78' transmission problems

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78' transmission problems

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78' transmission problems - 4/14/2008 4:06:12 PM

wojnar48

Posts: 4
Joined: 1/13/2008
Status: offline

Fellow Corvettesmen,
I have a original automatic 4-speed in my 78'. The shifting from 3rd to 4th the car buckles. (only in the process of shifting)
All other gears work like cream. What could be the problem? What would be the best action? A rebuild kit perhaps?
(I tried finding one on the web without seccess.

With Respect:Richard

Post #: 1

RE: 78' transmission problems - 4/14/2008 6:20:13 PM

78buckshot

Posts: 638
Joined: 1/28/2007
From: Michigan
Status: offline

Welcome to the site Wojnar48, the 1978 Vette factory automatic trans is a three speed turbohydramatic 350. If yours has a four speed automatic then it was converted at some point. If you can describe the problem with more detail we'll try to give you some diagnosis.

(in reply to wojnar48)

Post #: 2

RE: 78' transmission problems - 4/16/2008 3:33:28 PM

wojnar48

Posts: 4
Joined: 1/13/2008
Status: offline

I am sorry 78buckshot, I don't know why I wrote that its a 4 speed. Indeed it is a 3 speed original. I apologize. Well
all the other gear jump in smoothly but the shift from 2 to 3 is accompanied by a sligt crunching sound. As if the gear didnt want to shift. When heading down a hill, with less rpm the crunch is not there. The car also jolts . Thats about as best I can describe it.

(in reply to 78buckshot)

Post #: 3

RE: 78' transmission problems - 4/16/2008 6:08:25 PM

78buckshot

Posts: 638
Joined: 1/28/2007
From: Michigan
Status: offline

I would put the car on a hoist and check all of the universal joints first. Our Vette's have six u-joints, two each on the drive-shaft and half-shafts. Also check the mounts for the transmission and differential. If you don't find any sloppy u-joints or mounts then have the transmission diagnosed by someone you trust, it may be time for a tranny rebuild but you want to eliminate the rest of the drive-line first.

(in reply to wojnar48)

Post #: 4