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85 4+3 3rd gear off throttle stick vibration

BlueCorvette

Active member
Joined
Feb 13, 2016
Messages
29
Location
Florida
Corvette
1985 two tone blue Z51 4+3
I have an 85 with the 4+3. I'm getting an off throttle vibration in 3rd gear. The stick will violently start shaking like it's coming out of gear. As soon as I touch the gas it goes away. Shifting is smooth and no grinding.

I had the transmission out, and when I put it back in, I used a gauge tool in the side of the shifter for alignment so I could adjust the linkages.

The OD seems to work fine. I have the first gear switch shorted so I can control it with the console switch.

I didn't have this problem before, and I set the linkages according to the FSM specs.

Could this be as simple as a slightly out of adjustment linkage? If I wasn't completely in 3rd gear wouldn't I have other problems on the gas?

Worn 3rd gear synchro?

Any ideas?

Thanks
 

BlueCorvette

Active member
Joined
Feb 13, 2016
Messages
29
Location
Florida
Corvette
1985 two tone blue Z51 4+3
I was playing with the 3/4 gear lever on the transmission. I think the ball detent in 3rd has a problem. I detached the shift linkage pin for that gear and I can push lever into 3rd. But I can also push it slightly past the detent, and then when I release the lever it rocks back into the detent. I think the 3/4 lever mechanism on the side plate is worn and off throttle it is vibrating a little past 3rd and then into the detent. I'll have to take the side plat off and look.
 

DonB

Well-known member
Joined
Mar 25, 2015
Messages
339
Location
Chicago
Corvette
2019 ZO6 in Elkhart Lake Blue
Could the detent spring be worn or broken? I'm NOT familiar with the 4+3, but I've seen worn detent balls and broken detent springs in other transmissions. If it "goes in" easier than the 1-2, I'd look at the springs, etc.
 

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