This is a problem my brother is having with his 79 Z28. He has the 4 speed and the shifter has a vibration in it. That is the only place you can feel it. It does it both in neutral and in gear with and without the clutch depressed. We've had it up on blocks and ran it and the only place you can feel it is in the shifter. Anyone else had this problem?

 

Something about the engine is probably unbalanced. Did this start after anything was changed, like the clutch for instance? If so, the flywheel probably needs to be balanced. If it just started it up by itself, take a look at the harmonic balancer and make sure the rubber "inertia ring" liner (blob of spooge) hasn't failed like they always do, which allows the outer ring to wander around however it wants to.

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