Ok, here's what I've got.
1984 Z28, 5spd L69 engine.

I'm just learning how to drive a manual.
When I shift into 3rd, the car starts shuddering. If I shift into 4th at that point, the shuddering goes away.

Any idea what this could be from?

My wife (she's driven manuals for 8yrs) says she felt it too. Seems like you're only in 3rd for a second or two before you have to shift it again.

As far as the clutch... I bought the car 6 months ago (was away for 3 months so didn't drive it). I was told it was ~6 months old so I don't really know how new it is. It seems like if it was the clutch, though, it would happen in all gears.

Any help would be appreciated.
Randy

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Randy
84 Trans AM LG4, 700R4 T-tops
1984 Z28 L69, 5 Spd, T-tops
"Don't sweat the petty things...Just pet the sweaty things"

 

check ur mounts, mine did it to, found the tranny mount was broke