Loubo40
Well-Known Member
its a 67 coronet r/t with a 67 440 and a later model A833 OD. 4:10 gears.
the car is as smooth as can be until i start approaching 70. the vibration starts around 65 and goes away around 80.
its a pretty fast frequency so it feels like drive shaft related.
i changed both u-joints, there is no slop or play at the yoke where it slips into the tranny so i think the bushing is fine.
when its vibrating sometimes i can get it to go away by not accelerating or decelerating but holding it somewhere in the middle.
it gets worse or at least feels worse when i push the clutch in, almost like it shifts from the drive shaft to shaking the whole car.
what i know is it was changed to a four speed, the tranny mount looks good and tight, appears new. someone put in 4:10's in place of the 3:23's, which is what im thinking may be my problem.
when the cars on jackstands and in gear the driveshaft looks dead straight, the drivers tire looks like it might have the slightest out of round situation but very minimal.
if it run it at speed on the jackstands, in fourth gear up to 70, there is definitely a good vibration.
where do i start? driveshaft balance? it was obviously redone to accommodate the four speed and they are not factory weights, and it does not look like any are missing.
how can i narrow it down more?
any help would be very much appreciated as it vibrates the worst at the most common highway speed.
the car is as smooth as can be until i start approaching 70. the vibration starts around 65 and goes away around 80.
its a pretty fast frequency so it feels like drive shaft related.
i changed both u-joints, there is no slop or play at the yoke where it slips into the tranny so i think the bushing is fine.
when its vibrating sometimes i can get it to go away by not accelerating or decelerating but holding it somewhere in the middle.
it gets worse or at least feels worse when i push the clutch in, almost like it shifts from the drive shaft to shaking the whole car.
what i know is it was changed to a four speed, the tranny mount looks good and tight, appears new. someone put in 4:10's in place of the 3:23's, which is what im thinking may be my problem.
when the cars on jackstands and in gear the driveshaft looks dead straight, the drivers tire looks like it might have the slightest out of round situation but very minimal.
if it run it at speed on the jackstands, in fourth gear up to 70, there is definitely a good vibration.
where do i start? driveshaft balance? it was obviously redone to accommodate the four speed and they are not factory weights, and it does not look like any are missing.
how can i narrow it down more?
any help would be very much appreciated as it vibrates the worst at the most common highway speed.
