Drive line vibration

[Tom Wright]

I have a 67 BB coupe, 4speed. It has a vibration at highway speed that seems to get worse the longer I drive it. On short trips less than 15 miles the vibration is very slight. At 70 mph and 3000 rpm the vibration is bad. If I press in the clutch at 70 mph the vibration stops. If I rev the engine to 3000 rpm with the clutch depress and coasting at 70,there is no vibration.
I have ruled out tires as the problem. It has new drive shaft universal joints and half shaft u-joints. I would like an educated guess as to where to start.

[Craig S.]

Re: Drive line vibration

Tom - has the bushing in the tailshaft of the transmission been checked for play and wear? This may be wobbling under load and casuing a vibration, since the coast at the same speed and revving the engine through this rpm without load is smooth...just a thought....Craig

[Tom Wright]

Re: Drive line vibration

I will check the bushing and report on this forum. It will be about 2 weeks before I can get the car on my lift as I have my 57 T-bird on the lift getting a new interior and wire harness. Thank you for the response.