hi i bought a 66 gt coupe, when i test drove it it ran well but i drove it incity limits so i never got it higher than 30 mph. when i was briging it home after buying it i could not exceed 30 mph because there was a very bad vibration. i rang the lad i bought it off and he said it could be something to do with the clutch plate been put back on incorrectly.its hard to describe but the vibration only happens when i am slowling down with my foot completely off the throttle or wen i keepin a constant speed over 30 mph. when i accelerate it is fine.
Any help lad would be much appreciated.

 

I have this problem too. Is it a vibration, or like a shake? I just got my Mustang on the road since I've had it though (been doing body work and stuff) and I get a bad shake over 30. Right now my car is in the glass shop, so I'll get it back today and I can take a look at it. The first thing I've going to do is get my old wheels off and my new ones on. I've heard here that a bad shake over 30 is a sign of an out of round tire or a bent rim, which is easy to accept because old cars might now move for years (like mine).

 

Vibration underDeceleration a classic sign of a bad universal joint. (although this may not be the issue). Check the u-joints on the driveshaft for excessive play.

 

no its def the tires or wheels it something mechanical some where

 

Sound like a drive shaft issue to me as JMD said, as it smooths out under acceration, what happens when you drive at 30+and then put the clutch in (you have a manual don't you?)

 

yea its manual, and it stil vibrates the same at that speed

 

Does not sound like a clutch problem..

 

Does the vibration exist when the car is sitting still and the engine is brought to a comparable RPM as if you were driving?

If so, this added to the remarks by the seller concerning the clutch, might indicate that the wrong balance flywheel was used.

 

when revved up it does not vibrate the same, i think its the speed because it did not matter what gear i was in

 

If it doesn't vibrate reving it in neutral sitting in the drivewaythen it's prolly the u-joints