65 coupe vibration ?

[Bruce B.]

My 65 coupe (300 HP, PG trans) makes an noise when accelerated quickly from a low speed or from a stop. Slow or "normal" acceleration does not exhibit the problem. When I step on the gas especially when the car has some weight in it I experience what I can only describe as a rubbing noise or a strong vibration at the rear of the car. Once acceleration slows down it stops.
I have removed the back tires and see no evidence of rubbing.
With the car on the lift I have checked the driveshaft and halfshafts and don't find anything abnormal. I have also rotated the axles and can't find anything wrong.
Any suggestions as what could be the problem or what else I could check?
Thanks.

[Wayne W.]

Re: 65 coupe vibration ?

Probably a bad snubber bushing from the description.

[Tom H.]

Re: 65 coupe vibration ?

Can't see evidence of the driveshaft rubbing the floor ???

[Edward J.]

Re: 65 coupe vibration ?

Bruce, form the what your explaining it sure sounds like a u-joint gone in the driveshaft, sometimes a visiual inspection may fool you, I will look for a rusty powder around the u-joint caps which is a sure sign of a failure. Also a look at all the mounts, transmisson, snubber, and rear diff. cross member cushions.

[Jim D.]

Re: 65 coupe vibration ?

Bruce, form the what your explaining it sure sounds like a u-joint gone in the driveshaft, sometimes a visiual inspection may fool you, I will look for a rusty powder around the u-joint caps which is a sure sign of a failure. Also a look at all the mounts, transmisson, snubber, and rear diff. cross member cushions.

Sounds like a u-joint to me as well. Look at page 2, post #88 for an example of that rusty powder - https://www.forums.ncrs.org/showthre...79970&uid=6751

[James G.]

Re: 65 coupe vibration ?

Agree with all the above.

[Bruce B.]

Re: 65 coupe vibration ?

Thanks for all the replies.
Here's what I have;
New u joints which are installed properly.
No rub marks on the driveshaft or on the floor.
Motor mounts and trans mounts are in good condition.
It appears that the yoke on the differential might be rubbing on something, I can't see the floor above the yoke but there seem to be some marks on the O.D. of the yoke.
If thats the problem I figure it could be due to a bad snubber which is mounted on the differential mounting bracket.
Any other thoughts?

[Edward J.]

Re: 65 coupe vibration ?

Bruce, The snubber will hold the drive shaft in a straight line, to much movement on accel and you loose center line of the shaft, hence the vibration. one other note the snubber bushing that fails is hidden in the recess of the rear axle bracket, The one you see is generally good, If the rear axle has a pinion seal leak the oil destroys the rubber after a few years.

[James G.]

Re: 65 coupe vibration ?

Replace the Snubber, even if it looks OK. They strech when torqued. 5-7 years average life.

[John H.]

Re: 65 coupe vibration ?

Bruce -

Snubber bushings - classic/chronic midyear issue, VERY common.

[Bruce B.]

Re: 65 coupe vibration ?

Again, THANKS.
I'll replace it tomorrow so I can drive the 65 up to the McDorman auction.

[Bruce B.]

Re: 65 coupe vibration ?

Jim and John:
Good to hear from the both of you.
Brings back good memories of Nolands Roast.

[Bruce B.]

Re: 65 coupe vibration ?

Attached are some pictures of the old rubber snubber I replaced in my 65.
The new lower snubber is pictured in the center.
The noise is gone and I can now hit the gas without concern.
Thanks to everyone who posted and my wife for helping me with the installation.