High Speed Vibration Noise

[Hawkk72]

I have a 1975 model with a 2.3 liter automatic. At speeds over 60 MPH I'm experiencing a noise similar to this: vrump...vrump...vrump along with steady vibration. It sounds like engine but feels more like tranny. I know the tranny was swapped at one time. Is it possible that the drive shaft angle is not correct? Or, maybe this is normal noise for a four-banger at higher speeds?

 

[eaglecap]

How old are the tires? I had the same thing and one of the tires had a spot where the tread was separated from the casing. It had sat for several years in a garage and the tires looked good at first glance.

 

[Dano78]

Check your tranny mount. It may have been fine when they swapped the tranny, but over time seperated from the rubber. This can cause the noise you're hearing. Some driveshafts back then had a transmission yoke on them that had a balance weight on them that looke similiar to a harmonic balancer. Pretty much what it was too. See if it has moved, or damaged.

Also check-

Tires out of balance
Driveshaft out of balance
Tranny mount worn/loose/broken
Driveshaft U-joints

 

[Hawkk72]

Thanks guys.
The tires are brand new with alignment last week...didn't make much of a difference in the problem. I'll have the other things checked. Appreciated!

 

[eaglecap]

I am sure you have thought of this but if this started after the tires were installed I would go back and have them checked. One may be out of balance or defective.

 

[Hawkk72]

Thanks, but the noise was there before the tires were purchased.