Marathon vibration and noise

[frodrummer]

81 marathon. Has a strange noise and vibration at take off and when coming up on top speed. When I hit mid throttle, the noise/vibration goes away, then slowly returns when approaching top speed. I thought it was the drive clutch, but installed a new comet clutch and still have both symptoms. The noise sounds like its coming from the rear passenger axle area. With the rear end jacked up, no noise or vibration. There is a moderate amount of play in the pass side axle. I can move the tire forward and backward about 2.5 inches in both directions. I also grabbed the tire and pulled outward and noticed about a 1/4" of movement in and out. Is this movement normal? I noticed the drivers side does not move in any direction, so I'm guessing something in the pass side is fouled up.

I pulled off the hub, snap ring, and pulled the axle and bearing out. I didn't see any excessive wear on the splines, and the bearing spins fairly well. Not sure what to look for though.????

I also checked the drums and shoes for some abnormality.... It looks good to me.

I do believe my motor mounts could stand to be replaced, which I'm sure is adding to my vibration woes.

Any advice would be most helpful.

[racin161]

I think you found it Ford Motor mounts would be my answer. I've replaced them in both of mine for the same reason and the noise went away.

LOU

[redcloud]

Mounts will do it but i would also check all the mountings for your muffler as they will crack mounts even were you can't see and give nasty vibrations...
Had to weld up both side on my 91 marathon.