maxmachz

Well I'm getting through the small issues on my '81.

52,000 miles.

I've done the half shaft u joints (shot), put new BFG Radial T/A's on, balanced of course. The Firestones were 15 years old, so I thought I would be safer with new rubber. Hoped the vibe was a tire. It got a little better, but I want this thing perfect!

Still have a vibe that comes in at 45, stays until 50 then slowly goes away at higher speeds. No matter if under load, or coasting, and it is in any gear. I beleive that rules out the engine / trans.

All the wheel bearings feel good, no play; drive shaft u joints feel good, no play when I spin the shaft by hand back and forth.

Where do I go next?

Thanks for this great site!

larryg3

I know you said the tires were balanced but it sounds like the tires are out of balance. Worth a shot

maxmachz

Thanks for the quick reply.

The car did it before the tire replacement, after rotation of the old Firestones, and after with the new BFG's. I would have thought that would rule out the tires? Appreciate your input.

bobs77vet

as i always say.....dont forget to look at the fan clutch....look carefully around the shaft where it goes into the clutchand see if there is any evidence of uneven wear.

maxmachz

I have replaced that; maybe worth mentioning, the harmonic balancer appears to have slipped, the timing mark is off quite a bit but it runs great, I timed it by ear, getting 16 mpg.

Could it be that balancer?

maxmachz

top

gdh

I had the same thing, went to my local GoodYear tire shop and the owner has been doing this for 40 yrs. He did both dynamic and static, with dynamic still had the vibration then he did the static and vibration is gone. He said that it was the wheel and not the tire. Very few do static anymore unless they are fairly small shops and can't afford the equip't. I had always thought that dynamic would have identified the wheel itself being the issue. Just a thought about taking it to some old school muscle car wheel guy.

69MA

Check out this link that a friend sent me yesterday. It's a new way to balance tires with no weights. Dyna_Beads It's a pretty neat process that i have never seen it before. Best part you don't need weights on your wheels and you can do it yourself. Again i have never tried it; my friend said he was going to get a kit for the front tire on his bike.

gq82

Definitely....it's designed to absorb internal vibrations.

billcarson

i spent a lot of time on my car trying to eliminate a similar vibration that you are having.the driveshaft spins 3x faster than the halfshafts on average and could be the cause.balance or u-joints a possibility.check the driveline phasing.i had to raise my transmision 3/4" to get it close to being correct.the transmission and differential driveline must be as close to parallel as possible.they should be offset somewhat also so the joints do their job.one thing to note in my case was that i had a disintegrated needle roller in one halfshaft joint that i could not detect until i removed it.hope you find it.

maxmachz

Thanks for all the replies.

Will be changing the prop shaft u joints, and the harmonic balancer and checking back in.

damoroso

If the balancer has slipped, I'd start there as it should be replaced anyway...