Aggravating Vibration - Can't pin it down

[Idaho Slim]

Took a long trip to Reno in April on old worn out tires, no vibration even at speeds I should not publish. :nono Got new tires, Nitto NT555's and on the rear put 315x35x17's on 11x17 ZR1 Sawblades. Developed a vibration that starts to be noticeable at 45 mph and worsens at higher speeds. Re-balanced all tires, one rear was off 3/4 oz. Seemed to be better, but still there. Took it to my Corvette mechanic at the dealership. Checked out a lot of items; alignment, u-joints, even torque converter bolts and engine pulleys found everything tight. He thinks "maybe" in the tranny as it is most noticeable in drive and OD. I plan on re-building the tranny anyways in the future for drag racing, but the vibration was improved after the rear re-balance of the tire. So yesterday had the drivers side inner tie-rod replaced as we try to find this issue, it was a tad loose. Re-aligned after and now the Vib is worse. The align shows my camber is off .3 to .4 on both fronts, is this the culprit? Did not have the bushings but wanted to inquire if this is worth the expense and could be the issue? This is maddening mad Any ideas ??????

 

[geekinavette]

Took a long trip to Reno in April on old worn out tires, no vibration even at speeds I should not publish. :nono Got new tires, Nitto NT555's and on the rear put 315x35x17's on 11x17 ZR1 Sawblades. Developed a vibration that starts to be noticeable at 45 mph and worsens at higher speeds. Re-balanced all tires, one rear was off 3/4 oz. Seemed to be better, but still there. Took it to my Corvette mechanic at the dealership. Checked out a lot of items; alignment, u-joints, even torque converter bolts and engine pulleys found everything tight. He thinks "maybe" in the tranny as it is most noticeable in drive and OD. I plan on re-building the tranny anyways in the future for drag racing, but the vibration was improved after the rear re-balance of the tire. So yesterday had the drivers side inner tie-rod replaced as we try to find this issue, it was a tad loose. Re-aligned after and now the Vib is worse. The align shows my camber is off .3 to .4 on both fronts, is this the culprit? Did not have the bushings but wanted to inquire if this is worth the expense and could be the issue? This is maddening mad Any ideas ??????

So...

Installed new tires, vibration at 45MPH and above that was not there before suddenly appears...and "mechanic" suspects a transmission problem. :ugh OF COURSE it is more "noticeable" in drive and OD...you're going faster! Alignment issues will not cause vibrations.

The vibration is worse after replacing the tie-rod end because that piece is now no longer "absorbing" some of the vibration.

Were the tires road-force balanced? If not...have it done. Spin balancers are not perfect. At the very least the balancer should be of the type that instructs the user how to position the tire on the wheel for the best balance.

Also, as the wheel/tire is spinning on the balancer, visually watch for a "hop". ANYTHING noticed outside of a visually perfectly smooth rotation ("hopping"...etc) means you will most likely feel a vibration, and can be caused from anything to a defective tire to a wheel that is out of round (not unheard of on C4s).

 

[96gs917]

I agree with "geekinavettte". Tire issue for sure for the reasons he discribed. It is not uncommon
for the brand new tire to be out of round, or defective, and impossible to balance. Go back to the tire installer.

 

[bucwheat]

Road force balance,the way to go.

 

[Idaho Slim]

What's a "road force" balance ? I agree all of a sudden after new tires this appears. Thanx Geek, the "it got worse" after new tie rod has me thinkin tires. With it now worse after the repair, I would assume it's the fronts. To be continued .......

 

[geekinavette]

What's a "road force" balance ? I agree all of a sudden after new tires this appears. Thanx Geek, the "it got worse" after new tie rod has me thinkin tires. With it now worse after the repair, I would assume it's the fronts. To be continued .......

A Road Force balancer has a large roller that applies force to the tire as the tire/wheel assembly is spinning on the balancer. The goal is to "simulate" the force of the road against the tire as it is rolling on the car.

 

[Robertwav1]

Just to add to all this at one time I had a vib in the car and turned out to be a poorly recut rotor on the front of the car. I don't know if the brakes were messed with on your car as it wasn't mentioned but thought it might be worth something if they were.

 

[Idaho Slim]

So we thougt we found the issue, one if the front new tires were out of round. Got the new one on today ....... No change it still vibrates. Not happy, beginning to hink it is mechanical and I am leaning towards u-joints.

 

[Baldie88]

Just a suggestion but you might check that the inner part of your wheels are clean. I had a vibration even with new tires much like you describe and someone suggested checking the inner part of the wheel. I found out it had about 20 years of gunk and grease on it. After cleaning them up the vibration went away. Sounds crazy (I would have thought a spin balance would have negated any wheel imbalance) and this might not help in your situation but it's pretty easy to check without throwing money at your car.

Good luck.

Ron
"Baldie88"

 

[Idaho Slim]

FINALLY !! The driveline was out of balance BAD, new U-joints and balanced. Smoooth !!!!

 

[roger longman]

Well done Slim ! Glad you were able to diagnose and, fix the problem......Roger.