Cannot figure this out

[nitrox2595]

I am having a bad vibration at 85-95 MPH- ( i know, don't drive 85-95)... . Truck has an 8" pro comp lift, 22. 5 alcoas, brand new trans,--- had the vibration on acceleration and got a 1 piece alum driveshaft and that disappeared. brought the truck in to get the front tires balanced and the guy did that. big difference, but it still shakes like crazy at those speeds. Under accel, or not. I have the steering stabilizer and i am going nuts... Any idea what this could possibly be?

 

[B.G. Smith]

Might be out of round tire? bg

 

[AEdelheit]

Did you check the front driveshaft too?

 

[Cosmo]

8" lift? Could be pinion angle issues, could be just those gigantic wheels/tires, unbalanced driveshaft(s)

Our tire balancer is normally set to round to the nearest quarter ounce, and usually that's good enough, but even when it zeros out after balancing, you can enable the static balance and see how even if it's "balanced" there's still an imbalance. You can also turn off the rounding and check what the actual values are. One tire I saw today was 0. 00 / 0. 00 with rounding, but 0. 23 / 0. 16 with rounding turned off, so obviously there is still some imbalance in the set that may or may not annoy the customer.


You could also have a tire that is out of round. Continental gave us a lot of trouble with the 2010 Outbacks, some of the tires were over 1/4" out of round and I don't care if you get them perfectly balanced, it's not going to ride smoothly once you put the tire to the ground.

 

[AH64ID]

That's well above the speed rating of those tires they are probably not designed to go that speed and stay as true as they can.

But do a good check of front and rear pinion angles and u-joints.

 

[GaryCarter]

Road Force balancers will cure most tire issues, used properly.

On some tough cases I have had to get the on-vehicle balancing done, which has never failed me. But it's hard to find anyone who knows how to true and balance on the truck any more.



You should be able to feel by the frequency of the vibration if it's driveshaft issues or tires and wheels.

 

[nitrox2595]

UPDATE: I just got to North Carolina from NY. The truck was fine up to 79-83mph. Then it started vibrating, but only when not under acceleration. I checked the front shaft, when i grabbed it and twisted it, there was about 1/2? of play. Would that be a problem? The guys that put the lift in said that they have the parts for the pinion angle adjustment, but i never got it up to that speed till weeks later. If they do the pinion angle adjustment, What does that entail? It almost feels like a prolonged (less violent death wobble. ) I had a truck tire shop with a hi speed balance redo the wheel balancing and he said all was good. I would really like some more input if you guys have any more ideas. Thanks Again. The tires are Yokohama 22. 5 mild tread pattern.

 

[Bob4x4]

pull the front drive shaft out and take it for a spin then you will have eliminated that

 

[Cosmo]

Yup, pull the front shaft and take it for a spin. That's the single easiest way to eliminate the pinion angle as a concern.