I need some help.....

I recently purchased Prostar XP 17x9 for the rear along with a set of Nitto Drag Radials. Now I purchased these rims because the 16x8 Prostars I had were bent. Let me also say that I did experience a slight shake about 70-80mph. Now that I have the new rims on I get this shaking (not vibrating) around 50 mph. it feels as if I have rims in the shape of an egg...if that gives you any idea of the shaking. But after 50mph its seems to kind of go away. Yesterday I took the rims & tires back to Mr. Tire to recheck the balance and they are definetly in balance. Is there a certain way that this combination should be balance? maybe they are doing it wrong???

I have LCA, relocation brackets & panard bar...all Sphon equipment.

No I have been looking on this forum for some common remedies but can't seem to narrow it down.....

I have an aluminum drive shaft with the orignal U-joints. Hard to believe as my car snatches 2nd & 3rd Gear. Could this be the problem?

Please help ! ! !
:hail:

 

My first thought would've been balancing, but you said you had that checked. My next thought would possibly be a slipped belt, but the tire guy should've caught that. The only other thing I can think of at this point is maybe over-inflation. How much air do you have in them? Keep in mind, I'm only throwing out ideas here. My Jeep appears to do the same thing, but only between about 73 and 78 mph (weird huh), and I can't figure out what the problem is.

Did you let the place that mounted the tires and wheels take it for a drive? Maybe you can act like it's their fault (who knows, it might be), and you can get them to figure out what the problem is.

Good luck,

Eric

 

Do you have access to a set of stock rims and tires- if so the you should try temporarly borrowing them to drive on and see if there is any difference. If not then it must be in the axle or driveshaft.

 

Put the rear axle up on jack stands, with the stands under the axle tubes; run the drive train at 40 mph or so; and watch for wobbly wheels. If one wobbles, trade the wheels from side to side; if the wobble goes to the other side you have a bent wheel (not likely but not impossible either); if the wobble doesn't move, you have a bent axle (more common than most people realize).

 

Bring the car back to the tire dealer . Tell them u still have a vibration , and you want a road force test done to the tires . what the raod force tire balancer does is put a load on the tire with hydr. roller , simulate the road . It can then determine how much soft or firm the tire is . Think of a tire like bunch of coil springs . If you have one section of really hard coil springs in the tire , or hard spot , then tire wont absorb the road the same as it rotates ( im not good at explaining things) So if the road froce detects more than accetable , which is about 25lbs , then the tech will have to measure rim runout , or warpage . He can then determine if this hard spot is due to bad tire or a high spot in the rim . After the runout the machine will calculate if it can bring the tire and rim combo back into accetable readings by spinning the hard spot into the low spot on the rim , a.k.a match mounting , if not one will have to be replace , tire or rim depending wich is at fault .
I personally have 4 bad tires , with hard spots in them . All are them are from 25lbs -34lbs . Its from letting the car sit for 1 1/2 years . I have a vibration at 70+ . I also have seen perrellis ,(spelled it wrong ) on a 2001 one saab just off the truck , so out of round when i drove above 25mph i couldn't hold the steering wheel , no kidding it was that bad . I didn't road force the tires on that car because that dealer was to cheap to spring for a 30k hunter balancer .
Well i hope thats kinda clear what i tryed to say , like i said not good with explantions . If you have any questions let me know .

 

KUDOZZZ TO CAPPY AT SUMMIT RACING.

When I purchased these rims from Summit (didn't order from Cappy) the salesman informed me that since I already had Prostars 16x8 rims that I would be able to used the same lugs on the new rims. That is where the problem lies.... the hole on the new XP's requires a 1/2" shank. The lugs fit loosely in the holes and at speed (50mph) the wheel shifts and isn't centered on the hub which gives a "egg" shaped whobble. It makes total sense when you think about it. I also called Weld and spoke with Dan about the problem and he reinfored what Cappy said. These wheels require a special Lug (part #6011912) 12mm x 1.5 but the shake is 3/4". So for anyone getting these rims please keep this in mind so you don't have the hassel I had.

I am so relieved because I had planned next week to get my driveshaft balace and U-joints replaced and also have my axles checked. Who would have thought that one piece of "bad" advice might have caused so much trouble.

Thanks to Breadfan, RB83L69, AGood2.8 & Eric's85TA for all of your input on my problem. I have found a salesman at Summit that really cares about satisfying the customer and getting me the correct product. You can reach him at extension #5835.

THANKS AGAIN CAPPY !!!!!

 

That would certainly do it!!

Glad it was so easy.