G37s Coupe.

I'm hoping someone can give me some ideas/suggestions on what may be causing these front-end problems:

I have a slight vibration between 70-80. I can feel it in the seat and see the steering wheel vibrate slightly. Been to the dealer twice and they did a roadforce balance on the front wheels. I had an alignment done at NTB while I had it in for a flat repair (rear tire.) Dealer says possible tire problem, but the tires are new (Hankook Ventus V12) and it didn't do it for the first few weeks they were on.

Appreciate any suggestions...

Thanks,
David

 

Sounds like a balance problem. It happens some times. Maybe the tire is ever so slightly out of round. Is it possible there's some rim damage and the wheel is slightly out of round? If it's not, and if they can't balance them to get the vib out, then you need to see about making a claim for defective tire.

 

The above is correct in regards to a defective tire. Did they weight balance it or actually shift the tire on the rim?

Why do you think it is in the front?

Rear wheels being out of balance will also shake the steering wheel. There is an adage that if the steering wheel shakes forward and back it is the rear wheels and if it shakes side to side it is the front. This is not really accurate anymore as suspensions have drastically changed. Which tire is causing the problem really depends on the resonance to speed correlation - in which you are experiencing the issue. You still may not be able to delineate which corner/side/end is causing your vibration purely from symptoms.

FWIW Do not rule out a balance. Too many ‘techs’ balance tires incorrectly; slapping weights in the middle is not the answer. There was a website somewhere that had a good description of the difference between static and dynamic imbalance. Most people do not consider the tire can be out of weight or out of round. All that said I have been unhappy with a balance job and taken it back 2-3 times.

There are many other reasons that you may be having a vibration issue. Spent or worn bushings, bent wheels, out-of-spec / bent suspension, alignment, ‘force variance’/soft or uneven sidewall stiffness, tire wear, etc, etc.

hope this helps...

 

bent rim, shot wheel bearings, bent camber/control arms
good luck!

 

I'm thinking out of round tire or bent rim (which essentially causes an out of round tire). Probably fades as you slow down as opposed to an abrupt start/stop at 70 mph. Probably also gets worse above 80, assuming you have a place to safely drive that fast. *insert random illegal/unsafe on public roads warning here*

Do you drive hard? burnouts? That'll warp the tires and leave them out of round often.