Around 75-80mph I seem to notice the whole car start vibrating in a cyclical manner.

It comes and goes.

I look at my passenger seat, and it's shaking a little bit.

Does this sound like driveline or tire balance issue?

 

How many miles? Definitely start with wheel and tire balance, check for play in suspension. Also check the condition of your motor mounts(brake torque test). I've had a similar vibration that is noticeable at those speeds, gets really bad above 90 mph. I plan to replace them next weekend. All of the suspension has been already replaced and wheels and tires.

 

I'd go get a road force balance. It usually solves my vibration issues.

 

If you feel the vibration in your butt or feet, then a rear wheel is out of balance.
If you feel the vibration in the steering wheel then it's a front wheel.
Yes, it can also be due to engine/gearbox mounts, the prop-shaft middle bearing, or suspension issues, but the most common cause is a wheel weight has dropped off.

 

agree on the balance. I can attest that you can drop a weight but also the car is susceptible to not having a wheel on just straight?
Road force balance if possible but not a MUST.

Start w the basics and remind them (nicely) to please hand torque. Who knows how they were torqued....

 

I would look at tire condition, central bearing and rubber mounts at first.

 

155k miles
michelin pilot sport tires brand new put on 1/2/23
tein coilovers - under 15k miles
new lower ball joints
new lower control arms
new lower control arm bracket bushings
new front wheel bearings
new brakes


tires installed / balanced originally at Discount Tire. Usually Ive had good luck with them in the past.

 

Similar issue solved by Road Force balance at Discount Tire. I have also had good luck with them, however, some of the locations in my area have the Road Force balance equipment and some do not. You might want to go into the back and ask the shop manager to show you the machine. I did and they didn't seem to mind. The doughnuts I brought the guys in the back didn't hurt.

 

Yep. tires or rims. Mine was at 55 mph. Replaced tires and that helped, but a bent rim (that I could not see till I checked runout with the wheel on the car and a gauge) was the culprit. Replaced ALL four wheels and the problem disappeared! Bingo.

 

I will also say balancing the front and rear tires should be your first step. I had an issue with a GS 430 that had a constant vibration after changing the wheels and tires and changing the motor mounts, it ended up being a worn transmission mount. Fairly easy to replace, but made a huge difference. I even had a shop check the transmission mount from underneath, and it looked fine, but after it was removed, the rubber was all torn and obviously causing the vibration in the drivetrain.