High speed vibration
 

Hello I am hoping someone can give a second opinion/ suggestions for my issue I’ve been trying to figure out for some time. I’m experiencing aggressive vibration/shaking on the floor, seat, shifter and steering wheel when accelerating past 140km/h (87mph). I rechecked alignment, tire balancing and re torque suspension/mount bolts, no play in suspension components.
2019 370z 6MT 44,000km (27,340mi)
- SPL FUCA
- SPL rear camber and toe arms
- bc coilovers
- aftermarket wheels and brand new tires less than 1000km with correct hub centric rings
- hotchkis front and rear sway bars
- stock bushings
Alignment spec:
Front
Camber -1.5°
Caster 5.1°
Toe 0.08°
Rear
Camber -2.9°
Toe 0.14°

Have you checked your driveshaft. See if there is any grease splatter up above the U-joints.. also see if it gets worse by lightly pressing the breaks. And it could be in the stearing. The shaking in the stearing wheel is sonthing to check into.The rear camber would be lil high for my likings closer to -1.5 will have alot less ware.

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It is the tire balancing 99% of the time. Did you install a cheap set of wheels or cheap tires. This makes it more difficult to balance them correctly.

I’ve noticed a bit of grease around the heat shied where the u-joint sits at. It’s currently on te37sl with Firehawk indy 500. It gets better when I brake and decrease speed.
I agree -2.9 is a bit aggressive for street driving but not sure if it’s due to the ride height of the car, but I’m maxed out on threads for positive camber.

When did the vibration/shaking first appear? Did it appear following one of your suspension upgrades? You may be able to isolate the source if you retrace the timing of the upgrades to the beginning of the vibration.

Hard to isolate the source since I did all of the suspension upgrade at once, I noticed the vibration/shaking concern last summer. I don't have a way of swapping parts since I sold most of my stock components..

Time travel starts at 88 mph. Have you upgraded the vehicle to handle the bending of time and space?

Tire balance is the most likely culprit if the suspension is installed correctly.

Update: Replaced driveshaft assembly, swapped back to oem wheels and rebalanced. Still having vibrations about 120km/h (75mph). Where else could I inspect for rotational vibrations?

Maybe do the wheel bearing checks too?
Top to bottom and side to side…


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I had similar issues with my first z no matter how many times the wheel was rebalanced it would still vibrate, I worked at a Vw dealership at the time so I had access to the balancer didn’t know what was going on. Anyways took it to the Mercedes store which was owned by the same company they had a road force balancer which is much better than your standard and simulates road conditions when balancing. Problem solved. Try getting your wheels roadforce balanced

So not to say the obvious but were the wheel mating surfaces to the wheel hub properly cleaned? Then were the wheels properly torqued in a star pattern with the proper bolts for the new wheels? Just a thought.