Vibration Diagnosis After Last track Day

[b_w.]

Hi F80 team. I have a 2016 m3 6mt that developed a nasty vibration or grumble after my last track day on Monday and trying to figure it out.

I have done 9 days this season and the car has about 72,000 km (45,000 miles) on it.

I have been running stock blue brakes with PFC 08 pads and high temp fluid. No idea if the stock rotors have been replaced. I have owned the car for 1.5 years.

vibration is noticeable from about 35 kmh on (20 mph +/-) and it stays constant up to high way speed, although the frequency is not quite as harsh the faster I go.

I just replaced the front hubs thinking that was the cause and no help. I feel it in the front drivers floor plan.

Suspension looks tight, no visible leaks from the diff.

I replaced all diff bushings with a turner dual mount and power flex bushings. Trans mounts with rogues. Fresh bolts all around.

Before I order new rotors is there any other usual suspect i should be looking at? Vibration is not RPM dependent, stays constant with clutch in or out, and varies in pitch as speed increases.

All work was done back in the winter. Only change was coilover springs.

supposed to be at the track this afternoon but feeling I am not going to have this sorted in time.

If this sounds like a rotor issue I can order today and have them early next week .

Appreciate any suggestions.

[D_SheerDrivingPleasure]

Could it be a wheel imbalance? Are you using spacers?

Vibration from the rotor would only be felt when applying brakes so I would probably rule that out.

[b_w.]

Pulled spacers and no change. Going to toss stock wheels on later as well.

[b_w.]

437s back on and vibes are gone. Off to the tire shop to see whats up.

[D_SheerDrivingPleasure]

Originally Posted by b_w.

437s back on and vibes are gone. Off to the tire shop to see whats up.

Could be as simple as a melted off wheel weight. Be sure to apply HVAC tape over the wheel weights so they don't fly off and unbalance your wheel...and bust a windshield on track.

[torpeteo]

Is it a vibration or a grinding/groaning coming through the chassis/driveline?

[b_w.]

It was rotational groaning. Have not put the wheels back on yet to retest but tire shop said both rears were out of balance.

[robbo mcs]

What do the tires look like?

Sometimes a combination of wear and/or rubber pickup from the track surface can cause this

[b_w.]

Tires had some pickup on them for sure.

Rebalance helped but not completely. Might just have to chalk nt01s up as having more nvh than the extreme contact forces they replaced.