Vibration from the rear of the car between 75-85mph

Take it to the service center. They'll solve it for you , and you may get a new drive train whether you really need it or not

manni786 said:

So I thought it was my tires, got me new tires. Still there is noticeable shaking in the rear section of the car once you go over 75mph. Then I thought it might be my wheels, took it to a wheel straightening shop, while they were some adjustments they made, the car still shakes from the back. It is very smooth before the 75mph, but after that speed up till 85mph it shakes noticeably.


Anybody else has experienced this phenomenon ? I will appreciate it insight anyone else has in regards to this ? Can it be my control arms ? Bushings ? I had this issue on my 2001 740i at 55mph from the front of the car. Can it be a similar situation ? Anyone else has experienced this ?


My car


2013 P85+ with staggered rims.


25K miles. Daily driver.

Click to expand...

Yes, I experience the exact same symptoms you describe. I've experienced it since the car was new and, like you, have assumed it was a rear tire balance issue. I'm disappointed to hear that it may not be (I haven't had to change tires yet).

I have 12,250 miles on mine and no service center within 350 miles to take it to.

Mike

Did you try to do the pencil test to isolate what components might be causing the problem?

Methodology:

1. You need a second person.

2. Get a pad and a pencil or felt marker (not a ball-point pen).

3. Drive to where the vibration happens and where you can hold the speed for some time.

4. The person with the pad and pencil then taps the pad in time to the vibration for ten or fifteen seconds.

5. Calculate the dots per minute and compare that to the rpm of the tires. If it's similar, you know that the problem is with the tires, wheels, bearings, CV joint, etc. If it's much faster or slower, then it's some other component.

You went to a tire shop, but did they do the Hunter Road Force Balancing? (not all shops have the machine, my BMW dealer does). This is the only way to 100% eliminate the tires/wheels as the issue. You can have a tire that balances perfectly well, but is essentially not round when rolling down the road under force (may appear round when spun on a regular balancing machine). In all my experiences balance issues show up around 55mph with Wheel/Tire roundness issues showing up closer to 75-80. On my BMW, I spent months tracking down a high speed vibration and was not cured until I insisted they do the road force. Ended up being 3 bent wheels plus they needed to rotate one tire on it's wheel to eliminate a high spot which was identified with the road force balancer (they match a tire high spot to a wheel low spot and they cancel each other out).

Once this has been done 100% eliminating the tires, and the issue still exists, time to look at the drive-train.

I second the road force balance suggestion. I had an Audi TT with such problems, not fixed with repeated reg wheel balancing. One road force balance, and fixed, perfect. The higher skilled shops can do road force balance. They check whther wheel is true (not warped) as well as roundness and balance. One risk is small scratches on the wheel, since the sensors contact the wheel while spinning. Ask/warn them to be extra careful... -Alex