F82 Rear end vibration 75-80 mph

[emmfore]

My m4 has a very weird vibration through the car at all speeds but becomes very noticable at 75-80 mph with a bassy rumble from the rear of the car on the road.

Spent quite a bit of time trying to diagnose this with very little success , cluminating in recently replacing the diff with no improvement.

Things i can discount completely from this scenario is the wheels because we've had the car in the air with wheels off and run the car at speed with the same results. The harmonic of this vibration seems to be 74-80mph but it is evident pretty much all the time. There does not appear to be any visble parts rotating that are worn , clunking or rattling and all appear on the face of it to be running true.
This vibration is felt throughout the whole car but nothing through the steering wheel.
I have searched a fair bit but not seen much other than hard acceleration vibration.. Not in my case , its just at a given speed the intensity of this vibration becomes very apparent. Repeatable
I'm about to go down the propshaft replacement route but before i do , my current thoughts are some kind of engine/transmission to diff/rear subframe mis alignment as ( AFAIK) there is no universal joint on the propshaft and its a 1 piece direct connection so little margin for errors here and because the subframe is bolted directly to the chassis then transmission of vibration is going to be through these mounting points for sure.

It's a real head scratcher for sure and i'm putting this out there to see if anyone has had similar and a successful resolution.

[TheShadow]

Check your wheel bearings

[emmfore]

Originally Posted by TheShadow

Check your wheel bearings

I have replaced one wheel bearing to no avail , the vibration felt shakes the whole car and I very much doubt a wheel bearing will cause that effect. This has to be a reasonable mass rotating outside its own axis but as described before, the cars been in the air and run up to speed with no wheels attached and a proper visual inspection while running at speed with nothing obvious.

Going to expose the propshaft next amd check that out.

Anyone had driveshaft issues before before?, cars done 60k

[vrptstyly]

Solution?

[NYG]

Wheel bearings happen at a much slower speed.

I'd double check to see if you have a bent wheel or a balance weight missing on the wheel or drive shaft.

[emmfore]

The wheels were off the car and spun up ( to take wheels completely out of the equation)

We ran the car with prop exposed , no apparent issue there. Both wheel bearings have been replaced as has the diff and it has dumbed the vibration down a little but still very apparent.
Its not engine revs dependent , purely speed. The only other 2 things that have not been replaced that rotate are the driveshafts and the prop itself. but because the vibration type , we're going for the prop guibo next as although the prop seemed to run true there was a very very small oscillation about it. Once guibo done then we are going to drain the oil from the diff and remove the driveshafts , then run the car again , this time the prob being the only rotating part. ( for a short period of time should be fine with no load on the diff) Then add the driveshafts and see how we go .

[icebiker]

Spacers? Some folks have reported vibrations from certain spacers at exactly that speed range.

[RKP]

I had a very similar issue and it turned out my rear wheel had a slight bend.....almost unnoticeable to the eye. The wheel shop was able to make it perfectly straight and the car no longer vibrates anymore around 70-80 mph.

[kmouze]

I'd make sure your tires aren't damaged from potholes or whatnot. Looking for bubbles or unevenness in the tires. Had this happen before on my other cars.

[agentrnge]

Good luck. Super uneducated guess here, but I want to say the drive shaft is fairly constrained in its movement. So if it were out of balance/missing a balancing weight, it might not be apparent but still transferring that energy into the car. Can you get a feel for which direction/axis the vibration is? Mark the rotating parts with white grease/tape to watch the rotation to see if it matches the wobble rate in the car?

[vrptstyly]

Interested in some advice on this as well. This seems like the best ongoing thread before I start my own. Either on the problem itself or how to deal with BMW to get it resolved.

I have an 2017 F80 ZCP with 45k miles. Vibration comes on at highway speeds 70-75mph and gets worse 80-85mph, felt in the seats, armrests, and once it gets so bad even in the steering. Does it in different gears, dropping into neutral doesn't change anything. I've had the wheels checked and tried a different set with no luck. Checked bushings, wheel bearings, seem fine. Car is smooth otherwise.

Car has been to the dealer, and while they tried they weren't any real help. They could not duplicate the problem. Mostly because they wont take a customer car up to those speeds (lawyers talking). I mentioned concerns about the CV/driveshafts, they told me that a drive line imbalance would present itself at lower speeds. I'm concerned about how they would proceed, even if they could duplicate it.

I'm calling BMWNA on Monday and probably taking the car to a different dealer for another opinion.

[2011ninja]

Originally Posted by kmouze

I'd make sure your tires aren't damaged from potholes or whatnot. Looking for bubbles or unevenness in the tires. Had this happen before on my other cars.

Would be an extreme step but try load balance the wheels.

[deeldoo]

I have the exact issue, road balancing did nothing at all.

Had the car hoisted too everything is perfect, no flex or bend anywhere.

My rotors are bad though, i think this is it. Remember that while your wheel spins so do a lot of other things. If your rotors are bad/unbalanced, have tons of deposits, etc. They can definitely cause this at higher speeds.

Also i don't know about anyone else but mine gets worse when i have other passengers/weight in the car.

[///MCollection]

If it's coming through the seats it's most likely rear, after a run jump out and touch the wheel rims and make sure there similar temperatures side to side. I have put spacers on my f85 and now have a vibration at a certain speed so if you have spacers maybe worth a shot. Make sure the hub faces of both hub and wheel are cleaned with no grease on the face and also worth checking the driveshaft can be slid in and out on both sides. Also look for rust coming out of a up on prop or diff. That's about all I can think of for a minute but hope you find it.

[hoppes-no9]

My guess is wheel balance or wheel damage.

I chased a similar issue when I put on my first winter wheels/tires. Had to go to 3 different tire shops to find one that could properly balance the wheels. Learned that not all tire shops are equal and that the right equipment and know-how matter a great deal.

[maddmatth]

Is it possible to have a workshop take off the driveshaft and check it for balance?

I know regular driveshafts can be rebuilt and balanced. A carbon fiber one, not so sure... But I would think they could still check it to see if it is balanced.

[vrptstyly]

Happy holidays everyone!

OP any updates?

I've done my brakes chasing my vibration. I was having some shudder under heavy braking as well. Brakes are butter but no change regarding my highway vibration unfortunately.

I was able to study it some more tonight on some open road. At 85mph it's at its worst but car is smooth 110mph+. I was thinking something in the driveline as well, but it looks like you've eliminated a lot of it already.

I was also convinced that it was a wheel/tire issue, but I've had two sets of wheels balanced twice and nothing has changed.

I'm taking mine back to the dealer this week. BMW NA advised me to have them open a case even though the dealer initially dismissed that under the assumption that BMW would not participate in something like this at the speeds I'm experiencing.

See how things go.

[DML]

Are you the original owner?

[vrptstyly]

Originally Posted by DML

Are you the original owner?

I am not. Second owner.

[dezzracer]

I bet Driveshaft

[Jim B]

Originally Posted by dezzracer

I bet Driveshaft

Did OP get shafted?

[rams.rams]

whats the update OP