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Discussion Starter · #1 ·
I recently purchased a 2000 M5 with the Dinan stage 1 package. 88K miles and I love it, but there is a mystery vibration that has been unsolved by high speed wheel balance, alignment, suspension adjustment (on BC coilovers and I had them raise the car up slightly as it was VERY low) and even a detailed inspection by a BMW only shop. The peculiar details are that the vibration only occurs over 65mph after a few miles of hwy driving. It begins low and gradually increases to become so severe that I have to pull off the hwy. If I come to a dead stop for a moment and hop back on the hwy it is good for however long I need to drive from there. It seems to be coming from the rear of the car and feels like wheel hop. The BMW shop did determine that one of the axles was going bad so it was replaced and I had hoped that was going to solve it, but not so. The tire shop certainly made improvements as one of the wheels were not seated properly and severely out of balance, but still not truly solved. I am at a complete loss. I would blame the differential, but it was rebuilt about a year ago and it doesn't make sense that coming to a resting stop would 'solve' the issue for the rest of the drive... I am desperate for answers and ideas if anyone has heard of anything like this.

PS: trying to resolve this issue to sell the vehicle as I'm going through a job change and I need to unload some toys unfortunately - this was a second, recreational car. In case anyone has interest...
 

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Guibo and driveshaft center support bearing. Could show up as rotating masses get warm, and rubber becomes more flexible. Or a tire with a belt issue.
 

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Discussion Starter · #3 ·
Guibo and driveshaft center support bearing. Could show up as rotating masses get warm, and rubber becomes more flexible. Or a tire with a belt issue.
Thanks. So if it was a tire issue, this would not go away after coming to a dead stop and should be identified when wheel and tire are being balanced - right? So seems maybe the Guibo and drive shaft should be focused on...agree?

But does it make sense that after coming to a resting stop that these would settle into place and be ok after getting back onto hwy?
 

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Next time it happens pull over then check the wheels for heat. The DSC units for these cars have been failing more frequently and one of the ways they fail is to apply a brake to straighen the car out in their computer mind. Just a guess in the dark but worth your time. Don't touch the rotor as so many have in the past or you will burn your finger, the hub will be warmer than the others.
 

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The last guy was trying to solve this - he sold it - tires and wheels are the first to be checked - then steering and brakes. Driveshaft is next - is it balanced? Is the center bushing / bearing assembly healthy, is the Guibo ok - if it is new, ensure it is installed in the correct orientation? This is fiddley detail work. When the car was up on a lift, did anyone shake the driveshaft? The driveshaft has a CV joint at the back as well. Swapping wheels is my first thing to try, but you may not have a set to swap.
 

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Discussion Starter · #6 ·
The last guy was trying to solve this - he sold it - tires and wheels are the first to be checked - then steering and brakes. Driveshaft is next - is it balanced? Is the center bushing / bearing assembly healthy, is the Guibo ok - if it is new, ensure it is installed in the correct orientation? This is fiddley detail work. When the car was up on a lift, did anyone shake the driveshaft? The driveshaft has a CV joint at the back as well. Swapping wheels is my first thing to try, but you may not have a set to swap.
Yeah...I really appreciate that guy. He is on this forum somewhere too... anyhow, I don't have a set of wheels to swap, but I would think the tire shop could determine if the wheels are the issue since they do a 140mph balance - right? They've discovered no issue aside from some balance being out, but nothing crazy. We'll find out when I pick the car up tomorrow. They checked the suspension and made adjustments per my request but nothing stuck out. So my next stop is back to the BMW shop to have them look more closely at the driveshaft components as you pointed out. There was some play in the CV joint and so one of them was replaced when in the shop and it improved, but it's still there...so I think that must be the source of the issue and just determining which part is in need of 'help.' I think maybe just replacing all of it (short of the diff) might be the best route. Love when car enthusiasts don't fully disclose issues and then ghost you when you ping them after sale for some ideas and direction...
 

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There are CV joints on the axles - but the back of the driveshaft has a CV as well. That is the one I meant in my response. I will say that a driveshaft imbalance would likely not change - it would not get better or worse. How old are the tires? Can you have them spin balanced after being driven and warmed up? Maybe that could help rule them out - and just the rears, from what you describe
 

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Discussion Starter · #8 ·
I think I have isolated the problem to the rear end components for sure. Just picked the car up after being raised 20mm, tires rotated and high speed rebalance and alignment. Drives smooth, great. Until that vibration comes from rear end. I pulled off the road and put my hand on the wheels as someone suggested here and sure enough, the rear wheels are HOT - too hot to lay your hand on vs the front wheels which are just appropriately warm. So there is obviously something WRONG. I pulled the service paperwork and found that the shop that rebuilt the differential in February recommended replacing the drive shaft joint as it was "a bit notchy." Doesn't look like that was executed and may be the next place to look...
 

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I pulled the service paperwork and found that the shop that rebuilt the differential in February recommended replacing the drive shaft joint as it was "a bit notchy." Doesn't look like that was executed and may be the next place to look...
That would not make both wheels hot. Repeat but this time take a squirt bottle with some water. Spray the rotor with one shot and if it steams it is the ABS acting up, nothing else will make the rotors that hot other than the brakes dragging.
 

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Discussion Starter · #10 ·
That would not make both wheels hot. Repeat but this time take a squirt bottle with some water. Spray the rotor with one shot and if it steams it is the ABS acting up, nothing else will make the rotors that hot other than the brakes dragging.
I will try that. This doesn't seem like something that would dissipate and be ok once coming to a resting stop though, right? I will note that while it does subside once I come to a stop for about 5 minutes, the wheels remained very hot upon arriving to destination 10 miles later.

DSC should also throw some codes, no? This is my first BMW so I don't know...
 

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This doesn't seem like something that would dissipate and be ok once coming to a resting stop though, right?
You would think the ABS module would throw some codes or turn the lights on, but no. When they fail they do it very well. There have been a couple of examples of one wheel having the brakes applied but only at a certain speed. There is no rime or reason. Some will have a brake on with the car off but be fine over the DSC threshold speed of 10 kph.
There is not really a good way to test it unless you by pass the DSC unit. All you can do is get close to a diag and then hope like heck you are right.
 

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I know you are looking to move on from this car - but if the rear brakes are getting this hot - the bearings are going to have taken a beating. If it was the outer CV that was bad, look at that corner first.
 

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Discussion Starter · #13 ·
You would think the ABS module would throw some codes or turn the lights on, but no. When they fail they do it very well. There have been a couple of examples of one wheel having the brakes applied but only at a certain speed. There is no rime or reason. Some will have a brake on with the car off but be fine over the DSC threshold speed of 10 kph.
There is not really a good way to test it unless you by pass the DSC unit. All you can do is get close to a diag and then hope like heck you are right.
Spray bottle investigation was a good idea. Sure enough, the rotors are HOT in the rear when the vibration has begun. Still weird that after a ~5 minute stop it is good to go to destination. Tried turning off the DSC but still had issues on a later drive. So looks like we're getting closer to the root cause now.

I know you are looking to move on from this car - but if the rear brakes are getting this hot - the bearings are going to have taken a beating. If it was the outer CV that was bad, look at that corner first.
You're right. I will have this checked too. Whether I fix it or not will determine on estimate, but I will make sure it is disclosed to any potential buyers. There is some noise coming from rear aside from the vibration and it is relatively minor, but definitely sounds like a wheel bearing that could be on its way out.
 

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Still weird that after a ~5 minute stop it is good to go to destination.
If it is an on off thing it is likely the module(electric controller) rather than the hydro side. Just send it to module masters or one of the Ebay stores that do this. If they find nothing when they get it, they often have no charge. The reality is you want to have the work done regardless as most of these things need the resolder and cleaning.
 
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