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Discussion Starter #1
Hey guys,
I have a problem with my E34 M5 that has plagued me since I have owned the car. There is a distinct vibration coming from the rear of the car. You only feel it at certain speeds, like 30-35 mph, 50-55mph and it's most prominent between 80-95 mph. It "feels" like a tire out of balance or a warped rim, but it is not.

Here is what I have done to date to try and get rid of the vibration:

I have replaced all four of my 18" M-parallel wheels with brand new factory rims, and put new Bridgestone S-03's on the car, and they are perfectly balanced, so that is not it.

I have replaced all four shocks (Bilstein sports). I have had my mechanic check the entire suspension for bad bushings etc...to no avail. The suspension is Bilstein Sports surrounded by Racing Dynamics sport springs and RD swaybars (the green ones). The suspension does lower the car about 1 - 1.5 inches.

I thought it might be drivetrain related, but the vibration is present at the same speeds regardless of gear, engine rpm's or even if I have it in neutral out of gear with the clutch pushed in. For example, I drove today at 80 mph in fourth gear, fifth gear and in neutral. The vibration was there all three times.

Not being a mechanical genius, I am guessing that it has to be a moving part like the drivetrain or an axle that is always turning when the car is moving.

So, my question is this: Have any of you suffered from this and found the answer? Do any of you have any ideas for me that could help me pinpoint the possible cause of this vibration? Does the changed suspension geometry put any undue stress on the axles, differential or the drivetrain?

TIA for any help you can give me. I REALLY LOVE THIS CAR, but it is frustrating to drive such a nice car on a long trip somewhere and have the car vibrate the entire trip at cruising speeds.

Thanks
Robert Collins
 

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Rob,

I would first check the rear subframe bushings. These may seem OK, but are for a large part responsible for the cars stability. A visual inspection of these parts on my car did not show any faults (cracks), but I had some difficult to explain problems like vibrations around the 110km/h mark and a settling delay of the rear suspension when cornering.

I could not think of anything otherwise than the rear subframe bushing, replaced them as it is the cheapest and simplest part that can be replaced and hoped for improvements. After 4 laps on the Nordschleife and one trip to the Alps, I can say that my guess was right. No more vibration and no more settling delay of the rear suspension.

Second, the hardy disk (rubber damper between the gearbox and the drive train) may be cracked.

Good luck,

Raymond
 

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I surgest you check the propshaft, for loose or missing
fixing bolts...and especially the centre coupling,
then move on to the half shafts & bolts.
 

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EDC controversy continues

Hey guys,

I'm having a little difficulty posting a new topic... SO I took the freedom of posting it here
Anyways, I just bought a 1995 M5 Shadowline with 44000kms. It had only one previous owner and all check-ups until now have been logged at an authorized BMW dealer. The car is MINT.

My question regards the EDC. If the car has been babied by the previous owner and is in great condition, how much longer will they last until I have to inflict some serious damage to my bank account for new EDC shocks? (in terms of miles). IS it really that bad if I decide to put a conventional Hartge system and disconnect the EDC?

This ride kicks serious ***:)
Thank you
 

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After having removed my front wheels for cleaning, I experienced a kind of shimmy at 80kph (whatever the gear and clutch released or not) for a while until it disappeared by itself. Recently I changed my rear tyres and asked to swap the front and the rear wheels. Since then, the shimmy is back. I would describe as an hesitation of the car and I can feel it through the steering wheel. I doubt however that passengers can feel it (unless they are very sensitive and pay attention to it).
I think it is connected with the fact the wheels have been removed and and I expect it will cease like the first time :rolleyes:
 

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Robert
I had a vibration on mine for a 6 months:crying: like you I thought I checked everything.
Until I replaced the clutch,and found that the center bearing and rear gearbox mounts all cracked and split.
The prop center bearing is a hard one to check you have to remove the exhaust and heat shield, but its not that expensive to buy,
:cheers:
Graham
 

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Discussion Starter #7 (Edited)
Thanks guys

Raymond, my mechanic agrees with you to this point. He thinks it is probably the rear subframe bushings and says he has heard of this before.

His question for you (and mine, too) Do you replace all four bushings in the rear subframe? I assume you are talking about the larger bushings on the outer edges that sit vertically. There are also two smaller bushings in place that sit horizontally where the back of the subframe attaches as well. Do you recommend those as well?

One more question Raymond, do you think that any of the other bushings in the rear suspension could add to this problem?

Alan, I think your suggestion about the drive shafts and the associated parts is our next logical step. If it is not the bushings (the easier of the two to check and fix), then we are definitely going this route next.

I tend to agree with you on this one, but my mechanic says that the vibration is not fast enough or constant enough to be a driveshaft problem. What was your vibration like? He said if it was the driveshaft, then the vibration would be at all speeds and not come and go as speed increases. I actually thought different speeds could cause it to go in and out of balance. He is the expert though, so I guess we'll check the bushings first.

I'll keep you guys up to date. The Beast goes in for Round 1 of surgery on Thursday.
 

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my driveshaft only gave vibrations at 5-15 mph. car has 117K miles.
changed driveshaft and vibrations disappeared.
Bought a new driveshaft from the dealer. $550 was not much more than the rebuilts. it also came with a new flex disk and center support bearing.
mike wong
 

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Robert
If I remember it was on when I changed from 1st to 2nd and then depending on how many people in the car or how I drove itgrrrrrrr , Thats how I also remember going crazy trying to fix it:eek:
Since then I have also replaced all the rear bushes and had the alignment checked and adjusted,BIG DIFFERENCE:thumbsup:
Hope the op goes okay
:cheers:
Graham
 

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Discussion Starter #10
Hey Raymond, Alan Archer, everybody...

to everybody that responded to my first post, here is the update. The sub-frame bushings and the motor mounts have been replaced and we took it for a drive.

The vibration is still there but much more subtle now. Unfortunately, it IS stilll there, so we must now move to the second guess of what it is. We think the only logical conclusion is the drive shaft, and the corresponding parts.

Another question that came up, is the limited slip differential. Have any of you ever heard of the limited slip causing vibrations at speed or a grinding feel in the gas pedal during straight line acceleration?

Final comment, when my mechanic pulled the car off the rack and we drove it, there is now a SUBSTANTIAL THUMP coming from the rear end when you have it in gear and then hit the gas pedal hard. It is as if you are costing in gear with no gas, but when you do punch the gas the car is squatting down and giving one large THUD. Raymond, could this be the new bushings because they're alot harder and more firm than the old ones? Is this sound normal, or did the mechanic maybe leave something off.

Any help is greatly appreciated, as my warranty to cover these parts runs out tomorrow!!!

Robert Collins
 

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Discussion Starter #11
Hallelujah!!!

The warranty company is going to cover the driveshaft. So we're down to this; if it not the subframe bushings, if it is not the motormounts, and if it is not the driveshaft, then I'll give up. At that point, it will either be down to a ghost in the machine (Police album) or some wierdo automobile "harmonics" crap that I really don't care to hear about. I do NOT like dealing with problems that have no solutions, so hopefully we have this licked.

The only remaining question is this: Could there be a limited slip differential issue?

Thanks for anyone's help on this. I truly think the new driveshaft will take care of the problem though. It comes with a new center bearing and a new flex disc (and I think the U-joints are part of it as well).

Any other thoughts or comments are welcome as I look forward to losing this ghost.

Robert
:byebye:
 

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Robert

Not sure if this will help but also for the info of others on the board....

About two years ago on my 93 318is I had a weird lurch/low speed intermittent vibrations that I felt through the shifter and also sometimes at high speed 80-90. Everything was tight on the car and tires and rims had been roadforce matched twice. Finally, after letting my mechanic have the car for two days to drive back and forth to his house so he could get a sense for how the car behaved.... he finally pegged it to be the driveshaft center bearing. By looking at it and shaking the driveshaft it felt tight but upon taking it apart it was evident this was the problem (135k, was on 3rd flex disc but center bearing was original). Also, since all the other driveshaft/tranny mounts/rear sub and diff mounts etc were in such good condition it was masking the effect of this one parts failing condition.

Hope this helps ;)

PS - I hate vibrations with a passion and my mechanic knows it!
 

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Robert
For sure its the drive shaft (or just that center bearing)

I hope its not the LSD :crying: (but if it is,one good side you can change the ratio ):confused2

No like I said its the drive shaft :thumbsup: (I HOPE)


Good luck

Graham
 

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911/M5 said:
Hallelujah!!!

The only remaining question is this: Could there be a limited slip differential issue?

Robert
:byebye:
Robert,

I jusr received your PM and started to read this thread again. Due to a busy schedule, I have not followed each topic in this forum. That is why I did not respond to your post of 20 August. Shame on me. :eek: :eek:

Let's get back to business:

Now you have replaced the rear subframe bushings, there are other things that could go wrong. THe LSD differential is definitelly a possibility, but given the cost of this part I would not touch it unless it is absolutelly necesary.

It is not clear to me whether or not you replaced the smaller bushings in the trailer arms. Like the big rubber pots, these can be worn out also and would allow a larger movement of the rear axle. This in return would stress the bearings inside the diff when the rear axles would move to far.

The second possibility is the Hardy disk. This 'small' rubber donut between the gearbox and the driveshaft is meant to limt vibrations. Like any other rubber part, after 10 years, this part is worn and due for replacement. Especially on 300+hp car. You would not want the hardy disk to burst. In that case, the drive shaft would penetrate your car. Admitted, this hardly happens as the driveshaft bearing would decide to leave you much earlier. But the risk is there. When there are cracks in this disk, replace it. In general, it is best to replace this part every 60k miles or every 8 to 10 years.

The Diff could be a possibility also. Not the gearing itselfe, but likely the bearings. This is not an uncommon failure, but most people choose not to repair this as this is an costly exercise. Especially on cars that have been used hard without replacing the fluids in time, can suffer from this.

Good luck,

Raymond
 

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Discussion Starter #15 (Edited)
GDA, g, and Raymond,
Thanks for your input. I am getting the driveshaft replaced tomorrow, so we'll see after that.

Raymond, the flex disc (guibo) was replaced within the last 15,000 miles, so I seriously think that is not it (although nothing is impossible.)

The small bushings in the subframe were not replaced, but my mechanic looked closely at them and determined they were in much better shape than the big ones. That would be my next choice, though.

My mechanic let the fluid out of the LSD yesterday and said it was clean as a whistle, so I doubt there is anything wrong there either. He refilled it with Redline, so hopefully that would make any potential feel coming out of there a little smoother. I really asked that question because that part is connected to the problem, but we had not discussed any potential problems that arise out of it.

Anyway, it will probably be mid-week next week before the drive shaft is in, so I will keep you all up to date.

Thanks again for all your help. The people on this board really do go out of their way to help each other out, just like the Porsche 993 board on Rennlist.

I'll report back soon.

Robert Collins
 

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911/M5 said:
Raymond, the flex disc (guibo) was replaced within the last 15,000 miles, so I seriously think that is not it (although nothing is impossible.)

The small bushings in the subframe were not replaced, but my mechanic looked closely at them and determined they were in much better shape than the big ones. That would be my next choice, though.

Robert Collins
Robert,

OK, let's assume your mechanic draw the right conclusion about the condition of the trailer arm bushings. Then, only the driveshaft and/or the LSD remains.

If the hardy disk has been replaced just 15k miles ago, you must check if the driveshaft is properly alligned. Be sure your mechanic does that. If not, you continue to keep problems.

Rgrds,

Raymond
 

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While we are on this area I would like to ask about a different but probably connected fault.

On the odd occasion that I spin the wheels, from standstill or not,
there is a very loud BANG BANG BANG from the nsr wheel.

My mechanic has replaced the larger subframe bushes which were slightly split but cannot find any other faults from a visual inspection.

What and how should be next on the list or would a main dealer be best to seek the problem.

The banging is more pronounced on a dry or grippier surface and has been worse since fitting Bridgestone SO3's.

Thanks

Andy
94 3.8
 

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Hmm,
last time i had a nasty bang from the back of a 5 series
it was the anti roll bar drop link.
I did the mother of all standing starts (in my 528) on
a grippy surface & snapped the drop link clean in half !

This is the little cast double ended link piece that connects
rear roll bar to trailing arm.

However Andy, i'm affraid your problem could be driveshaft
related, the only way to tell would be to raise the vehicle
and give the diff & drivetrain some close inspection...
rotate the wheels & so on to see if there's any undue
movement/play in the shafts.

Regards,


Alan.
 

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Discussion Starter #19
Well, one more update for this never-ending thread (thanks for all the help, by the way).

The shop has put on the new drive shaft, to go with the new rear sub-frame bushings and the new motor mounts. The car now feels tight as a drum, but still has some minor vibration at random speeds. My mechanic has made all the aforementioned repairs, as well as checking the limited slip for any problems, replacing shocks all the way around and new control arm and bushings in the front of the car.

I hate to say it, but I must conclude that this vibration I feel has to be either:
(1) some problem with 4 BRAND NEW 18" M-parallel wheels with slightly worn S-03's, or
(2) the car simply has some resonant vibration due to the stiffness of the suspension etc...

Don't get me wrong, this vibration is very bearable, very slight, and is only there at random, so I can live with it, but it is frustrating as hell to do everything you can to fix something only to have it linger around.

Since the wheels are brand new, I think the only culprit wheel/tire wise could be that I rotated the tires from l-r and r-l, meaning fronts and rears swapped with each other. I did this because, as you all know, S-03's are uni-directional. Uni-directional tires combined with the negative camber these cars have drastically shortens the life of a tire. If you rotate side to side, the inside tire lip on each side becoes the outside tire lip on the other with a uni-directional tire. (I hope that made sense). Could this possibly be part of the problem? If so, no one has ever told me NOT to do it, including the place that does it for me.

Alas, if it is some resonant (harmonic) vibration, I do not think there is anything I will be able to do short of returning to the original wheels, tires, suspension etc... or just selling the **** thing and getting a 740iL (cushy) so I can float to work every day instead of vibrating to it. :eek: :rolleyes:

Anyway, thank you guys for all your help, and please let me know if you think of anything else.

Robert Collins
 

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:rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes:

Shock mounts ???

Just my twopence

Steve Mac:cheers:
 
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