BMW M5 Forum and M6 Forums banner
1 - 20 of 28 Posts

·
Registered
Joined
·
153 Posts
Discussion Starter · #1 ·
Well, i knew it wouldnt take long before an issue cropped up:

Having had the car a month now and having put 500 miles on it since its new pads i took her out for some spirited driving. When i say spirited driving i mean 1 or 2 straight line sprints down my local private road (no corners). The car has performed perfectly since i picked her up, braking at normal road speed has been nothing other than normal. However;

Last night on the first run (in M mode, M Dynamic on, S5 shifts, Suspension on sport) i hit 100mph and applied the foot brake. What i got was quite a serious vibration through the steering wheel. Not expecting that i took my foot off the brake (now doing 80) and reapplied it to be sure i wasnt imagining it. It vibrated again, but less aggresively, and then when below 70 it stopped vibrating completely. I then took it back round for a second run.

I decided to take it to 115mph this time and instead of applying the brakes in stages i would apply it at a constant medium wieght until the car came down to 40mph. So, at the stated speed i put my foot on the brake. Again the vibration returned but i didnt lift off. As soon as it dropped to 70 it just stopped vibrating.

I then drove around the local loop of roundabouts and slow roads to see if there was anything amiss at all at low speed. With my left foot lightly on the brake and my right holding the speed at 30 i could feel no vibration or movment of the pedal. Corner braking and braking to a stop were all fine with just the normal faint grind that you get from having drilled discs. From there i headed back home.

Now, the car had new discs all round not that long ago, maybe 3k or so. Its not been pushed hard and there is no sign of any excess wear or much of a lip. When i got the new pads fitted i followed the bedding in procedure and didnt do any high speed or hard driving until last night when i was sure they were well bedded (which i wouldnt say was anywhere near hard for this type of car). According to the I Drive i have 8k left on the pads and the fluid is due next march so its not like im late for anything.

Anyone got any ideas? I do have an insured bmw warranty so if the discs are warped (possibilty?) is this something that will be covered? Any chance it could be an ABS issue as it only vibrates above 70?

Eddie
 

·
Registered
Joined
·
6,353 Posts
Check the shims! Usually, the brake pads do not align perfectly to the rotors hence upon expansion ( heat ), they shake! Believe it or not, I have this problem on my StopTechs!
 

·
Registered
Joined
·
153 Posts
Discussion Starter · #4 ·
Out of interest, what is the correct bed in procedure for new pads and discs on these cars? Just want to check i got it right.
 

·
Registered
Joined
·
1,535 Posts
I had the same problem, 70+ Speed vibration, the dealer told me I had a bent right front wheel. Since I got the new wheel the car has been great but on rocky roads the steering wheels vibrate, I don't want to go back to the dealer but I might have too!
 

·
Registered
Joined
·
6,353 Posts
Out of interest, what is the correct bed in procedure for new pads and discs on these cars? Just want to check i got it right.
Bedding procedure is simple:

Find a stretch of road with no traffic. Get up to 70mph and brake hard ( without activating ABS ).. DO NOT come to a stop, accelerate once again and repeat this procedure about 8 times. ( NEVER come to stop with brakes applied fully ).

Cruise at moderate speeds for about 5 minutes to allow brakes to cool down!

Repeat this whole procedure once more... finish off with the cruise.

You are all set!
 

·
Registered
Joined
·
153 Posts
Discussion Starter · #7 ·
I had the same problem, 70+ Speed vibration, the dealer told me I had a bent right front wheel. Since I got the new wheel the car has been great but on rocky roads the steering wheels vibrate, I don't want to go back to the dealer but I might have too!
Not convinced its a buckled wheel myslf as it only occurs under braking. I'll redo the bed in procedure again.
 

·
Registered
Joined
·
6,353 Posts
Not convinced its a buckled wheel myslf as it only occurs under braking. I'll redo the bed in procedure again.
DO NOT do that! If your shims need to be looked at, you will warp your rotors if you try this bedding procedure!
 

·
Registered
Joined
·
25 Posts
I had a similar braking symptom plus a bit a vibes in the steering wheel around 55-60mph (w/o braking). After a couple of visits, service dept found the left front wheel had a bad bearing. Good luck to ya.
 

·
Registered
Joined
·
153 Posts
Discussion Starter · #11 ·
I had a similar braking symptom plus a bit a vibes in the steering wheel around 55-60mph (w/o braking). After a couple of visits, service dept found the left front wheel had a bad bearing. Good luck to ya.

Thanks mate, i think i'll pop her into my local dealer and see what they say. Ive got BMW Insured Warranty so im hoping it'll be covered.
 

·
Registered
Joined
·
153 Posts
Discussion Starter · #12 ·
Ive just been out in the car again (after some research and thinking about shims) and attempted a 're-bed' of the pads. All went well and the discs look a lovely uniform silver colour with no excess material deposits or obvious signs of error. Once that was done i took her down the 'private strip' for another higher speed brake test. Same issue crops up again. The brakes are fine below 70mph but above, say 100, there is a definate shake in the steering (not the brake pedal), sometimes quite violent. From that i reckon we can say that the discs and pads are fine and that i should be looking nearer the suspension /control arms / bushes / ball joints. Only thing for it is to book her into BMW and see what they find (thank god for my Insured Warranty). Ive now taken to leaving the car in 1st when parked up with no handbrake applied to see if this helps but i really do think my problem is suspension / steering based.

Another thing i noticed was that there is a very slight vibration in the steering when cruising at 70, but you only see it when you take your hands off the wheel. Bushes? or something similar?
I'll keep you posted when she goes in.

Eddie
 

·
Registered
Joined
·
18 Posts
lol. Either that or the very bruised dogs. Seems im following you around the forums at the moment.

I was thinking the same lol although maybe I've been following you! Joined this forum quite a while ago but only recently started using it after buying an M5.

I'm still not sure where to locate the horn unit (I think one has stopped working) - I don't want to go taking the whole bumper off if I can access via a headlight or similar. At this rate I'll have to call BMW!

Good luck.
 

·
Registered
Joined
·
153 Posts
Discussion Starter · #18 ·
I've taken a look at www.realoem.com but either I've missed it or it doesn't contain the info I need.
Fair enough. I take it you've put your head in front of the bumper while someone presses the horn? Might be a quicker way of establishing where it is exactly. Just protect your ears a little. Failing that, phone DMS or similar in the morning and ask them how to get to it.

Eddie
 

·
Registered
Joined
·
18 Posts
Hmmmm...you obviously have a fully functioning horn?!! I hate the idea of using mine as it sounds so wimpy lol. So no, I haven't done the obvious. I've read access is via bumper removal but it may be accessible via a headlight - maybe!

I'll call them in the morning.
 

·
Registered
Joined
·
153 Posts
Discussion Starter · #20 ·
Did some research today on the cars previous repair history and came across this:

New N/S/F shocker due to vibration around 60mph and was found to be leaking - June 2010.
Both Lower front control arms replaced due to wear - October 2010.

Could this be a suspect issue / repair? The car is booked in to BMW next wed and is going for an inspection on saturday at my local BMW specialist as a pre warning / assesment.

The trouble is that because the shocker was replaced under manufacturer warranty it wont be covered by parts warranty as the manufacturer warranty ran out in the summer. The 2 year parts cover only applies when the repair is done after the cars 36 month point. Lower control arms will obviously be covered by parts warranty. My own BMW Insured Warranty wont cover it either as ive not owned the car for more than 30 days. Poo! Here's hoping its a cheap fix.
 
1 - 20 of 28 Posts
Top