This is definitely NOT normal for the M5. Could be alignment, wheel out of balance, failed bushing. Sorry for the hassle - but get it fixed!

 

Originally posted by Need4Spd:
After I drive the car a while on the freeway, sometimes when I have to use the brakes moderately, the initial application sets up a shimmy in the steering wheel. If I step on the brakes hard a few times, it goes away. Any ideas on what's causing this? Warped rotors? But there is no "pulsing" when I use the brakes under any other circumstances. Odd, isn't it? Anyone else experience this?

How many miles on the car? I strongly suspect one or both front wheel bearings. These bearings are a known weakness on the E39s and will cause exactly the symptoms you described. Tell your BMW service writer that you suspect your wheel bearings are exhibiting excessive runout after they've come up to temperature. After they are replaced, I expect your shimmy problem will vanish.


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Dave Z.

 

Could also be excessive bearing runout (I think it is technically called hub runout)or loose/improperly torqued rotor-to-hub bolts. The shimmy will be more pronounced if you have upgraded to a fixed piston big brake kit. BMW specs runout very loosely to avoid bearing warranty work and then uses floating calipers to isolate the runout, making it less noticeable. This is a relatively common problem in E39s and early X5s (before they switched back to the traditional single nut assembly). Greg is right - take it in and have it looked at. You could also go to knowledgeable mechanic who is skilled at measuring (and isolating) hub and rotor runouts.


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143366
'00 E39 M5
'97 E39 540i six speed

 

Shimmy....check in the following order.

1. Lug bolt torque...should be 100-110nm
2. Wheel bolts, if different from stock, should be checked for proper flange seat diameter
3. Wheel runout...look for the obvious, ie, a bent wheel.
4. Rotor runout....measured cold
5. Hub/bearing runout......mesured hot
6. Suspension damage or wear.

A comment I made ahile back regarding the X5 bearing change was inaccurate. The AWD cars (X5 & the old 325ix) use a sealed bearing unit that looks like a rear wheel bearing. In April 2000, the bearing was increased in size from 45x85x41 to 49x90x45...the opening in the knuckle assembly had to be made larger to accommoate this size increase. Perhaps BMW could increase the size of the E39 bearing as well. SD

 

Thanks for the clarification Steve.

You wouldn't happen to be Steve "The Ultimate Garage" D would you?

If so, you had earlier suspected that the M5's clutch problems *might* be the result of a bogus profile gasket. Have learned any more since then? I'm real curious.

 

Sounds brake related to me. This happens with faulty calipers or rotors warped or worn down. I noticed the same problem in my E320 driving at high speed for some miles and then getting on the brakes hard. Mine is a faulty caliper, it wears pads down unevenly on the one side. Pads come out 3 80% and one 30%, go figure.

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Jim
07/00 M5 Titanium over Red

 

I've noticed a front end vibration, but not related to braking. Seems to come on at exactly 70mph, grow to about 80 and then reduce a bit, but not completely. Dealer took off fronts and re-balanced yesterday, but the vibration is still there. Car is a new '01 with 2300 miles on it. I'm at a loss and the dealer's not making much effort to research further. Gave me BS about the tire tred being aggressive, thus the vibration! I asked when, then does it only occur at 70+ mph, and on any road surface. No reply!

 

Thanks for the advice. The wheel bearing diagnosis sounds like it's the most likely problem. I'll get it checked, along with the rotors/calipers.

 

I have noticed the same on my car, particularly when braking moderately at highway speeds and steering slightly left.

God I love this board. Nice to know there are common problems out there.

 

Yep. Called to make an appointment today and before I got to finish the sentence and say "shimmy," the appointments person finished it for me.

 

Steve's list is fairly concise but I would add a few to his list:

1. Lug bolt torque...should be 100-110nm
2. Wheel bolts, if different from stock, should be checked for proper flange seat diameter
3. Wheel runout...look for the obvious, ie, a bent wheel.
4. Rotor runout....measured cold
5. Hub/bearing runout......mesured hot
6. Suspension damage or wear.


- tire runout (side to side)
- tire round
- wheel round

If it's ONLY under braking, I suspect warped rotors 90% of the time. Then move on to the others, starting with hub/bearing runout.

Why does it only happen at certain speeds? Because vibrations are strongest when they hit a certain resonant frequency. In this case, the wheel vibration matching the resonant frequency of the rest of the car / suspension. Typically, this is usually around 60mph. The fact that it's 70mph in this case could be due to the stiffer suspension.

 

Thanks. I suppose it could be rotors, too. I played around a bit more today and the amount of shimmy increases with brake application at higher speeds, i.e., there's more shimmy at 80 than at 60. Like I said, however, a few hard applications and the amount of shimmy goes down regardless of speed.

 

I had exactly the same symptoms and the problem turned out to be that one of the brake pad retaining pins was missing ... light pressure and the pads were probably moving around ... heavier pressure and they were probably holding firm.

 

So Need4sp, what was it?

 

I haven't posted because I didn't get the car fixed until today. I actually haven't tried it out on the freeway yet to make sure it's been fixed, but the dealer found warped rotors and replaced both front rotors and pads. If it's still there (seems doubtful; my computer tells me they, uh *thoroughly* test drove it), I'll post more, but hopefully that's it. BTW, if someone wants a Titanium Silver/(all) black interior M5 w/aluminum trim, BMW of SF has one. They're asking +15k over MSRP, but given the way the stock market is going, I'd bet you could do some haggling, and you'd not have to wait months to take delivery.

 

Took it to high speed today (won't say how high!); seems cured. Knock on wood! Now I have to discipline myself to take it easy for a bit until the new brakes bed in.

[This message has been edited by Need4Spd (edited 05 April 2001).]