[k1f1]

Hi guys,

I drive a 2005 320D E90.
I've noticed in the last 3 months that when I brake the steering wheel vibrates and it's getting worse. I don't notice any vibrations anywhere else other than in the steering wheel.


It happens at low speeds ~50km/h and high speeds 120km/h

All pads were replaced about 3,000km ago. Rear calipers were also replaced at the same time.
I don't drive the car much - maybe 220km every 2 weeks (I get the train to work, visit my parents once every 2 weeks ~100km away).

The front drivers side tyre has a slow puncture - it goes from 32psi to 27psi in 2 weeks.
The vibration is still there immediately after I pump it.
I also can't find where the injury is in the tyre - there is a cut in the sidewall but it doesn't look like it's deep and so I'm not confident this is the issue (although a possibility?).

My ideas:
Tyres? Could the nick in the sidewall cause this?
Solution: 2 new front tyres fitted (Cost ~€120)

Tension strut/Lower control arm replacement?
Is there any way to check if these need replacing?
Solution: Follow guide at http://www.e90post.com/forums/showthread.php?t=778726 (Cost ~€150 + Tracking €50)

Tracking?
Could the car (wheels?) be out of alignment and need to be tracked?
Solution: Bring to garage to get tracking fixed (~€50)

Balancing?
Wheels need balancing?
Solution: Bring to tyre fitters to balance, or maybe just get new tyres altogether (Cost ? / ~€120)

Anything else to suggest?

My initial thoughts also were a warped rotor, but after some reading some people suggest that modern rotors do not warp.

Thanks for any help!

[Boland01]

The car will judder if the rotors are warped. I wouldn't discount that as a possibility.

[jwebb335xi]

Originally Posted by Boland01

The car will judder if the rotors are warped. I wouldn't discount that as a possibility.

+1. Check, or have a shop check rotor run-out

[jumbosrule]

Originally Posted by Boland01

The car will judder if the rotors are warped. I wouldn't discount that as a possibility.

Warping really does not happen anymore - hasn't for years.

Uneven pad deposition on the rotor is the cause. Re-bed the pads by getting them hot (in a safe area). Rotors with this issue are suddenly cured from bad run-out when re-bedded.

WARPED ROTOR MYTH
http://www.stoptech.com/technical-su...nd-other-myths

BEDDING
http://www.stoptech.com/technical-su...and-procedures

What kind of pads did you install? Did you install new rotors at the same time? If no, what kind of pads were on the car before your new ones?

[Jaronbwall]

Go ahead and blast some mountain/canyons and don't cool down your brakes before stopping. See if there warped after that.

[jumbosrule]

Originally Posted by Jarronbwall

Go ahead and blast some mountain/canyons and don't cool down your brakes before stopping. See if there warped after that.

They won't be. You are depositing hot pad material unevenly on the rotor. Any runout or thickness variation is due to pad material, not miss-shaped metal.

This is exactly why you don't use your brakes when coming off a track session - you will "imprint" pad material onto the rotor - you can actually see the shape of the pad on the rotor, and feel it every time it passes under the pad.

You learn something every day!

[jwebb335xi]

Originally Posted by jumbosrule

They won't be. You are depositing hot pad material unevenly on the rotor. Any runout or thickness variation is due to pad material, not miss-shaped metal.

This is exactly why you don't use your brakes when coming off a track session - you will "imprint" pad material onto the rotor - you can actually see the shape of the pad on the rotor, and feel it every time it passes under the pad.

You learn something every day!

Would lightly sanding the rotors, cleaning with brake clean and re-installing them clean off the pad material without "damaging" the rotors?

I have gone through the "re-bedding" process in the past. It absolutely worked once, but on another occasion it did nothing and I was told be a reputable shop that runout was too large, rotors too thin and I should replace. I ordered and replaced as recommended; all good after that.

[jumbosrule]

Originally Posted by jwebb335xi

Would lightly sanding the rotors, cleaning with brake clean and re-installing them clean off the pad material without "damaging" the rotors?

I have gone through the "re-bedding" process in the past. It absolutely worked once, but on another occasion it did nothing and I was told be a reputable shop that runout was too large, rotors too thin and I should replace. I ordered and replaced as recommended; all good after that.

Actually yes - you can clean off pad material by lightly sanding the surface, but it can be difficult to do evenly. No brake cleaner needed.

Once a rotor is worn too thin, turning it to remove pad deposits is no longer an option. Re-burnishing could be an option but not a guarantee to fix thickness variation. If you have ever over-heated your pads, they may not re-burnish properly.