[BlueNGT]

Afternoon All

Apologies as I sure this has been done to death before. I have judder through the steering wheel when applying the brakes fairly heavily from circa 70mph.

I have a very string feeling there are pad deposits on the disc(s) - the reason I am sure of this is when coming to a stop slowly I can actually feel through the pedal and steering wheel as if there are peaks on the disc surface (hard to describe).

How do people go about getting this checked and then cured?

The car is a 2006, UK, E90 330i...

Thanks in advance

[- LB -]

There is a good chance your control arm bushings have expired. Are they original to the car? You typically replace the entire control arm with the bushing, that is how they are most commonly sold.

There is a similar discussion happening here:
http://www.e90post.com/forums/showthread.php?t=908294

The description to the problem may read differently but I think we're all referring to a similar problem if not the same.

Brake rotors could be unevenly worn causing this judder. It's hard to detect such a problem, start with a process of elimination from any parts in the brakes and front suspension you may have recently replaced and go from there. It could be a combination of issues like some guys reporting in the other thread.

I myself had a pretty extreme "judder" under braking at high speed and found a night and day difference after replacing rotors and pads. Hope you find the source of your problem.

[1QuikWS6]

If it is actually pad deposits on your rotors - normal braking should eventually remove them over time.

One method that is used is to purposely install a set of particularly abrasive pads - they will remove the deposits (& some of your rotor ), then you switch back to your normal pads. - still better than turning the rotors or trying to sand by hand.

Some others say to use a wire brush in a drill while rotating the disks to burnish the deposits off.

Then there are others that say to soak the rotors down with window cleaner, then go out and conduct bedding procedure - claiming that the ammonia in the cleaner reacts at temp to remove the deposits quicker

[BlueNGT]

Thanks for reply fella's.

I forgot to add that my car is an Auto so of course more prone to the pad transfer.

I had read the other thread and also experience the slight 'shimmy' whilst traveling at 60 to 70+mph.

I see people recommend the M3 control arms - where is best to get these in the UK?

Are the M3 arms a straight swap?

Any other arm/bush worth changing at the same time?

Thanks

[rdub315]

I would try going through the bedding process to see if that helps.

http://www.coolcarbonperformance.com/bedding.html

[BlueNGT]

rdub315 - thanks for that but the vibration is so bad from hard braking this achieves no results at all and I avoid hard braking whenever possible.

[ajsalida]

Rather easy to confirm or refute your hypothesis, take the wheels off and look at the disks. Also, given how old your car is if the pads haven't been replaced yet they may just be severely worn, rotors warped etc. So inspect pads & thickness. Manually turn rotors, look for warping, loose stuff, etc.

Hard to tell without getting your hands dirty, but easy to rule out simplest things just by visuals.

[serotoninsteve]

How has this pad deposit happened? Over a long period of time or by breaking hard?

Usually if there is pad deposit on the disc it will heat more at this spots.
This changes the metallic structure of the disc, the hotter it got the lower under the surface it will transform.
This is invisible to the eye, but even when you choose to get them resurfaced the deposit will eventually form again depending on the deepness of the spots and the material they remove while resurfacing.
It depends on the disc's actual thickness of how much you can remove while resurfacing.

Regarding the work, the time the car is out off order and the price you pay for resurfacing I would replace them and call it a day.

Brake disc aren't that expensive anymore (as long you don't purchase them from the stealer).

Here is a good read regarding this:
http://www.stoptech.com/technical-su...nd-other-myths

Originally Posted by 1QuikWS6

One method that is used is to purposely install a set of particularly abrasive pads - they will remove the deposits (& some of your rotor ), then you switch back to your normal pads. - still better than turning the rotors or trying to sand by hand.

Agreed. I wouldn't turn them, just buy new ones instead. There's no telling how "true" the machine will turn them and removing material from the rotor, in the first place, will make them more prone to depositing pad material again IMO. It's just not worth it.

[BlueNGT]

Car will be in for a service soon so will get some new discs fitted then. What brand do people rate? I've seen Pagid and Brembo also Eicher, Apec and Bosch.

Is it the general thinking that at 70k miles the control arm bushes are past their best and new arms would wise to get rid of the judder and very mild steering shake at speed (all wheels have been balanced)?

[Meeni]

In order check:
lug bolts on wheels are properly tight
inspect tire for bulges/pot-hole damage
inspect wheels for pot-hole damage
inspect control arm for play
inspect rotor for "pad marks" (should look like a shadow that has the shape of the pad)
have the wheels rebalanced