Last ditch effort to eliminate dreaded brake 'chudder"

TurnAround · #1 05-05-2011, 12:30 AM

I've been living the nightmare of the dreaded X5 brake 'chudder' steering wheel shakes for about 4 or 5 years now. I feel like I've tried everything.

Its caused by uneven brake deposits on the rotors and the pads. Deposits are normal, and good. You want the brake pad material to transfer into the cast iron rotors. That's brake bedding. But, this layer has to be even, otherwise you have a 'grab' / 'slip' / 'grab / 'slip' chaos pattern that sets up a vibration with the brakes that transfers to the steering wheel. Replace the pads, massively rebed them in until smoking, or sand them down.. voila.. the chudder is gone for 2 months. .. until the uneven deposits come back. All cars get uneven deposits. Its the darned suspension design of the 5 series. I have two Z3's, both with 'no dust' pads and I've never had a single problem. The suspension arms are shaped differently and come in from more of a side angle. Uneven deposits don't cause vibrations.

On the X I've had the front strut arms replaced (that replaces both sets of front bushings). Made a 15% improvement. Still violent steering wheel shake when braking above 55mph.

I've replaced the rotors, and replaced the Centric Posi-Quiet ceramic pads (near zero dust.. is the attraction to these pads) with Stop Tech Street Performance pads to introduce some bite to clean off the un-even deposits. Same pattern. All great for 3 months, then the F-ing chudder is back! AND.. my wheels are completely covered in brake dust. Worse than factory pads.

I've made the following decision; I'm replacing the rotors one last time, but I'll use slotted and cross drilled in the hopes that it will introduce some 'anti-chaos' pattern for the brake pads. I'm going back to low dust pads. If necessary, I'll replace them once a year.

Another $400 and a weekend lost.

I'm so tired of this, but I don't know what else to do. I love my X5, but I hate the fucking brakes. Blackened trashed brake dusted wheels.. after only 5 days of driving, is unacceptable. But so is massive steering wheel vibration every time I brake above 55.

Any last ditch suggestion welcome.

JCL · #2 05-05-2011, 01:52 AM

I wouldn't be looking to the brakes at all, but rather to the front suspension. Something is loose. The brakes are simply setting it off. The shudder is in the suspension or steering linkage.

I certainly wouldn't put up with it for five years.

Edit:

Suggest you read these two threads:

http://www.xoutpost.com/bmw-sav-foru...installed.html

http://www.xoutpost.com/bmw-sav-foru...r-part-ii.html

TurnAround · #3 05-05-2011, 08:19 PM

Quote:

Originally Posted by JCL

I wouldn't be looking to the brakes at all, but rather to the front suspension. Something is loose. The brakes are simply setting it off. The shudder is in the suspension or steering linkage.

I really like and trust my indi mechanic. Of course, there's no way to tell for sure if he's just shining me on, but he assured me that he inspected and then torque tested all the suspension components and couldn't find any significant wear... except in those front struts. I guess I could take it back.

Since they were just replaced, its too late to go with the heavy duty rubber bushings. Although that's a great find. I'll keep that in mind... as I had hoped to keep this car for another 8-10 years.

I just seems to me that slotted and cross drilled rotors would introduce enough surface differentiation in the rotor that the pads would be less likely to 'dominate' with uneven deposits. I realize it wouldn't 'clean them', but still, there'd be less surface area to develop deposits on, right??

JCL · #4 05-06-2011, 12:44 AM

Quote:

Originally Posted by TurnAround

I really like and trust my indi mechanic. Of course, there's no way to tell for sure if he's just shining me on, but he assured me that he inspected and then torque tested all the suspension components and couldn't find any significant wear... except in those front struts. I guess I could take it back.

Since they were just replaced, its too late to go with the heavy duty rubber bushings. Although that's a great find. I'll keep that in mind... as I had hoped to keep this car for another 8-10 years.

I just seems to me that slotted and cross drilled rotors would introduce enough surface differentiation in the rotor that the pads would be less likely to 'dominate' with uneven deposits. I realize it wouldn't 'clean them', but still, there'd be less surface area to develop deposits on, right??

I wasn't promoting the HD bushings as much as showing how many other people had very similar symptoms due to looseness in the suspension. Personally, I would use OE bushings, but I am sure the HD would work fine.

The suspension holds the wheel in position, and a small deposit variation on the rotor (which only takes a few months to form) sets off the vibration when braking at highway speeds. Unless you have a heavily pulsing pedal at parking lot speeds, I would just focus on the suspension a lot more than on the brakes. That said, braking hard and late isn't easy on the brakes. You can get them hot enough that any pad contact while stopped can lead to more and uneven pad deposition. Given that driving style, a rotor that gets hotter faster because it has less thermal mass (ie a drilled and/or slotted one) is a step in the wrong direction. I would use OE rotors and whatever pad works for you. I would also look at the control arms, and would likely replace them just to see if it helped.

E55AMG2 · #5 05-05-2011, 03:33 AM

Do you ride your brakes around town? This seems to be a pretty common problem with people who seem to always be on the brakes. The rotors hotspot, and you get the juddering on the highway.

gerry_miranda · #6 05-05-2011, 09:22 AM

I used to have an issue with my M3 and X5. After some research it seems that BMW had these issues a LONG time ago and after much research on their part, figured out the proper combination brake pad compound and rotor alloy to avoid it. After trying many many diff combination...I went stock rotors and pads from the BMW dealer....no more issues on either cars.

E55AMG2 · #7 05-05-2011, 03:07 PM

I've seen it happen even with stock pads/rotors. Riding around constantly on and off the brake pedal (as opposed to letting the car coast) and mashing down on the pedal when stopped (vs just putting enough pressure to keep the car from idling away). These are the things that cause this sort of judder.

TurnAround · #8 05-05-2011, 08:25 PM

Quote:

Originally Posted by E55AMG2

I've seen it happen even with stock pads/rotors. Riding around constantly on and off the brake pedal (as opposed to letting the car coast) and mashing down on the pedal when stopped (vs just putting enough pressure to keep the car from idling away). These are the things that cause this sort of judder.

Not sure I understand. I don't drive in the city with my foot hovered over the pedal, and braking slightly and often, if that is what is meant. I'm generally a late braker. But.. you are mentioning another behavior that I do have; Once I'm done braking med to hard-ish and come to a stop, I let off all but the minimum pressure needed to keep the car from moving. I developed this habit after reading on forums that hard braking (that's me) followed by hard on pedal at a stop, can 'stick' the pad to the rotor from the heat not having anywhere to escape, and when you finally let off you 'pop' some of the brake pad material off on to the rotor face... IOW.. leave an uneven deposit. You're saying mash harder? Even after braking hard (lots of heat)?

E55AMG2 · #9 05-05-2011, 11:58 PM

Quote:

Originally Posted by TurnAround

Not sure I understand. I don't drive in the city with my foot hovered over the pedal, and braking slightly and often, if that is what is meant. I'm generally a late braker. But.. you are mentioning another behavior that I do have; Once I'm done braking med to hard-ish and come to a stop, I let off all but the minimum pressure needed to keep the car from moving. I developed this habit after reading on forums that hard braking (that's me) followed by hard on pedal at a stop, can 'stick' the pad to the rotor from the heat not having anywhere to escape, and when you finally let off you 'pop' some of the brake pad material off on to the rotor face... IOW.. leave an uneven deposit. You're saying mash harder? Even after braking hard (lots of heat)?

Nope. If you're braking late then what I described does not apply. From my experience, the folks complaining of brake judder (that dont have worn out bushings/ball joints) usually brake gently and ride the pedal for a long period of time. Then, once stopped, they mash the pedal down hard like the car is going to bolt away. This behavior is notorious for hotspotting the rotors.

I brake late and hard, then come off the brakes and roll till I need to stop. To stop, I use minimal pedal pressure to keep the car stopped till it's time to move again.

It's likely you've got a busted balljoint if your mechanic has replaced the thrust arm bushings and torqued them with the car weight on them.

TurnAround · #10 05-06-2011, 12:10 AM

Quote:

Originally Posted by E55AMG2

I brake late and hard, then come off the brakes and roll till I need to stop. To stop, I use minimal pedal pressure to keep the car stopped till it's time to move again.

That's me too. That's exactly how I brake. And, if I'm performance driving for fun and for whatever reason am faced with a full stop situation, I've even used the hand brake, once at the full stop, so that the rotor brakes had zero contact and could cool.

Thanks for the info. It sounds like I need to take the car in again and go through it with him (under the car).