Help!!!! - Brake Shake
 

I have a '91 350SD and recently put new brakes and discs on it.

I used new Balo discs and PBR Pads Deluxe. I broke them in very carefully. Shortly after, I noticed that the steering wheel would shake when I lightly stepped on the brake. I took it back to my mechanic (MB Guy) and he thought it was one of the rotors. We carefully took the bump off the rotor. The car was great for a while.....now it shakes again.

It only shakes above 60mph, however, most of my travel is at 75-85mph. The brake components were checked out and all looks good.

What would you recommend for my next set of discs and pads?????

Help!!!

Thanks,
Richard

BTW, I changed the pads and discs a little prematurely because of a light squeal. The discs were fine but getting towards the end of their life.

These PBR pads don't squeal at all!

I'd like to get something both smooth AND quiet.

Pads
- Pagid
- ATE
- PBR
- Textar
- Juris
- MB OEM (from Dealer)

Disc
- ATE
- ATE Power Disc
- Balo
- Zimmerman Cross Drilled
- MB OEM (from dealer)

Also, can I change just the discs and leave the pads? The pads are only only 6 months old....

Thoughts?

It could be a sticking caliper that is causing some over-heat on that rotor. That would lead to rotor warp and then the vibration you are seeing. Need to check the temps of all of the rotors after some driving and then stopping with minimal or no brake use. The hot one or hot ones would be the culprits.

Don't quote me on this:
 

Someone here mentioned that worn sway bar bushings on the front would cause the appearance of uneven braking. :bulb: I guess if they are really worn?

It might be something to check. Just an idea.

If I remember correctly a member on the tech forum, Inted had problems with Balo discs on his S500. I don't know I guess a lot of people use them but you are not the first one to have problems with them. I guess the discs that are slightly out of spec are sold aftermarket. MB gets the perfect ones.

I have had great luck with ATE's 10k miles on them now and smooth as new.

What would you recommend for my next set of discs and pads????
 

First of all, the sway bushings would have shown up before the brake job I believe, not all of a sudden, but a front end check is advisable whenever this sort of problem arises.
Are you sure ASB isn't being activated for some reason? (like dirty sensors) Antilock and antiskid usually don't show up as a problem except at low speeds however, I just wanted to raise this as modern braking systems can be a little more difficult to diagnose than earlier ones.


The 350SD uses floating calipers, dual pistons too I believe, so if it is shaking during braking, then something is way out of kelter. I knew a man that owned one of these, it had the smoothest braking at 80+ MPH you could ask for. I believe the same brakes are on my '87 300D and they are perfectly smooth except at very slow speeds occasionally the ASB causes pulsing, not to be confused with shaking, pulsing can be felt in the brake pedal, warping is felt as shaking in the steering wheel and worsens under heavy braking.

I highly recommend ATE Power Discs, they make them for the front on the 350SD, they are slotted with a swirl-groove that allows gas to escape under heavy braking and also, when worn down, it indicates when you need to replace discs (handy, no?). I never used Balos, ATE has been my choice forever.
For pads are you using PBR metal masters by any chance? If so, that is your problem, dump them and use PBR deluxe pads or another pad, even the messy OE pads are not going to make your discs warp unless a piston is sticking (as was pointed out previously, its possible that during a brake job the installer damaged a piston by forcing it back over a lip in crud that builds up on the bore, then you have problems! It can be cocked sideways enough to drag, or it leaks fluid. I hope that isn't your problem :eek:
On the subject of Brake Pads. I like ceramic pads, I think you have to search for them for the 350SD, but if you find them they are smooth acting and as dust free as a pad can be and will not cause disc warpage. Best $50 I ever spent.

I use the ATE power discs and OEM pads on my car, they are very good, and have some REAL (smooth) stopping power. The old rotors I had were quite warped, the car would shake quite a bit slowing from above 45-50mph, worse the faster I went. My dad has the regular ATE's and those stop like heck too. The OEM pads make a lot of dust though, I don't mind it, I just wash it more often ;)

Wheel balance
 

A set speed vibration is almost always a balance issue.

Roy, it only shakes when he steps on the brake pedal. This rules out a balance issue.

Yes.
 

I would still rotate and balance tires for a speed vibration, very cheap answer.
Wheel bearings would be my next guess.

Perhaps the rotor/hub mating surfaces need to be wire-brushed.