Mmr1

Are there Glk front rotors that don’t warp? I have 50% pad life left, pads are MB. Rotors are Zimmerman and have warped. I had them turned 3000 miles ago and they just warped again. They are junk. MB rotors also warped.
I think the rotors are to lightweight. I heard of Cryogenically treated rotors but costs are much higher. Any better ideas?

angryartichoke

I don't know if it's warping exactly but I get the pulsing brake pedal with my W221 rotors just like I did with my stock brakes.

​​​A few hard stops seems to calm it down for a little while.

Mmr1

That could be a build up unevenly on rotor , I went that route first and used a wire brush on a drill and retorqued everything. It helped for awhile . Then it got worse so I got a caliper to measure it . They were warped. I think the rotors are too light to take the heat once they wear down .

Odd Piggy

I don’t have the GLK any more so I can’t look on the rotors for the part number. After fixing them many times, I worked with the dealer to get the same diameter rotor from a different application that used ceramic pads. I think the front discs are 330mm and a number of MBs use them. That solved both the pulsing pedal and the excessive brake dust issues.

The dealer parts desk said that rotor material had to be matched to the friction material, so both rotor and pad part numbers changed. Calipers didn’t need to be changed.

Mmr1

I just looked at FCP , the rotors I saw were all 330 x 32mm thick. Did you purchase a larger size rotor than stock?

andreigbs

Unless you're riding the brakes our GLKs are really not heavy enough (or fast enough) to warp rotors. Nobody likes to hear that, but it's the truth in 99% of cases we hear about online.

Most likely the brakes were not properly bedded in when installed, which leads to uneven deposits because of hot spots. These deposits will cause shaking every time you go touch the brakes.

Find an empty road and do about 10 stops from 60 to near zero, but never stopping completely. I mean hard braking that trips the ABS, one after another, speed up back to 60 and hard brakes again, repeat 10 times. Then just drive around for about 8-10 minutes without touching the brakes (probably get on a highway and go for a few miles). You will have cleaned both discs and pads, should have no shudder/shake after that.

Mmr1

I stop fast when needed in Chicago , but I put it in park or neutral so pads are not touching . I used a gauge , last year they were 2 and the other one 4 thousandths out, that is warped. I had them cut and in 3000 they are warped again! Zimmerman rotors. Mb pads. I know I need new rotors , but I still have 50% pads left so yes they warped too early . I now have new mb pads and just don’t know which rotors to get, maybe the cheapest from FCP is best

andreigbs

My commute is into/out of that hellhole known as Chiraq, so I'm very familiar with the excellent driving taking place around there... I survive a 200 mile roundtrip commute on the days I have to be in the office, no brakes warping here.

If you're going to buy new discs, FCP is a great place to get them and it's where I got my last set which has been completely trouble free for the last 12K miles. I would have recommended ceramic pads, but since you've already bought MB semi-metallics, they'll have to do.

Once installed, do the brake bed-in procedure I described above.

MBKLUE

If you believe the rotors warped because they're too light then it makes zero sense to have them "cut" as they will end up lighter. Why would you be surprised they warped again after making them lighter?

Mmr1

I had to try it , I know I’m stupid, I just didn’t think they would warp so fast!

John CC

I replaced my rotors a few months back. I'm pretty sure they were factory original. No warping or pulsing; they failed because too much of the back side was rusted. Replaced them with Zimmerman rotors and Akebono pads. I've used this combo many times in the past with no issues (on other makes and models.)

Are you sure your calipers aren't dragging?