AMG3.2

Hey all,

My buddy and I are going to be installing new front wheel bearings on the C32 in the coming week.

With that said, now seems like a good opportunity to go ahead and replace and bad brake parts.

Per the pictures blow, do my front or rear rotors look bad?

The front rotor (drilled pic) looks like it has a pretty big lip that has accumulated on it from wear.

I'm not to sure about the rear, but it doesn't look too bad.

Please let me know what you guys think!

Thanks!

Supgee

There's not really too much visual inspection you can do on a brake rotor. Unless it is blueish from overheating or has obvious gouges. The rotor surface wears in thousands of an inch. The Only way to truly know if the rotor needs replacing is to check the thickness with a caliper and then measure the surface runout for uneven wear.

91RS

It's good practice to replace the rotors with new pads. They're cheap enough on these cars anyway.

fleishman

Min "allowable" rotor thickness is 28mm New rotors are 33.5 mm thick says my feeler gauge.

I'm replacing mine today too! I just did wheel bearings. Note: re-tighten wheel bearings after driving if you don't have a set gauge! I replaced mine last week and found play in them today doing rotors! I set tight again and backed off 1/4 turn. No more play.

Also: last owner of the car installed 13" rotors, my new ones are 13.6". My pads are only at half life but the rotor wore a groove in and i can't get away without new pads.

fleishman

Pics of wrong size rotor..

fleishman

New rotor

AMG3.2

Thanks for the help guys!

How much were OEM pads and rotors?

Also, thanks for the hint about the wheel bearings.
I bought the following parts.

Timken Bearings
MB Bearing Grease
Rear dust cap ($9.99 at the dealership)

Any other parts I'd need?

fleishman

Are you doing front or rear wheel bearings? I bought the front kit came with new lock ring in addition but i wouldn't say that is a necessity. I used one full tube of grease per side.
Rears need a press i believe.. Search i find a few diy write ups.

Two front rotors $220 shipped from parts.com $135 each at local dealership. Napa 4 front premium pads $104.

AMG3.2

Just the fronts. Wow, a whole tube of the OEM grease?!

saer1one

Stick with OEM pads, zero brake dust..

pointman

+1. New formula. They are fantastic.

AMG3.2

Really?

Saaboteur

If you're gonna do the brakes, might as well get pad sensors too - they can break easily on removal, plus they are cheap to buy new, like well under $5. If memory serves you only need two.

fleishman

Only one sensor on my passenger side front. Came out fairly easily but I agree for $5 it wouldn't be worth taking the wheel off again if you did break it.

Each front wheel bearing kit came with one tube. After packing both inner and outer bearings, filling the back the hub, i used the remainder in the dust cap and forced it into the bearings when tapping the cap back on. When i removed the caps most of the grease had worked its way into the hub while driving.

Zeppelin

I agree if you got 60k out of the pads. In my case I have gone through 4 sets of pads with the original rotors. No point changing them if they are well above the minimum thickness.

AMG3.2

Thanks guys.

I'll try to be careful with the sensor. Worse comes to worse, I just pick up another one at the dealer.

Are there any other little parts I'll be needing for front pad/rotor install? I'll be ordering parts tonight via parts.com.

saer1one

In my case the torx screw that holds the rotor on the hub was rusted.. I stripped the head on two screws, I just replaced all four at $2 each..

Garrett@Oscaro

You should use a micrometer to check the thickness of the rotor. A cheap micrometer is available for around $20 from a discount tool store. As leishman says, if they are thinner than 28mm, its time to replace them.

In my own personal experience, I would recommend replacement if there is noticeable wear. This wear comes in two places:

1. At the inside and outside of the rotor, showing the surface the pad touches
2. 'Ripples' or 'Grooves' in the rotor surface, where the pad touches.
3. When performing brake work, carefully remove the ABS sensor and clean any metal particles off the magnet, as it will increase your ABS system performance.

We currently have the OEM pads for $67.94: Genuine Mercedes Front Disk Brake Pad from Oscaro

The OEM rotors for $118.80: Genuine Mercedes Front Disk Brake Rotor from Oscaro

A complete front wheel bearing kit, which includes the inner & outer wheel bearings, inner & outer bearing races, wheel seal, dust cap, spindle nut, and grease for $49.50: Genuine Mercedes Front Wheel Bearing Kit from Oscaro


This is a very good call. It's very frustrating to stop your project for one of these sensors should it break, or stops working after pulling it out and re-installing it.

We have one from Bowa, the company who supplies these sensors to Mercedes, for $7.91: Bowa Brake Pad Wear Sensor from Oscaro

And as always, shipping is always free on orders over $65.00.

Other than the parts listed above, I would recommend a few other parts:

• Purchasing brake parts cleaner to remove the manufacturers coating form the brake rotors
• During installation, applying anti-seize to lubricate the disk brake hardware

And some other helpful tips I've learned:

• A good breaker bar is helpful for removing the calipers bolts.
• When compressing the caliper pistons with a c-clamp, be sure to open the brake bleeder screw, as the fluid can't back feed through the ABS module without potential damage

Your car has a fixed caliper setup, which makes it very straight forward to work on. Good luck with your project, and be sure to post up pictures of your progress & final result!

AMG3.2

Awesome! ^

Last question y'all: I've read that some Mercs need to have some electronic braking thing disabled before working on the brakes which could be dangerous. I'm pretty sure I also read that the C-class doesn't have this system and all is safe in terms of DIY.

I skim so many threads on this forum that I forget what I actually read down the road.

saer1one

I didn't disable anything when I worked on mine.. ESP came on for a couple minutes after starting the car but then disappeared.. Never came back..

pointman

Not on our cars.

AMG3.2

Thanks!

AMG3.2

Y'all, I'm having a bit of a problem.

Every time I try to compress the the caliper on one side, the other side seems to pop out.

How do you compress the calipers so that both sides of pistons stay in?

This is for the front btw.

Thanks!

ghiaguy

make sure the fluid reservoir cap is open - that will help with the pressure.

AMG3.2

Yup, I had it open but I was still having the problem.

Luckily, I was able to use a c-clamp with the old pads to keep one side from popping out while pushing in the other side.