DIY- rear brake pad replacement
 

So i got around to replacing the rear brake pads in my 2008 C350 today. Oddly my rear pads ran low before my front pads, I expected it to be the fronts to go first since most of my experience with other cars has been that way. But I will outline the steps to replace the rear brake pads below. I did not replace the rotors this time around and I have not changed the front pads yet either. Please note that I am not a mechanic or certified to work on cars in any way so please read the following and work on your car at your own risk.

The procedure to replace the rear pads was quite simple and if you have ever done it before, it will probably take you an hour after reading this. I have installed Duralast Gold pads which have a limited lifetime warranty from Autozone they cost about $50, the dealer wanted $200 for the parts and labor, here you can do it for about $50 and one hr. of your time. Oh, also please note that I was close to setting off my brake sensor but it did not hit the rotor yet, so I didnt have to replace mine, but you may have to replace yours. Unfortunately, I did not take picture of the procedure, but I will try to be as descriptive an verbose as possible.

Tools that you will need:
17mm lug wrench
floor jack
jack stand
wheel chock
7mm allen wrench
flat head screwdriver
caliper spreader tool
brake quiet paste
new brake pads.
new brake wear sensor (if needed)
1/2" torque wrench & 17" socket

1. loosen the lug nuts on one of your rear passenger wheel (this side has the wear sensor)

2. lift the same side with your floor jack, and secure with jack stand and chock your front wheels.

3. remove the lug nuts and your wheel.

4. remove the two dust caps behind the caliper which are covering the two carrier bolts which are holding the caliper to the caliper carrier.

5. use your 7mm allen wrench to loosen the carrier bolts, there is no need to completely remove the, but you can. I had to push them out from the front with a thin screwdriver since they are held in place by rubber boots.

6. use your flathead screwdriver to pop the brake pad spring from the caliper. This spring is held in palce by two holes on the face of the caliper and it wraps around the caliper. It is held in place by tension. I just popped the top leg of the spring out of the retaining hole on the face of the caliper, its easy to do and once the leg is out, the spring is easy to remove.

7. pull the caliper off of the rotor, you will be pulling it to the left if you are facting the caliper, make sure that you put the caliper on a surface or suspend the caliper so that it is not hanging by the brake line, this can damage the brake line. I used a small stool and put the caliper on top of it.

8. use your caliper spreader tool to push the piston back into the caliper, this will allow you to put the new thicker pads into the caliper. I bought an effective & easy to use caliper spreader at Autozone for $9.

9. unplug the wear sensor wire from the caliper. It is the wire that is plugged from the inner brake pad to the back portion of the caiper. It is tight because it has a rubber seal, but just pull it straight out and it will pop out, be careful not to damage this if you plan to reuse it. Next pull the inner pad out, it is held in by a few spring clamps but if you pull it straight out with even pressure it will pop right out.

10. If you are reusing the wear sensor, carefully remove it from the inner pad and reattach it to the new inner pad. I used a screwdriver to help remove the sensor, if you have a new wear sensor, attach it to the new inner pad. The sensor has a pin on it and it goes into a hole that is drilled into the inner pad, you will see what it looks like once you pull out the old inner pad.

11. remove the old outer pad, when i removed the caliper, the outer pad remained on the caliper carrier and did not come off with the caliper. simply remove the pad, it is not held on by anything at this point.

12. apply the brake quiet to the back surfaces of both brake pads. I tend to overapply because i dont want any squeeks. the pink stuff i bought has a 10 min cure time.

13. pop the new inner pad into the inner (piston) part of the caliper, where you took the old one out of ealier.

14. attach the wear sensor wire to the caliper, just push it in all the way as it was when you pulled it out.

15. replace the outer pad on the caliper carrier.

16. slide the caiper back over the rotor and in position so that the carrier bolts are lined up with the holes on the caliper carrier.

17. screw in and tighten the two carrier bolts that hold the caliper onto the carrier.

18. replace the two dust caps that cover the carrier bolts behind the caliper.

19. reattach the brake pad spring, this can be a little tricky, and what i ended up doing was putting the bottom leg of the spring into the bottom hole, and then letting the bottom of the spring set in place around the caliper, then i put the top leg of the spring in the top hole, and then while holding this leg in place with one hand, push the top loop out and to the right, far enough so that it pops into place around the caliper. it should look like it did before you removed it. look at the drivers side as a reference if you need to but its pretty clear once you are looking at it in perosn.

20. replace your wheel and put lug bolts back on in the criss cross pattern. tighten as much as possible.

21. lower car, and torque lug bolts to spec.

Thats it, now you just have to do it for the driver side, but that side does not have the sensor wire, so skip the steps that instruct you to remove & replace it.

One strange thing I noticed about the Benz pad design is that a lot of the pad material is wasted because of the pin that is driven into the pad itself. In my pervious BMW, more of the pad could be used because the sensor was thinner. It looked like I had only used a little less than half of my pad, but the sensor was getting close to being triggered, however there was plenty of pad left IMO.

Anyway, i hope this help you guys! If any of you have more experience than I do please feel free to correct any missed steps or bad advice i may have given.

good writeup.

how many miles do you have on the car?

If the sensor goes off, is it ruined, or can it be reused even if it goes off?

i have 45K on my car. If the sensor goes off, it needs to be replaced, it can not be reused.
I have seen them for $5-$15 online.

I'm sorry if this comes as shocking, but I have never replaced brakes on any of my cars. As I am only 19, this is my second car. On my first car I only had for 2 years and have never had to do it. Being as this car I bought, I was wondering if you could answer a few questions I have:

When I talk to mechanics they always say that you have to "cut the rotors" but how the heck do you do that? And why do you have to do that? Wouldn't the correct term be to resurface the rotors such as to sand them down, or am I not understanding? I thought the rotors where the circle drums on which the wheel mounts to and the brake pad surrounds? How do you cut a circle thick piece?

Secondly, in reading your post I noticed that you complained about the sensor not allowing for full wear on the brake pad, and in your opinion, you could have got a significant amount of use out of the pad. My question is, is it possible to simply remove the sensor in total (much like the driver side) such that I can use the entire pad (Of course, I would monitor brake pad thickness so as not to damage my rotors. Contrary to the typical belief, I do pay for my car despite my age, and while I won't skimp out if I have to, where I live, dealers charge an average of $500 simply for rear pad replacement alone! So if I can save $450 here and there, I would certainly love too...

If not, would it be possible to buy the BMW pad sensors that are lower profile for the BENZ?

Thanks!

1. I think your mechanic is talking about resurfacing the rotors which makes them flat again, this is not always necessary.

2. you have to use the MB sensor, as the bmw sensor is different & wont fit. Also, i would not recommend taking the sensor out & driving with it plugged in but not mounted to the pad because the pad has a hold drilled into it so you will be missing part of the pad once you hit the drilled out portion. Basically, no I wouldn't do this, although it is possible to do.

I am for DIY and saving some cash by doing things yourself, but when you do it yourself, you still have to do it right, otherwise, its a hack and you can have unpredictable outcomes. If you are not mechanical or experienced, take it to the pros. An indy mechanic will charge less than the dealer.

Of course, I would never dream of doing somehting like this myself until I watched someone first, and even then be a bit leary. I just figured it never hurt to ask any questions, I am a very curious george, haha. I will be doing my brakes and rotate my tires with my father who used to be a mechanic years back (was making sure I didn't have to do anything special on MB compared to his old fords).

I'm sure he knows, but what would I use to go about resurfacing the rotors?

Secondly, I know I shouldn't do it every brake change, but how often - Should it be done every other brake change?

Thanks for the info!

Resurfacing rotors are not a DIY that im aware of, you will need to take it to a shop. You dont have to resurface them every brake pad change, usually only if they are uneven. Also, note that last time i checked, drilled or slotted rotors can not be resurfaced.

jctevere:

Resurfacing rotors is a reconditioning operation that is done on a lathe. It is done when pads have grooved the rotors (digging unevenly on the surface), generally from overuse, or the rotors are worn unevenly. With drilled and slotted rotors is not a recommended practice. Rotors are marked with fabricated thickness and minimum thickness for installation after rework. You will see that we are talking minute differences that have to be measured and done with precision tools. Thickness is usually measured on seven points with a micrometer, and warping (or rather flatness variations) with a stationary gauge while the rotor is turned in place.

As rule of thumb, a rotor is replaced every two replacements of pads. This is not allowing the pads to touch the rotors with the metal base plate.

Sensors are an integral part of your brakes and nothing to be tossed out since they are the best tool to tell you "Go replace your pads". Remember you bought a Mercedes, so you cannot dress it like somebody with a dress suit over an undershirt, no socks and sneakers.

You are on the right track, so if you get your dad's guide and look up shop manuals you'll do OK and shall enjoy your wheels.

@delerium when you pushed the roter back in did you over flow the master?

Delerium, Thanks for the write up. All filed away !! Carsy.

No it did not overflow the master.

nice!

I just put Akebono's on the front and rear. I was so tired of all the brake dust on the rear wheels. This was the first time i've ever done a brake job and I was pleased at how easy it was. Thanks for the DIY information, it helped me feel comfortable doing the work myself.
Ben

I'm glad the information was helpful!

I've got about 81.5K miles on my 2008 C300.

The brake pad light has not come on. I don't hear any screeching when applying brakes but I do have that uneven braking that you feel when the rotars need turning.

Should I just go ahead and replace the pads and rotars?

Hello Jim ,

An inspection will reveal all. You may only have to renew the fronts or rears depending on your driving style.

At 81,500 miles ( 130,400 kms) they do not owe you much.

Well done.

JC

so you did not have to bleed the system at all?

I think you're suppose to flush the brake system at least every two years anyway.

+1 That is what the service book says.

One very important step you forgot.
After replacement, but before moving the vehicle,step on the brake pedal and push it down only half way at most. Do this several times until you feel resistance. This pushes the pads out against the disk. If you push the pedal all the way, the brake system will think there is a fault and shut off the line going to that brake. There is a switch in the brake system that has the line from one front and one back brake on one side and the lines from the other front and back brake on the other side. If one side has very little resistance, a piston inside the switch moves to that side and shuts off the flow and sets a switch to show brake failure. This safety has been around since the 70's. If you push the pedal down fully, because the pads are not against the disk after pad change, the brake failure signal lights.
If this happens, you must re-center the sensor. To do this you need to open the bleed on one of the wheels attached to the other side of the sensor and then press the brake pedal until the light goes out (sensor re-centered). A pain in the XXX. Avoid this by slowly pressing the pedal only 1/2 way several times until you feel the resistance.
By the way, brake disks are so cheap that it is not worth having them cut. This is a thing of the past. And as you need to take them off and have the vehicle unusable for the time it takes to cut them, unless you have a disk lathe, plus thinner disks tend to warp faster, just buy new ones if the disk is warped, heavily grooved or thin. Otherwise reuse what you have.

hello all, does anyone know aftermarket brand for rear rotors?
i just change my brake pads and I realize realize i need change my rotors to.

Did this job today on my car, this procedure is fine but there are a couple of small points to note to make it easier.

First, my wear sensor had gone off so my pads were totally worn. You cannot use a 7mm allen wrench that fits on a socket drive, because the lower caliper bolt is blocked by the suspension from fitting the ratchet assembly behind it. You need a traditional 7mm allen to remove the lower caliper bolt. Also, when the pads are totally gone, the piston is fully extended. There is no way to pop the inboard pad off with the piston fully extended, because the length of its clip is longer than the available travel distance - so you must compress the piston with the inboard pad in place to make room, then you can pop it out.

Also, I don't see how anyone saves the wear sensor. Removing mine destroyed it, it just fell apart, so you have to be very careful to save it. Frankly, I don't see why you wouldn't just get a new one.

Have about 60,000 miles on my 08 C300 and I just replaced the rear pads and rotors..
I was planning on replacing both front and rear brakes but was surprised to find my front pads still has about 50% left..

Anyone else has notice that their rear wear out before front besides me and the OP??

Certainly. It has been discussed here hundreds of times and is common knowledge.

After 60K miles, what is the condition of the discs?

I have a 2008 c300 and found my fronts have drastically more pad left than rears. I just replaced my rears a few weeks ago. From what I've read, mercedes uses the rear brakes more during regular braking situations to reduce nose dive. During emergency braking situations the front brakes are engaged more.