DIY: Brake Pad Replacement DIY

Several folks have asked me to post a pad replacement DIY, so here it is. Today was not the best day to do this--it was raining and I don't have a garage--but my schedule dictated it. I will only go over the front pads. The rears are very similar.

Follow this procedure at your own risk. Brakes are an important part of your M3's safety system, and if you don't feel comfortable to service them yourself, don't attempt this. This may or may not be the best way to replace pads. Also, make sure your car is jacked and supported properly and safely before removing the wheels.

What you need:

1. 7mm allen wrench (and an extender 5"-6" bar/tube that would slide over your wrench if it is short and won't give you much leverage)
2. A 8" c-clamp or a piston retraction tool
3. 2 sturdy screwdrivers
4. Something you can rest the caliper housing on (this will become clear after you read the procedure)
5. Replacement pads

Here is the schematic for the front caliper assembly. What you will be doing is to unbolt the caliper housing (#1) so that you can remove and replace the pads. The caliper housing is bolted onto the carrier (#2) by two retaining bolts (#6 and #7).




STEP 1: Remove the pad wear sensor. It is clipped onto one of the brake pads. Just pull on it and it will come out. The chances are the tensioner clip will remain in the pad. Make sure to get it. They are not sold separately, and if you lose it, you'll need to buy a new sensor. Also, you can release the fluid line from the suspension to give yourself some more room.



STEP 2: Remove the large anti-rattle spring (#8). I use a couple of sturdy screw drivers to deflect and snap it out of place. Do not use your fingers; you'll get hurt. Also, there is a good chance the thing might come flying out, so don't be staring at it. Wear goggles if you are concerned.


STEP 3: Remove the 2 plastic caps (#5) that are protecting the retaining bolts. You should be able to do this with your fingers. If you can't, use a screwdriver. The caps look like this:



STEP 4: Now you have access to the retaining bolts. Insert the 7 mm allen wrench as seen in the pic below, and unbolt them.


A more detailed view on the wrench inserted in to the retaining bolt:


This is what the retaining bolt looks like if you were to slide it out of the caliper housing. You don't need to do that. You just need to unthread it.



STEP 5: You now need to push the brake piston back. You can do this while the caliper is still on the rotor, or if you have a piston retractor tool, you can do it after you remove the caliper housing. I'll show you how to do it with a c-clamp while the caliper is still on the rotor. Place one end of the c-clamp onto the pad itself and the other end on the back of the caliper housing. Be careful not to place it on the bleeder valve or the fluid line or anything else that can be damaged. Find a spot on the cast housing itself as show in the pic. Slowly contract the c-clamp. You will see the caliper housing move away from the rotor and toward you as the piston goes back in. This should not require too much effort. If it does, you are doing something wrong. When the piston goes all the way back in, you'll feel a distinct change in resistance, so stop. Also, keep an eye on the brake fluid level in your reservoir. As you push the piston back, it will rise slightly and should not be allowed to overflow.



STEP 6: Grab the caliper housing and move it away from the rotor and the carrier. Be careful with the fluid line. Don't yank on it. Do not try to rest the caliper housing on the ground; you will stretch on the fluid line. You need to put something under it to support it as seen in the picture below. I was using my jack container.



STEP 7: Remove the pads. They are held in the caliper and the piston by tensioner springs at this point and will come out when you pull on them. Here you can see the caliper housing with the piston pushed almost all the way back.



STEP 8: Clip the replacement pads into the piston and the caliper housing.



STEP 9: Place the caliper housing back on the carrier and the rotor. Insert and tighten the two retaining bolts. Do not over torque them. I don't have the exact torque spec. I just tried to remember how much of an effort it took to loosen them. It will be easier to do the bottom one first as the fluid line kind of gets in the way of the top one. You need to make sure the caliper housing is where it is supposed to be; one way to check that is to see if the pads are covering the entire swept area of the rotor. You might need to wiggle the caliper housing a little before the retainer bolts go in, but it's not hard to do.


STEP 10: Insert the anti-rattle spring back in place. Again, I use a couple of screw drivers to deform and push it in. Clip the brake wear sensor back into the inside pad.



It takes me about 15 minutes to do one corner including jacking the car and removing the wheel. If you have access to a lift, it will obviously be much faster.

DAMN we have big calipers! Thank you for the DIY!

This is great! Well done and thank you.

Just a couple of notes:

The torque for the guide bolts #6 and #7 is 22 ft-lb front and rear. The front bolts are different lengths, the rears are all the same.

The easiest way to get the front anti-rattle clip out is with a giant pair of water-pump pliers. Cover the jaws with tape to avoid scratching the paint and just stick one jaw through the hole and the other jaw on top of the caliper body. Squeeze gently and the clip just slips out.

BMW recommends an anti-squeal compound (#14 in the diagram) for re-assembly. They say to put a thin (really thin) layer on anywhere there's metal-to-metal contact in the caliper assembly. Bostik Never-Seez is on their recommended list. It works great for stock pads, but RS-19's will squeal regardless of what you do.

JAJ wrote

This is great! Well done and thank you.

Just a couple of notes:

The torque for the guide bolts #6 and #7 is 22 ft-lb front and rear. The front bolts are different lengths, the rears are all the same.

The easiest way to get the front anti-rattle clip out is with a giant pair of water-pump pliers. Cover the jaws with tape to avoid scratching the paint and just stick one jaw through the hole and the other jaw on top of the caliper body. Squeeze gently and the clip just slips out.

BMW recommends an anti-squeal compound (#14 in the diagram) for re-assembly. They say to put a thin (really thin) layer on anywhere there's metal-to-metal contact in the caliper assembly. Bostik Never-Seez is on their recommended list. It works great for stock pads, but RS-19's will squeal regardless of what you do.

Thanks for the additional info JAJ.

Yep, I didn't apply anti-squeal compound because these things will squeal like pigs not matter what.

Actually, I don't apply any to the stock pads either when I put them on, and they don't squeal (after bed-in), but maybe I just got lucky.

thanks Lucid my RS19's are enroute and I will soon be using this DIY

thanks for taking your time lucid !

Awesome, thanks Lucid!

Any issues bleeding the brakes while we're doing this?

Thank you Lucid!! I got my Yellow Pagids a few days ago and will need your DIY for my May 15th outing at Lime Rock.

Thanks for this DIY Lucid ..... i will use it.

Question: is it enough to change only front pads for track use (pagid yellow), or do we need to change both, front and rear ?

thooooorgal wrote

Thanks for this DIY Lucid ..... i will use it.

Question: is it enough to change only front pads for track use (pagid yellow), or do we need to change both, front and rear ?

You will get different answers on this one. If you want to preserve the f/r brake bias, you should do all 4 corners. Leaving the rears stock means you will have less friction and braking torque in the back (I can only assume RS19s have a higher coefficient of friction than stock pads overall--not to mention the rears will be prone to fade with the stock pads), and your brake bias will be shifted further up front. Having said that, some folks don't mind that. I personally do not think it is a good idea, and do all 4 corners.

Dascamel wrote

Any issues bleeding the brakes while we're doing this?

Nope. Always a good idea to bleed the brakes.

also does the idrive auto update with the new pad or do you need to have it reset?

Neil McRae wrote

also does the idrive auto update with the new pad or do you need to have it reset?

iDrive doesn't know anything about what pad is in your car or if it has been changed or not. It just guesses at pad wear based on deceleration data. However, if you wear out the contact wear sensor attached to the pad, the "BRAKE" light will come on on the dash, and that won't go away until it is reset with a tool. That has nothing to do with the miles to service number displayed on your iDrive screen.

Thanks Lucid. Immensely helpful.

Great DIY Lucid; many thanks.

Although I don't care, have to comment on this: I knew we had a 1-piston caliper, but thought the size of the pad (which is what stops the car) was the same as 4 or 6-piston calipers of similar dimensions. WRONG! Those pads are tiny; they look like my Honda's . Again, I don't care because will never track my car, and brakes feel fantastic to me, but BMW needs to up the ante with the calipers, especially on an M car. Even the 135 has sexy 6-piston calipers in front (2-piston in the back). Good day gang.

elp_jc wrote

Even the 135 has sexy 6-piston calipers in front (2-piston in the back). Good day gang.

A friend of mine with a 135 cannot seem to get decent braking at the track even after adding track pads. So the 6-piston calipers are not helping in the braking category.

Thanks Lucid. Great write-up.

One question about the anti-rattle clip. I am very familiar which changing brakes pads as I have done it many time on my E46 325Ci. Overall, seems to be a similar setup.

The anti-rattle clip looks quite different though and seems trickier to remove. Do you have input or close-up shots on how it is attached and how to removed.

I am installing Carbotech XP10 in about a week for a track day.
Thanks

FrenchBoy wrote

Thanks Lucid. Great write-up.

One question about the anti-rattle clip. I am very familiar which changing brakes pads as I have done it many time on my E46 325Ci. Overall, seems to be a similar setup.

The anti-rattle clip looks quite different though and seems trickier to remove. Do you have input or close-up shots on how it is attached and how to removed.

I am installing Carbotech XP10 in about a week for a track day.
Thanks

Take a minute to observe the clips when you remove the wheels. How they are compressed will become obvious. You just need to apply force to further compress them and they will pop out. I use a couple of relatively big screw drivers to bend them around. Some prying might be necessary.

Also, see below for JAJ's method:

JAJ wrote

The easiest way to get the front anti-rattle clip out is with a giant pair of water-pump pliers. Cover the jaws with tape to avoid scratching the paint and just stick one jaw through the hole and the other jaw on top of the caliper body. Squeeze gently and the clip just slips out.

lucid wrote

Take a minute to observe the clips when you remove the wheels. How they are compressed will become obvious. You just need to apply force to further compress them and they will pop out. I use a couple of relatively big screw drivers to bend them around. Some prying might be necessary.

Also, see below for JAJ's method:

Thanks Lucid. Appreciate the feedback.

Just finished installing Carbotech XP10 in the front in preparation for a track day on Friday. Went very smoothly. The job is easy and very similar to the E46 indeed.

The rattle clip was indeed a piece of cake to remove: Just slide a screw driver under the large flat piece of the clip in the middle and pull away (from the center of the wheel) to dislodge the middle tab from the caliper holding feature.

A couple of interesting notes though:
- The M3 has a brake wear sensor on both sides in the front. That was a surprised to me. The E46 had it on one side only.
- The Carbotech pads do not have a recess in the pad material for the brake wear sensor. I wrapped the sensor cable about the brake line.

FrenchBoy wrote

The Carbotech pads do not have a recess in the pad material for the brake wear sensor. I wrapped the sensor cable about the brake line.

It seems the back plates and the pad material have the recess, but the glue they use to fix the pad to the plate overflows and fills in. That's at least been the case for the 2 sets of front pads I've bought from them.

First, thanks Lucid, for this DIY. I had my dealer put my XP10's on (didn't have time or a jack before my track day), but saved a lot of money by removing them myself. Made me feel like I was mechanically inclined.

Second, my Carbotech's also had excess material in the space where the wear sensor goes. Just had to zip tie the sensor out of the way.

Finally, I second the recommendation to use a large pair of pliers to remove the clips. Wrap them so they don't scratch the brakes, and it makes removal very easy.