[aerof16]

2017 540i w/ M Sport Brakes

The brake light came on indicating that my rear pads need to be replaced. I pulled all four wheels and took a look, the rears are close to needing replacement but I was surprised to find the rotors need to be replaced as well (they've built up a nice lip on both the outer and inner portions of the rotors).

The fronts aren't far behind. Car is at 54k miles, so I assume the fronts have been done before (I bought it CPO). I drive the car a lot, this is my work/commuting car, so I am considering replacing the pads with something less aggressive for two reasons: first, it'll reduce the amount of dust and second, it will hopefully not eat up the rotors so quick.

Anyone have good recommendations on pads and rotors? I use Powerstop Z26 pads on my Hellcat (to reduce the dust - swap back to Brembos for track days) but it seems Powerstop only makes the Z26 for the rear on the G30 w/ M sport brakes.

Plenty of rotors out there but I want to make sure I get a good rotor that isn't going to warp easily and I don't want the hats to rust or discolor much. Just looking for OEM replacement quality.

I don't mind buying the BMW parts if they are the best option but the rear rotors are $236/ea, which is a little pricey. I really want an aftermarket pad.

Thanks in advance for any recommendations!

[claykin]

Measure the rotor thickness as BMW has a minimum allowable thickness. You may be able to take the rotors to a shop and have them machined.

[aerof16]

Originally Posted by claykin

Measure the rotor thickness as BMW has a minimum allowable thickness. You may be able to take the rotors to a shop and have them machined.

Yeah, I measured the rears at 23.5 mm, haven't looked up the min allowable yet but I typically just buy new rotors since the price on them is usually pretty low (especially for the rears). Didn't see it stamped on the rotor but I didn't look real hard.

If I don't find a good OEM replacement, I will probably have them turned (if able) vs buying new OEM.

[aerof16]

So it appears Brembo is the OEM supplier for the front brakes and they will sell them directly to the customer on their website for a pretty decent price.

This is where it gets weird - the rear brake supplier for the 540i looks like TRW, however they will not sell the rotors directly to the customer. Brembo has a rotor for the rear that is 345 x 24 and say they will fit a 2018 M550i Xdrive but will not fit a 2017 BMW 540i w/ the M sport caliper.

Aren't the 540i and M550i M sport brakes exactly the same?

Also, for the rear Brembo rotor, their tech drawing says 22.4 mm for min thickness. I'll have to pull a rear wheel of tomorrow and see if the min thickness is stamped on the rotor hat.

[aerof16]

Today's update:

The min rotor thickness is etched on the front of the rotor hats on both the front and rear rotors. For the front, it's 34.4 mm and for the rear it's 22.4 mm. I'm around 35.5 on the front and 23.5 on the rear, so I am going to take them for machining. If they turn out good afterwards, I'll put them back on. If I go below the min during the machining process, I'll buy the new rotors from Brembo.

I measured my rear rotor today against the technical drawing Brembo has on their website. Even though Brembo says their rotor will not work with the M sport rear brakes, all the measurements are identical to what is on my car now, so I'm sure it will work as a good replacement.

[540iSUP]

Good info aerof16 I'm going to be doing my brakes maybe by the end of the year and this info is super useful.

[jimk]

Originally Posted by aerof16

Today's update:

The min rotor thickness is etched on the front of the rotor hats on both the front and rear rotors. For the front, it's 34.4 mm and for the rear it's 22.4 mm. I'm around 35.5 on the front and 23.5 on the rear, so I am going to take them for machining. If they turn out good afterwards, I'll put them back on. If I go below the min during the machining process, I'll buy the new rotors from Brembo.

I measured my rear rotor today against the technical drawing Brembo has on their website. Even though Brembo says their rotor will not work with the M sport rear brakes, all the measurements are identical to what is on my car now, so I'm sure it will work as a good replacement.

If you use original BMW pads as a replacement, there is no need to resurface the rotors unless they are warped or have other issues. If you change the pad formulation by using aftermarket pads, then a resurface is recommended. I've paid $111 for the rear pads from BMW and just slapped them in and I have had no issues. I've measured my rotor thickness in three different points and they were all between 23.37mm- 23.39mm so plenty of rotor life left. If I had to resurface them, then I would have been closer to the minimum thickness or possibly below depending on the resurfacing method and I would have probably needed to buy new rotors. In my view, it is cost effective to just replace the pads with original BMW pads if the rotors are above minimal thickness. BMW TIS recommends just pads replacement if the rotor is above minimum thickness.

[aerof16]

Originally Posted by jimk

If you use original BMW pads as a replacement, there is no need to resurface the rotors unless they are warped or have other issues. If you change the pad formulation by using aftermarket pads, then a resurface is recommended. I've paid $111 for the rear pads from BMW and just slapped them in and I have had no issues. I've measured my rotor thickness in three different points and they were all between 23.37mm- 23.39mm so plenty of rotor life left. If I had to resurface them, then I would have been closer to the minimum thickness or possibly below depending on the resurfacing method and I would have probably needed to buy new rotors. In my view, it is cost effective to just replace the pads with original BMW pads if the rotors are above minimal thickness. BMW TIS recommends just pads replacement if the rotor is above minimum thickness.

"Resurfacing" the rotors can be done with sandpaper, which is what I would do if I change pads out and I don't machine/replace rotors but only if the entire surface is flat and smooth. However, the OEM pads have been eating into the rotors to the point of having a pretty decent lip on the inner and outer diameter of the rotors. I'm just going to have them turn the rotors enough to get rid of the inner and outer lip.

Plus, the dust from the OEM pads is ridiculous. My car is my commuter car, so that matters a lot for my use. I also put a lot of miles on my car and I don't want an aggressive pad like the OEM Brembo to reduce the lifespan of my rotors for the sake of "performance" I don't really need.

[aerof16]

I'm also really surprised to find my rear brake pads need to be replaced. I've never replaced the rears on any car I've owned before about 90k miles. My truck is a different story because they do some work hauling, so I get it, but even then I didn't have to replace the rear until 60k miles.

The front pads of my Hellcat get replaced every 30k (they need it) and the rears have gone 60k and look damn near brand new still.

I'll be doing this in about 2 weeks, just don't have time until then. I'll update after bedding in the new pads and leave some feedback here for others.

[aerof16]

Alright, so I worked on the brakes today.

After getting the car up in the air and the wheels off, I looked at the rotors and decided that I was not going to take them off and get them machined. They looked really good except for a small lip on the inner and outer diameter, on all four. I decided that I would slap the pads in, check the fitment, then test it out on the road. If I wasn't happy with it, I was going to put the car back up in the garage and have them machined.

Turns out it's not an issue at all, at least not in my case. So all I did today was replace the front and rear pads, as well as the front and rear sensors.

I used Powerstop pads. I wanted to use the Z26 pad because I have used it on my Hellcat but they only make them for the rear for the G30, which is odd, so I went with the Z23 pads in the link below.

https://www.powerstop.com/product/po...0Brake%20Discs

Overall, I am very happy with the pads. They don't have the initial bite that the factory Brembos have but the brake pedal feel is very linear and I haven't noticed any detectable performance difference. We'll see how they do with dust but I am confident they are going to be great, based on how the Z26 is almost dust free on my Hellcat. If you are going to track your car at all, this isn't the pad for you.

As far as the process goes, changing the brake pads on this car is just like any other car you've ever worked on. There is a manual way to retract the electronic parking brake but I have a scan tool with BMW software, so I used that. The front pads are super simple, just knock out the two guide pins and you can remove both pads and the anti rattle clip all together. Very similar to any other premium brake caliper. The brake pad sensor for the front is on the drivers side. I bought mine from BMW and they fit into the Powerstop pads no problem. Very easy to replace, just follow the wire up from the pad, remove it from the clips, disconnect it from the connector up in the wheel well and then replace with the new one.

I wish the rears were a true performance caliper like the fronts but they're not, they're just a single piston setup like any other non performance caliper. Still very easy, two 13mm (?) bolts to remove part of the caliper and then replace the pads and hardware. The brake pad sensor is on the passenger side for the rears and you'll have to remove 2 x 10mm fasteners from the wheel well liner to expose the box where the connection is made. Not a problem though, easily accessible.

I did scuff the rotors up with some 60 grit sandpaper but I am not sure it was really necessary. If the rotors look good and not glazed over, I'd probably just slap new pads on them and call it good next time (as long as they measure above the discard thickness).

The pads came with new anti rattle clips and grease for the front, as well as new rubber boots for the guide pins and new hardware for the rear. I just cleaned up the front guide pins with a wire brush and some steel wool since they did not come with the pads. The Powerstop clips for the front pads fit great but the hardware for the rear didn't fit quite as well as OEM, however it is still just fine to use. If you're OCD, maybe buy the OEM hardware as well.

Afterwards, I just followed the bed in procedure from Powerstop. That's it, overall not much to write home about. If you are going to do the rotors, there is just one bolt on each that needs to be removed to get the rotor off. That bolt is required to be replaced from BMW, so make sure you buy those from the dealer before you get the rotors off. I think they were like $4 each.

This is the scan tool I used. First time using it but so far so good. Spent some time with it and it seems pretty capable. Only complaint is it is a little slow communicating with the car. It's not terrible, just not cell phone fast.

https://www.foxwelleshop.com/wholesa...RoCOUgQAvD_BwE

Hope that helps anyone looking to do this project!

[540iSUP]

Originally Posted by aerof16

So it appears Brembo is the OEM supplier for the front brakes and they will sell them directly to the customer on their website for a pretty decent price.

This is where it gets weird - the rear brake supplier for the 540i looks like TRW, however they will not sell the rotors directly to the customer. Brembo has a rotor for the rear that is 345 x 24 and say they will fit a 2018 M550i Xdrive but will not fit a 2017 BMW 540i w/ the M sport caliper.

Aren't the 540i and M550i M sport brakes exactly the same?

Also, for the rear Brembo rotor, their tech drawing says 22.4 mm for min thickness. I'll have to pull a rear wheel of tomorrow and see if the min thickness is stamped on the rotor hat.

The brake calipers are the same, but the rears changed between preLCI and LCI cars. Pre LCI had 345mm rear rotors, LCI has 370mm rear rotors. The calipers and pads are the same, the caliper carriers are different. Both Msport and non Msport rear rotors are 345mm (preLCI) and 370mm (LCI).

[FullBolton]

https://youtu.be/O0UMXyiwdpY

[bmwdoodle]

Originally Posted by aerof16

Alright, so I worked on the brakes today.

After getting the car up in the air and the wheels off, I looked at the rotors and decided that I was not going to take them off and get them machined. They looked really good except for a small lip on the inner and outer diameter, on all four. I decided that I would slap the pads in, check the fitment, then test it out on the road. If I wasn't happy with it, I was going to put the car back up in the garage and have them machined.

Turns out it's not an issue at all, at least not in my case. So all I did today was replace the front and rear pads, as well as the front and rear sensors.

I used Powerstop pads. I wanted to use the Z26 pad because I have used it on my Hellcat but they only make them for the rear for the G30, which is odd, so I went with the Z23 pads in the link below.

https://www.powerstop.com/product/po...0Brake%20Discs

Overall, I am very happy with the pads. They don't have the initial bite that the factory Brembos have but the brake pedal feel is very linear and I haven't noticed any detectable performance difference. We'll see how they do with dust but I am confident they are going to be great, based on how the Z26 is almost dust free on my Hellcat. If you are going to track your car at all, this isn't the pad for you.

As far as the process goes, changing the brake pads on this car is just like any other car you've ever worked on. There is a manual way to retract the electronic parking brake but I have a scan tool with BMW software, so I used that. The front pads are super simple, just knock out the two guide pins and you can remove both pads and the anti rattle clip all together. Very similar to any other premium brake caliper. The brake pad sensor for the front is on the drivers side. I bought mine from BMW and they fit into the Powerstop pads no problem. Very easy to replace, just follow the wire up from the pad, remove it from the clips, disconnect it from the connector up in the wheel well and then replace with the new one.

I wish the rears were a true performance caliper like the fronts but they're not, they're just a single piston setup like any other non performance caliper. Still very easy, two 13mm (?) bolts to remove part of the caliper and then replace the pads and hardware. The brake pad sensor is on the passenger side for the rears and you'll have to remove 2 x 10mm fasteners from the wheel well liner to expose the box where the connection is made. Not a problem though, easily accessible.

I did scuff the rotors up with some 60 grit sandpaper but I am not sure it was really necessary. If the rotors look good and not glazed over, I'd probably just slap new pads on them and call it good next time (as long as they measure above the discard thickness).

The pads came with new anti rattle clips and grease for the front, as well as new rubber boots for the guide pins and new hardware for the rear. I just cleaned up the front guide pins with a wire brush and some steel wool since they did not come with the pads. The Powerstop clips for the front pads fit great but the hardware for the rear didn't fit quite as well as OEM, however it is still just fine to use. If you're OCD, maybe buy the OEM hardware as well.

Afterwards, I just followed the bed in procedure from Powerstop. That's it, overall not much to write home about. If you are going to do the rotors, there is just one bolt on each that needs to be removed to get the rotor off. That bolt is required to be replaced from BMW, so make sure you buy those from the dealer before you get the rotors off. I think they were like $4 each.

This is the scan tool I used. First time using it but so far so good. Spent some time with it and it seems pretty capable. Only complaint is it is a little slow communicating with the car. It's not terrible, just not cell phone fast.

https://www.foxwelleshop.com/wholesa...RoCOUgQAvD_BwE

Hope that helps anyone looking to do this project!

For the rear brakes, after using the bmw scan tool to retract the brakes, do you still need to press the piston into caliper with a C lamp or something, like a normal brake job? Or does the scan tool retract the piston for you? Thanks!

[jimk]

Originally Posted by bmwdoodle

For the rear brakes, after using the bmw scan tool to retract the brakes, do you still need to press the piston into caliper with a C lamp or something, like a normal brake job? Or does the scan tool retract the piston for you? Thanks!

You need to manually push and turn the piston back in. See https://www.bimmerpost.com/forums/sh...php?p=27669900

[admranger]

Would like the hear how power stops are doing for people. Amazon reviews are mixed.

[aerof16]

Originally Posted by admranger

Would like the hear how power stops are doing for people. Amazon reviews are mixed.

Well I’ve put almost 30k miles on my car since I started this thread, so here’s an update:

I’m still happy with mine for the reasons I bought them. First, they produce almost zero dust, which is awesome. Second, my brakes still look almost new and the rotors are in great shape, 30k miles later. I’m now at around 82k miles on the car. If I had used the factory Brembo pads, I feel like I’d be doing this again in another 5-10k miles. I just replaced my sway bar end links this weekend, so I took a look at the brakes while I was in there.

Only thing I don’t like about them is I can hear them moving around in the caliper a bit but maybe I just need to go in and apply some more grease. They do squeal when cold but if you put some heat into them with a few aggressive stops, it goes right away. Funny thing is, the Z26 pads I put in my Hellcat don’t do that.

[FinAdvsr]

Thanks for this, very informative. Question, would this process also work on a 2019 540i Xdrive?

Thanks!