DIY e46 M3 Front Brakes on a Non-M

These brakes fell in my lap right as I was about to pull the trigger a decent pad/rotor 330i setup for my 325xi, so I decided to make them work

Research online shows that you need to mill the m3 caliper bracket 6 or 7mm to fit non-M e46 cars. I went with 1/4" (mainly because my machine shop isn't fond of the metric system)

After the first test fit I had to go back to get him to clearance out some of the remaining adjacent areas to clear the mounting tabs on the spindles.





Once that is done, proceed with normal brake install and pressure bleed with your favorite fluid


note: m3 brakes use different set screws than non-ms hence the presence of lugnuts in this shot. Need to order 2 of those puppies up.

Lookin' Good


First Impressions:
Brakes are still a bit squirmy as I haven't really had a good chance to bed them in thoroughly. Once I did get heat in them, however, they were amazing. Haven't had any spirited driving with them yet to see how far off brake bias is front to rear. -May DIY the rears here shortly.

Install should be the same for 323i 325i 325xi 328i 330i 330xi.

Looks like the rear m3 brake mod will require swapping out for m3 trailing arms. interestingly enough 325xi should have the right parking brake to directly swap over to 330i rear brakes. I'll update this thread when I get more work done.

Originally Posted by redbull 325is

Install should be the same for 323i 325i 325xi 328i 330i 330xi.

323 is supposed to have smaller diameter discs front & rear so I do not
believe that this method works as the caliper bracket probably has to be replaced entirely.

Stock disc sizes (source: http://www.schmiedmann.se/ )

323i, Ci:
Front: 286x22mm Rear: 276x19mm

323 Ci cabriolet, 328i/Ci, 325i/xi/Ci:
Front: 300x22mm Rear: 294x19mm

330i/Ci
Front: 325x25mm Rear:320x22mm

M3:
Front: 325x28mm Rear: 328x20mm

Nice work, I take it you are using 330 discs? Or are they your originals?
You could use 330 discs but be sure to compare the minimum thicknesses of 330 vs M3.

I've been wondering about this for a while: do the M3 calipers have different connections to the brake hose? I have Goodridge SS hoses and would hopefully re-use them if I did this type of swap. The other problem I could forsee was that if the connection to the caliper is different, you may try M3 hoses but then the connection to the hard lines may be different

Steifan, I checked your sizes against ETK, I only found one minor error. I also added some other models for reference.

323i/Ci
F: 286x22 R: 276x19 (solid)

323 Ci cabriolet, 328i/Ci, 325i/xi/Ci (solid)
F: 300x22 R: 294x19

330i/Ci (solid/perforated)
F: 325x25 R: 320x22

M3 (perforated)
F: 325x28 R: 328x20

M3 competition package (perforated)
F: 345x28 R: 328x20

M3 CSL (perforated)
F: 345x28 R: 328x20

Originally Posted by steifan

323 is supposed to have smaller diameter discs front & rear so I do not
believe that this method works as the caliper bracket probably has to be replaced entirely.

Stock disc sizes (source: http://www.schmiedmann.se/ )

This will work on the front as the spindles are the same on all these cars, only the caliper & carrier change. Since you are swapping these out for m3 units anyways it shouldn't change a thing (for the front anyway).

Originally Posted by Dan330Ci~

Nice work, I take it you are using 330 discs? Or are they your originals?
You could use 330 discs but be sure to compare the minimum thicknesses of 330 vs M3.

I've been wondering about this for a while: do the M3 calipers have different connections to the brake hose? I have Goodridge SS hoses and would hopefully re-use them if I did this type of swap. The other problem I could forsee was that if the connection to the caliper is different, you may try M3 hoses but then the connection to the hard lines may be different

I'm using full e46 m3 system up front. I wouldn't try to mix and match caliper/carriers to different rotors as it could lead to offset issues and/or brake pads falling out of their housings when at minimum thickness.

I was suggesting it would be cheaper for 325xi people to use 330i rear setup as a cheap bbk since the xi already has the larger drum/parking break setup, which isn't the case for 323/325/328s than going m3 brakes which requires swapping the rear trailing arms (still working on this)

i used my factory brake lines up front with no issues.

Originally Posted by redbull 325is

I was suggesting it would be cheaper for 325xi people to use 330i rear setup as a cheap bbk since the xi already has the larger drum/parking break setup, which isn't the case for 323/325/328s than going m3 brakes which requires swapping the rear trailing arms (still working on this)

Really? So the 325xi has the same rear end/hub size as the 330xi? Only difference being the overal diameter and thickness of the brake disc?

Originally Posted by SamDoe1

Really? So the 325xi has the same rear end/hub size as the 330xi? Only difference being the overal diameter and thickness of the brake disc?

330s and 325xis use the same parking brake shoes and 325xi rear rotors are different from rwd rotors, leading me to believe that the 330i rotor and caliper will just bolt on.

Missed this the first go around - congrats, well done!

Sent from my HTC Flyer P512 using Bimmer App

Thanks for posting the pics...just got my carriers machined and I put them on my 325 touring yesterday. Your pics made it very easy to show the machine shop and get exactly what I needed the first time.

Redbull, any update on the rears? did you attempt anything, or find out more?

Great info guys thanks

My wife just picked up a 323ci as her D/D and i was wondering if I could through my old OEM front/Rear brakes off my E46 M3 to give her better braking w/o having to spend a crazy amount of money upgrading them with a new set.

Originally Posted by snikwad

Redbull, any update on the rears? did you attempt anything, or find out more?

not yet, been too busy at work, however i'm pretty sure that i'd have to swap trailing arms.

Originally Posted by metal massager

Thanks for posting the pics...just got my carriers machined and I put them on my 325 touring yesterday. Your pics made it very easy to show the machine shop and get exactly what I needed the first time.

glad to help ya out

Originally Posted by lrinco01

Great info guys thanks

My wife just picked up a 323ci as her D/D and i was wondering if I could through my old OEM front/Rear brakes off my E46 M3 to give her better braking w/o having to spend a crazy amount of money upgrading them with a new set.

let us know if you get the rears on there!

Redbull
I also purchased a set of M3 brakes and they are much bigger, and drilled rotors, I thought all were. These are around 15" in diameter, my calipers say M3 on them, did I buy something different>? I took a walk around Los Altos to take a looks see and all the M3s have drilled rotors on them, rears are same diameter too. What is different?

Thanks for the great pics, they are very helpful.

Originally Posted by redbull 325is

These brakes fell in my lap right as I was about to pull the trigger a decent pad/rotor 330i setup for my 325xi, so I decided to make them work

Research online shows that you need to mill the m3 caliper bracket 6 or 7mm to fit non-M e46 cars. I went with 1/4" (mainly because my machine shop isn't fond of the metric system)

After the first test fit I had to go back to get him to clearance out some of the remaining adjacent areas to clear the mounting tabs on the spindles.





Once that is done, proceed with normal brake install and pressure bleed with your favorite fluid


note: m3 brakes use different set screws than non-ms hence the presence of lugnuts in this shot. Need to order 2 of those puppies up.

Lookin' Good


First Impressions:
Brakes are still a bit squirmy as I haven't really had a good chance to bed them in thoroughly. Once I did get heat in them, however, they were amazing. Haven't had any spirited driving with them yet to see how far off brake bias is front to rear. -May DIY the rears here shortly.

Install should be the same for 323i 325i 325xi 328i 330i 330xi.

So if I understand you correctly, what you did on the front should work on my 323i, correct ?

How about the rears on the rwd ?

1/4th milling looks like plenty! I'm curious what you need to do to the ZCP carriers to do the same modification to get the 345mm rotors up front.

Originally Posted by crazyxzer0

1/4th milling looks like plenty! I'm curious what you need to do to the ZCP carriers to do the same modification to get the 345mm rotors up front.

Exactly the same what he has done to regular M3 carriers. CSL carriers are bigger in order to accommodate a bigger rotor, but CSL brakes have the same calipers as regular M3. So basically CSL brakes can be installed to regular M3 without any modifications, assuming you will use caliper carriers from CSL.

I have CSL brake set, so I tried out - the same 5-6mm should be taken off from caliper carriers in order to fit. I was thinking to get front hubs from M3 in order to avoid modification of the carriers, but that path is complicated, as you have to swap tie rods and front wishbones, maybe something else... also I'm pretty sure that will make 'front' wider... So I think the best way would be to mill calipers.

Update on the rears:
You can bolt an m3 rear caliper to a non-m but it will sit too close to the hub and won't allow you to fit the bigger m3 rotor.

Your front calipers pictured above are on my car IIRC.