F8X Brembo BBK Swap on E46 M3

Originally posted by Epsilon View Post

Nice write-up. Did you ask if the machine shop was able to help you machine the rear caliper?

They can definitely machine the rear caliper however they had to do it in their more expensive 5 axis machine. This was mainly due to their limited mounting options in the other machines. If you look at the post machining picture, you can see that there is a rectangle machined out of the center of the rear calipers. This was not the correct size because I was not certain how large the hole needed to be and I didn't want to remove more than I needed to. You can go to a machine shop with these measurements and have them remove slightly more material from the ends to make it an easy plug and play.

** I added an image of what the rear caliper looked like after machining.

Hey everyone!

I have been lurking on the M3Forums for years and used countless DIYs to work on my car. I hope that this DIY will be of some value to some people and help the community. Thanks to the NaM3Forum owners and moderators for starting this forum and keeping this community alive! No lie, I felt like an addict that had gone cold turkey when M3forums shut down lol.

There are couple other DIY threads but I felt like they lacked some detail and images, so I decided to make a more in-depth DIY with some good pictures and measurements. My goal is to take as much of the guess work as possible for other members.

First off, I must give credit where it is due. Jahaddow on M3Cutters created a DIY, which served as my guide to getting this swap done. I will be using some information from his thread as well. Between his thread and this DIY, you should get a very clear picture of what needs to be done.
https://forums.m3cutters.co.uk/threa...e46-m3.209320/

There are two main methods to get the front calipers to fit, adding shims behind the rotor to space it out 2.5mm or shaving down the caliper mounting points 2.5mm. I will only be covering the method that shaves down the calipers. More details on this later.

Okay, let’s get on with it!

List of Parts required:

Item	QTY	Notes
F8X Calipers	4	2 front and 2 rear
F8X Pads	4	2 front and 2 rear sets
F8X Rotors	4	Each rotor has a different part number.
Brake Lines (Custom Optional)	4	Custom lines, or OEM E46 m3 front and m4 OEM Rear lines.
F8X Parking Brake Shoes (optional)	4	I used the OEM E46 M3 parking brake shows here and it fit just fine.
M10 x 40mm - 10.9 bolt	4	Ensure pitch matches with bolt (use for rear bracket to car)
m10 - 10.9 nut	4	Ensure pitch matches with bolt (use for rear bracket to car)
M12 x 40mm 10.9 fine thd bolt	4	Connected Caliper to Bracket.
Custom Rear Bracket	2	I ordered these: https://www.ebay.com/itm/E46-M3-F80-...72.m2749.l2648
SPRAYON WL 738 (Optional)	1	Corrosion inhibitor used to coat the rear aluminum adapters

I was lucky enough to find a complete set of calipers/rotors with pads and lines on the F80 forums for a really good deal. This is how the calipers looked when they arrived.

Step 0.1: Machining Calipers

Before working on the car, I had a local machine shop shave down the caliper mounting points by 2.5mm. This ensures the rotor is perfectly center with the caliper. Some others have used an angle grinder and flat grinding disc to remove the 2.5mm with success. However, you will have to be very careful to keep things leveled and even so the calipers are not crooked. I also had them remove some material from the center section of the rear calipers. Since there were no exact measurements online, I just had to go with a conservative guess based on images. Much more material had to be removed later to properly fit.

Machined Calipers

Close up of front (2.5mm removed).

Close up of rear calipers with a portion of center section removed. More material had to be removed, but this definitely cut down on the total grinding and cutting time required for each caliper.

Step 0.2: One other step I completed before installation was coating the Rear Caliper Adapters with a corrosion inhibitor. They are made from a 7075-T6 Aluminum, which are strong but can degrade from the elements over time. Unfortunately, I did not take any pics of the actual process but here is what the adapters looked like before and the product I used. *Important* Remember to cover the surfaces that the mounting bolt will torque against! Failure to do so may allow the bolts to work themselves free if the coating heats up and flows away from the contact surface, lowering the tension holding the bolt in place. This is the same reason you don't powder coat certain surfaces on the BBK.

Step 1: Jack up car and remove wheels. At this point, I was ready to go and got the car up on the quick jacks.

REAR BRAKES
I started with the rear wheel since it would require the most work to get things fitted.

Step 2: Remove Rear caliper and rotor. I left the caliper attached to the brake line since I was going to be grinding and did not want to get debris in the system.

Step 3: Remove the top spring, brake shoe adjuster, and the two allen head mounting pieces to allow for the shoes to move. You can remove them completely, but I didn't want to mess with that bottom spring.

Step 4: Cut off the rear shield.I used an angle grinder with a 4 inch and 5 inch cutting disc. I This is what I originally cut off but all the metal that sticks up passed the parking shoe needs to be removed or else it will grind against the m4 rotors.

Initial shield cut out.

Don't be afraid to get really close. Here is where i ended up:

Step 5: Reattach the brake shoe equipment and adjust the brake shoe distance accordingly. I ended up bottoming out the adjusters and removing any slack at the hand brake.

Step 6 (only if needed): Ensure all bolts are the proper length. Jahaddow's DIY stated 45mm bolts were needed but I found these to be way too long. I put 40mm bolts but those may still be slightly too long. I ended up measure distances and found about 38mm to be a good distance for full thread engagement while preventing contact with the rotor. I ground my bolts down to about 38mm as shown below.

Step 7: Attached the caliper mounting brackets onto the car. Since the M10's will likely never need to be removed, I used some loctite red on them to ensure they don't budge. Place the nuts on the other side and torque these bolts down to 48 ft-lbs.
*Note that the contact surfaces are shiny without any coating, and the same is true for portions of the back side.

Step 8: Cut and grind the center of the rear calipers to fit. This is probably the worst part of the install because depending on your tools, it may take quite some time. I used a combinations of an angle grinder, dremel, and die grinder to get desired shape and it took about 1 hour per side. However, I was being really careful to not remove too much material. Some people have done it in a few minutes lol. I also tried my best to keep the radius the machine shop originally made to prevent a stress risers at the inner corners. Here is where I ended up:

Depth:

Length:

Step 9: Install Brake lines. If you have new lines, connect those to the car, then spin the caliper on to the line fitting. Thee OEM E46 M3 lines can work but I would not recommend it as there is a lot of stress on the line. As a temporary solution, I used the OEM M4 brake lines which were probably a few inches too long, but they get the job done. I will get some E46 M3 SS lines made with 90 degree to connections later as a permanent solution. Make sure you clean off any brake fluid as it will eat up the paint on the caliper.

Unfortunately, I did not take pictures of my lines but here are some images from Jahhadow's thread:

HEL Lines with the 90 degree turn for rear (Jahaddow)

Rear lines installed (Jahaddow's thread)

Step 10: Install Rotors and locking screws.

Step 11:Install Calipers. Torque carrier bolts to 48 ft-lbs. DO NOT use loctite here. I also installed the brake pads as well, which was super simple and only requires you to remove and install the two guide pins on top.

Woohoo! I was so excited at this point. These things look so damn good on there! Now it is time to move on to fronts!

FRONT BRAKES

These are much more simple to install as they are literally directly bolted to the carrier.

Step 12: Remove the front calipers and rotors.

Front pads removed. I put the calipers back on for reference.

Step 13: The shield has to be modified slightly to fit. Bend the shield all around to prevent contact with the rotor. I could not bend the shield enough at the Tie Rod section to permanently deform the shield, so I ended up cutting a small section around the Tie Rod. One other thing not shown in the ear on the bottom right side (5 O'Clock position) had to be bend almost all the way back to fit the caliper.

Front shield cut but not fully bent back on bottom right side.

Step 14: Installed the new brake lines. I reused my SS E46 M3 lines as they fit perfectly. Rotate the caliper on to the line. Make sure you clean off any brake fluid as it will eat up the paint on the caliper.

Step 15: Install front Rotors. I was a bit confused as to which direction these should face because my quick online search showed me both directions. I later learned that the internal veins dictate how the air flows and since these are directional, they should be facing the other direction. This will allow the air to flow from the center to the outside edge during forward movement. The way mine are installed, it will suck air in to the center.

I have heard that it honestly doesn't matter but my OCD will not let me leave it. I will fix it the next time I bleed the system LOL.

Step 16: Install Caliper. Torque Carrier bolts to 81 ft-lbs. Again, No loctite here.

That's it for this side of the car! I took a step back to revel in the glory of this BBK LOL.

Once you are done being appreciating how great and massive these look, move on to the other side.

Step 17: Repeat Step 2 through Step 16 for the passenger side of car.

Step 18: Bleed Brakes. I love the Scwaban power bleeder. Castrol SRF lifetime replacement is probably one of the best things on FCP Euro LOL.

Step 19: Adjust e-brake cable. I ended up removing about 1/2" of slack to get things nice and tight.

Step 20: Install wheels and lug bolts.

Step 21: Bed brakes. When I first got in to drive, the pedal went almost all the way down. After a few pumps, the pedal was a little better but the travel was still pretty bad. I figured there may still be air in the lines. After I went for a quick drive to bed the brakes, the pedal travel was much better and pretty much similar to stock. However I still think I have some bubbles so I will go back and bleed one more time.

Here are some shots of the car:

Front Wheels with OEM 19s

Rear OEM 19s

Alufelgen CS7 CSL Style wheels:

Final Comments: The brakes look beautiful behind the 19's and fill everything in nicely. The braking is now fantastic compared to the OEM brakes. The initial bit is intense and makes the tires chirp but then again I was bedding in my booboo daily tires. All in all, I would say the difficulty was a 6/10 with the grinding and cutting making it more difficult. This is such a worthwhile upgrade 380mm Front and 370mm Rear brakes for under $1800 installed is an unbelievable price. I would do this mod again in a heart beat.

Please feel free to contact me with any questions or concerns! I am in the houston area so if you ever want to meet up, just PM me! Stay safe everyone!