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Brake Disc Replacement
 
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Pelican Technical Article:

Brake Disc Replacement

Jared Fenton

Time:

3 hours3 hrs

Tab:

$50 to $200

Talent:

**

Tools:

T50 Torx head socket, rubber mallet, socket set, micrometer, anti-seize compound

Applicable Models:

R50 MINI Cooper Hatchback (2002-06)
R52 MINI Cooper Convertible (2005-08)
R52 MINI Cooper S Convertible (2005-08)
R53 MINI Cooper S Hatchback (2002-06)
R55 MINI Cooper Clubman Wagon (2008-14)
R55 MINI Cooper JCW Clubman Wagon (2009-14)
R55 MINI Cooper S Clubman Wagon (2008-14)
R56 MINI Cooper Hatchback (2007-13)
R56 MINI Cooper JCW Hatchback (2009-13)
R56 MINI Cooper S Hatchback (2007-13)
R57 MINI Cooper Convertible (2009-15)
R57 MINI Cooper JCW Convertible (2009-15)
R57 MINI Cooper S Convertible (2009-15)

Parts Required:

Brake discs, new pads, new disc retaining screws

Hot Tip:

Adjust your emergency brake while you have access

Performance Gain:

Better, safer braking

Complementary Modification:

Replace brake pads, emergency brake adjustment, install stainless steel brake lines, and install new wheel bearings
How to Maintain and Modify your new MINI

This article is one in a series that have been released in conjunction with Pelican Parts' new book, How to Maintain and Modify your new MINI The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 500+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any MINI owner's collection. The book is due to be released in late 2015. See The Official Book Website for more details.

Brake discs (or rotors as they are often called) are a very important part of the braking system. The brake pads rub against the discs to create a friction force that is responsible for slowing the car down. If the rotors become too thin, or develop grooves in them, then their ability to stop the car decreases.

When replacing your brake pads, you should always measure the thickness of your brake discs. If they fall below the specified value for your car, then they should be replaced with new ones. Check for grooves in the rotor, and make sure that you take several measurements of the disc in several different places. This will guarantee you that you get an accurate reading. If the brake disc has a groove in it, then it should most certainly be removed and resurfaced by a machine shop, or simply replaced with a new one. Discs with grooves not only brake less efficiently, but they also heat up to higher temperatures, and reduce your overall braking ability.

The measurements that you take with your micrometer should be made from the center of the disc. It is common for OEM rotors to have the minimum thickness stamped on the rotor hub. If you can't find this information, use the following chart to determine if your rotors need to be replaced.

Type and Year Min Thickness
Front Vented Rotor, MINI Cooper R50/R52 (2002-08) 20.4mm
Front Vented Rotor, MINI Cooper S R52/R53 (2002-08) 20.4mm
Rear Solid Rotor, MINI Cooper R50/R52 (2002-08) 8.4mm
Rear Solid Rotor, MINI Cooper S R52/R53 (2002-08) 8.4mm
Front Vented Rotor, MINI Cooper/Cooper S R55/R56/R57 (2008-on) 20.4mm
Rear Solid Rotor, MINI Cooper/Cooper S R55/R56/R57 (2008-on) 8.4mm

The first step is to jack up the car and remove the road wheel. If you haven't already, remove the brake pads from the caliper (Refer to our project on replacing brake pads for more details). There should be two bolts that mount the caliper and hold it in place. After you remove these two bolts, you should be able to move the caliper out of the way of the disc. Exercise caution when moving the caliper around - make sure that you do not let the caliper hang from the rubber brake line, as this will most certainly damage the line.

After the caliper is removed and tied out of the way, you must remove the caliper retaining frame. This is secured to the back of the wheel housing with two 16mm bolts. (see Figure 1 and Figure 2) They are torqued down very tightly, so you may need to use a breaker bar in order to get them loosened. Once you have removed the bolts, guide the frame over the brake disc and out of the way. (see Figure 3)

Once you have the caliper and it's retaining frame out of the way, remove the small screw that holds on the brake disc. You will need a T50 Torx head socket for this task. You should now be able to pull the disc off of the hub. Sometimes, the metal can gall between the disc and the wheel hub. This occasionally locks the disc to the hub even with the retaining bolt removed. If there is any resistance, use a rubber mallet to tap the brake disc off. (see Figure 4 and Figure 5)

NOTE: Keep in mind that for the rear discs, you only need to remove the brake disc mounting screw to remove the disc from the hub. Just carefully guide the disc over the hub and out of the mounting bracket. (see Figure 6)

Installation of the new brake disc is a snap, simply push it onto the hub, taking care to line up the holes for both the lug bolts and the brake retaining screw. Put a small dab of anti-seize compound on the threads of the new retaining bolt. This is cheap insurance to prevent the screw from stripping the next time you remove it. Now, hold the disc in place with your hand and install the retaining screw. You will want to torque the screw to 20 ft-lbs. (27Nm). (see Figure 7)

After the new disc is installed, reattach the brake pad carrier. The collar bolts are torqued to 81 ft-lbs. (110 Nm) and the rear are torqued to 48 ft-lbs. (65 Nm). Next, install the calipers and new brake pads. Your new rotors should last a long time, and you should see an improvement in your braking after the wear-in period for your new brake pads.

ThisPicture shows the two 16mm bolts that secure the caliper mounting frame to the wheel housing (green arrows).
Figure 1

This picture shows the two 16mm bolts that secure the caliper mounting frame to the wheel housing (green arrows). On the front brakes of the MINI, this frame must be removed in order to remove the brake disc.

These bolts are torqued down very tight, so you may need to use a breaker bar to loosen them up.
Figure 2

These bolts are torqued down very tight, so you may need to use a breaker bar to loosen them up. Once the bolts are removed, maneuver the frame out from in-between the wheel housing and the brake disc.

Before you remove your brake discs, it is important to first measure them to see if they need to be replaced.
Figure 3

Before you remove your brake discs, it is important to first measure them to see if they need to be replaced. Use a micrometer to perform the measurement. If you use a dial caliper, then you might get a false reading because the disc wears on the area where the pads make contact, not on the edges of the disc. Make sure that you take several measurements in order to compensate for potential low or high spots on the disc.

The brake disc is secured to the wheel hub with a countersunk T50 Torx bolt.
Figure 4

The brake disc is secured to the wheel hub with a countersunk T50 Torx bolt. Once removed, the brake disc should simply pull off. Sometimes, the disc can stick to the wheel hub. If it is stuck on, use a rubber mallet on the backside to knock the disc off.

This is what you should see once the brake disc has been removed from the wheel hub.
Figure 5

This is what you should see once the brake disc has been removed from the wheel hub. it's not a bad idea to clean the mating surface at this time.

For the rear discs on the MINI, you don't need to remove the caliper mounting frame.
Figure 6

For the rear discs on the MINI, you don't need to remove the caliper mounting frame. Just remove the disc retaining bolt and maneuver the disc off the hub and out of the frame.

It's a good idea to put a small dab of anti-seize compound on the threads of the new disc retaining bolt before installing it.
Figure 7

It's a good idea to put a small dab of anti-seize compound on the threads of the new disc retaining bolt before installing it. Then, line up the new disc with the mounting hole on the hub. You will likely have to hold the disc in place until the bolt starts threading in. You will want to torque the screw to 20 ft/lbs. (27Nm)

This is what you should see once the new discs, pads and caliper have been re-installed.
Figure 8

This is what you should see once the new discs, pads and caliper have been re-installed. Make sure to follow the particular break-in procedures for the new brakes.

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Comments and Suggestions:
Qik Comments: What is the torque spec on the caliper bolts?
November 23, 2016
  Followup from the Pelican Staff:

I don’t have that info.


I would grab a repair manual. It will have the procedure, special tools and torque specs.


Give our parts specialists a call at 1-888-280-7799.- Nick at Pelican Parts
 
Mittenjake Comments: The t50 bolt is a real monster.oddly enough mine is actually t45... more like t45.2 and a very shallow one at that. I wish mini would design the hub to have bolts that extent all the way through to the lug nuts like gm cars... but i guess the rotors would need to be about a half inch bigger. Seems worth it to me because I CANT budge that t45
October 1, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Ed Comments: I have followed all directions I could find they have been most helpful. The rear brake seems to put enough pressure on the disc that it is hard to turn. Any thoughts? Park brake is off.
July 16, 2015
  Followup from the Pelican Staff: The caliper could be faulty. Not releasing properly. - Nick at Pelican Parts  
Husband of Mini owner Comments: Pads are designed to wear. The better the pad quality will usually result in more even wear and better braking. This will also help the rotors last longer and stay in better shape. Pads & rotors should not wear at the same rate, they are very much two different materials.
I do have a question about slotted & drilled rotors. Someone at work said slotted rotors are better in the rain. As I think about this, I see an added avenue for rain to be introduced under the pads? I understand the performance reasons for drilled& slotted rotor. What do you think.
June 16, 2015
  Followup from the Pelican Staff: In my experience, rotors and pads both wear, which is why MINIs and BMWs have quiet powerful brakes. When rotors are measured, they are close to or at the replacement spec along with the pads.

The slots do eject water, increasing performance. - Nick at Pelican Parts
 
tampafan1983 Comments: When I asked my dealership about doing a brake job they told me they world have to replace the rotor a sensors as well since the rotors were one time use. Has anyone heard of this because I have not and have changed plenty of brakes.
April 18, 2015
  Followup from the Pelican Staff: The rotors do wear as fast as the pads most times, requiring replacement. The sensors need to be replaced as well. - Nick at Pelican Parts  
Tiger Comments: If I were to wanna buy some extra T-50 torx bolt, do you know what size holds the brake disc in place? Im afraid of stripping the bolt by accident.
January 15, 2015
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
p38sheep Comments: Also don't forget to include the torque of the caliper mounting frame/pad carrier into your reassembly.
April 16, 2014
  Followup from the Pelican Staff: Thanks for the feedback. We don't always have access to torque specs, they are however listed in repair manuals. I would grab one. - Nick at Pelican Parts  
p38sheep Comments: BMW level 3 tech checking in.
Previous comment is NOT recommended it is very easy to do if you have an impact driver, or if you let it soak with a bit of Pen oil or WD-40. A touch of milk of magnesia acts great as a dry anti-seize, I use this because the heat of the brakes will not "melt" it like normal anti-seize, and yet retains its function of keeping things manageable for removal. A touch of normal anti-seize around the hub will also prevent it from rusting to the hub be sure to put the lightest coat possible on however as you don't want this to run I use copper Anti-seize when I do use it.
April 16, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Don't have one Comments: You should tell everyone that they will most likely have to drill the the t-50 flathead bolts that hold the rotors out and replace them. It's one of the most idiotic engineering designs I've seen. You'll need to replace them because they locate the rotors.
April 7, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 

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