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Front Brake Rotor Replacement
 
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Pelican Technical Article:

Front Brake Rotor Replacement

Jared Fenton

Time:

2 hours2 hrs

Tab:

$50 to $400

Talent:

****

Tools:

T30, T40, T50 Torx drivers, rubber mallet

Applicable Models:

Porsche 955 Cayenne (2004-08)
Porsche 955 Cayenne S (2003-08)
Porsche 955 Cayenne Turbo (2003-08)

Parts Required:

Front Brake Rotors, new caliper mounting bolts

Hot Tip:

Coat the hub/retaining bolt with anti-seize paste

Performance Gain:

Better braking

Complementary Modification:

Replace brake pads

Brake rotors (or discs as they are often called) are perhaps the most important part of the braking system. The brake pads rub against the rotor to slow the car down. At the same time, the rotor also dissipates heat from the friction generated. If the rotor becomes too thin, or develops grooves in the surface, then their ability to stop the car decreases.

When replacing your brake pads, you should always measure the thickness of your brake rotors. If they fall below the specified value, then they should be replaced with new ones. Check for grooves in the rotor, and make sure that you take several measurements of the rotor in several different places. This will guarantee you that you get an accurate reading. If the brake rotor has a groove in it, then it should most certainly be 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. Additionally, the rotors can warp from the excess heat generated.

Use a micrometer to measure the thickness of the brake disc. From the factory, the brake discs on your Cayenne will be 34mm. The wear limit is 32mm. Compared to most cars, this is a very fine tolerance and it has been my experience that most rotors end up falling below 32mm and require new discs. This is due to the weight of the vehicle and the increased heat generated by the rotors compared to those on a much lighter sports car.

If you do find that you need to replace your rotors, replacing them is a pretty simple job. The procedure for the front or the rear rotors is very similar, but for the sake of this project, we'll look at replacing the front rotors.

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 article on replacing front brake pads for more details. You'll now need to remove the bracket holding the hard/soft brake line and the brake wear sensor harness. This is held in place with a T30 Torx bolt at the top and a T40 bolt at the bottom on early Cayenne's. Later Cayenne's have a simpler setup and only have one T40 Torx bolt to remove at the bottom.

Now unbolt the caliper from the front strut. There are two 21mm bolts that mount the caliper to the front strut. After you remove these two bolts, you should be able to move the caliper up and off the rotor. Exercise caution when moving the caliper around - make sure that you do not let the caliper hang from the rubber brake line assembly, as this can damage the line. Once the caliper is off the strut, hang it in place with a bungee cord.

Now remove the T50 Torx bolt that holds on the brake rotor. You should now be able to pull the disc off of the hub. If there is any resistance, use a rubber mallet to tap the brake disc off. Sometimes the disc will require some heavy smacks with your rubber mallet to get it off.

It's a good idea to clean the face of the wheel hub once the rotor is removed with some brake cleaner and a soft brush. Once clean, I like to put a light coat of anti-seize compound on there. It helps to prevent corrosion and also keeps the rotor from sticking to the hub.

After the new rotor is installed, replace the retaining screw with a new one (part no. N-910-282-02-M1002) and also the caliper mounting bolts (part no. N-906-854-03-M100) Porsche uses a coating on the threads of these bolts to secure them in place and are designed to be used only once. Torque the fasteners to spec (see below) and install 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

Shown here is the front brake caliper and disk.
Figure 1

Shown here is the front brake caliper and disk.

Rotate the front strut outward as much as possible so you can access the brake line bracket.
Figure 2

Rotate the front strut outward as much as possible so you can access the brake line bracket. Shown here are the two bolts that hold it in place (green arrows). Note that on later Cayenne's, this assembly has been simplified and you only need to remove the bolt at the bottom holding the bracket to the strut.

Remove the T40 Torx bolt at the bottom of the strut.
Figure 3

Remove the T40 Torx bolt at the bottom of the strut.

Now remove the T30 Torx bolt at the top of the strut.
Figure 4

Now remove the T30 Torx bolt at the top of the strut. A set of Torx sockets as shown here make the job much quicker.

Carefully remove the bracket from the backside of the strut.
Figure 5

Carefully remove the bracket from the backside of the strut. Take care not to damage the hard brake line going to the caliper.

Shown here are the two 21mm bolts that hold the caliper to the wheel hub (green arrows).
Figure 6

Shown here are the two 21mm bolts that hold the caliper to the wheel hub (green arrows). These bolts are designed for one use only and must be replaced after removal.

The caliper bolts are torqued down to 200ft/lbs from the factory.
Figure 7

The caliper bolts are torqued down to 200ft/lbs from the factory. You'll want to use a large ratchet or breaker bar to loosen them up.

Once the caliper is removed, never let it hang by the brake line.
Figure 8

Once the caliper is removed, never let it hang by the brake line. Use a bungee cord to secure the caliper up near the strut.

Now remove the T50 Torx screw that secures the brake rotor to the hub.
Figure 9

Now remove the T50 Torx screw that secures the brake rotor to the hub. The rotor should just pull off at this point. If it doesn't, hit the rotor on the backside with a rubber mallet.

Shown here is the wheel hub with the rotor removed.
Figure 10

Shown here is the wheel hub with the rotor removed. It's a good idea to clean the face of the hub (green arrow) with brake cleaner and a soft brush. This removes any dirt and/or corrosion that may have built up. Additionally, I like to put a light coat of anti-seize compound on the face of the hub.

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Comments and Suggestions:
sadman Comments: Would be nice if you included the 21mm bolts in the brake kit.
November 26, 2016
  Followup from the Pelican Staff: I'll pass this info on to the Pelican Team. - Nick at Pelican Parts  
Tom Comments: This was very helpful.
June 18, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it. I'll ask someone to contact you.
- Nick at Pelican Parts
 

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