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I decided to make a DIY tutorial for how to change the brake pads on a 2008 Cayenne Turbo. These calipers are different from other turbos in that you must remove the calipers to change the brake pads. Also, this might help others, so I'll share my thoughts on brake pads. Avoid the TRW ceramic pads! They squeal badly and don't fit the calipers perfectly. As a result, the pads shift slightly when you go from reverse to drive and vice versa. I swapped these out for Textar pads and am very satisfied with them for daily driving. Hope this video helps some of you out there!
When I do any brake job I always thoroughly clean the parts with brake parts cleaner and then apply grease to any moving surfaces such as the pistons onto the back of the pads, and the slide pins. Basically any metal to metal surface needs some lubricant to prevent squealing.
Most of the time, brake squeal is caused by a harmonic that occurs between the back of the pad carrier and the caliper pistons, not between the pad material surface and the rotor. In watching this video, I'm surprised the Cayenne doesn't use the normal Porsche pad dampeners which are an adhesive material attached to a metal prong. The adhesive sticks to the back of the pad carrier and the metal prong fits into the caliper piston and this is what prevents the chattering of the pads that results in squeal. The look like this and I'd need to check PET to see if they're shown for the Cayenne or even available in the proper size for the Cayenne caliper pistons.
Alternatively, what works well is Permatex anti-squeal, which is a paste you apply to the back of the pad carrier just before assembly and then it sticks the pad to the piston and prevents the chattering.
Also, when switching pad material and reusing your same rotors, you should really be cleaning the rotors with brake cleaner and a roloc or scotch-brite pad to remove the old pad material at a microscopic level. When you follow the bedding-in procedure for new brake pads, the purpose of that is to transfer some of the pad material into the rotor as this is what gives you the high initial bite when you press the brake pedal. You want the same material embedded into the rotor and in the brake pad that's contacting the rotor.
Without doing this refreshment procedure to the rotor surface, you can limit the effectiveness of the brakes (they'll work, but not as well as they could) and you can also create the sensation of what feels like a warped rotor, where it grabs and releases and grabs and releases as the rotor spins between the pads.
Most of the time, brake squeal is caused by a harmonic that occurs between the back of the pad carrier and the caliper pistons, not between the pad material surface and the rotor. In watching this video, I'm surprised the Cayenne doesn't use the normal Porsche pad dampeners which are an adhesive material attached to a metal prong. The adhesive sticks to the back of the pad carrier and the metal prong fits into the caliper piston and this is what prevents the chattering of the pads that results in squeal. The look like this and I'd need to check PET to see if they're shown for the Cayenne or even available in the proper size for the Cayenne caliper pistons.
Alternatively, what works well is Permatex anti-squeal, which is a paste you apply to the back of the pad carrier just before assembly and then it sticks the pad to the piston and prevents the chattering.
Also, when switching pad material and reusing your same rotors, you should really be cleaning the rotors with brake cleaner and a roloc or scotch-brite pad to remove the old pad material at a microscopic level. When you follow the bedding-in procedure for new brake pads, the purpose of that is to transfer some of the pad material into the rotor as this is what gives you the high initial bite when you press the brake pedal. You want the same material embedded into the rotor and in the brake pad that's contacting the rotor.
Without doing this refreshment procedure to the rotor surface, you can limit the effectiveness of the brakes (they'll work, but not as well as they could) and you can also create the sensation of what feels like a warped rotor, where it grabs and releases and grabs and releases as the rotor spins between the pads.
The instructions I used from AllDataDIY explicitly said not to grease the back of the brake pads, so I didn't. As for bedding the brakes in, I think what you mentioned is overkill and ineffective. If you can get the old pad material off with a scotch bright pad, the bond with the rotors is very weak. In normal driving, you will remove much of the pad material deposited. Aside from how dangerous it can be to bed in your brakes in public road, your brakes will bed themselves in slowly through normal driving. I say this with no disrespect, but just what I've noticed after several brake changes on several cars. My new pads had great bite immediately and make zero noise.
The instructions I used from AllDataDIY explicitly said not to grease the back of the brake pads, so I didn't. As for bedding the brakes in, I think what you mentioned is overkill and ineffective. If you can get the old pad material off with a scotch bright pad, the bond with the rotors is very weak. In normal driving, you will remove much of the pad material deposited. Aside from how dangerous it can be to bed in your brakes in public road, your brakes will bed themselves in slowly through normal driving. I say this with no disrespect, but just what I've noticed after several brake changes on several cars. My new pads had great bite immediately and make zero noise.
The Permatex I mention isn't grease (though they do make a grease product), it's an adhesive more like a hi-temp silicone that sticks the piston to the back of the pad, but with a vibration adsorbent cushion - essentially the opposite of grease.
I've done probably 20 brake jobs on everything from dirt bikes, Saab Turbos, many Porsche, Infinitis, a Honda Pilot, GMC and Ford Pickups, etc using my method of cleaning the rotors, bedding the brakes, and using a product like the Permatex on the back of the pad carrier and never once had squeaky brakes afterwards, irregardless of the brand or type of pad being used, or if the rotors were reused or replaced.
There are also plenty of places to do a safe bedding procedure, even if it's in a big, empty parking lot.
11-05-2017, 11:30 AM
2008 Cayenne Turbo Brake PAD DIY Video!
