I had my first brake service done in March at 112k miles. The front rotors were replaced as well as front pads and rear pads, by Porsche dealer. They said the rear rotors were at the limit, but that they usually just leave them. I have noticed that the brakes don't bite as before. Went back to dealer last month and they did a brake flush and said its fine now. Still not the same bite as before. My question is would the fact that the rear rotors were not replaced cause this lack of initial subtle bite and they are at the wear limit. I feel like I have to pump the brakes in order for them to grab. When they were done the first time (march) I attributed this to the fact that they were new brakes that needed some miles to bed-in. Its been 2-3k miles already.

 

The rears are at their limits but they left them? No doubt they'll have ridges on them if they've worn that far, you don't want new pads on old ridged rotors. Something smells fishy, get them to explain why they didn't replace the rears if they're at the limit...

 

What type of pads did you get? OEM? What type of pads did you replace; OEM or aftermarket? How do they brake after they have some heat in them...better?

 

oem replacing oem. With some heat in them, normal driving, they feel the same

 

2 things:
1) sounds like the brake flush was done poorly and you still have air in the system. The pedal will feel firm REGARDLESS of whether the pads/rotors are not mated.
2) You will need a little time for the rotors and pads to mate up. Rear rotors will get circular grooving that takes some time for the pads to wear into.

-td

 

Do not like the fact the dealer didn't replace the at the limit rear rotors. At 112K miles you got your money's worth. I think I managed close to 100K on the rear rotors from new.

The lack of bite is not the rear rotors per se. My guess is the new pads (front and rear) and the new rotors (front) and the old rotors (rear) need to be bedded in properly to maximize braking action.

Briefly, the bedding process involves where and when safe taking the car up to speed (a reasonable highway safe/legal speed is good enough) and then applying the brakes with considerable force to really slow the car down.

You do not want to brake hard enough to activate the ABS or cause the tires to skid, but you want to slow the car from say 65mph to around 20mph then release the brake pedal and accelerate up to speed and repeat the process.

My experience is you might notice a bit of increase in brake bite the 2nd time you apply the brakes and certainly the 3rd time. A 4th time is not really necessary.

In fact given the rear rotors are at their wear limit you might want to err on the side of caution and only do this two times. The brakes may not be 100% bedded in but they'll be well on their way.

Important: Do not bring the car to a complete stop at any time during the process. The brake hardware is hot, on purpose, and bringing the car to a complete stop can cause uneven pad material deposition on the rotors and the brakes will have a pulsing to them afterwards.

After you do the last slowdown drive the car long enough to ensure the brakes are completely cooled down.

Then the brakes are ready for about anything.

Sincerely,

Macster.

 

I didn't mention that a few weeks after the brake service in March, I took the car to a POC track event at el toro. If the bed-in hadn't occurred the few weeks before, I thought it would occur at the track. It was my first time, had a great instructor and the car performed really well. I did notice that the pedal position was lower after a couple of hot laps which I attributed to the new OEM brakes starting to fade, but not bad at all. We did four 20 minute sessions that day. Pedal would be firm by the next session. but overall, after a few months, the initial bite is different than what it had before. I'm wondering if I cooked the pads on the track. The pads and front rotor only had about 150 miles before the el toro event, so I assumed they needed more time to bed-in.

 

Bed in takes no real 'distance' to do, but merely doing some cycles.

 

Yah I had it down one time but senility has me lost for if its hard braking then soft and back to hard to break pads in. Even though the pads are packed hard the surface needs to be prepped with a breaking in.

 

Here is a link to bedding brakes.