A friend and I did a brake job on my 2003 MCS recently, replacing stock components with Powerslot rotors, Hawk HPS pads, and Goodridge lines. I have two concerns:

First is that after the car sits overnight, on most, but not all initial start-ups, there is a metal rubbing sound, a bit of a squawk that goes away after pulling out of the garage (sometimes it does it twice - once in reverse and once in first). Again, it happens most, but not all of the time, whether the emergency brake was engaged or not. It d/n do it for the rest of that day, but will do it again the next morning. I used a liberal amount of Disc Brake Quiet on the backside of the pads, and wonder if this might have something to do with the problem

Second, after this brake job, the pedal feels a bit softer with a longer throw. The car stops just fine - I can't tell if it is really any better than stock, and I was hoping for an obvious, if not dramatic, improvement. This is the second brake job on this car, the first time I used stock rotors and pads, and d/n have either of these issues. Three brake bleeds with several cycles through, and I am positive there is no air in the lines.

Any suggestions on what the problems might be if any, and possible solutions?

Any ideas would be greatly appreciated.

Len

 

1. You still have air in the hydraulic unit if the throw is longer and the feel softer. These are very difficult systems to bleed and the old fashioned method of just bleeding from the slaves is inadequate. You need a large reservoir and a pressure bleeder if you did not take care to keep the hydraulic unit from getting air (brake lines should not have been disconnected to replace pads).

2. Your pads/rotors will take awhile to properly mate. You should detect a substantial improvement in braking within about 100 miles. When I first installed my JCW brakes, the stopping distance verged on the unsafe. After they wore in, they are far superior to the stock brakes.

3. Regarding the chatter, did you reinstall the spring clips and pad wear sensors properly? Borrow someone Bentley manual for full explanation.

 

HPS is a metallic pad so some noise is expected, but it will quiet down after some mileage.

The soft and long travel of brake pedal means there is air in the system. With replacement of line, as you have done with Goodridge SS line, there will be a lot of air in the system. I used pressurized bleed system and I had to bleed the system twice with 2 quarts of brake fluid to get the system air free.

 

If you do not bed them, they will not feel near as good. The rotors likely have a rough texture since they are new. The noise is probably just because of the flat new pad and a rough rotor. It will go away. Bedding will speed up the process. My bobcats felt the same as stock until I bedded them. Now they are much better! Smoke was bellowing from them and they still worked better than stock!

 

Cant help on the noise.

Could be the pads. Had similar experience with Hawk HPS, softer peddle and till they got heat in them they didnt stop very well, once had heat they stopped ok but still had a high (compared to stock) peddle effort.

 

Thanks for your responses - I will probably go back through, take another look, bleed the system again.

Len