Brakes didn't get bedded in right

[Flying Low]

I did a 2 day PCA event at Spring Mountain's Hunt "B" configuration with 3 Time Trial groups and one HPDE run group for everyone that didn't want to time trial. My M4 had 285/30X18 in front and 295/30X18 rear with PAGID's new RSL race pads. This was my first outing with this car so I did the HPDE since I didn't know what to expect. As it turned out, I was one of the fastest in that group but only right in the middle of the results of the "Orange" group which was the middle time trial group. The "red" group was almost all trailered race cars but with some street GT3's. and other high performance cars.

I'm pretty happy with the performance of the car, especially under braking. However, I never did get the RSL pads bedded in properly and I had major judder. And that is the point of this post. I put the OEM pads back in (steel brakes) after I sanded off all visible signs of the RSL transfer layer. After driving about 2500 miles with the OEM pads back in, I still have annoying judder.

So do I try sanding again or have the rotors turned down a bit? My research basically says that the transfer layer extends into the pores of the rotor which may take a really long time to wear through. Another obvious choice is to buy new rotors. But these are like brand new. New rotors are $377 each for the front and out of curiosity the CCB rotors for the front are $4200 each. Has anyone else had success getting rid of judder and how?

I dearly wanted camber plates for this event but nothing was available. The outer 1/3 of the front Hoosiers were doing almost all of the work. I swapped sides half way through the event to even out front tire wear.

But here is another question. With maybe only 1 degree of negative camber in front, did this contribute to what seemed like really good braking? Has any one studied the possible trade off between lots of camber for cornering and straight up tires for braking? F1 cars have lots of camber and brake really well but do they even have a trade off or does their high profile tires help?

For those that don't know already, for stock or adaptive suspension, TC Kline has camber plates available now and Ground Control should have theirs in another 3-4 weeks.

Terry

[Gearhead999s]

I was told not use the RSL pads by Andreas who is the Pagid tech guy due to the issues that people where having with bedding them in.I have never had that issue ever with RS29 or R14's.

[gthal]

I agree with Gearhead. I have also been told the RSL pads can be an issue. Swap them out for RS29 next time.

If you leave them on and run them cold on the car for a day or two, it should remove the deposits and fix the judder. See this link for more discussion... http://www.zeckhausen.com/avoiding_brake_judder.htm

[CanAutM3]

I ran the RS29 without issue, never tried the RSL though...

To remove the deposit, I would keep the Pagid pads on for street use as they are likely more abrasive than the stock pads. And be patient, it can take several weeks to scrape that deposit off. Sanding just won't do the job.

Hopefully your discs have not gone through a metallurgical transformation with the deposit (deposits results in thick spots that in turn result in hot spots that transform the metal in "hard spots"). If that is the case, you will need to replace the rotors as the judder won't go away. I would avoid resurfacing the rotors. First, it removes a useful amount of brake thickness and second it can mask surface hardening of the disc (if there is) that will just come back next time you are at the track. But as I stated, be patient, wait at least 2~4 weeks of street uses before you replace your discs.

[Flying Low]

Thanks for the comments. I intended to buy the RS29 for the M4. I have been using the RS29 for a few years on my turbocharged E46 M3 with good results. But I got talked into the RSL because of the better initial bite compared to the RS29. Nothing like being a beta tester.

Unfortunately, the RS29 seems to be backordered everywhere and are about 4 weeks out.

[evanescent03]

Originally Posted by Gearhead999s

I was told not use the RSL pads by Andreas who is the Pagid tech guy due to the issues that people where having with bedding them in.I have never had that issue ever with RS29 or R14's.

what are your bedding procedures with the RS29s? first time with them for me and on my way to the event ... hehe

[evanescent03]

I had a brake judder problem with my e46 M3 and I could not resolve it and ended up replacing the pads and rotors in selling the car. those were hawk HP + pads and I even followed all of the bedding procedure is recommended by hawk. I am nervous that I will be in the same boat as you… I absolutely hate brake judder. good luck and keep us posted!

[Gearhead999s]

Originally Posted by evanescent03

what are your bedding procedures with the RS29s? first time with them for me and on my way to the event ... hehe

Usually drive to event with them and find a good side road where I can do a bunch of stops from about 100 to 30 mph till you get a lot of smell coming the pads and bit of a softer pedal.Then drive at least 10 minutes with no braking till they are cool.If you have done properly the discs will be a dull grey colour which indicates you have a good transfer layer on the disc and are good to go.

[CanAutM3]

Originally Posted by evanescent03

I had a brake judder problem with my e46 M3 and I could not resolve it and ended up replacing the pads and rotors in selling the car. those were hawk HP + pads and I even followed all of the bedding procedure is recommended by hawk. I am nervous that I will be in the same boat as you… I absolutely hate brake judder. good luck and keep us posted!

Hawk HP+ are far from being the best track pad out there. They are a decent el-cheepo solution, but not much more. If you do not manage them well, they can overheat a smear the discs. I've used them for a while on my E46 and E92, but decided to swap for PF08 on my E92. The PF08 were almost double the cost but ended up lasting twice as long, which dismissed the price advantage of the HP+. I haven't looked back since.

[evanescent03]

Originally Posted by CanAutM3

Hawk HP+ are far from being the best track pad out there. They are a decent el-cheepo solution, but not much more. If you do not manage them well, they can overheat a smear the discs. I've used them for a while on my E46 and E92, but decided to swap for PF08 on my E92. The PF08 were almost double the cost but ended up lasting twice as long, which dismissed the price advantage of the HP+. I haven't looked back since.

I am just nervous about the same situation on the F80 and want to avoid that at all cost… Literally and figuratively

[Flying Low]

One thing we haven't mentioned here is that the pads and rotors need to be mated to each other so that one portion of the pad is not doing most of the braking and overheating locally. Our cars are so new that this mating shouldn't take very long at all. But as the rotors wear down and become grooved a bit; then the car should be driven a time under relatively light braking to mate the rotor to pad interface. Then the bedding (transfer of brake pad material to the rotor) can begin using more aggressive braking.

[CanAutM3]

Originally Posted by lo flyn

One thing we haven't mentioned here is that the pads and rotors need to be mated to each other so that one portion of the pad is not doing most of the braking and overheating locally. Our cars are so new that this mating shouldn't take very long at all. But as the rotors wear down and become grooved a bit; then the car should be driven a time under relatively light braking to mate the rotor to pad interface. Then the bedding (transfer of brake pad material to the rotor) can begin using more aggressive braking.

The "matching" you mention usually happens after only a few hard stops. In my experience, it take longer to properly bed the brakes than it does "matching" the pads and disc.

[MasterP]

I own Rotor Hones for this reason.