Questions about brake judder and bedding race pads

GetBlown2k3

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Well I threw my PFC 01 compound pads on a few days before Daytona, and drove on them and drove to the event on them to clean off street pad material transfer off of the face of the rotor. BUT, being an idiot, I didnt properly bed them in properly on my first few laps at Daytona, and immediately began driving hard on them during my first session without regard to proper bedding procedures (series of high to low speed braking with a cool down afterwards) :bash:. I noticed in my first session that I had noticeable brake judder during threshold braking into turn 1. I noticed this through the first session, but didnt really notice it at all (at least dont remember feeling it) during the remaining 3 sessions and seemed like it went away. Could the rest of the sessions have evened out or cleaned off the uneven pad deposits?


One thing I DID notice though was a sound the pads were making against the rotor during threshold braking that I never noticed with my street pads; it was a "ssshhhhhhhhhhhhh" sound, lol, thats the best way I can describe it, kind of like the sound of a sandpaper going over the rotor, but nothing like a metal to metal sound. Is that normal with a race pad; is that just the abrasive sound it makes under heavy braking or should it be fairly quiet?


Also, for those of you who run race pads; how do you bed them in at the track? I've heard people say bed them in the night before the event, but that seems kind of pointless since the drive TO the track will scrape off the material transfer since the race pads will be very abrasive under operating temps on the street. For race pads, do you have to do a specific bedding procedure, or will a half-dozen 100 to 30 stops on the track transfer enough pad material onto the rotor that it would be "bedded" and judder-free?


I just wanted to "test" the bedding procedure on these pads to get a feel for how I would do it on track; is this how the rotor should look after bedding pads?

217141_593167327799_203802289_33148330_6661889_n.jpg
 

wheelhopper

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Scott, the sound you are hearing is probably due to the dimpled rotors you are using. Slotted, drilled, and dimpled rotors will tend to make a noise vs. smooth rotors.

When using a new type of pad with an old rotor, you should lightly sand or use scotchbrite pad on the old rotor to clean the previous pads material off. Since you did not do that, the juddering you were feeling was probably due to the different materials not meshing well together and the material on the rotor wore off after your first session of hard use.

If you drove on the new pads for a couple days prior to the event, they were probably bedded enough to work correctly.

When bedding at the track I typically take the car out to just outside of the track and do about 6-8 firm stops from 60mph to 10mph. I then drive a minute or so to let them cool down and try to give them a couple more hard stops from around 70-80mph. This usually does the trick for me.
 

GetBlown2k3

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Scott, the sound you are hearing is probably due to the dimpled rotors you are using. Slotted, drilled, and dimpled rotors will tend to make a noise vs. smooth rotors.

When using a new type of pad with an old rotor, you should lightly sand or use scotchbrite pad on the old rotor to clean the previous pads material off. Since you did not do that, the juddering you were feeling was probably due to the different materials not meshing well together and the material on the rotor wore off after your first session of hard use.

If you drove on the new pads for a couple days prior to the event, they were probably bedded enough to work correctly.

When bedding at the track I typically take the car out to just outside of the track and do about 6-8 firm stops from 60mph to 10mph. I then drive a minute or so to let them cool down and try to give them a couple more hard stops from around 70-80mph. This usually does the trick for me.

awesome! i think i will do that when i head to Sebring next weekend; they've got a nice backroad right outside of the raceway.
 

wheelhopper

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Perfect. When I am at VIR I use the road that connects the North and South paddock.

At Summit I just head out the gate, do what I got to do and drive back in.

You sure are getting a lot of track time in. You'll be in advanced groups before you know it, if you are not already. I'll be at RA in December if your looking for some track time then.
 

GetBlown2k3

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Perfect. When I am at VIR I use the road that connects the North and South paddock.

At Summit I just head out the gate, do what I got to do and drive back in.

You sure are getting a lot of track time in. You'll be in advanced groups before you know it, if you are not already. I'll be at RA in December if your looking for some track time then.

Haha, I've still got a lot to learn. I've finally got heel-toe down, and want to work on trailbraking.

What weekend is Road Atlanta? I'd love to run that course. I'll be running the Daytona Full Rolex course with the high banks either the 2nd or the 9th... not sure yet. Either with ReZoom or Hooked on Driving. You should go from RA down to Daytona to run that event! It should be a blast running the high banks.

Did you see the video of the Daytona PDX I did with SCCA? Any critiques?

Also, here's a cool video I made with the GoPro when bedding in the brakes tonight...
[nomedia="http://www.youtube.com/watch?v=o_zQEj1eQKk"]YouTube - CTS-V Brake Bedding - PFC 01 Pads on PFC 2 piece rotors[/nomedia]
 
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David Hester

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Dimples and holes are for Wussies. REAL men lighten their rotors by ripping them in half like a telephone book with their Baer hands........ arrRRRRrrrrr!:banana:
 

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