Pulsating brakes - not warped
Thread Starter
Safety Car
Joined: Nov 2003
Posts: 4,979
Likes: 5
From: San Diego, CA "leaf" "tee" "e"
Pulsating brakes - not warped
I know from this:
http://www.stoptech.com/whitepapers/...otors_myth.htm
That it's unlikely my rotors are warped. I bet it's just buildup. This site, and a couple other sites, say to use garnet paper. Well, I'm not exactly sure what garnet paper is, or where to get some. So the question is, can I use steel wool? With iron rotors and semi-metallic pads I don't see what the problem would be. If I must use garnet paper, please let me know where to look for it. On another site it said to pick up 100A grit paper. Thanks!
http://www.stoptech.com/whitepapers/...otors_myth.htm
That it's unlikely my rotors are warped. I bet it's just buildup. This site, and a couple other sites, say to use garnet paper. Well, I'm not exactly sure what garnet paper is, or where to get some. So the question is, can I use steel wool? With iron rotors and semi-metallic pads I don't see what the problem would be. If I must use garnet paper, please let me know where to look for it. On another site it said to pick up 100A grit paper. Thanks!
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Have you changed pads recently??
I think the first thing I would do is go rebed your pads.
Go find a nice low traffic long straight road.
take the car up to 40 mph then stomp on the brakes. Stomp on the brake peddle very hard, almost hard enough to activate ABS, but not quite.
40 to 5 mph and do this three to 5 times.
Then 80 to 5 mph 4 to 5 times.
Drive the car around for 30 to 40 min at a relitively legal normal speed to cool the rotors and brake pads.
Put the car away for 24 hours ( not over night ) to continue the cooling process. do not set e-brake.
Then see if the pads still pusate after this procedure.
Good luck
I think the first thing I would do is go rebed your pads.
Go find a nice low traffic long straight road.
take the car up to 40 mph then stomp on the brakes. Stomp on the brake peddle very hard, almost hard enough to activate ABS, but not quite.
40 to 5 mph and do this three to 5 times.
Then 80 to 5 mph 4 to 5 times.
Drive the car around for 30 to 40 min at a relitively legal normal speed to cool the rotors and brake pads.
Put the car away for 24 hours ( not over night ) to continue the cooling process. do not set e-brake.
Then see if the pads still pusate after this procedure.
Good luck
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
What pads and rotors are you using??
When you change pads or rotors you should change one or the other, not both at the same time. But if you must change both pads and rotors at the same time, then do it. It is really not a good idea to use different pad material on the same rotor. If yo uare changing to a new pad get new rotors. Rotors are cheap. Raybestos rotors $25 each at NAPA. No need to spend any more then that unless you want the drilled and slotted. Also at NAPA Raybestos D&S at $50 each. Rember no D&S for track days.
The other possibility is that the pistons do not push all the way back in. When changing pads clean the piston boots and pistons as best as possible and put a little grease on the piston. This will allow the piston to to move in and out easer.
Also always bleed your brakes when changing one or the other. It is a good time to do so and your right there anyway.
There is a lot of good info on the Stoptech site.
http://www.stoptech.com/whitepapers...rotors_myth.htm
http://www.stoptech.com/
The Wilwood site also has lots of good info
http://www.wilwood.com
When you change pads or rotors you should change one or the other, not both at the same time. But if you must change both pads and rotors at the same time, then do it. It is really not a good idea to use different pad material on the same rotor. If yo uare changing to a new pad get new rotors. Rotors are cheap. Raybestos rotors $25 each at NAPA. No need to spend any more then that unless you want the drilled and slotted. Also at NAPA Raybestos D&S at $50 each. Rember no D&S for track days.
The other possibility is that the pistons do not push all the way back in. When changing pads clean the piston boots and pistons as best as possible and put a little grease on the piston. This will allow the piston to to move in and out easer.
Also always bleed your brakes when changing one or the other. It is a good time to do so and your right there anyway.
There is a lot of good info on the Stoptech site.
http://www.stoptech.com/whitepapers...rotors_myth.htm
http://www.stoptech.com/
The Wilwood site also has lots of good info
http://www.wilwood.com
Last edited by AU N EGL; Dec 12, 2004 at 07:27 PM.
Thread Starter
Safety Car
Joined: Nov 2003
Posts: 4,979
Likes: 5
From: San Diego, CA "leaf" "tee" "e"
I didn't change my pads recently, although I do have a new set of Napa rotors and PFC-Z pads sitting on the shelf. I know those things are going to develop pulsing occasionally, no matter how careful I try to be. As cheap as rotors are, I still don't want to swap rotors every time they start pulsing, especially since that means having to rebed that rotors/pads. My goal today was to try to get rid of the pulsing without risking a ticket by rebedding them. I took some steel wool to the rotors and lightly sanding them, the goal being to get rid of highspots from pad buildup. I bled the brakes and took it for a test drive. So far it seems fine. I did lots of 35 mph to 0, and one 55 mph to 0. Not much of a test, but I have plenty of braking to do on the way to work tomorrow, so I'll know if it worked for sure tomorrow morning.
Team Owner
Joined: Jul 1999
Posts: 50,808
Likes: 8
From: Buy USA products! Check the label! Employ Americans
Take it to 180 MPH and then test the ABS 
it will clear everything after ten cycles Only kidding. i used to swap the pads and rotors as sets keeping all things as they were on the car when reinstalling them.
it will clear everything after ten cycles Only kidding. i used to swap the pads and rotors as sets keeping all things as they were on the car when reinstalling them.
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Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Dave
That is ok to continue the thread. We all learn by asking questions.
I have a few questions for you, if you dont mind?
Where your pads even thickness when you put the new rotors on??
and did you "bed" the rotors in as described above??
How are your caliper pistons?? do they move in and out smoothly or do they need to e cleaned and a little grease put on??
these answeres will help with understanding your problem.
Tom
That is ok to continue the thread. We all learn by asking questions.
I have a few questions for you, if you dont mind?
Where your pads even thickness when you put the new rotors on??
and did you "bed" the rotors in as described above??
How are your caliper pistons?? do they move in and out smoothly or do they need to e cleaned and a little grease put on??
these answeres will help with understanding your problem.
Tom
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 447
From: Atlanta metro Ga.
I'll share my experience..
I have the Sportbrake dimpled rotors, and Performance Friction Z-rated pads..
This set up is great on the street, no noise, excellent stopping power..
Took the car to the track (Talladega G.P.), and by the second session, about mid way through (10 mins), I started getting a fairly significant vibration thru the steering wheel / pulsing thru the pedal..
After allowing the brakes to cool, (came off the hot-lap pace) everything returned to normal.
3rd session, same thing again, backed off, everything came back.
Kind of disappointing seeing how this brake issue impeded my attempts to turn lower lap times.. Oh well. But I certainly did not want to trash my relatively new brake set up.. (BTW, this combo had at least 500 miles on it before this track day)
I'm guessing this was a pad problem (i.e. I need to run a more track-oriented compound), but I'm not entirely sure.
I have the Sportbrake dimpled rotors, and Performance Friction Z-rated pads..
This set up is great on the street, no noise, excellent stopping power..
Took the car to the track (Talladega G.P.), and by the second session, about mid way through (10 mins), I started getting a fairly significant vibration thru the steering wheel / pulsing thru the pedal..
After allowing the brakes to cool, (came off the hot-lap pace) everything returned to normal.
3rd session, same thing again, backed off, everything came back.
Kind of disappointing seeing how this brake issue impeded my attempts to turn lower lap times.. Oh well. But I certainly did not want to trash my relatively new brake set up.. (BTW, this combo had at least 500 miles on it before this track day)
I'm guessing this was a pad problem (i.e. I need to run a more track-oriented compound), but I'm not entirely sure.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Thanks Dan good info
Yes it is difficult to find a pad that can be used both for street and agressive track braking. Most ppl change pads back and forth.
I use the Raybestos rotors and Wilwood "H" pad with Catrol SRF brake fluid. Great combination as it stops exeptionaly well ( I think better then the PFC01 pads I use to use) very minimal fade or pad ware.
Some times it feels like I am doing a 'stoppie' when I stomp on the brakes at 135 mph down to 60 mph to take a corner. I feel the rear wheels get very light.
I do minimal street driving with my car so I dont change pads or rotors and dont do any last minute braking on the street either.
Yes it is difficult to find a pad that can be used both for street and agressive track braking. Most ppl change pads back and forth.
I use the Raybestos rotors and Wilwood "H" pad with Catrol SRF brake fluid. Great combination as it stops exeptionaly well ( I think better then the PFC01 pads I use to use) very minimal fade or pad ware.
Some times it feels like I am doing a 'stoppie' when I stomp on the brakes at 135 mph down to 60 mph to take a corner. I feel the rear wheels get very light.
I do minimal street driving with my car so I dont change pads or rotors and dont do any last minute braking on the street either.
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
Originally Posted by AU N EGL
Dave
That is ok to continue the thread. We all learn by asking questions.
I have a few questions for you, if you dont mind?
Where your pads even thickness when you put the new rotors on??
and did you "bed" the rotors in as described above??
How are your caliper pistons?? do they move in and out smoothly or do they need to e cleaned and a little grease put on??
these answeres will help with understanding your problem.
Tom
That is ok to continue the thread. We all learn by asking questions.
I have a few questions for you, if you dont mind?
Where your pads even thickness when you put the new rotors on??
and did you "bed" the rotors in as described above??
How are your caliper pistons?? do they move in and out smoothly or do they need to e cleaned and a little grease put on??
these answeres will help with understanding your problem.
Tom
Dave
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Originally Posted by leaftye
I know from this:
http://www.stoptech.com/whitepapers/...otors_myth.htm
That it's unlikely my rotors are warped. I bet it's just buildup. This site, and a couple other sites, say to use garnet paper. Well, I'm not exactly sure what garnet paper is, or where to get some. So the question is, can I use steel wool? With iron rotors and semi-metallic pads I don't see what the problem would be. If I must use garnet paper, please let me know where to look for it. On another site it said to pick up 100A grit paper. Thanks!
http://www.stoptech.com/whitepapers/...otors_myth.htm
That it's unlikely my rotors are warped. I bet it's just buildup. This site, and a couple other sites, say to use garnet paper. Well, I'm not exactly sure what garnet paper is, or where to get some. So the question is, can I use steel wool? With iron rotors and semi-metallic pads I don't see what the problem would be. If I must use garnet paper, please let me know where to look for it. On another site it said to pick up 100A grit paper. Thanks!
Safety Car
Joined: Jun 2004
Posts: 4,769
Likes: 15
From: Lovin Life Oh
Originally Posted by TT_Vert
Sorry to continue in this thread, but.. lol
AU, i have sportbrakes rotors and OEM pads front/rear. The problem was there before changing rotors.
Dave
AU, i have sportbrakes rotors and OEM pads front/rear. The problem was there before changing rotors.
Dave
no seriously did you?
i used to change the rotors on my cavalier every 3k cause i never torqued the wheels
oh well lifetime warranty
but serioulsy aluminum wheels dont mix well with over torqued lugs
