Brakes Pulsate!
Thread Starter
Racer
Joined: Nov 2002
Posts: 288
Likes: 0
Brakes Pulsate!
Hey Guys,
I need your advice on something that I have been noticing while driving my
car. My brakes are pulsating during medium to hard stopping. I had one of
my club members test drive the car and he seems to think that the brake
rotors are warped. He feels that the rotors are so warped that it is hard
to differentiate the pulsing of warped rotors from the ABS pulse. The
brakes seem to pulsate starting a speed of 40 mph...an indicator that it is
possibly a rotor problem. I'm not so sure how this condition manifested
itself but it has gradually increased in severity as time progressed (about
3,000 miles) . I'm not so sure that the dealer could fix this problem with
any degree of proficiency so I am looking for a good specialist here in the
Atlanta area. Any suggestions? Thanks!
Cha-Cha
I need your advice on something that I have been noticing while driving my
car. My brakes are pulsating during medium to hard stopping. I had one of
my club members test drive the car and he seems to think that the brake
rotors are warped. He feels that the rotors are so warped that it is hard
to differentiate the pulsing of warped rotors from the ABS pulse. The
brakes seem to pulsate starting a speed of 40 mph...an indicator that it is
possibly a rotor problem. I'm not so sure how this condition manifested
itself but it has gradually increased in severity as time progressed (about
3,000 miles) . I'm not so sure that the dealer could fix this problem with
any degree of proficiency so I am looking for a good specialist here in the
Atlanta area. Any suggestions? Thanks!
Cha-Cha
Instructor
Joined: Jan 2003
Posts: 204
Likes: 0
From: clarkston mich
Re: Brakes Pulsate! (lyonsh)
quote:
--------------------------------------------------------------------------------
I would say that your rotors are warped. Get them turned or buy some new ones. Good Luck! :iagree:
--------------------------------------------------------------------------------
I would say that your rotors are warped. Get them turned or buy some new ones. Good Luck! :iagree:
Race Director
Joined: Aug 1999
Posts: 15,466
Likes: 0
From: GARDENA Ca, State Of Konfusion
St. Jude Donor '05
Re: Brakes Pulsate! (Cha-Cha)
If you do any road racing or hard braking the rotors my get hotter than normal, warping has been a common problem over the years. In 00 it was very hard to get the dealer to replace under warrant, but they would turn them.
Safety Car
Joined: Jun 2002
Posts: 4,122
Likes: 0
Re: Brakes Pulsate! (wallstAL)
Turned rotors just warp quicker.
Get new ones.
Sometimes this is caused by a build-up on the rotor and they are NOT warped.
Do a search....there are alot of posts with links about this common problem.
Get new ones.
Sometimes this is caused by a build-up on the rotor and they are NOT warped.
Do a search....there are alot of posts with links about this common problem.
Advanced
Joined: Nov 2002
Posts: 86
Likes: 0
From: Fayetteville GA
Re: Brakes Pulsate! (Cha-Cha)
Cha Cha!
Take a look below!
Subject: [*C5NET] [*C%NET]TECH: Lug Nuts and Rotor Warpage
Gregory and a few others asked me to post this again so here it is.
Many new Corvettes start to exhibit brake pedal pulsation due to rotor warpage within 10,000 miles. GM has instructed the dealers to replace the rotors rather than resurface them. Resurfacing simply thins the rotor in the area of the warp and the rotor will warp even more. I believe that the problem starts with the dealer when he gets the car from the factory. The lug nuts are torqued at the factory. The dealer must install the locking nut on each wheel during his prep work to get it ready for the new owner. One lug nut is removed and the locking nut put on. They practically always use an air wrench with a "torque stick" to tighten this nut. Torque sticks are notoriously inaccurate and tightening only one nut can result in uneven torque on the rotor and it will start to warp immediately. Depending on how the car is driven this warpage will show up within a few thousand miles.
The fix is simple. Loosen and retorque all the lug nuts as soon as you take delivery. Use a regular torque wrench and tighten the lug nuts in stages. First, loosen all the lugs and then tighten them all to 30 ft lb, then 60 ft lb and finally 100 ft lb. Tighten them in a star progression to avoid putting uneven stresses in the rotor.
If you already feel some pulsation in the brake pedal then you need to straighten the rotors after retorquing the lugs. This requires that the rotors get very hot and then cool slowly and evenly. Take the car out where you can run it up to 75 or 80 and apply the brakes hard and steady to slow to 30. Do this three or four times in quick succession. Drive home at moderate speeds and avoid using the brakes to hold the car at stop lights. Holding the car with the brakes will cause the area under the pads to remain hot while the rest of the rotor cools. Do not apply the hand brake (it doesn't work anyway) when you get home. (The hand brake is a drum brake attached to the rear rotors. It is unlikely that this could cause a problem but the goal is even cooling and anything that could affect this should be avoided.) Let the rotors cool for a few hours or overnight and you will find that they have straightened out. I noticed the problem when I had less than 10,000 miles on my car. I straightened them using this procedure and I now repeat the procedure every 10,000 miles. I have 50,000 miles on the original rotors and pads and they are still straight. The pads are less than half worn.
Whenever I have new tires put on the car I insist that they use this procedure to tighten the lug nuts and watch as they do it. An ounce of prevention is better than a pound of cure.
This procedure is much less than required by the aftermarket rotor suppliers such as Baer Claw. Check out their site to see their procedure. http://www.baer.com/Support/TechTips.aspx?TechTipID=4
Take a look below!
Subject: [*C5NET] [*C%NET]TECH: Lug Nuts and Rotor Warpage
Gregory and a few others asked me to post this again so here it is.
Many new Corvettes start to exhibit brake pedal pulsation due to rotor warpage within 10,000 miles. GM has instructed the dealers to replace the rotors rather than resurface them. Resurfacing simply thins the rotor in the area of the warp and the rotor will warp even more. I believe that the problem starts with the dealer when he gets the car from the factory. The lug nuts are torqued at the factory. The dealer must install the locking nut on each wheel during his prep work to get it ready for the new owner. One lug nut is removed and the locking nut put on. They practically always use an air wrench with a "torque stick" to tighten this nut. Torque sticks are notoriously inaccurate and tightening only one nut can result in uneven torque on the rotor and it will start to warp immediately. Depending on how the car is driven this warpage will show up within a few thousand miles.
The fix is simple. Loosen and retorque all the lug nuts as soon as you take delivery. Use a regular torque wrench and tighten the lug nuts in stages. First, loosen all the lugs and then tighten them all to 30 ft lb, then 60 ft lb and finally 100 ft lb. Tighten them in a star progression to avoid putting uneven stresses in the rotor.
If you already feel some pulsation in the brake pedal then you need to straighten the rotors after retorquing the lugs. This requires that the rotors get very hot and then cool slowly and evenly. Take the car out where you can run it up to 75 or 80 and apply the brakes hard and steady to slow to 30. Do this three or four times in quick succession. Drive home at moderate speeds and avoid using the brakes to hold the car at stop lights. Holding the car with the brakes will cause the area under the pads to remain hot while the rest of the rotor cools. Do not apply the hand brake (it doesn't work anyway) when you get home. (The hand brake is a drum brake attached to the rear rotors. It is unlikely that this could cause a problem but the goal is even cooling and anything that could affect this should be avoided.) Let the rotors cool for a few hours or overnight and you will find that they have straightened out. I noticed the problem when I had less than 10,000 miles on my car. I straightened them using this procedure and I now repeat the procedure every 10,000 miles. I have 50,000 miles on the original rotors and pads and they are still straight. The pads are less than half worn.
Whenever I have new tires put on the car I insist that they use this procedure to tighten the lug nuts and watch as they do it. An ounce of prevention is better than a pound of cure.
This procedure is much less than required by the aftermarket rotor suppliers such as Baer Claw. Check out their site to see their procedure. http://www.baer.com/Support/TechTips.aspx?TechTipID=4
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