Just because they are new they may not be 100% true. As gve stated, use a dial indicator check for run out.
Brakes vibrating on stop
Thread Starter
Racer
Joined: Nov 2001
Posts: 392
Likes: 6
From: Churchville PA
Brakes vibrating on stop
When hitting the brakes, the pedal was vibrating a bit and you could also feel it in the floor. Felt like warped rotors so I replaced the rotors when I replaced the pads a few weeks back. On the front right, the inside pad was worn down to the pad's backing plate and the piston was tough to push back at first. I figured the caliper was shot and the piston was stuck so I replaced the caliper too.
After new pads, rotors and caliper, the vibration is much, much better however, it's still there a bit. When I ease the brakes on lightly or mash the brakes and stop quick, the vibration is barely noticeable. When applying normal braking pressure coming to a redlight or stop sign, you can still feel the vibration a little bit (nowhere near what it was before but, still there a bit).
I drove it about 300 miles with new rotors and pads before replacing the caliper. Is there a chance the pads have to reseat or something?
After new pads, rotors and caliper, the vibration is much, much better however, it's still there a bit. When I ease the brakes on lightly or mash the brakes and stop quick, the vibration is barely noticeable. When applying normal braking pressure coming to a redlight or stop sign, you can still feel the vibration a little bit (nowhere near what it was before but, still there a bit).
I drove it about 300 miles with new rotors and pads before replacing the caliper. Is there a chance the pads have to reseat or something?
Melting Slicks
Joined: Jul 2005
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From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Have the rotors resurfaced, or at least the one you think is warped. Best to do all that were replaced. Your first mistake is that they should have been resurfaced as soon as they were re-hubbed. But never too late.
Melting Slicks
Joined: May 1999
Posts: 2,897
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From: Moon Township PA
Iirc, the problem occurs because you have an out of round rotor and even a hub that may not be true, as others have stated. The way I check mine is to use a dial indicator on the rotor while it is attached to car.
Gary
Race Director
Joined: Nov 2002
Posts: 12,142
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From: Taylor Michigan
Out of round rotors is not uncommon but merely turning them may not solve the problem. I have read on the NCRS DB that the best way to ensure true roundness is to have the rotor turned while it is on the car. I remember reading that some Chevy dealers have this machine.
Iirc, the problem occurs because you have an out of round rotor and even a hub that may not be true, as others have stated. The way I check mine is to use a dial indicator on the rotor while it is attached to car.
Gary
Iirc, the problem occurs because you have an out of round rotor and even a hub that may not be true, as others have stated. The way I check mine is to use a dial indicator on the rotor while it is attached to car.
Gary
How do I know, well we have two of them
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Racer
Joined: Jul 2005
Posts: 499
Likes: 1
From: Winnipeg Manitoba
Install the rotor on the car and check runout using a dial indicator as noted.
Mark the high spot on the outside of the rotor and on the end of the bolt that is closest to the high spot.
Take the rotor off and repeat this check with the rotor in all 5 positions.
If the high spot follows the rotor mark, the the rotor needs to be turned.
If the high spot follows the bolt, the hub is off.
Turning the rotors on the car will eliminate runout.
However, if you ever take the rotors off, you have to make sure they
go back exactly the same way or they could be out again.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
why is or are there so many individuals afraid to take a rotor off. Chucking the rotor on the races makes them as square as you can possible get. The rotor machine eliminates all the guess work and cuts it at the same time truing it. Thats all that necessary. You dont have to degree a rotor, it`s not a camshaft. 
Racer
Joined: Jul 2005
Posts: 499
Likes: 1
From: Winnipeg Manitoba
You can turn that rotor all day and it will still have runout if you mount it on a hub with a 0.002" bump.
