Strange Brake Problem
Thread Starter
Instructor
Joined: Jun 2004
Posts: 156
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From: Port St. Lucie FL
Strange Brake Problem
I just put new rotors and brake pads on my car. I still have the same pulsating brake problem when I apply the brakes as before the new parts. Any Ideas/Comments as to the problem?
Jim in Pompano Beach, FL
Jim in Pompano Beach, FL
Burning Brakes
Joined: Apr 2004
Posts: 857
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From: Olympia WA
Its possible the hub that the rotor bolts to is bent, would need to check runout. I have also seen rotors that needed to be turned that were new. Good luck. 
Just another thought when I put mine on I took a wire brush and cleaned up the rust between the hub and the rotor.
Just another thought when I put mine on I took a wire brush and cleaned up the rust between the hub and the rotor.
Last edited by binkysgarage; Mar 2, 2005 at 01:54 PM.
CF Enhanced Member
Joined: Jul 2003
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From: Section 326 Row A!! Finally. Go STARS!!
Cruise-In VI Veteran
St. Jude Donor '06
Originally Posted by binkysgarage
Its possible the hub that the rotor bolts to is bent, would need to check runout. I have also seen rotors that needed to be turned that were new. Good luck.
Even new I have them turned before installing....
Burning Brakes
Joined: Sep 2004
Posts: 1,003
Likes: 1
From: Richmond VA
Originally Posted by jim49tx
I just put new rotors and brake pads on my car. I still have the same pulsating brake problem when I apply the brakes as before the new parts. Any Ideas/Comments as to the problem?
Jim in Pompano Beach, FL
Jim in Pompano Beach, FL
If it does not stop I will have mine turned and that should stop it. If they drive you nutty, any brake shop can turn them, it is just a PITA to get them back off and go through that again!
Team Owner
Joined: Sep 2001
Posts: 23,283
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From: Lake Elsinore, CA
Another thing to check is the hub surface behind the rotor. If there is a build up of rust or dirt, it can force the rotor to wobble as if the runout were off. You can often wire brush that surface thoroughly to restore the original flatness of the mating surface on the hub to keep the rotor running true.
Burning Brakes
Joined: Dec 2004
Posts: 1,234
Likes: 2
From: New Jersey
First we must bed and season the new parts:
-Drive the vehicle to a remote area and
-perform at least 30 brake applications of 3-second
duration.
-Use light/medium deceleration with varying starting speeds. Leave at least 10 seconds between each brake application.
After the repeated stops, drive the vehicle for a few miles with little or no braking in order to adequately cool the components.
Note: When the system achieves elevated brake temperatures for the first time, a slight increase in pedal travel and pedal effort may occur. After this first "fade" and proper cooling, the system will maintain its optimum performance at all temperatures.
If you have zinc or any kind of anti-corrosion coating the brakes will not feel right until that is worn off. The above will help that along.
People should clean the rotors before installation with warm, soapy water if it's just a "oil" like coating or fine steel wool if it's zinc or paint.
Also, Patches advice is very good.
Your not alone:
http://forums.corvetteforum.com/show....php?t=1026392
-Drive the vehicle to a remote area and
-perform at least 30 brake applications of 3-second
duration.
-Use light/medium deceleration with varying starting speeds. Leave at least 10 seconds between each brake application.
After the repeated stops, drive the vehicle for a few miles with little or no braking in order to adequately cool the components.
Note: When the system achieves elevated brake temperatures for the first time, a slight increase in pedal travel and pedal effort may occur. After this first "fade" and proper cooling, the system will maintain its optimum performance at all temperatures.
If you have zinc or any kind of anti-corrosion coating the brakes will not feel right until that is worn off. The above will help that along.
People should clean the rotors before installation with warm, soapy water if it's just a "oil" like coating or fine steel wool if it's zinc or paint.
Also, Patches advice is very good.
Your not alone:
http://forums.corvetteforum.com/show....php?t=1026392
Last edited by Mighty-Mouse; Mar 2, 2005 at 03:51 PM.
Le Mans Master
Joined: Jul 2004
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From: Saraland Alabama
St. Jude Donor '11-'12-'13-'14-'15-'16
I have seen on previous posts that the main problem with this is improper torque of wheel lug nuts. If it is not done in the proper sequence and pressures it will distort the rotors. The pulsating is simply your calipers moving back and forth to keep up with your distorted rotors.
Racer
Joined: Jul 2004
Posts: 278
Likes: 0
From: Tallahassee FLorida
Jim, I just put on the GM drilled and slotted rotors last week on the front of my car and you guessed it, same pulsating feel through the system. I have cleaned them 3 times and it does not change. I do not know what is wrong either, as I bought a set of NAPA rotors and they did the same thing, but worse. Cleaned the hub and it does not help. I can't believe that two separate sets of rotors were both problematic considering two different companies and both were new.
I wonder if it is the brake pads, but that would not make sense? You think we should have new rotors turned a little for the fix?
Josh
I wonder if it is the brake pads, but that would not make sense? You think we should have new rotors turned a little for the fix?
Josh
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Burning Brakes
Joined: Dec 2004
Posts: 1,234
Likes: 2
From: New Jersey
Originally Posted by FLACHUSNRET
I have seen on previous posts that the main problem with this is improper torque of wheel lug nuts. If it is not done in the proper sequence and pressures it will distort the rotors. The pulsating is simply your calipers moving back and forth to keep up with your distorted rotors.
That's another good point.
It sounds like a run-out problem. Have you checked the run-out on the car?
If you haven't and either own or are willing to buy a dial indicator then go to the following post:
http://forums.corvetteforum.com/show....php?t=1026392
If not, you can take it to a shop.
First however:
1. Check lug-nut torque
2. Clean the hub where the rotor mounts
3. Clean the back face of the wheel where it contacts the rotor
4. Do the proper break-in and bedding procedure (see my other post above)
Then:
5. Measure the run-out, should be no more than 0.006
While many things can cause judder and vibration the most likely are:
-DTV - disk thickness variation: Rare on brand new rotors, but coatings can make it an issue.
-Dirty rotor: Grease or oils on the rotor can cause vibration from skipping
-Out of spec run-out
-Out of spec flatness: should never occur on a quality brake rotor, especially when brand new
Last edited by Mighty-Mouse; Mar 2, 2005 at 03:50 PM.