Friend asked me to look at his car. The brakes "pulsate". It feels like they are cyclically grabbing and letting go...grabbing and letting go. Not severe, but enough to warrant further investigation. Front disc, rear drum. I had him slow the car using the e-brake only and the effect wasn't there, so I'm assuming it's coming from the fronts. Rotors look good, no scoring, no bluing, very little "ridge". No obvious pad material transfer. No vibration in the pedal or steering wheel. What else can I check?
minor brake issue
- Thread starter RF Overlord
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Warped rotors is my call. You can turn them but I bet the issue will return quickly. New rotors and pads are what i would do.
Originally Posted By: Danno
Warped rotors is my call. You can turn them but I bet the issue will return quickly. New rotors and pads are what i would do.
Agree...just get them replaced...my mechanic told me there was no need to replace them because they could machine and turn them. Did that and a month later they were back to wobbling again.
Warped rotors is my call. You can turn them but I bet the issue will return quickly. New rotors and pads are what i would do.
Agree...just get them replaced...my mechanic told me there was no need to replace them because they could machine and turn them. Did that and a month later they were back to wobbling again.
Get it going about 70-80 and brake hard and steady for as long a distance as possible without tripping the ABS.
Don't panic stop, you want to get the rotors very hot while applying steady pressure.
Don't leave the brake on stopped right after doing this, if you have to hold the car stopped use the ebrake, you don't want pressure on the very hot rotors.
Brake normally after that. It just may relive the pulsation.
If it looks like i have to do rotors and pads anyway i always give this a try first, it works in many cases. If the pads are worn out don't bother, your just wasting your time.
I did a 99 deville years ago that pulsated like crazy braking from over 50 mph, everything looked great, the pads looked almost new.
After it was smooth as glass without a hint of pulsation and stayed that way.
BTW I am cheap. I hate throwing parts at something until i know for sure i need to. I fix what i can (if it can be repaired properly) and replace what i must.
Don't panic stop, you want to get the rotors very hot while applying steady pressure.
Don't leave the brake on stopped right after doing this, if you have to hold the car stopped use the ebrake, you don't want pressure on the very hot rotors.
Brake normally after that. It just may relive the pulsation.
If it looks like i have to do rotors and pads anyway i always give this a try first, it works in many cases. If the pads are worn out don't bother, your just wasting your time.
I did a 99 deville years ago that pulsated like crazy braking from over 50 mph, everything looked great, the pads looked almost new.
After it was smooth as glass without a hint of pulsation and stayed that way.
BTW I am cheap. I hate throwing parts at something until i know for sure i need to. I fix what i can (if it can be repaired properly) and replace what i must.
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The re-bedding procedure posted by Trav would probably let you know if you have a problem with pad deposits or rotors that are worn unevenly. Giving it a shot before replacing parts wouldn't be a bad idea.
If the re-bedding helps, I would guess it's more likely a pad deposit issue.
If the re-bedding doesn't help, I would guess it's more likely a rotor that's worn unevenly, causing thickness variation. That will also lead to pedal pulsation. It can be caused by hub runout, junk between the hub and rotor or other things.
If the re-bedding helps, I would guess it's more likely a pad deposit issue.
If the re-bedding doesn't help, I would guess it's more likely a rotor that's worn unevenly, causing thickness variation. That will also lead to pedal pulsation. It can be caused by hub runout, junk between the hub and rotor or other things.
I'll try "Trav's Trick" when I see my buddy on Sunday. I'll let you know how I make out. Thanks...
The first thing to do when brakes pulsate is to clean off all mating surfaces with a wire brush, preferably motorized. I then schmear on some never-seize to the mating surfaces. Just enough to cover/coat.
Clean of dirt and rust: Wheel to rotor (outside), rotor to whatever underside surface it touches.
While you're cleaning, check to make sure your slider bolts are cleaned and lubed properly, and your brake pads are sufficient.
Again, do this BEFORE you start checking other things. Corrosion on the mating surface is the most common cause of that pulsating feeling.
Second most common occurance would be the uneven rust on the rotor surface. The rust from sitting around and getting rained on or even high humidity. It's rusty where the rotor was exposed and clear where the pads were. Grab/smooth/grab/smooth. Pulsation.
Next would be the uneven surface from a long, hot stop and sitting there with the brakes on at the stoplight. This causes uneven brake pad material deposition on the rotors. Do a series of moderately agressive stops to even it all out. 10 maybe. IF that doesn't work completely try another 10. If it doesn't work at all it really COULD be the rotor.
Not very many people work their brakes to hard, so hot that they warp. It's usually something else.
Clean of dirt and rust: Wheel to rotor (outside), rotor to whatever underside surface it touches.
While you're cleaning, check to make sure your slider bolts are cleaned and lubed properly, and your brake pads are sufficient.
Again, do this BEFORE you start checking other things. Corrosion on the mating surface is the most common cause of that pulsating feeling.
Second most common occurance would be the uneven rust on the rotor surface. The rust from sitting around and getting rained on or even high humidity. It's rusty where the rotor was exposed and clear where the pads were. Grab/smooth/grab/smooth. Pulsation.
Next would be the uneven surface from a long, hot stop and sitting there with the brakes on at the stoplight. This causes uneven brake pad material deposition on the rotors. Do a series of moderately agressive stops to even it all out. 10 maybe. IF that doesn't work completely try another 10. If it doesn't work at all it really COULD be the rotor.
Not very many people work their brakes to hard, so hot that they warp. It's usually something else.
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