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Discussion Starter · #1 ·
Ever since I can remember, there is this pulsating sensation I get when I apply the brakes. Is this the ABS working in a normal case or are the rotors warped. The pulsation kinda goes away when the rotors are hot after driving hard and braking hard. Car has about 12,000 miles and has been down the quarter a few times and has seen one autoX. The car brakes really well and does not pull to either side when braking.
 

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There's a good change you have deposits built up on the rotors. A truly warped rotor is a rare thing. Go and re-bed in your pads in a safe place then see where that gets you. Do 5-7 moderate stops from 50 -5 w/o ever fully stopping, then (if you can) do some 80-0 full ABS stops, about 4-5... it's a ton of fun :D Be sure to let the brakes cool a bit in between each stop. Then go home and let the car sit for almost a day, or overnight. This will remove all the deposits and re-bed your pads/rotors.
 

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It sounds like your rotors or a rotor is warped in the front, causing the pulsating. I replaced my rotors well before 12K miles, although I had about 4 DE's on them. Rotors are inexpensive, you can get a set for under $100 at NAPA Auto Parts. :thumb:

Bob
 

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I had the same problem on my brand new 2002 Z28. Ended up with shattered rotors!!! :eek: If you looked closely, you could see a spider web effect through the entire rotor. Replaced with some drilled and slotted aftermarket rotors and never again had a problem. Car would stop smooth every time! :thumb: I personally have never felt the pulsation of ABS but if your steering wheel is shaking, it's the rotors. :D
 

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Discussion Starter · #5 ·
There is no vibration in the steering wheel. I can only feel the pulsation from the front end of the car. The car does not shake. Almost as if the brakes are grabbing the rotor and then letting go, but at a really fast rate. It goes away when hot, then comes back after the brakes have cooled back down. I thought maybe it was the ABS but wasnt sure if I was supposed to be feeling it.
 

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I almost sounds as if the ABS is activating when it doesn't need to. When you bury the pedal to ABS, it feels exactly as you describe and it's supposed to. You also mention that the problem goes away when heated leading me to believe that you may have a bad wheel sensor.
 

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Throwing any Codes? Try running a self diagnostics on your DIC. This wil tell you if a sensor is going bad.
 

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Discussion Starter · #8 ·
No codes as far as I know, I will run a self Diagnostic to see if anything pops up. I will try rebedding in the brakes to see if that works.
 

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Warped rotors.
If it was the ABS you'd get a code or a warning.
The rotors will warp if they wern't broken in properly or they are really over worked.
IMHO
 

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Three possible things, from most to least likely:

(1) warped rotor(s)
(2) wheel bolts not torqued down properly/equally
(3) sticking caliper
 

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Discussion Starter · #11 ·
I do not recall breaking in the rotors when the car was new. I picked up the car at Bowling Green and drove it to FL in the rain. :(
 

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Cobra4B is likely right on the target. As much talk as we hear about warpped rotors ..very few really are. Rebedding sounds good to me. If you have air tools with scrubbing pads I'd clean up the front rotors before doing the rebedding thing.

Tony #54
 

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ELF Z06 said:
Cobra4B is likely right on the target. As much talk as we hear about warpped rotors ..very few really are. Rebedding sounds good to me. If you have air tools with scrubbing pads I'd clean up the front rotors before doing the rebedding thing.

Tony #54
I'll put my money on warped rotors. :z:

.
 

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Again a truly warped rotor is a very rare thing... it's generally all about how the pad and roor are wearing, they don't just "warp". If driven too easy a high performance brake pad will never come up to temp and won't develop a transfer layer betweent the rotor/pad. Also you may want to clean the hub surface to ensure that the rotors seat properly.
 

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I'd also bet on warped rotors. It is very common where I'm from. Not sure why some say it is uncommon. As a side note, have you ever washed your car IMMEDIATELY after driving it? That is a big "no-no", as the cool water from the hose will crack and warp the hot rotors. If you don't track the car often, have the rotors turned, or for slightly more money (and piece of mind), buy new napas.

Let us know the outcome. :z:
 

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Discussion Starter · #17 ·
The car never sees water and hardly ever sees water from a hose. I have never washed the car while the brakes were still hot. I will go home and check the torque on the bolts and inspect for cracks. It is pouring down rain here so unfortunately I can not drive the car. :(
 

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Discussion Starter · #20 ·
I did find a few bolts on the rear wheel that were a little loose. Not a lot, but just a little, maybe 90lbs vs. 100lbs. I tighten them and will go for a drive to bed them in once the weather clears up.
 
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