Pulsating brakes on 93 Z28 - Team Camaro Tech
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post #1 of 14 (permalink) Old Feb 23rd, 02, 06:39 AM Thread Starter
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Jeff
 
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I'm trying to figure out what is causing my brakes to pulsate on my 93 Z28. I don't think it's the rotors or pads because I've tried two sets of rotors, 1 which is freshly turned and the other is a pair of dimpled high performance rotors and the brakes pulsate with both sets on the car and I find it hard to believe both sets went bad or both sets of brake pads went bad at the same time. I'm thinking it's the wheel bearings. Any suggestions before I start buying parts to replace things and waste money.

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Jeff H - 93 Indy 500 Pace Car(supercharged) & driven daily, Hugger Orange 69 Z28 with JL8 brakes, cross-ram & GM fiberglass hood, TI setup, heater and radio delete, being restored

[This message has been edited by Jeff H (edited 02-23-2002).]
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post #2 of 14 (permalink) Old Feb 23rd, 02, 06:42 AM
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I had the same problem with a '97 Z28 that my mother owns. She's real easy on those brakes, but all the rear rotors warped. Go figure. The easiest way to tell is to pull them off and check them for warpage. That way you'll know for sure.

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post #3 of 14 (permalink) Old Feb 23rd, 02, 07:00 AM
 
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Jeff, you'll have to do a run-out test on the rotors..
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post #4 of 14 (permalink) Old Feb 23rd, 02, 07:09 AM
msb
 
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Cars now a days have to have the wheels torqued evenly to the correct ft lb's. They are made much lighter and thinner than the old style one piece hub/rotor.

Another thing is to make sure there is no rust or dirt between the rotor and hub.

You can warp your rotors with out even starting the engine if you do it wrong.

As a licensed state inspector(VA) it's also the law.
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post #5 of 14 (permalink) Old Feb 23rd, 02, 07:23 AM Thread Starter
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Jeff
 
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When the car is cold after sitting for a while, the car stops like it normally would. But once it has been driven for a mile or 2 it will start to pulsate. That makes me think it isn't the brakes because they haven't really been used yet. My first stop is 1/2 mile up the road and no pulsating. Then a mile later it will start on the first downhill turn. That's why I'm thinking it's wheel bearings. Also, the amount of pulsating and the severity of it differs from time to time. Sometimes the pedal itself will pulsate, other times it's barely there. When hitting the brakes at 65 mph it's almost violent, but at 30 it's almost nothing.
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post #6 of 14 (permalink) Old Feb 23rd, 02, 08:29 AM
msb
 
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A sticking caliper/slides or bad brake hose can cause that also. Heat buildup from the pads draging will have the same effect.

My experence with bad wheel bearings is you hear noise before they get bad enough to be loose or cause other problems.
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post #7 of 14 (permalink) Old Feb 23rd, 02, 09:36 AM
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How about tire balance/worn suspension parts?

I know you said it only does it after driving 1-2 miles, but it sounds like you've eliminated everything else.

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post #8 of 14 (permalink) Old Feb 23rd, 02, 10:04 AM
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If the steering wheel shakes while braking, your problem is the front wheels.
If you feel the shake in the whole car or the brake pedal, its the rear brakes.
post #9 of 14 (permalink) Old Feb 24th, 02, 11:02 AM
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One question, did you have the original wheels on it????

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post #10 of 14 (permalink) Old Feb 24th, 02, 12:40 PM Thread Starter
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Jeff
 
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I just pulled off the front rotors and pads and cleaned everything up and made sure there was no rust or dirt buildup behind the rotor and it was seated properly. Took it for a drive and the problem is still there. I think it's the rear brakes because I haven't noticed the steering wheel moving but the pedal can get violent sometimes with the pulsating. Thanks for the suggestions, I didn't want to waste money replacing the wrong parts.

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Jeff H - 93 Indy 500 Pace Car(supercharged) & driven daily, Hugger Orange 69 Z28 with JL8 brakes, cross-ram & GM fiberglass hood, TI setup, heater and radio delete, being restored
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post #11 of 14 (permalink) Old Feb 26th, 02, 02:54 PM
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Have you had your anti-lock braking system checked? It may not have anything to do with it, but maybe there is some type of malfunction going on there.
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post #12 of 14 (permalink) Old Feb 27th, 02, 12:25 PM
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Check your front wheel bearings? Jack up the car (use jackstand) grab the tire at the 12 and 6oclock position then try to rock the tire up and down any movement here can indicate wheel bearing needs repacking/replacing and even bad ball joints hope this helps
Jeff
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post #13 of 14 (permalink) Old Feb 27th, 02, 02:03 PM
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Checking the runout of the front and rear flanges where the rotors mount would be the first place I would check. Get a magnetic mount dial indicator and after you have taken the wheels, brake calipers, pads and rotors off, slowly turn the hub/axle flange and see what you get, it should be extremely small if you have any at all, maybe .002 or .003.

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post #14 of 14 (permalink) Old Feb 27th, 02, 02:56 PM
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well first off pull ur parking brake and if it pulsates then u know its the rear if not its the front if it only happens when the brakes r depressed then i would say 99.9 percent of the time it is in the brakes (being certified in brakes that is) from all that i have seen somehow maybe yes the abs


(does the petal pulsate???)
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