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Bad vibration and pulsing when braking

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Old Dec 23, 2007 | 12:23 PM
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Default Bad vibration and pulsing when braking

2000 z28. it was pulsing and has vibration badly through the brake pedal when brakes are applied. I was assuming it was warped front rotors and brakes, I changed all that with new rotors and brake pads.... the problem still exist....what do you think?
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Old Dec 23, 2007 | 12:24 PM
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Mybe an Alignment is needed also.
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Old Dec 23, 2007 | 12:49 PM
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an alignment or possibly your tires, when was the last time you rotated/changed your tires? check your lug nuts(sounds newbish but check them) could be broken...are any of the brake lines being pinched?
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Old Dec 23, 2007 | 01:05 PM
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Originally Posted by bryan04h
an alignment or possibly your tires, when was the last time you rotated/changed your tires? check your lug nuts(sounds newbish but check them) could be broken...are any of the brake lines being pinched?
YUP--or maybe a weight fell of 1 of your front rims...
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Old Dec 23, 2007 | 01:08 PM
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Make sure your tires lug nuts are torqued down correctly, for the longest time I couldn't figure out why I had some vibration on my 3rd gen car under hard braking, but it turned out my torque wrench was way off the mark causing me to overtorque the lugnuts by quite a bit.

I'd also check if your brake caliper slide pins are properly lubed and that the pistons on the calipers moves easily in and out. If one of the pistons is on the verge of seizing, it would have a hard time releasing and possibly add an incredible amount of braking force to that piston alone causing uneven breaking. Last is check for any broken suspension parts in the front. If you notice that your car tends to nose dive a bit more on one side, that would affect the weight distribution on the tires while breaking.

Alignment issues usually slow up while attempting to drive straight as well as slowing down.
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Old Dec 23, 2007 | 06:42 PM
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the lugnuts were inspected and appeared ok as bolted them back on yesterday...the car, had the same problem before putting new tires on and new weights. so far nothing has changed. the car feels solid .as far as alignment the car drives straight as an arrow....

i didnt observe any lines pinched. it feels as if the brake pedal is fighting back at me... for the longest time i thought it was a warped rotor......... i have no clue...

Last edited by venom346; Dec 23, 2007 at 10:06 PM.
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Old Dec 24, 2007 | 12:43 AM
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Have you replaced or had your rear rotors turned yet? They can also cause a pedal pulsation
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Old Dec 24, 2007 | 01:40 AM
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i vote for warped rotor.
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Old Dec 24, 2007 | 02:40 AM
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Originally Posted by Toronto_LT1
i vote for warped rotor.


have the new rotor checked out on a brake lathe.
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Old Dec 24, 2007 | 02:19 PM
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new front rotors causing the same sensation as the old ones? the reason for the new rotors i just installed was because i thought the old ones which were drilled and slotted were warped.. the new rotors are oem and as i went for a test drive after the install, nothing had changed even with new front pads and rotors..........

As for the rear rotors.... i havent inspected or changed those yet... hmm..
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Old Dec 24, 2007 | 08:11 PM
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Originally Posted by venom346
new front rotors causing the same sensation as the old ones? the reason for the new rotors i just installed was because i thought the old ones which were drilled and slotted were warped.. the new rotors are oem and as i went for a test drive after the install, nothing had changed even with new front pads and rotors..........

As for the rear rotors.... i havent inspected or changed those yet... hmm..
When you check your rear rotors, check for rust pits. this will cause a pulsing sensation when braking.
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Old Dec 25, 2007 | 07:02 AM
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Check your front end. A bad tie rod, out of round tire & unbalanced tire/s will cause your vibration.
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Old Dec 28, 2007 | 01:21 AM
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maybe a bent axle? i had a similar feel when i bent my rear axle. it felt like it was pushing back with the rotation of the wheels, made a pretty bad grinding noise too. might as well check anything and everything if the prob is still there
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Old Dec 28, 2007 | 03:44 AM
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i dont know much about ls1's but i know on older brake systems there is a proportional valve? that plays a vital role in appying equal brake pressure to all wheel cylinders?
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Old Dec 28, 2007 | 09:10 PM
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Have you had your ABS system checked out? Should give you a brake warning light but maybe not also.
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Old Dec 6, 2008 | 10:40 AM
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Have the exact same issue. I replaced the brake rotors and pads, put on some different tires and wheels and still have the exact same issue. When I am coming to a low speed stop...especially going down hill, with light brake pedal pressure...the car will surge as the brakes grab and release (pulse). It is a little different feeling then warped rotors now that I think about it compared to everytime I warped the rotors on my vette.....but it was my first attempt to fix.....now what no brake error messages. But I suspect it has something to do with the brake unit...anybody try bleeding.
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