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front brakes pulsating
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front brakes pulsating - August 18, 2008, 05:55 PM

Ok went on the biker bash. Front brakes were pulsating bad. Up front I have new steel braided lines left and right, new HH pads, and new wave rotors. I checked the runout when I first got them in. It was good. Now the brake lever pulsates at low speeds so much Ican feel the bike doing the same. This is also all after the hit and run. PLEASE HELP!!!!!!!!!


Sorry forgot that calipers are fine, it's drained and flushed, bled. Did the rear brakes to, they work fine. Just looking for some opinions.

Last edited by importcraz; August 18, 2008 at 06:20 PM..
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GDMFSOB
 
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August 18, 2008, 06:51 PM

Hard to say, my friend. Are they new rotors? Did you follow torque specs and tightening sequence? Run out of .010" -.015" will not generally be noticeable at all, especially at low speed. Did you clean the rotor surfaces with a solvent to remove grease/ oil/ fluid after you put them on? Maybe they are hitting a greasy spot and slipping on you.
Let me know some more info. Be careful until you get it solved. It may be the wave in them, but who knows.


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B
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August 18, 2008, 07:02 PM

scotchbrite the rotors if that doesn't work they could be mounted wrong on the wheel or warped.


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August 18, 2008, 07:27 PM

followed tq specs and order, cleaned when I got them after installed then again before first ride. they are wave rotors. Yeah I don't know I've checked everything. I needed a head bearing adjustment since before the accident. Maybe it got worse my front tire was cuping before the tire change but not bad. I guess I'll ripe it all back apart again. I just got the bike together for the biker bash and kids with cancer ride in sept.

I only rode the bike for about 150 miles, 50 on sat. and about 100 on sunday. Just wondering if they didn't get broke in enough since I didn't really use the front break much. Thought it might just be a combo of new lines,rotors, and pads. Was hoping someone could fill me in. I'm at a loss. I'm a pretty desent mech build and work on plenty of bikes and cars. Just confused by this.
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August 18, 2008, 07:30 PM

how about axle bearings or head bearing I haven't replaced them and bought the bike used. Put 15,000 on it last year. but bike only had 2,000 when I got it. Also forgot to regrease the axle but had the old grease on it still.
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August 18, 2008, 08:11 PM

Its most likely the rotors , they could be defective and arent str8 or warped, call the company u got them from, they should exchange them


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August 18, 2008, 08:51 PM

When was the hit and run? was it before or after the rotor install? Do you feel the brake lever pulsate? or is it the bike that moves? It is unlikely that both rotors are warped, but anything is possible. you should start by testing rotors individually. this is tricky, and should be performed on a closed circut, by a professional rider. remove 1 caliper and tape an old pad into place so the new pads have something to keep them in place. Zip-tie the caliper in a safe spot, and test ride. if the problem is still there, it is the other rotor, if it goes away, it is the one you disconected. If the problem is still there, you need to do the reverse, and test the other side.


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August 19, 2008, 02:56 PM

The install was after the accident.
So I bled the brakes again and again it kinda goes away. But it did the same thing sunday. I'm just goin to ripe the front end off again and check everything again.
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B
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August 19, 2008, 03:17 PM

Bleeding the brakes probably won't do much to help.

When were the calipers last rebuilt?
Did you tighten the rotors in a star pattern onto the wheel?
Is there a chance the wheel is bent?

Like I said, scotchbrite the rotors, get them cleaned up, then remount everything onto the bike again. Make sure your forks are even, do this with the axle with the wheel off (boomboom929 taught me this) because that might be a problem.


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August 19, 2008, 04:14 PM

calipers are in great shape rotors where installed properly. Wheel is straight. fork height is spot on. Already roughed the rotors. But thanks for the input just trying to see if there might be something I forgot without having to take it all back apart. But oh well. Feedback more then welcomed!
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August 19, 2008, 04:18 PM

but to double check rotor tq is 16.5 lbs. correct. axle bolt is like 78 lbs. and the for axle and collar bolt tq is 16.5lbs.
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B
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August 19, 2008, 04:30 PM

the reason you feel it pulsing at low speed is because it's not warped much yet, that may change as you use them more, and may become a high speed chatter later.

If you've checked all that stuff I'm going to say it's a bad rotor(s). If you have the old set I'd try and take one you know is straight and put it on both sides and check for pulsing, you may be able to determine which side is off... this is assuming you know for a fact the calipers are fine and aren't warping the rotors. Sometimes one piston pushes and the other doesn't and that can cause warping.

FYI - I have a set of 320mm? rotors, or 01-03 gsxr rotors, you're welcome to borrow and test with.


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August 19, 2008, 04:39 PM

Thanks anyway bro, I still have the stockers and are fine in great shape just replaced them last year.
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B
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August 19, 2008, 04:45 PM

toss both of the stockers on, if the problem goes away... I'd send those bitches back.

If not then it's something with the calipers or alignment.

Best of luck, post up what you find. I did a LOT of fiddling with a warp on my front with my racebike this season... finally decided it's a bad wheel.


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August 19, 2008, 04:47 PM

Quote:
Originally Posted by gixrB
toss both of the stockers on, if the problem goes away... I'd send those bitches back.

If not then it's something with the calipers or alignment.

Best of luck, post up what you find. I did a LOT of fiddling with a warp on my front with my racebike this season... finally decided it's a bad wheel.
+1.

Eliminate the variables. Go with the safe knows. Use EBC rotors.


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