Opinion about warped front rotors
10-14-2009, 08:37 PM
#1
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Opinion about warped front rotors
I'm pretty sure that my front rotors are warped, but would like some confirmation before I go on the hunt for some new ones. I just got back from Deals Gap and while I was there I noticed at around 50mph when I took my hands off the bars, the front had a shake back and forth. It wasn't major, but enough that I put my hand back on them to keep from getting worse. Another time I had to get hard on the brakes and also noticed the brakes seemed to fade (pulse). While riding though I really didn't notice.
I'm guessing they are warped and I'm going to need new ones. But if there is something else I should check, let me know.
Thanks!
I was going to hit up Classifieds/Ebay for anyone that might have some laying around, but if you know somewhere else (retail) I should look let me know. I don't have a lot of funds to upgrade to something else like Galfer's.
I'm guessing they are warped and I'm going to need new ones. But if there is something else I should check, let me know.
Thanks!
I was going to hit up Classifieds/Ebay for anyone that might have some laying around, but if you know somewhere else (retail) I should look let me know. I don't have a lot of funds to upgrade to something else like Galfer's.
10-14-2009, 08:46 PM
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Are you sure it isn't pad deposits on the rotor? Uneven friction can cause that. Try going over the rotor carefully with some fine grit paper on a wood block and clean it up good with brake cleaner. Wouldn't hurt to scuff the pads too to remove any glazing.
10-14-2009, 08:46 PM
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How are your fork seals? You trashing the rotors with fork oil? Once your pads are oil soaked they are garbage. Get new ones soon. Find out where the oil is coming from. Rare instances of calipers leaking but has happened.
10-14-2009, 09:13 PM
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So you were getting head shake when just going 50, and not on the brakes?
Unless the rotors are warped enough to be dragging while the brakes are not applied it doesn't really sound like warped rotors to me.
As for brake pulsing while stopping, that can be warped rotors, but more often (as already mentioned) it's brake pad deposits on the rotors.
Unless the rotors are warped enough to be dragging while the brakes are not applied it doesn't really sound like warped rotors to me.
As for brake pulsing while stopping, that can be warped rotors, but more often (as already mentioned) it's brake pad deposits on the rotors.
10-14-2009, 09:23 PM
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Warped rotors will shake your bars when you apply the brakes. They'd have to be really bad to shake without brakes applied, and then it would worsen as you put on the brakes.
I would check your steering stem bearings and/or the locknut torque, it should be 18 ft/lbs.
I would check your steering stem bearings and/or the locknut torque, it should be 18 ft/lbs.
10-14-2009, 10:07 PM
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It doesn't really sound like warped rotors would be your problem based on the shaking. As far as the pulsing, you should try having the rotors bead blasted. A machine shop can do it for you. Ask them not to blast the centers, just the brake sweep area.
10-14-2009, 11:15 PM
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I had that problem with my '04 'Busa. I could hear the front brakes dragging at low speed. Looking at the right side rotor, part of it was worn shiny. Also the brake pads were nearly worn out on that side.
Not sure how this happened. I thought maybe the shop bent the rotor when they installed a new front tire??
Anyhow, I replaced it ($300) and the pads on that side and it's as good as new again.
Not sure how this happened. I thought maybe the shop bent the rotor when they installed a new front tire??
Anyhow, I replaced it ($300) and the pads on that side and it's as good as new again.
10-15-2009, 12:03 AM
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2 different issues as indicated above but I'll review.
Issue #1: Letting go of the bars at 50mph (and thus decelerating) can be a sign of worn a front tire, misaligned rear wheel (chain adjustment unequal side-to-side), and/or loose/worn steering head bearings (which can be checked by jacking up securely front of bike on engine sump and grabbing fork tubes and rocking steering stem making sure fork slider bushings are not also badly worn). Align rear wheel, check caliper alignment, check head bearings and slider bushings, replace front tire, etc first to eliminate them as a cause.
Issue #2: Pulsing brake lever could be build up of pad material and/or dirt/oil on rotors, hard spots on rotors, loose wheel bearings, unevenly worn rotors, unevenly tensioned rotor bolts, warped rotors, and/or misaligned calipers. Cleaning rotors with a red 3M Skotchbrite pad and 91% isopropyl alcohol or by removing and bead blasting rotors will remove pad material, oil and dirt. Remove and check rotors for flatness with a steel straight edge or on a 1/4"+ thick piece of glass. Rotors can be broach milled if rotors are not warped such that machining takes them down thinner than service limit stamped on rotors. Aftermarket replacement rotors are a cheaper option than OEM rotors.
Issue #1: Letting go of the bars at 50mph (and thus decelerating) can be a sign of worn a front tire, misaligned rear wheel (chain adjustment unequal side-to-side), and/or loose/worn steering head bearings (which can be checked by jacking up securely front of bike on engine sump and grabbing fork tubes and rocking steering stem making sure fork slider bushings are not also badly worn). Align rear wheel, check caliper alignment, check head bearings and slider bushings, replace front tire, etc first to eliminate them as a cause.
Issue #2: Pulsing brake lever could be build up of pad material and/or dirt/oil on rotors, hard spots on rotors, loose wheel bearings, unevenly worn rotors, unevenly tensioned rotor bolts, warped rotors, and/or misaligned calipers. Cleaning rotors with a red 3M Skotchbrite pad and 91% isopropyl alcohol or by removing and bead blasting rotors will remove pad material, oil and dirt. Remove and check rotors for flatness with a steel straight edge or on a 1/4"+ thick piece of glass. Rotors can be broach milled if rotors are not warped such that machining takes them down thinner than service limit stamped on rotors. Aftermarket replacement rotors are a cheaper option than OEM rotors.
10-15-2009, 03:59 PM
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skokievtr that makes a lot of sense.
I'm going to be getting some new tires anyway so I'll have it apart when I go to mount and balance. I'll go through those steps and check it from end to end for those possibilities.
Great info folks!!! Thanks!!!
I'm going to be getting some new tires anyway so I'll have it apart when I go to mount and balance. I'll go through those steps and check it from end to end for those possibilities.
Great info folks!!! Thanks!!!
10-19-2009, 06:57 PM
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I would ask how many miles on your front tire? They often wear unevenly toward the end of their life and the balance changes exacerbating the symptoms.
If you want to check your rotors for brake material build-up, you can remove the caliper on one side and put a bolt through the mounting hole and turn the wheel slowly, marking the areas that touch the rotor with a marker. Sand or sandblast the rotor focusing on high areas and lightly blasting/sanding the OK areas to make the surface uniform. Test your work with the bolt again. You'll have to check 4 sides(PIA). Remove the glaze from the brake pads by light sanding on a piece of glass. You'll need to re-bed the brakes/rotors as if they were new.
I believe one of my **** Shanghai rotors may be slightly warped because it still shows slight unevenness with the bolt test above after sanding. I won't know if the shudder under hard braking will subside til I change damaged front bearings and cupped front tire. I'll post what I find later.
If you want to check your rotors for brake material build-up, you can remove the caliper on one side and put a bolt through the mounting hole and turn the wheel slowly, marking the areas that touch the rotor with a marker. Sand or sandblast the rotor focusing on high areas and lightly blasting/sanding the OK areas to make the surface uniform. Test your work with the bolt again. You'll have to check 4 sides(PIA). Remove the glaze from the brake pads by light sanding on a piece of glass. You'll need to re-bed the brakes/rotors as if they were new.
I believe one of my **** Shanghai rotors may be slightly warped because it still shows slight unevenness with the bolt test above after sanding. I won't know if the shudder under hard braking will subside til I change damaged front bearings and cupped front tire. I'll post what I find later.
Last edited by nath981; 10-27-2009 at 07:14 AM.
10-19-2009, 07:40 PM
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on the shaking; i'd be inclined to check the balance of the front tire...if you find out your rotors are warped i'd suggest looking into direct fitment of rotors from other bikes that may be more common than the hawk, i think the 954 uses same rotors..something i noticed when looking at a buddy's bike. use that as an example though. don't take that literally and buy some 954 calipers cause i said they look the same. search the forum there may very well be some posts on direct fit rotors...
10-26-2009, 10:03 PM
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I bent one of my rotors while breaking the bead to change tires. Very annoying but only noticeable while braking. Put the front wheel up in the air and spin it...it will be painfully obvious which rotor is bent. Took a while but I finally found a set on Ebay for less than $100.
Worn tires (even when they still appear new) can cause wobbling, and in my experience it is usually right around 45mph, faster or slower it goes away.
Quit riding with no hands! That's very dangerous...and a stunt reserved for 8 year old boys showing off to their mothers (Look Ma! No hands!)
Worn tires (even when they still appear new) can cause wobbling, and in my experience it is usually right around 45mph, faster or slower it goes away.
Quit riding with no hands! That's very dangerous...and a stunt reserved for 8 year old boys showing off to their mothers (Look Ma! No hands!)
11-01-2009, 06:57 AM
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was your headshake evident under hard braking only?
11-01-2009, 05:14 PM
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No,The only time I noticed it was when I took my hands off the bars coasting along and then it was almost unnoticeable.So maybe I caught it early.Head bearings had been replaced long ago and it was a new tire.Didn't even consider the brakes.Seems to me that a brake related problem would mostly show up during braking.
Brakes: if there is an uneven build up of material on the rotors, or if one of the caliper pistons is not retracting, or if the rotor is warped a little, then you might get some shaking.
So far I found a rough wheel bearing on one side, a cupped and irregular worn tire, and some brake drag when I push the bike into the garage. No play or roughness in steering stem.
i'll let you know if I can get her smoothed out and you do the same and maybe we'll learn something, huh.
11-09-2009, 06:24 PM
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No,The only time I noticed it was when I took my hands off the bars coasting along and then it was almost unnoticeable.So maybe I caught it early.Head bearings had been replaced long ago and it was a new tire.Didn't even consider the brakes.Seems to me that a brake related problem would mostly show up during braking.
Just installed Q2's and wheel bearings and this symptom disappeared. Front wheel bearings were rough when turned with fingers so I got some new ones from AllBalls(had em in two days). Front tire had uneven wear. So far the Q2's are awesome, but with only 100 mi, too early to comment.
Pulsing under hard braking:
Can't speak definitively yet, but pulled rotors and looked in at pistons. On the right side caliper, pistons were extended more on one brake side than the other by double at least. On the left side caliper, pistons were extended evenly on both brake pads. So I assume this may be the source of the roughness/pulsation under hard braking. I'll be searching threads to find out what I need and how to do it.
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