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Brake Shudder

Old 05-21-2012, 11:55 AM
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Brake Shudder

So I bought an 02 superhawk recently. Only 12,000 miles, original pads and hardware I believe. Lots of meat left on the pads front and back. However the front brake lever is really weird when pulled in, still plenty of braking power, but it shudders, almost like the rotors are warped. Hard pulls get the bike stopped quick with minimum shudder, light pulls are fine for a lil braking, but medium pulls cause the lever to shudder and the forks and going up and down as the brakes go on and off at medium pressure. Very uncomfortable to say the least.

The lever action just isn't that smooth, compared to my dads triumph sprint, which has good solid feel throughout, my lever is just jerky to use.

Can floating rotors warp? Do I have pad material melted on there that I can buff/sand off the rotors? Or is it the master cyl?

Note that I'm also using racetech springs/gold valves up front setup for 185lbs so the suspension shouldn't be the problem.
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Old 05-21-2012, 12:47 PM
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Sounds like a bent/warped rotor. If you can raise the wheel off the ground and spin it you may be able to see it.
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Old 05-21-2012, 01:22 PM
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Originally Posted by GTS View Post
Sounds like a bent/warped rotor. If you can raise the wheel off the ground and spin it you may be able to see it.
If you can get a dial indicator, set it up and check if they are warped. I don't remember the amount that is acceptable but its in the manual. If the run-out is within spec you probably have material on the rotors. I had mine bead blasted and installed new pads. Once the new pads were bedded in the braking was smooth. It took a couple hundred miles to bed in the new pads.
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Old 05-21-2012, 02:34 PM
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Yeah a dial indicator is best but not something everyone has, nor are they cheap, at least for a decent one. If there is material on the rotors you should be able to see it and use some scotch brite or an S.O.S. pad or something similar to remove it. Just be careful not to remove a bunch of actual rotor material in the process.
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Old 05-21-2012, 07:18 PM
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Okay, I'll try that. Pretty sure I can scrounge up a dial indicator or something to measure them. If I sand/scotch bright/whatever the crap off there, assuming its brake pad material, can I still use the old pads?
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Old 05-21-2012, 07:34 PM
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Yes but you should sand them smooth first. Take them out and look at the surface of the pads.

You can use the scotchbrite rotary black plastic things on a drill that are "rust removal". Home depot or even walmart has em. You cant really get results by hand.

I do this to my racebike rotors all the time to get optimum braking then ball hone them for circular scuffs.

In all reality tho'..... you have a bum rotor. But check wheel bearings too for the p.o.m.
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Old 05-21-2012, 07:35 PM
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just put the front end up on a stand and spin the wheel. Watch for any deflection with the rotor.

could be the calipers need to be cleaned - one of the pistons may be sticking causing it to drag or shudder. (your initial description does sound like a bent rotor though...)

Was it dropped? Any obvious crash damage to the fairings or bar ends?

How long has it been sitting?
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Old 05-21-2012, 08:58 PM
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This is a typical symptom to bent rotors, once you have the wheel in the air, check the rotors and the wheel as well, if the bike hit a curb (which is also typical) you may have a bent wheel too.
If you find the wheel to be bent, it is fixable in most cases.
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Old 05-21-2012, 09:36 PM
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Also remeber that testing even semi floating rotors with a dial indicator can be next to impossible.

You can also make sure that all the buttons are clean and undamaged besides the the other tips given
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Old 05-22-2012, 08:32 AM
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Just another thought how is the condition of the front tire?
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Old 05-22-2012, 10:13 AM
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Originally Posted by zmaniv View Post
Just another thought how is the condition of the front tire?
Good point! If it's severely cupped it could cause some issues as well.
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Old 05-22-2012, 10:31 AM
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Also here is an old thread on the topic and a like to some info from a rotor manufacturer https://www.superhawkforum.com/forum...th-fact-23802/
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Old 05-23-2012, 07:42 AM
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Wheel bearings are tight. Front tire is a barely used pilot power with no cupping or anything. Wheel is fine, bike's never been dropped. Not sure how long its been sitting. Maybe since last october from the previous owner? He rebuilt the carbs this spring and was selling it.

Been slow about getting things done, but I'll try some of these solutions soon. Hopefully don't need new rotors.
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Old 05-23-2012, 07:53 AM
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Its highly unlikely that both are warped. Most likely just one. (so you can be only half as shocked)
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Old 05-23-2012, 08:10 AM
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It's also exceptionally easy to bend a rotor in the process of breaking the bead/dismounting a tire, especially if done on an automotive machine. I've seen it done, and it's not obvious until it's back on the bike.
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Old 05-23-2012, 10:25 PM
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Originally Posted by smokinjoe73 View Post
Its highly unlikely that both are warped. Most likely just one. (so you can be only half as shocked)
Absolutely right!
BTW, talking about tires, you mentioned the bike was sitting for a while, although unlikely for the time period, but tires get impression on the ground contact area, if the bike was not moved at all the tire could have a low spot, it could contribute to the problem.
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Old 05-29-2012, 08:01 AM
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My thinking is the master cyl is shot, it just pulls so unevenly and lever feel is sticky. Been scouring the net and coming up empty for rebuild kits. Looking to stick with a cheap kit before dropping $60+ on a f4i/rc51 m/c.

Only one I can find is this....not even sure it fits.
Honda Front Brake Master Cylinder Rebuild Kit

Anyone know other sites I could get a rebuild kit from?
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Old 05-29-2012, 08:07 AM
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The description you just gave now sounds to me like a worn/unlubricated bushing on the lever itself. If it's an aftermarket lever, there may not be a bushing (which is sure to cause this issue in short order) and if it's a stock lever, then take it off the master cylinder, clean the lever pivot well with brake clean and a q-tip and inspect the brass bushing for galling or being out of round. If it looks ok, then apply a dab of grease to the hole and to the pivot bolt (inspect clean this as well) and reassemble. Not saying you don't have other issues, but this could certainly contribute.

-R
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Old 05-29-2012, 10:05 AM
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If it's sticky through the lever travel it could be a worn bushing or junk in the master cylinder. Though I think it if were junk in the master it'd be prone to leak. However if it's pulsating at a contant pressure on the lever it's more likely something with the rotor and a master cylinder rebuild isn't going ot help that.
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Old 05-29-2012, 10:09 AM
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Originally Posted by GTS View Post
If it's sticky through the lever travel it could be a worn bushing or junk in the master cylinder. Though I think it if were junk in the master it'd be prone to leak. However if it's pulsating at a contant pressure on the lever it's more likely something with the rotor and a master cylinder rebuild isn't going ot help that.

Agreed. I suspect it could be a few things combined, with a warped/bent/contaminated rotor, and a bad pivot all contributing.
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