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Discussion Starter #1
Can a slightly warped cause my brakes to feel weak?

I've been having issues since my GSXR brake swap with my front brake just not being as strong as it should be. It just doesn't feel like it's really grabbing. I also thought I was getting some uneven stopping from my front brake. That's gotten to the point where I can now feel some pulsing at the lever as I'm coming to a stop. Could that be making my brake feel so weak? Or am I dealing with two seperate problem here?
 

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The pulsing is definitely a warped rotor. As for the uneven stopping my only guess is that the pads might be glazed.
 

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Definatly Yes, if you have a slight warp in your rotor the pistons will not be able to squeeze efficiently. I have had this problem from stones hitting the rotor thrown from cages. What I did was get the front end off of the ground so I could spin the front tire, put a solid object up to the rotor as a reference point, spin the wheel to see if there is any wobble in the rotor. Then I used a soft hammer ( dead blow ) and very gently pried the rotor out and back into alignment. It solved my brake issues with no cost and a little time.
 

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Pulsing for sure means that there are waves in the rotor. Glazing can cause brake fade in addition to high temps in the fluids (not common unless racing and braking a lot. ) Check your rotor the same why you would check to see how true your wheels are. I make up a small rig that holds a sharpie and have it just touching the outside (not the surface but the blade if you will). The will give you a good marking to go by. Another step I do is marking on the surface to by just having the sharpie held about 3mm away(or whatever tolerance you want) ...

Easiest way to get see of it is glazing is by looking. If unsure, give them a very light sanding.

Check to make sure they are not excessively rubbing as well.

Take it for what its worth ($.02) - If all else false - take it to the shop and talk to them about some options.
 
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usualy pulsing is from rotor braking surface been warped.fix is to replace rotor.
uneven feel if you talking about lever sometime coming closer to bar than other times is from bent carier.fix with hammer as mentioned above.
 

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miggs said:
The pulsing is definitely a warped rotor. As for the uneven stopping my only guess is that the pads might be glazed.
INCORRECT

pulsing in brakes can also be caused by a warped/bent wheel, with perfectly good rotors

the only way to know what is causing the pulsing is to take mesurements with a dial indicator
 

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RandyO said:
INCORRECT

pulsing in brakes can also be caused by a warped/bent wheel, with perfectly good rotors

the only way to know what is causing the pulsing is to take mesurements with a dial indicator 
That is true...but a warped or bent wheel would also cause a pulse or shimmy while riding, as well as braking.
 

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Discussion Starter #8
The wheel is fine. It has a less than 1 mm hop in it, but that's it. It also has new wheel bearings. No, I'm pretty sure what I'm feeling is the rotors.

So, bottom line, can a warped rotor cause the weakness in the brakes?
 

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Not necessarily. A bent wheel can ride as smooth as a straight one. You've got to measure.

Warped rotors should not cause weak brakes. The clamping forces are substantial enough to force the mechanical bits where they need to go. Measure everything and look for brake glazing.
 

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Discussion Starter #10
andyauger said:
Not necessarily.  A bent wheel can ride as smooth as a straight one.  You've got to measure.
I did measure. That's why I know there's a <1mm hop in the rim.
 

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zoltan said:
I did measure. That's why I know there's a <1mm hop in the rim.
then why do you think it's rotors if you have documented warp in rim? did you measure the rotors too?

I just replaced a warped rim, but first I replaced rotors & calipers only to find out it didn't fix the problem
 

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Discussion Starter #12
RandyO said:
then why do you think it's rotors if you have documented warp in rim? did you measure the rotors too?

I just replaced a warped rim, but first I replaced rotors & calipers only to find out it didn't fix the problem
Because allowable in the rim is 2mm or less, so I'm well under. I haven't measured the rotors yet, the dial indicator is still on the way.
 

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I'm sending my wheel to McWheel to get it straightened so I have a spare set for my motard tires, It's bent/warped enuf to feel pulsing but I could not see anything remotely visible to the naked eye when I spun it, last year when my pulsing problem developed my dealer did the measurements, since then I had been watching ebay, I finally scored a good deal, $400 for a pair of wheels with brakes rotors, cush drive & sprocket

I have no clue how my wheel got bent? I hope it's your brakes
 

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A warped rotor will cause weak braking because the pistons will be forced back into the caliper. This will leave a small gap between the pad and rotor surface that must be taken up before braking starts. The master cylinder has a limited amount of volume thus limiting the amount of braking power.
 

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1+ as stated above a bent/warped rotor will weaken your braking efficiency. It has happed to me a few times and will happen again. check your rotors when you get yor dial. Most times you can fix it your self.
 

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Basic symptom of warped rotor is if the bike is parked and you pump the lever all feels solid and good. Then when you ride and try it, you have to pump it up with the first pull to push the pistons back the amount they were displaced by the warped rotor "wobbling". IF the lever feels the same rolling and stopped, it is not a warped rotor, more likely a glazing or pad issue.

Just my 2 cents
 
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