Warped rotor(s), clunking front brake...

Hi guys.

My 400 Seca came with a warped front brake rotor, and the resulting pulsing, squealing, etc.

But the most annoying part is that at low (parking lot) speeds, the front end "clunks" every time the wheel goes around. I assume this is the warp in the rotor knocking the inboard brake pad against the caliper??? Putting slight pressure on the brake lever makes it stop, and at speed nothing is noticeable.

I bought a used rotor off of e-Bay. It looked good, but is warped even worse than my original.

Does anybody have any experiences/fixes for this? Is there anybody out there that turns motorcycle rotors?

Thanks-
Herb

 

I have a warped rotor on my bike too.. Mines not SO bad, I only know it when I'm braking and it pulses, but its still annoying.. Both dealers I've called told me that it is dangerous to turn bike rotors and no one will do it. I think it probably has to do with the fact that there isn't a whole lot of meat on a bike rotor to begin with, and cutting a warp out of a rotor takes a lot off of it. It would probably just get it past the minimum thickness real quick.

 

experience: if you turn steel that thin that has been work hardened buy the brake pads it will warp worse
theory: heat warped it, heat caused internal stress in the metal and it bent

experimental: put it in the oven, as hot as it goes, for a hour let it cool in the oven slowly, this might relieve the stress in the steel
maybe it will flatten back out ?
never tried this on a rotor, but what is there to loose ?

 

Rotors are a use-it-and-chuck-it part. Once warped, it's done. New ones are called for.

 

XJers:

Thanks for the replies and information.

At $235 for a new one (which is "backordered" and probably discontinued), I guess I'll just live with it, or blow another $20-$30 trying another used one.

Thanks again-
Herb

 

I used a dial indicator on my rotors to get them straight. Raise front end off the ground. Hook up the dial indicator to the front axle and put the plunger on the rotor, then set it to zero. Spin the front tire and watch the gauge. On a straight rotor the runnout should be close to zero. + or - .010 for a nice smooth stop. If it is not find where the largest swing is on the dial and start tweeking the rotor. I know this is hard to follow. I will post up a pic as soon as I can.

 

Sam:

How do you "tweek" the rotor?

Herb

 

I just use a 12 inch crescent wrench. Make sure there is no play in front wheel bearings and the pistons in the caliper are not frozen up as well. Here are a couple of pics of the set up. I had to do this to mine when I got it. Just slightly bend the rotor in the direction of the warp. Be very careful if the rotor even starts to crack it WILL need replaced! You dont need to bend it much to make a difference. This will definatly let you know how much the rotor is warped. The idea here is to get the needleon the indicator to move as little as possible from the zero mark. It may take more than one try. Good luck.

 

Samsr:

I did the 12-inch Crescent "tweek" on my brake rotor this weekend -- BIG improvement!

This was my first time using a dial indicator (which I recently "inherited"). I didn't have a way to mount it to the axle, so strapped the mounting rod tightly to the fork tube. I quickly found the wave in the rotor, and after a few attempts to figure out how much muscle to put on it, had the oscillation reduced substantially.

Thanks for the tip!

Herb

 

I'm surprised you got a warped rotor of eBay.

You might try ... "Prepping" the surfaces of BOTH the Rotor and the Wheel where they mate.

If there is anything at all between the two surfaces when they are married ... it cannot rotate true.

Prep the "Points of contact" by dressing them with #-320 Finishing paper.
Feel for burrs and and peels.

A "Peel" is a thin fragment that peeled-off the old rotor when you removed it and stayed on the mating surface of the wheel.

 

Glad it worked for you as it did me. It takes a lot of patience to get those rotors close to flat again. Keep an eye on the mounting bolts of the rotor. They like to back themselves out if run a little warped. I guess it vibrates them out. Lock tite is our friend?