today I was trying to ride and felt a wierd shaking of my foot when braking sometimes looked like brake lever was shaking or something. A friend of mine told me most probably it's a rear brake disk and that I'll need a new one. I did go to the mountains two days ago and since it was scary I did quite a bit of breaking, so I guess it can be it. Now the question is, can it be somthing else and if not what disk should I get and where can I get it cheapest? I feel sooo  bad about the whole thing... kinda hoped to ride quite a bit next week  

This sounds like you are talking about the rear brake but,.... :dunno:

Check to make sure you have pad material on the pad plates. I've seen two examples of rear brakes with NO MATERIAL on them. That'll mess up either rotor in a short time not to mention you have very little stopping power until it all welds together.

Take a load off the suspect wheel and rotate it while looking at the brake rotor. You may be able to see any misalignment. It may require a dial indicator while the wheel is turning.

Make sure all the hardware holding the rotor is tight. While you are at it, make sure all the caliper hardware is tight.

What year bike is this anyway?

sorry, this was a crazy weekend with some heavy drinking involved so yesterday while writing I obviously failed miserably to keep my train of thought in line yes, it is a rear disk. and I will try to look at it tomorrow. I tried to make a few snapshots of my brakes when I was changing fluid, but I was not sure where i should look, so I don't know if the pics will make too much sense to you, but anyway they are here:

http://ravichev.com/moto2/

now what is a dial indicator? oh, btw bike is '90. hardware should be tight as I changed the tires a few weeks ago and tightened everything I could

A vibrating brake is usually caused by a warped rotor.  If your rotor was thin to begin with, heat from use might make it warp.

I had a warped rotor on the front and I felt these pulses through my hand at low speed braking. It was quite unsettling. If you want to keep the rotor take it to get lathed and smoothed out. Or get a new one. An easy way to see if it is warped is to set it on a flat surface and press around the edge and see if it pops up.

If it's too warped, you're stuck with getting a new one.

I had a car that LOOOOOVED to warp rotors.  I could get them lathed once...  Then needed new ones...  They warped faster when they were thinner.

After a while I just got used to braking with warped rotors. :dunno:  Like poor man's ABS.   :mrgreen:

now, if I am stuck with getting new one, what's the cheapest place? cause I looked at bikebandit, it's like 180 green right there   also what is the right way to use the brake then, so that rotor doesnt get warped?

Check out EBC rotors. They look pretty, too.

is it a brand or a website?

Brand. As for website, I dunno. EBC is a good disc though.

ebc is a brand,  but if you look in the forsale forum there usually is a couple

http://www.gstwins.com/forum/viewtopic.php?t=13871

Look at this post re: EBC disks made by Kerry.

Should be pretty on point.

I don't think he made those... I think he just told you how to install them.

He also has a (long-in-the-tooth) Brake Parts page on his website with some sources and prices.


Well, I haven't been totally worthless while I've been gone ... I did update my Chains and Sprockets page last month.  

Maybe I'll update the Brake Parts page sometime during my 2 weeks off.  If I get real adventurous I might even turn both pages into real HTML - with links!

thanks guys for the info! you really save me a lot of trouble! Especially Kerry's pages with replacement parts/sites/prices absolutely rock  

I just went to parts411 and there they have 3002 recommended on Kerrys' page and also "pro-lite contour" which is 3002c I think. Do you know what's the difference? 3002 is $117, 3002c is $113, not a big difference but still. here's a link

http://www.parts411.com/acb/showdetl.cfm?&DID=9&Product_ID=23560&CATID=23

also I was told that I'll need new pads not to scratch new disk with old ones, which ones are good? there are so many of them mentioned on Kerrys page

Quote from: Soaring
also I was told that I'll need new pads not to scratch new disk with old ones, which ones are good? there are so many of them mentioned on Kerrys page

I recently picked up a set of EBC HH pads (front) and am happy with them so far.  They definitely perform better than what was previously on the bike.  

But you're looking for rear pads, right?  Personally, I wouldn't spend much $ on pads for the rear.  Anything more than bare metal would suffice.  Course I use the rear brake rarely, at best, so YMMV.

Dave