Been feeling/hearing a slight ticking noise coming from the forks the last couple rides. Finally had the time today to get the wheel off the ground to inspect it. It appears the front rotor is bent. The wheel spins smoothly until one section. Looks like the rotor is rubbing be pad and sticking at that section. Can see a bit of side to side movement in it too.

I'm going to take off the wheel to make sure it's not something else. I replaced the bearings not long ago, so possibly it was knocked out of alignment? Will check it.

Anyway, if it IS the rotor, how good are those disc protectors? I'm assuming it was bent in a fall on larger riverbed rocks. Would these things help if a rock bashes it?

Thanks

 

Pulled the wheel and removed the rotor. Hard to tell by eye if it's bent, but laying it on a flat surface shows its not completely flat. Can push the edges and the other side comes up a bit. No idea if that's a valid test.

On a side note, I measured the rotor thickness and it's right at its service limit (2.8mm). How is it possible that the pads would outlast the rotor?? Pads still got a couple mm's to go. I do a lot of mountain downhill braking, but wow... Maybe I'm measuring it wrong somehow.

 

Unlikely you would wear the rotor before the pads are they the OEM pads?

 

Yeah, OEM

 

Most rotor protectors for the front are plastic and more about keeping mud and crud from them from what I've seen.

Here is a Motorcycle News article on checking rotors. They say max runout on the CBR600RR they did was .2mm, which is around .007". There are youtube videos too.

I'd test the rotor for a bend by attaching something to the fork with a pointed tip at the rotor then move it in for a closer look. .007" would be quite easily seen. Ideally it would be a mag block with a dial or test indicator, like this, but that would be ideal - aka expensive - unless you know someone who has one. The V block would attach quite nicely to the fork.



Actually a piece of wire with a pointed end attached somehow would serve the purpose in general. Find a magnet that could hold on the fork and maybe use a punch. You could carefully use blade feeler gauges to approximate the bend or warp in the rotor.

When it comes to measuring thickness careful use of a micrometer is significantly more accurate than a caliper, especially if the mic measures in tenths (.0001"). Proper technique to avoid over tightening is important. I've seen production workers over tighten by .001-.002".

 

Just borrowed a digital caliper for a more accurate than a ruler measurement. It's around 3.2mm at it's thinnest. 3.3 average. That's a bit below standard thickness in the service manual, but above the service limit.

I'll see what I can rig up to find the runout. Just looking at it though, I'd say it's moving a good millimeter or so. Enough to catch the brake pad and stop the wheel.

I gave it a spin without the rotor on and it appears everything is in alignment. But hard to say 100%

 

You can pick up KLX300R and 250S round (aka not petal cut) for less than $50 on ebay. I got one for less than $30. They are interchangeable on the S model. Not the case with the SF, that one ain't gonna be cheap!

 

Will first generation klx rotor fit second generation? Found a front rotor from an '06 for cheap. Mines a '14

Being near Japan, I'm also looking for D-tracker rotors. Found a reference from Zeta saying a d-tracker will fit the klx. (Heck, my bike came with a d-tracker English manual)

 

I zip tied a punch to the fork and spun the wheel. I got the tip as close as I could without touching. Most of the rotor spins and looks ok. But the last 20% moves over and rubs the tip.

Yeah, it's pretty obvious I need a new rotor.

Is there any major disadvantage using the round rotor vs petal cut? It's just a matter of heat build up and weight, right? The heat could be a problem. I lost my rear brake last week on a major downhill. Brake "fade" is what I think. Drizzled a little water on it and it boiled it to nothing in seconds. Eventually came back. I try not to ride the brakes, but it gets hard not to in these mountains.

 

Yes it does fit if you have the S model. If you have the SF, too small diameter. Hub bolt patterns are the same.

I have the older style on my 09 model, the previous owner had two sets of wheels and apparently sold the other set with the 09 petal cut rotors. Didn't break my heart. I went to the smaller 07 style rear rotor and carrier anyway, since I mainly use the front heavily for braking and minimal rear in most cases. I also wanted the smaller rotor for more feel when off roading. The 09 and newer use a larger rear rotor. I think it is a 240mm versus a 220mm, probably more for the street oriented or new rider who won't use the front as heavily. Start using your front brake more along with some engine for your mountains.

There is no major value with the petal cut over the standard style. The real purpose of most petal or wave rotors would be that the curve sweeps the rotor causing a scraping cleaning effect - same as slots or holes. Unless you're racing the weight difference is negligible. On mine the slots scrape the whole pad. It's more about looks than function.



If you have the cash to do so, get the SF 300mm front rotor/carrier.