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front brake question

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Posted by: 89kdx200rdr---------------------

what does it mean if the front rotor is only showing wear on the outer half of the rotor? i think i know but i wanna hear what u guys have to say.


Posted by: JasonWho---------------------

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Posted by: canyncarvr---------------------

What causes that is uneven pad application to the rotor.

Hey! Did I figger that out all my myself?

It's the 'why' of it you're after, I'm sure.

As Jason implies, pads hanging up on guide pins is one possibility.

Some others:
Caliper slide bolts. If you don't have a multiple piston caliper then the caliper must slide to apply (hopefully) equal pressure to both sides of a rotor. If the pieces the caliper slides on are out of whack obviously the pressure applied will not be 'even'.

Warped rotor. They can look straight when they are not. Heat changes things..and maybe what looks straight cold won't be (straight) when it's blue-hot.

Damaged caliper. If someone ran a set of pads well past the backing plates a new set of pads may not be sitting square to the rotor.

Foreign object. Something maybe between the pad plate and the caliper is holding the pad at something other than parallel? This would include anti-squeek spacers, shims or other associated pad hardware.

Improper pad installation. Related to the above. Are there any pieces between the pad and the caliper/piston that keep the pad from sitting at any other situation than parallel to the rotor?


Posted by: 89kdx200rdr---------------------

its only doing it on one side. guess i'll have to take the caliper apart and look at it.


Posted by: JasonWho---------------------

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Posted by: canyncarvr---------------------

Is that a Titax rotor?

I don't need to hear from everyone that has used them with good results....but I've seen that before. It was a goobered caliper in that case, I think.

Even on the side that looks to be contacting 1/2-way right the surface of the rotor looks to be on the rough side.

Brakeline (sp?) makes a decent rotor. Not quite as cheep as a Titax.

Which is to say, not even close.


Posted by: wibby---------------------

Looks better then my rear brake rotor!

I don't have half the contact area you are getting

My caliper is tweaked


Posted by: Jackpiner57---------------------

It appears to me that on the right side pad, part of the material is broken off completely. That's because on the inner half of the right side of the rotor, there appears to be mud marks.


Posted by: 89kdx200rdr---------------------

jackpiner57 they are new pads only two rides on them.
cc not sure about rotor brand it came on the wheel i bought from yabe it seemed fairly straight it only drags slightly in one spot.


Posted by: JasonWho---------------------

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Posted by: canyncarvr---------------------

Certainly I haven't seen every brand of rotor there is...but of the 4-5 brands I have seen the only one the color of yours is Titax.

I don't think you can find a cheaper...uh excuse me...less expensive rotor anywhere.

Runout would be interesting but it's not causing the trouble you have. If the rotor was THAT out of whack you could see it from 30 paces.


Posted by: 89kdx200rdr---------------------

tore caliper apart today. both pistons had worn spots on them, one had small cracks. one of the brake pad pins had a pretty good groove in it (at the pad that was wearing unevenly). replaced pistons and pins. will have to wait until tomorrow to see if this helps.


Posted by: 89kdx200rdr---------------------

cc what do you think of the ebc rotors? i put an ebc rotor on my old kdx front wheel but i didnt have many rides on it before i put the kx front on. oh yeah have you tried out the vforce3 yet?


Posted by: JasonWho---------------------

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Posted by: YZ165---------------------

Quote:
Originally Posted by JasonWho
How did you get the pistons out?


Remove the caliper from the mount bracket, remove the pads, and pump the brake lever until they pop out.


Posted by: canyncarvr---------------------

He blew'em out!

Is there another way?

Wow. Both pistons he says. Isn't THAT a haughty-taughtyt KX-frontend attitude!

I'd guess the grooved pin was the problem with the pads...and maybe with the piston, too.

I haven't used an EBC. Their clutch stuff is (just) ok. The last set of EBC clutch springs varied in length out of the same box by 1.5mm!! Yeah, maybe free length isn't necessarily important, but I want them to be all the same!

I haven't checked for a month or so...there is a DFIII for the KDX now? Is it a 12-petal?

Good luck on your brakes. Update the thread when you find out what's up.

You kept the rotor? The one that was worn crooked already? Kind'a spendy putting new pistons, pins and pads on a wonky rotor.

Oh-oh...you didn't say you replaced the pads.


Posted by: 89kdx200rdr---------------------

yes i blew them out with the air comp. if u need to do it heres a tip stick a piece of 3/8 in fuel line in front of the pistons. hehe cc i had another caliper with better parts in it that i put in the one i run. the better caliper will not fit my setup but the pieces out of it will. i had to do this to ride tomorrow.


Posted by: JasonWho---------------------

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Posted by: 89kdx200rdr---------------------

get yourself a blowoff with a rubber tip. it doesn't take much pressure at all. yes they will make a popping sound and shoot out of the caliper. thats why i stuck the rubber hose in front of them. 90 psi should shoot them pretty far. watch your fingers. one other thing if you are trying to get two pistons out you will also need a c clamp. pop one out to where you can pull it out by hand then put the clamp on it so it wont come out any further then blow the other piston out. then pull the one you had the clamp on out by hand. not sure what you mean by dust seal?


Posted by: JasonWho---------------------

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Posted by: 89kdx200rdr---------------------

jw it should come out unless its really beat up. soak it in some dot3


Posted by: canyncarvr---------------------

Yes, the dust seal (that would be the seal that keeps out the dust! ) needs to come off. Take it off the caliper so it comes out with the piston.

If I recall correctly (Ha!) you put the seal back on the piston before you reinstall it, then place it on the caliper when the piston is back in far enough.

That's a general disc brake thing....not specifically meant for any specific KDX.

You might try pushing the piston back into the caliper (C-clamp, whatever) before you try (again) to apply huge flatulent forces to remove it.

Here it is Sunday night and I don't see a post about how the brakes went today.

Well??


Posted by: JasonWho---------------------

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Posted by: canyncarvr---------------------

re: and the piston still couldn't be pushed in far enough to get the dust seal off.

Those two are related?

Again, from a general disc brake point of view and maybe having nothing to do with this particular piece.....The seal is a separate piece that fits into grooves on both the caliper and the piston. It is removed by displacing the seal from the groove it's seated in.

The chance of getting it out in decent shape if it's very old, dirty or has been real hot are about zip.

...which in real life makes the process (successful seal removal) a bit less than zip. .


Posted by: JasonWho---------------------

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Posted by: 89kdx200rdr---------------------

i didn't get to ride sunday but i'll post something when i do.


Posted by: 89kdx200rdr---------------------

i finally got my front brakes straightened out. i bought a new ebc rotor but that didnt help. needed a new rotor anyway. i pretty much took two brakes and made 1 good 1. i ended up using the caliper of another brake i had with the support bracket off the caliper i was using. put new pads on bled brakes and rode around the house enough to see that i was getting even wear on both sides of rotor. going to put them to the test tomorrow. the caliper i was using looks like the fingers (for lack of a better word) werent straight. i was going to take some pictures but it got dark. i may still take some and post them.


Posted by: JasonWho---------------------

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