front brakes are scraping...

i'd been hearing a squeaking sound coming from my brakes for the past month or so. i figured i might have to change the pads before too long, which i planned on doing anyway. of course i put it off, and yesterday as i was riding home, i had to hit the front brakes pretty hard. as i proceeded home i remember thinking, "man that car in front of me gotta do something about that scraping noise"

of course when i got home, i realized it was coming from the bike. i turned it off and put it in neutral, miving the bike forward i could hear the metal-on-metal scraping sound. and one part of the rotation scraped harder than normal. looked closely at the front brakes i could see the metal was touching the rotor.

1. what did that hard brake mess anything up?
2. why would it not unlock, or resume it's normal position of not scraping?
3. is it difficult to switch out the pads, if you guys don't think i messed anything else up?
4. any guidelines, suggestion, or links to threads about changing the pads?

thanks guys!

 

I think you have the floating callipers on there & they need to be maintained to make sure they 'float'
If the rotor isn't scored too bad you should be ok.
Changing pads is one of the easier jobs, just follow the book.

 

thanks for the advice. how bad would you say is "bad" when talking about scored rotors? in other words how can i tell or whats rule of thumb?

 

Rub your thunb across the rotor. You will be able to feel the grooves or inconsistancies if it is bad. Just make sure you swap out the pads to when you change the rotor otherwise you'll get the same problem a lot sooner

 

sh!*. looks like i gotta change the rotor. thanks for giving me another job that i don't have time to do. jk.

so changing pads are an easy job. is changing the rotor just as easy (pleeease say yes)

 

Rotor isn't too hard to change. Its a matter ofputting things back exactly the way you took them off
if you want I can tell you how to do it step by step. But it is pretty much no harder to change a cars rotor than a bikes.

 

if you wouldn't mind could you give me a step-by-step. i'm going to try to work on it this by next weekend after i order some parts tonight. can't stand not being able to ride with the weather getting nicer and the gas prices creeping higher. i would forever be grateful. thanks!

 

Get a 2nd opinion on the state of your rotor, they all have grooves if they have done some work, thickness is the important thing, pads are cheap & bed into grooves, rotors are mucho expensive.

 

Well do you know how to remove the caliper and front wheel? After that is done the rotor is attached by tabbed washers, the tabs are bent to hold the bolts secure.
Bend all of those tabs down and remove the bolts holding the rotor on.
put the new rotor on in its place but also replace the tabbed washers. Tighten the bolts to about 14 1/2 to 15 foot lbs.... but evenly. And your rotor is good. Seriously, though... to clarify, and wizard is right... the thickness of your rotor is what you really need to check. But me, personally, the way I was tought was rubbing my thumb... actually my thumb nail across the rotor and if it would catch my thumb nail the rotor should be replaced.

If you don't need to replace the rotor and your caliper needs a rebuild, have someone experienced do it. It actually sounds like you might not have enough meat on the pads or you knocked the caliper out of whack... I don't know much about calipers but I do know when I stop there and let a pro do it. The hard braking on an old caliper just might have caused a problem outside of the pads or rotor.
If I am not mistaken, your brakes are hanging up, right? Meaning you hear the squeeling or rubbing or grinding even when you arent touching the front brake lever.
I would change the pads at first unless you know for certain they are still good with a lot of meat on them. But worn pads will eventually hang.

 

Round-Off the sharp edges of the Pads. "Chamfer the Pads"
The Chamfer will keep the Brakes from squealing.

Just sand the edges off the Pads. Round-'em-off.
That usually quiets-down any squealing going on.

Once you have Chamfered Pads in there, ... you can "Ride the Brake" and feel is the Rotor is warped of tilted.

 

Rebuilding the caliper on an XJ is quite simple, it just requires patience and attention to detail. There are two "seals" on the caliper piston that fit into grooves inside the caliper body, and that's it.

The difficulty comes in getting the grooves METICULOUSLY clean before installing the new parts.

If you drag your thumbnail across the rotor, it shouldn't CATCH in any of the grooves. Some MILD grooving is OK, as Wiz said they all develop them to some degree and don't degrade performance. If the pad tore up the surface of the rotor, then you'll need to find one.

 

I have an 82 XJ750J maxim. The rotor on the brake lever side is actually dragging on the rotor. The piston side (outside) of the caliper where the brake pad is will touch the rotor making a lot of noise. I installed new aftermarket pads and it almost seems like they are too thick. What I think is happeneing is that the inside pad will not allow the piston side pad to compress inwards enough and move the caliper off the rotor. I dont know if something is bent or not - but the rotor seems good and I didnt have any issues with it before the pad replacement, so I am trying to diagnose the problem here. Overall, I have recently replaced the pads, the piston seals and the master cylinder. Everything seems to work fine, and I have good pressure and everything now. The piston for sure moves, because I took it off the bike and tried to push the pistion out, and it move quite a bit. So I put it back into the caliper and same thing.

What do you mean 'float' the caliper? Is that a certain way of putting the caliper system back on the bike, and over the rotor? I wonder if I should loosen up the caliper, pressurize the pistion more by squeezing the lever, and then trying to tighten it down on the fork?

any help would be appreciated. I have thought about replacing the pads with a different set, or perhaps sanding/grinding the ones I have down, or even using an old pad with the new pad so i can get some clearance off the rotor.

One last thing, what are the bolts for on the caliper that have the rubber boots on them? There are two of them, with one for sure being on the front of the caliper - facing the front of the bike, near the bottom (they are horizontal when the caliper is on the bike. Under the boot is a nut that looks like it could be adjusted. Is that anything that could be adjusted to open up the caliper just a hair and get the caliper edge off of my rotor?

thanks to anyone that can help me here!!! This has been stressing me out. After all of the advise on here, I can't seem to get my brakes back to normal.

 

To get your Brakes back like new ... you have to;

Remove the entire Caliper and Mount,
Separate the Caliper from the Mount

Service the Caliper
Remove the Caliper Piston
Remove the Seal
Clean to bare aluminum the Channel the Seal fits into.

Clean the Bores in the Caliper that the Mount slides into.
Remove the O-rings and refinish the Rods that the Caliper FLOATS on.
Clean-out and Lube the bore
Refinish, replace O-rings and Lube the Mount Float Rods
Use waterproof synthetic grease.

Reassemble the whole works and bleed the brake after Chamfering the Pads.

 

Per my previous post, my problem wasn't the brake pads, it was the caliper dragging on the rotor. I didn't put many miles on it... just around the block a few times. On my xj750j there is a tab on the caliper that will hit the rotor if it isn't lined up right. My friend said I should tighten up the pinch bolt, then the axle nut. Even though I had the spacer in there, it pinched the forks too close together. To solve my problem I loosened the pinch bolt, then retightened it. This solved my problem. Also, I have about 1/8" - 1/4" gap between the spacer and my fork. The tire doesn't seem to wobble or anything, so I guess I'm done messing with my squeeky brakes.