99 WR400 Front Brake Rub after tire change

[emagnuson]

This one is frustrating me. I have a 99 WR400, I mounted a new front tire and after re-installing the wheel, my brake is rubbing. Enough that if I spin the tire, it goes around like 3 times before stopping. I followed the instructions per the manual. Install the axel, torque the axel nut, keep the pinch bolts loose, cycle the forks a few times with the brake locked. No cigar. It still rubs. I have taken it apart and tried the whole routine 4 times now.

Some things it's not: not a bent rotor, didn't forget any parts.

Anyone have similar experience that can help me get back on track? I'm definitely new to this. I could be on the wrong track entirely.

Thanks!

E

[emagnuson]

Update...

It's centering, but barely enough room to get the rotor between the pads. What's the process for releasing pressure on the pads?

[SJMC_DON]

This one is frustrating me. I have a 99 WR400, I mounted a new front tire and after re-installing the wheel, my brake is rubbing. Enough that if I spin the tire, it goes around like 3 times before stopping. I followed the instructions per the manual. Install the axel, torque the axel nut, keep the pinch bolts loose, cycle the forks a few times with the brake locked. No cigar. It still rubs. I have taken it apart and tried the whole routine 4 times now.

Some things it's not: not a bent rotor, didn't forget any parts.

Anyone have similar experience that can help me get back on track? I'm definitely new to this. I could be on the wrong track entirely.

Thanks!

E

How do you know the rotor is not bent?

[SJMC_DON]

Update...

It's centering, but barely enough room to get the rotor between the pads. What's the process for releasing pressure on the pads?

Usually you just pry them back (compress the caliper pistons) with a screw driver. After wheel is installed just pump the brakes back up and all is good:thumbsup:

You can crack your bleeder valve real quick:excuseme:

[emagnuson]

Thanks! I was able to spread the pads apart by putting pressure on the pistons. The pads are still tight against the rotor once I put the wheel back on though. The rotor looks straight when it spins, I can eyeball it and don't see any variation as it spins. It's definitely more a case of a brake issue than the wheel being centered. it's equally tight on both sides from what I can see.

[Darkplague]

I wouldnt worry about it too much unless its very very tight on the rotor.

Ive owned at least 20 different bikes, and they've all rubbed slightly on the disc, but after a good ride they are good to go.

If you get up to speed, and put the clutch in, can you feel the bike slow down in the front end without using the brake lever?

[matt4x4]

Brake pads will always touch/rub the rotor.

The brake pads aren't tied to the caliper or pistons in any fashion, and the system is not designed to pull pads back and away from the rotor, it only releases any positive pressure applied to the pads/rotor by the piston action.

If you are getting 3 rotations, that is not bad at all, some people get even less, not due to brakes, but due to the gears for the spedometer/odometer which are also working against the wheel spinning freely.

The caliper is designed in such a way that it is able to slide from side to side to some degree - not on the mounting bolts, but on separate slide pins, this is due to two reasons - it allows the pressure from the pistons (located on one side only) to spread evenly between both pads since the inner pad is static, and to accommodate the wear on the pads - as the inside pad wears, the caliper needs to move out more to compensate (eliminate) for what would otherwise be an ever growing space between the inside pad and rotor - if the caliper were to be static, uneven pressure will be exerted on the rotor - actually, you would only get pressure on the outside pad, forcing the rotor to start twisting inwards from pressure on the outer pad until it is stopped by the inner pad - if the slide pin is seized, your rotor can get damaged very quickly, it is recommended to lube the slide pins regularly - I have had great success on all sorts of caliper style brakes using anti seize compound on these pins.

[emagnuson]

Great info. It does make sense that the pads would be, at least, touching the rotor. The fact being that I had to pry the brake apart when I was putting my wheel on would suggest that there isn't a mechanism to pull the brakes apart, only to press them together. Just to validate, I'll check a couple friends bikes to make me feel better. There is definitely conflicting info out there on this topic. I've seen posts that say it's fine/normal to have the brake pads touching the rotors. I've also seen posts that say the wheel should spin freely. I just don't see how that could happen.

thanks again. This was my first post on this site, as expected, my concerns were addressed.

E

[matt4x4]

If it would stop in one revolution, you would have too much drag.

Remove the speedo cable, you'll gain a few revolutions, remove the speedo gear and replace it with a YZF spacer and you'll gain a few more revolutions, remove the brake and get a few more - at which point you're pretty much down to bearing drag only.

[SJMC_DON]

I have had a front brake lock up on me as air bubbles have worked there way up to the top after a brake bleed with a vacuum bleeder after I had changed the front brake line...

If your rotor is not bent, the front wheel should spin freely enough despite slight rubbing from the brake pads, to spin more than 2 or 3 revs..?

I would still bleed a little pressure off and see what happens...

[emagnuson]

I never opened the brake system. Would air still be able to get introduced?

I did take the bike on a spin on the road to test the braking at speed (That's right, it's CA plated!). I didn't notice any issues. The bike rolls fine, brakes hook up just fine. Also, when I got home, the rotor wasn't hot like it would be if there were any real pressure from the pads. I think I'm ok. I'll keep my eye on it though. I'm going to Gorman over Thanksgiving. There will be some more mechanically experienced riders with us to give their opinions. I should be able to work it out with their help. I'll just be sure and bring everything I need to swap brake fluid. I wish I would have rolled the wheel on the stand prior to taking it off to know if it was in a similar state before I removed it. I think I good to go though.

Thanks for your advice on this. Much appreciated.

E

[steve10391]

Your bike is 8 years old now. It is possilble the the piston inside the caliper is dirty or slightly corroded. That could cause excess pressure because it can't go back to to a static position. I have had this problem a few times over the years and most of the time a good cleaning will solve the problem. Steve

[PatrickM]

I had this same issue so I just bled the brakes and it fixed the issue.

the brake caliper piston is possibly not putting equal pressure across the pad. You could even take off your brake pads and check them for uneven wear.

good luck!!!

Patrick M.

[emagnuson]

Ok, now for a basic question...

what's the best method to bleed brakes? I've seen the syringe method from the bottom and the "open the bleed valve, pump the brake, close the bleed valve" method from the top. If you've never done it before, what's a good way to get up to speed?

A) get a bleeder kit

? get fluid

C) drain the old fluid and add new fluid from the master cylinder end of the system?

[PatrickM]

Bleeding the brakes on a bike are similar to doing it on a car. the only difference is that the front brake and the back brake are not connected. so if you mess with the front brake you dont need to mess with the back brake.

all you need to do it just find the bleeder valve on the brake caliper and presurize the system (pump the brake lever about 10 times and hold it) then open the bleeder valve on the brak caliper and let out the air and when pure fluid comes out of the bleeder valve then you can bled the brake system of an air bubbles (which could lessen the power of brake system). Just make sure to be adding fluid to the master cyclinder as you go.

if you follow that method you could bleed out all of you fluid and replace it as the fluid comes out.

I am sure there are other ways to do it and searching TT would get you more detailed version of what I said.

Good luck getting your brakes working right (if the dont work right, you could be in a world of pain:censored: ? )

Patrick M.

[emagnuson]

I've officially gone from ? to

For the purpose of helping someone in a future search, I'll finalize this post. Yes my brake rubs a little, My wheel will spin about 4 revolutions with a semi hard attempt at spinning the wheel. It's not a problem though. I just came back from 4 days at Hungry Valley SVRA. Lot's of front braking and zero issues. The rotor wasn't getting burned or discolored. My brake was definitely hooking up fine. I could feather it on the wicked downhills and didn't get any lock up, etc, etc.

Erick

1999 Yamaha WR 400