What the heck is wrong with my rear brake?

[BlackCR25098]

Okay so let me start off by saying I've not experienced with brake work what so ever. The other day, I took off my rear wheel to replace a stripped chain adjuster lock nut. Successfully did so, and taught myself how to adjust the chain. Now with the brakes and rear caliper, I essentially did not touch it when the rear wheel came off. When it came time to put the rear wheel back, one of the brake pads had fallen out of it's forward position on the little mantle. It was the one opposite of the piston. So, I just carefully placed it back up there and then I just lined up the rotor and buttoned the wheel and all back up.

Fast forward to the next day I fire her up to go ride, I get about 2 seconds into the trail and notice my rear brake is going to the freaking floor...Ok. So, I bring her back last night, take the wheel BACK off and think maybe it's binding up somehow against the rotor or something, so this time I actually compress the piston to give more room between the brakes even through that same brake pad keeps falling out of it's forward position on the mantle, and I keep putting it back, so I put it back, piston compressed, rotor goes on everything looks good. Brake is still spongy and going to the floor.

Okay so I thought I probably have air in my lines from compressing the piston back, but it still doesn't make sense why it was mushy the first time when I didn't compress the piston. Anyway, today I probably refilled the master cylinder 10 times while bleeding the brakes and working in the new fluid. Needed a fluid change anyway, but the rear brake NEVER tightened up, it's still going to the floor after 15 times of refill, and using the caliper bleeder.

Am I just being impatient? Is it something else other than air in the lines? It's wayyyy too coincidental that my master cylinder just failed at the same time I took off the rear wheel and messed with the brakes and everything back there, so just hoping someone has some insight...This is why I'm always hesitant to dive in on my bike and try to teach myself new things.

[XXxxXXxx]

You need to press the brake a few times after the piston has been pushed in,

Just press the rear brake pedal until the brake returns to normal...

[BlackCR25098]

Ha if only it was that easy....It goes all the way to the floor. So far I have hooked up a fuel line to the bleeder valve on the rear caliper and have flushed/ bled an entire bottle of brake fluid through it trying to get out all of the bubbles...I mean, is that typical??? My right hand (pumping hand) is actually hurting from how many times I have pumped it.

My way of doing it is cap removed to keep adding fluid, fuel line on bleeder valve, I pump pump pump then pump and hold it down and as I'm holding it down I crack the bleeder valve open and then closed being sure not to let up on the pedal. I'd say I've refilled the reservoir about 20 times and gone through 1 entire little bottle of brake fluid. What is the deal?

I know my master cylinder didn't just randomly decide to go bad. It'd be way too coincidental that that would happen right as I start messing with the brakes and push the piston back in. Like I said the first time I didn't even compress the piston, just put it all back together and the pedal has been mushy ever since. Anyone please give me some insight.

[heart_of_darkness]

If your rear brake system hasn't been fully bled after a whole container of brake fluid, something is certainly wrong. Are you certain that the reservoir is never going empty during the process?

Did you get any oil or grease or brake fluid on the rotor or pads?

[MXHalofan]

Looking hard at the pics, looks like your wheel spacer on the caliper side is not installed. My 97 definitely has one there. Looks to me like your wheel is too far over, causing your pads to slip off the "mantle" they sit on.

The alignment of the cal/pads and rotor is all off compared to mine. Gotta be a wheel spacer missing.

[BlackCR25098]

Nah man I installed both wheel spacers, they kept wanting to fall out during but they ARE in there and the chain is adjusted and wheel is the same distance on each side of the swing arm. That one brake pad would fall out if I even touched the caliper the wrong way WITHOUT the wheel even on, so I don't think it is that.

I do remember wiping the rotor down while I had the wheel off but I didn't do it with grease or brake fluid or anything...

Well I'm thinking that my simple bleeding process just isn't cutting it. My buddy just called who's real knowledgeable and has a pump and I got some more brake fluid LOL so hopefully we can get it all sorted here. I'll keep yall updated I just simply need it to get that pressure back so I can freaking ride this weekend!!!

[Eddie8v]

It looks like that wheel spacer is missing man. I hope that you didn't forget it, then crank the axle up until the nut ran out of threads to climb, bending the swingarm "arms"...

Edited February 23, 2012 by Ed2006CRF450R

[MXHalofan]

Yea ^, double check the wheel spacer is there. As pictured above, it's not.

If you put it on after taking pics, then I'd pull the wheel off, and look at the perchs on the caliper that the front of the pads sit on. Maybe one broke.

EDIT You can see the perches those pad sit on from the side, looking through the spokes.

Edited February 23, 2012 by MXHalofan

[BlackCR25098]

Okay guys and I'm not sure which picture makes it look like the wheel spacer isn't there but I can assure you it is. I believe it was just the angle of the picture that was trying to capture above the brake and kind of to the opposite side of the spacer so it makes it look like it's not there although in every single pic with the wheel on there you can see the edge of the spacer right there.

Again, the spacer is just the little things that go onto each side of the wheel right?? They kept trying to fall out when re-installing the wheel but they are definitely both there!

I just ran down and snapped a pic for you guys to verify we are all talking about the same thing...although it's pretty blatantly obvious what a wheel spacer is and they're both absolutely in.

Here it is...and if you look at the rounded edge of the actual spacer you can reference it in the other pictures.

Edited February 23, 2012 by BlackCR25098

[MXHalofan]

I can see the spacer better now. The cal piston isn't pushing out in the pics. So fluid squirts out when you hit the pedal and crack the bleeder?

You might have a bad brake line that's expanding. Or the MC could be bad. You could see if you can hook your front MC to the rear cal and see if it' pushes the piston out.

When bleeding, it really shouldn't take more than four or five bleed cycles to get all the air out. A whole bottle is way more than needed. Sounds like your method is spot on.

You might sleep on it tonight see if gravity can work a bubble out of there. I normally have to re bleed the next day when I have a MC go dry. Can't get every last bubble out until it's set, or been ridden.

[JJRace]

remove the caliper mount from the swingarm and grease the slide pins

[BlackCR25098]

Yeah they do seem like they're binding up on that pin kind of. I'm starting to think it was something wrong with me just placing the pad back up in there and slapping it on.

Guys the MC, the line, nor piston magically went bad all of the sudden. It was working perfectly before I decided to take off the rear wheel by myself, then the pad fell out and boom now it's all mushy. I definitely am starting to think it's the pin. I originally tried to take the pin out I took off the little flat head cover screw? If you know what I'm talking about, then inside the actual pin I found a allen wrench that fit in there but the freaking thing would NOT budge so I didn't want to risk stripping it. Am I using the right tool to remove that dang pin?

I get so frustrated because I'm perfectly capable but I keep getting hung up on little areas like this pin, not sure how to remove it just with an allen wrench or something more? Please lemme know I may just remove the wheel and try to start over this time while greasing the pin, but guys basically upon first compressing the brakes after I pushed the piston back, the piston came out and pushed the brakes to where they're hugging the rotor but it still has good free wheel sping which is what I think it's supposed to do right? I can see the piston moving back and forth ever so slightly when I push the pedal but the pads themselves are not sliding on the pin....

[gavin198]

i had this problem but this was due to me getting my brother to fit my pads :s he made a cock up of it and the pad didnt sit where it should so pin taken out and replaced the pads and was all fine

1 bottle of fluid could do all my bikes

any leaks? i would take apart and start again

[BlackCR25098]

Yep we fixed it today. Took it to my knowledgeable buddies house. At least it's got brand new fluid! LOL Funny thing is there wasn't any air in the lines. I guess somehow the pads went in crooked and the piston side pad was bent a little. No biggie, took it apart and the retaining clip was in upside down first of all, and then we bent the piston side pad back, re greased the all the pins, and made sure everything was cherry, put it back together and pumped up the brakes and magically all is well. I just don't understand brakes at all. It's going to take more 1 on 1 time with me doing it myself. My buddy goes a little fast and I'm just left nodding and saying hell yea.

Brakes work AND I got a great session of riding in today, got the bike back and fully cleaned before dark. Yea I'd say today was a good day. I'm gonna order another set of pads asap but it's really all good as it is now.

Edited February 24, 2012 by BlackCR25098

[Piney Woods]

When you order the pads tell the parts guy to add a service manual to the list. Read it.

[BlackCR25098]

When you order the pads tell the parts guy to add a service manual to the list. Read it.

Already got one, and the section regarding the rear caliper is vague at best, but thanks. I learn by messing up and then correcting, but when I order I do need a new caliper pad pin, so thanks for the reminder!

Edited February 24, 2012 by BlackCR25098

[gavin198]

glad to hear you sorted you problem were ready for yopur next one lol

[BlackCR25098]

glad to hear you sorted you problem were ready for yopur next one lol

Haha hey you guys would be proud if you've seen how much I have taught myself since owning this bike, not to mention rebuilding the motor! Next is suspension and bearings, hydro clutch, black rear wheel, and maybe a PWK.

[frdbtr]

Already got one, and the section regarding the rear caliper is vague at best, but thanks. I learn by messing up and then correcting, but when I order I do need a new caliper pad pin, so thanks for the reminder!

Take a look at Rockymountainmc.com. They have tusk brake pins that replace the allen bolt with an 8mm hex head bolt. I replaced the ones on my bikes with them and I like them a lot. Much better then the allen bolt pin.

[BlackCR25098]

Take a look at Rockymountainmc.com. They have tusk brake pins that replace the allen bolt with an 8mm hex head bolt. I replaced the ones on my bikes with them and I like them a lot. Much better then the allen bolt pin.

Yea I saw that tusk pin in rocky mountains "how to change pads" video. Pretty sure I watched every single brake bleeding video on youtube this past week, but I will definitely be ordering that monday asap, along with new pads. The bike freaking RIPPED today at the track.