[kars10]

So, I just bought a used 2002 Ninja 500R back in June.
The bike had 7750 miles on it and what appeared to be stock tires.
The rear tire was bably in need of replacing, so I bought some Pirelli Sport Demons online.

I didn't want to pay twice as much to take the bike to a shop mount the tires, so I removed the rear and front wheels and had the tires mounted off the bike. (By the way, had a hell of a time getting the rear axle out. The axle bolt was rusted onto the sleeve that runs through the bearing in the center of the wheel).

So I brought the wheels home and reinstalled them on the bike. Everything seemed good until I took the bike for a test drive. Now I seem to have issues with the rear brake.

I can press the brake pedal all the way to its stop and I still get very little braking power.

At the suggestion of another motorcycle owner, I tried bleeding the lines. This seemed to work properly, but I still have no braking power.

If I look close at the caliper/rotor as the pedal is pushed, I can see motion of the inside pads (i.e. it looks like the disc is being squeezed. Actually, it looks more like the disc is being pulled (away from the rim) when the pedal is pushed. This seems wrong to me. Shoudn't the brakes apply equal and opposite forces to the disc (i.e. no movement)? Could the rear disc be out of alignment (shifted 1/4" to the left side of the bike)?

What else could be wrong?

*Note:
While I had the wheels off of the bike, I accidentally tested the brakes and ended up pushing the pads right out of the calipers. I had to recompress the pistons a little to get the pads back into place. As far as I can tell, I replaced them properly and mounted the wheels with the discs inbetween opposing pads.

 

[Mad Matt]

The brake calipers should float on their mounts so they automatically center on the disc. It sounds as if the rear has frozen into place. Take the caliper off and have a look at the bushings/pins under the rubber boots to see if they slide back and forth. You may have to break these loose and lube them to get function again.

With a rusty center bushing in the wheel I'd expect that these are probably rusty too. Did the rear sit in water at some point?

 

[kars10]

I'm not sure if the rear ever sat in water. As I said, I'm the new owner of the bike and the previous owner didn't mention anything about it.

What bothers me is that the rear brake worked fine, prior to my removal and reinstallation of the rear wheel. So if the caliper was rusty, why would it bind up now?

Do I have to take the whole rear wheel off again to get the caliper off? It seems to me that the axle goes throught the steel angled bracket that supports the caliper part of the brake. If I removed the bolts that attach to this bracket, can I remove the caliper and leave the wheel/disc/rotor all on the bike?

 

[knightslugger]

are your spacers installed correctly? There is a certain side to each one...

 

[kars10]

Which spacers are you referring to?
I thought at first that I might have put in the spacer (#92027) in backwards, but it is installed as in the above picture, with the smaller diameter facing the wheel, and the larger diameter against the bracket the holds the caliper.

 

[kars10]

ok the picture didn't attach properly, but it is the same picture available in the microfiche for the rear wheel.

 

[knightslugger]

it didn't attach because you didn't upload it. next time use the attachment feature in the reply window. anyway i know what you're talking about, and what I'M talking about is if you swapped sides by accident. it's easy to do...

 

[kars10]

Let's see if this image works...

I'm pretty sure I've assembled the spacers correctly. I'll be sure to take this picture out to the bike when I get home and check.

Any other suggestions?

[attachment deleted by admin]

 

[Mad Matt]

Do I have to take the whole rear wheel off again to get the caliper off? It seems to me that the axle goes throught the steel angled bracket that supports the caliper part of the brake. If I removed the bolts that attach to this bracket, can I remove the caliper and leave the wheel/disc/rotor all on the bike?

The caliper just bolts to the aluminum bracket that is captured between the swingarm and the wheel spacer. So just the two allen bolts hold it in place. At least check to see that the caliper is floating on the pins since it is easy to do.

Actually reading a little more closely I see where the disc is being pulled away from the wheel. That's weird. Does the brake continously drag?

 

[dad1]

It is possible to get the brake pads both on one side of the rotor. If that was done, you're applying the brake to the metal back of one of the pads and metal to metal on the other side. Make sure that's not what you did because you'll wreck the caliper.

The pedal is moving freely, yes? Not rusted up and operating tight? Other than that, it's all in the bleed and changing the tire should have no effect.

 

[kars10]

It is possible to get the brake pads both on one side of the rotor. If that was done, you're applying the brake to the metal back of one of the pads and metal to metal on the other side. Make sure that's not what you did because you'll wreck the caliper.

The pedal is moving freely, yes? Not rusted up and operating tight? Other than that, it's all in the bleed and changing the tire should have no effect.

I'll check on the "both pads on the same side of the caliper" theory when I get a chance later, but I don't think thats what I did. I was pretty careful when reassembling everything.

Yes, the pedal is moving freely. I can push it all the way to its stop. If I put the bike on its center stand, I can spin the wheel freely. Then, if I press the pedal to its stop, the brake engages, but not with sufficient force. I can still turn the rear wheel by hand (slowly, and with extra effort). When I'm riding the bike, the weight/forward momentum of the bike is much greater than the braking power I get on the rear wheel.

The above symptoms lead me (and others) to believe it was a bleed issue. If there was air in my lines, it would keep the caliper from applying full force to the disc.

Perhaps my bleed procedure was wrong. Here's what I did:
1) Removed cap from bleed nipple on the top of the caliper.
2) Attached a piece of tubing and ran into a clear glass container on the ground.
3) Using a wrench, I loosened the bleed opening (valve? orifice? nipple?)
4) I had a friend press down on the brake pedal and hold it down.
5) Re-tightened the bleed opening.
6) Released the brake pedal.
7) Repeat steps 3-6 as needed
8) Add additional brake fluid to the resevior as needed
9) I stopped when each press of the pedal forced out an amount of brake fluid (i.e. no longer forcing out air)

After many repetitions, the brake force did not seem to improve much. I must have pumped at least 20-30 times.

The caliper just bolts to the aluminum bracket that is captured between the swingarm and the wheel spacer. So just the two allen bolts hold it in place. At least check to see that the caliper is floating on the pins since it is easy to do.

Actually reading a little more closely I see where the disc is being pulled away from the wheel. That's weird. Does the brake continously drag?

I see now what you mean about how the caliper can be removed. I will pull it off and experiment more when I have the time. Perhaps I can readjust the brake pads better/make sure they are clipped in correctly.

The brake does not continuously drag. The rotor seems to return to a normal flat shape when the brake pressure is removed.

 

[Jsvob03]

for the bleed procedure, i've used that technique before, but came out with unfavorable results. try this.

1.) (this is the unnecessary step) remove cap, drain fluid from reservior, add new fluid. this helps to get fresh fluid, but repeated bleeding does the same. otherwise, just make sure you are FULL.

2.) fit the tube back over the bleeder, so as to avoid brake fluid getting on anything.

3.) have your friend press down the brake lever. With him/her holding, open up the bleeder. the lever will sink to the end of its travel. tighten the bleeder. have your friend pump the pedal about 3 times, or until firm.

4.) repeat step 3 until you have fluid with no air bubbles in the line.

Note: during the process keep the reservior above the low line, otherwise you'll introduce air into the system, and make the job longer.

also, as everyone said, get some brake lube (axle grease works too, as its heat resistant) and make sure the pins are sliding freely.

 

[dad1]

The rotor is moving?! Something is assembled wrong or a part missing. Even if air was introduced in attempting to bleed, the problem started as an assembly error.

Make sure there is one pad on each side of the rotor, spacers on each side of the wheel as well as the one in the sprocket hub, and that the brake anchor bracket is properly dogged into the slot in the swingarm. If you're not sure, use an online microfiche for a display of the parts assembly sequence and to make sure you didn't lose a spacer or something. What used to be a brake is now a broke. (Sorry, couldn't resist.)

 

[kars10]

I posted some photos on Flickr.

Feel free to take a look and see if you can spot anything out of place or determine what the issue is.

http://www.flickr.com/photos/[email protected]/

 

[Mad Matt]

Good pics. I don't see anything overtly obvious. If something is jammed on that holder so the piston is pushing the pad against it instead of the disc then the whole caliper will move outward and the inner pad will push the disc ouboard. Take the caliper off and ensure it floats on the holder and that the piston is not somehow pushing itself or the outboard pad against it. It's got to be something wrong in that region.

 

[Jsvob03]

let me know what you discover here. i've had the same problem with my brakes. I can hammer the rears, and get very little response. granted, my rotors aren't in the best shape, but they aren't so bad that i get almost no response. I even had my buddy with an 07 500 ride it, first thing he said was how bad they were. maybe i'll compare his (jesus why didnt i think of this before now?!)

 

[ERAU944]

now that i've ridden the '90 a bit since adjusting the valves, i noticed i've got my own issue. when i had the wheel off to replace the tire (nearly a year ago), i checked the shoes and the drum, everything looked good. now, when i use the rear brake, the first stop of the day is great, and every time i use them after that i don't get near the stopping power... is there an issue there? or are the shoes burning off a little moisture and then settling to their regular 'grippiness'. i never noticed this before. if i press hard enough on the pedal i can get the wheel to lock up, so i know they're working. it just seems that such a difference in stopping power between the first and second uses of the rear brakes might indicate an issue.

just for the record, i don't use my rear brake ONLY for stopping, but since i've noticed this i've been checking to make sure it's actually happening, not just in my head.

 

[Jsvob03]

i know when i first got the bike, i could lock the rear with no problem (scary actually, as i wasnt trying to), now i can romp on the lever, and it hasnt locked. maybe the michelins grip that much more, but it just doesnt feel as solid as it did..

 

[fog]

These kind of problems are almost always caused by missalignment of the caliper due to stuck sliding pins (caliper cannot center itself to the disc. Or stuck pistins in the caliper. (same missalignment) . Read my piece on Complete Caliper Service. in the FYI section.

FOG

 

[ERAU944]

i've determined that my rear brake operates normally. the grabbiness is just like my father's '97 F250 with rear drums. a little grabby at first, then just about right.