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Old March 29th, 2015, 10:54 AM   #1
archaeofreak
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Rear pads wearing very unevenly

Hey all,

I have been having noise from my rear pads since I adjusted my rear wheel alignment several months ago. A little squealing/scraping sounds like in a car when it is time for new pads. I finally got around to taking off the rear calipers and checking the pads and whoa! they look really terrible! One of the pads is worn crazy unevenly, and the other has no material left! Is this caused by the pad seating incorrectly in the caliper? Or from an incorrect rear wheel alignment? Do I need a new rotor now? I spun the rear wheel with the caliper off on the center stand and it doesn't look "wavy", but there are small grooves that can be seen and felt with a fingernail in the rotor surface. I am guessing I might need a caliper rebuild/cleaning now as well, given the amount of metal shavings that must have been removed from the pad holder.
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Old March 29th, 2015, 11:13 AM   #2
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Looks like one of the pistons seized causing an uneven braking
Surface. You may need to rebuild or buy a new caliper assembly.
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Old March 29th, 2015, 11:17 AM   #3
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The piston probably needed a cleaning and got stuck, causing the uneven wear. You may want to get a new rotor too.
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Old March 29th, 2015, 11:45 AM   #4
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The slider pins are your main cause of this.

Your caliper needs to be serviced, here's my how-to guide, enjoy

Quote:
For those of you whom are scratching their heads, here you go,*


Front Caliper Service (also rear as well)

Many folks have posted here with a Varity of front brake problems.*

*Many of which are attributable to the lack of proper maintenance.

*Here’s how you can always have a brake like when your bike was new.

A short list of the problems and the causes.

Soft lever or lever goes to the bar.

The usual cause is the pistons are pushed too far back into the caliper by a flexing a warped, coned, disc.*

*Using up too much piston travel before the disc is pinched.

Juddering in sync with wheel rotation.

The disc is worn, and its thickness varies. *This causes the caliper to “sink” into the thin part and when the thick part comes around, it gets wedged into a smaller space causing a tightening of the brake. Then the tight spot passes through and it like the brake is released. Then repeat, repeat.

Cupped, coned, or warped disc.

Unfortunately this is a common problem with EX’s the cause is the disc is stretched in the center due to being rigidly bolted to the wheel. *The huge force of braking is transmitted to the wheel through the webbed center of the disc which gets stretched and becomes larger than the space it occupies in the center of the disc. This causes the center to push to the side trying to find room for itself.*

*Resulting is a cone shaped disc.

Soft lever 2

The caliper has pistons only on one side, so as the pads wear the caliper must shift sideways apply even pressure on both sides of the disc.*

*To allow this the caliper floats on two pins. *If these pins get dry (no grease) dirty or bent. The caliper won’t center itself and bends the disc to wherever it is.

*This take up lever travel and when released pushes the pistons further back than necessary.

**If not fixed will eventually destroy the disc (warp it).


Ok how to prevent all of the above.

When new pad time comes around, resist the temptation to just pop in new one and go.

*Every time you must do these things.

Remove caliper disassemble and clean it.

Clean and re grease the sliding pins.

Polish the caliper pistons to remove dirt. If you just push the pistons back into the caliper leaks will result. Or binding.

Tools required:*
12 mm socket
8mm open end wrench
3” or bigger C clamp
a supply of new bake fluid.*
wire brush and or steel wool.

Remove the caliper from the fork leg but leave the brake line on.

Remove the old pads and the mounting frame (the sliding pins)

Remove the cover from the Master Cylinder on the Handel bar.

Attach the C clamp to one of the pistons but don’t squeeze it. *Pump the lever on the bar slowly to push out the other piston almost all the way. *Put the C clamp on that piston and push out the other one.

Remove both pistons by hand.

Remove all the rubber part from the caliper, the seals are in the grooves in the caliper and dull pointed thingy will get them out easy.

Disconnect the caliper from the brake line.

Soak all the rubber parts in new clean brake fluid * ONLY!!!!! * Rub them with you fingers till as clean as new.

The caliper can be cleaned with a wire brush or even a Moto tool for the internal grooves, NOW’s the time to paint it if you wish.

Polish the pistons till they are smooth and shinny. They are chrome plated. If any of the plating is chipped or damaged below the dust cap groove. *Replace it.

The master cylinder is the subject of another write up and we’ll assume it in good working order here.

If you suspect your disc is bad, your bets bet is to replace it with an after market one fro EBC or Galpher.

*Don’t remove the disc unless you intend to replace it. *It will assume a new shape if it is * stressed and will not be flat again. You can try to check its condition by placing a straight edge across the face of the pad swept area looking for any distortion.

Re assembly

Take the nice clean rubber seals and install them into the caliper then the Dust covers.
Wet all the rubber with new clean brake fluid and partially fill the caliper with new fluid.

Push the pistons though the dust seals and into the caliper body until the dust covers snap into the grooves.

Fill the MC with new fluid and pump the lever while holding the Line above the MC till clean fluid flows.

Connect the line to the caliper while holding it above the MC.

Pump the lever with the bleeder valve open till fluid flow from the bleeder.

**Hold the caliper so that the bleeder is the highest point.

Close the bleeder and pump more fluid into the caliper but don’t push the pistons all the way out.

Then squeeze the pistons all the way back in and install the new pads.

Re grease the slider pins and assemble the dust seals and re mount the caliper on the forks but leave the bolts loose.

Now clamp the caliper to the disc with the brake lever.

Look at the space between the fork lugs and the caliper, clamp and release a few times as you tighten the bolts by hand. It one lug touches much before the other the odds are you mounting bracket is bent. You can straighten it.*

*After you get it the best you can. Some shim washers made from alum can stock can be fitted to the loose side.*

** *What we are doing here is trying to minimize the bedd in time and gets the best pad life.


Ok with everything tight you should be through, Notice we don’t need to bleed the brakes, but if you screwed up in any of the above steps, you might do that here.

Be careful to Bedd in the new pads gently.

**Too much pressure too soon will burn the pad material as only a small area will be gripping at first. You also won’t have full braking power till the pads are fully familiar with the disc
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Old March 29th, 2015, 11:57 AM   #5
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Can anyone provide OEM part numbers for the parts I should replace when rebuilding the caliper? Is it just the dust covers? I am having trouble finding which parts must be replaced and the part numbers for them. Thanks guys!
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Old March 29th, 2015, 12:06 PM   #6
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Quote:
Originally Posted by archaeofreak View Post
Can anyone provide OEM part numbers for the parts I should replace when rebuilding the caliper? Is it just the dust covers? I am having trouble finding which parts must be replaced and the part numbers for them. Thanks guys!
Hopefully none are damaged to need replacement, but it can happen, just be careful upon disassemble and you should be okay, but here's the diagram just in case.

http://www.partzilla.com/parts/searc...AKE/parts.html

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Old March 29th, 2015, 12:08 PM   #7
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Quote:
Originally Posted by Ghostt View Post
Hopefully none are damaged to need replacement, but it can happen, just be careful upon disassemble and you should be okay, but here's the diagram just in case.



So is it just 49006 and 49006A that typically need replacement? These are the dust covers for the rear caliper?
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Old March 29th, 2015, 12:14 PM   #8
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http://faq.ninja250.org/wiki/Brake_caliper_rebuild

States there are 4 seals per caliper that should be replaced every 20k. I am at 19k now so probably should do then huh?
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Old March 29th, 2015, 12:15 PM   #9
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Quote:
Originally Posted by archaeofreak View Post
So is it just 49006 and 49006A that typically need replacement? These are the dust covers for the rear caliper?
Yes they are for the slider pins only!

Part #'s 43049 &43049A are for the piston
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Old March 29th, 2015, 12:16 PM   #10
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Quote:
Originally Posted by archaeofreak View Post
http://faq.ninja250.org/wiki/Brake_caliper_rebuild

States there are 4 seals per caliper that should be replaced every 20k. I am at 19k now so probably should do then huh?
Personally I would, after all its the brake system, one thing you NEVER do half arse


Here's a handy bookmark for you,

http://www.partzilla.com/parts/searc...50R/parts.html
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Old March 29th, 2015, 12:57 PM   #11
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Hey lemme know if you need a rotor. I took mine off from my 07 with less than 6k on it.
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Old April 3rd, 2015, 06:14 AM   #12
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Quote:
Originally Posted by Ghostt View Post
The slider pins are your main cause of this.

Your caliper needs to be serviced, here's my how-to guide, enjoy
That wall.

My money is on a siezed piston. Do a rebuild, lube, and fresh brake fluid should be good to go.
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Old April 3rd, 2015, 07:48 AM   #13
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Quote:
Originally Posted by agentbad View Post
That wall.

My money is on a siezed piston. Do a rebuild, lube, and fresh brake fluid should be good to go.
Yeah, I guess it is, I never realized it before,
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Old April 4th, 2015, 01:00 PM   #14
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Thanks for the info guys. I am waiting on the parts to do the rear caliper rebuild.
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Old April 4th, 2015, 01:02 PM   #15
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Originally Posted by Singh2jz View Post
Hey lemme know if you need a rotor. I took mine off from my 07 with less than 6k on it.
How much you want for it? Whats your zip for shipping? Not sure I need it yet, but you never know. After I rebuild the caliper, Ill see how it feels and may want to purchase a new rotor.
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Old April 4th, 2015, 02:07 PM   #16
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How much you want for it? Whats your zip for shipping? Not sure I need it yet, but you never know. After I rebuild the caliper, Ill see how it feels and may want to purchase a new rotor.
Just shoot me a reasonable offer. Shipping will be usps 2-day flat rate from 5-7 bucks.
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Old April 12th, 2015, 11:41 AM   #17
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OK, I got the parts in and removed the caliper, however one of the pistons is stuck inside the piston chamber! Any ideas on how to remove? I took some pics of the other piston that came right out, after cleaning. I see some faints marring. Is this piston in good shape? Pics below.

Should I lube the first piston and reinstall, then fill back up with brake fluid and start pumping the rear brake while holding the piston inside the caliper, so the other piston is pressurized, and hopefully will budge?
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Old April 12th, 2015, 11:45 AM   #18
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Please take another look at my write-up again, all the answers you seek are there.
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Old April 12th, 2015, 12:36 PM   #19
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I read through it again, but don't see anything about removing a stuck piston. Because I am impatient, I reconnected the caliper banjo bolt, filled the rear reservoir a bit, re-lubed the other piston and pushed it back into the caliper, and started pumping the rear brake lever. I get nothing. Now, even the piston that previously came right out doesn't move.

Could this be caused by air in the line? It is like I am not getting any pressure from pumping the brake lever. I am about to go get a grease gun and try pumping the caliper full of grease to move the pistons if I cant move them using the brake fluid. Any help would be much appreciated!
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Old April 12th, 2015, 01:01 PM   #20
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hit it with a hammer. hone the cylinder walls VERY LIGHTLY after to remove the corrosion. take it to a fine grit and polish the walls. replace the piston if its damaged
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Old April 12th, 2015, 01:04 PM   #21
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You gotta make sure there's full pressure going to the pistons. So take air out and then slowly apply the brake and the Pistons should come out
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Old April 12th, 2015, 01:24 PM   #22
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If you have access to an air compressor, fill caliper with fluid and then very slowly apply pressure, be sure to use the C-clamp as directed in my write-up.

Quote:
Attach the C clamp to one of the pistons but don’t squeeze it. *Pump the lever on the bar slowly to push out the other piston almost all the way. *Put the C clamp on that piston and push out the other one.
Another way is a pair of channel locks, wrap the piston with something that will protect it from damage, like a piece of leather, etc. Then grab hold and slowly and easley twist and pull at the same time. Be VERY careful not to damage the piston.
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