Front Brake Rebuild questions..

2334 Views 25 Replies 8 Participants Last post by bandit, Jul 13, 2011

MechaJubei

Discussion Starter · Jul 6, 2011

So someone dumped something corrosive on my tank the other day and ate away at the paint, so since I had to take the tank off and repaint I thought it would be a good time to do some other things on the bike - mainly the front brakes.

Originally I was just going to replace the brake pads but then I noticed a small build up of brake fluid around the calipers and that my brake fluid resevoir was empty. I took off the calipers and noticed that one of the pistons was stuck down. I think I've been running off of just one caliper piston, which might explain my squeaky brakes. That and my brake pads were almost non-existant.

Here's my problem though - I cannot get the stuck piston out. The other is already out but the stuck one just won't budge. I have it soaking in WD40 right now and am hoping that will help but I am a bit doubtful. Is there a trick to removing a seized caliper piston? I'm hoping it's not damaged so I just have to buy a rebuild kit and not a whole new caliper.

Another question is where is a good place to get the steel braided brake lines everyone says we should switch over to?

Thanks in advance, sorry to always be posting questions like this. This is my first bike I've actually had to work on and it's definitaley a learning experience.

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Blue Fox

· #2 · Jul 6, 2011

About the only way to get that piston out is to put the first one back in and then use the MC to pump both out together. Put a paint stirring stick or equiv where the pads go in the caliper so that one piston doesn't come completely out first. Then bleed the system and pump them out. When they reach the stick, you should be able to remove by hand. If you think you have to grip the piston with a metal implement, try to only grip at the very outside of the piston. If you get too far down, you are likely to score the piston where the seal is made.

I have also heard of replacing the bleeder screw with a Zerk fitting, replace the other piston and pump out. Kinda messy, but should work. Another way is to use a air nozzle directed into the bleeder hole. First piston back in, stick in place, wrap with a large shop towel and keep your fingers away from the inside. Air pressure may not be enough if one of your pistons is really stuck, you may have to use one of the other methods.

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bandit

· #3 · Jul 6, 2011

you are going to need to put the other piston back in.and hold it in with a g-cramp.

then,the method i used,was to hook the caliper up to an air compressor,wrap in a towel,then crank it up.

others use a grease gun.probably safer,but not as much fun.

once out,put it back in,after cleaning,and use the same g-cramp with a timber packer,to let both out equally.

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MechaJubei

Discussion Starter · #4 · Jul 6, 2011

Thank you both for the direction. My hump now is getting the one piston back in there. The rubber O-Rings are thrashed and the piston doesn't want to fit back in. I dunno if it is safe to try and force it in....now I'm all paranoid about messing up either the piston or the caliper.

When I get home I'll see what I can do though. Hoping that soaking it in WD40 will help out and maybe I can pull it out with pliers using a towel so I don't scratch the piston.

Did anyone have any insight on a good cheap place to get the steel braided cable? Saw some on eBay but dont' even know what kind I need to get.

bandit

· #5 · Jul 6, 2011

MechaJubei said:
Thank you both for the direction. My hump now is getting the one piston back in there. The rubber O-Rings are thrashed and the piston doesn't want to fit back in. I dunno if it is safe to try and force it in....now I'm all paranoid about messing up either the piston or the caliper.

When I get home I'll see what I can do though. Hoping that soaking it in WD40 will help out and maybe I can pull it out with pliers using a towel so I don't scratch the piston.

Did anyone have any insight on a good cheap place to get the steel braided cable? Saw some on eBay but dont' even know what kind I need to get.

MJ,FOR NOW...KEEP THOSE jagged pliers/grips away from the piston.have you a g cramp.if you havnt , get one

the old piston came out,it will go back,even stead pressure

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MechaJubei

Discussion Starter · #6 · Jul 6, 2011

bandit said:
MJ,FOR NOW...KEEP THOSE jagged pliers/grips away from the piston.have you a g cramp.if you havnt , get one

the old piston came out,it will go back,even stead pressure

Thanks Bandit, I will take your advice. I'll snag a G-Clamp on my way home today. Last thing I wanna do is mess up the who kit-n-kaboodle and have to buy a new caliper / piston setup. There doesn't appear to be any rust or anything on the other bore / caliper so hoping the stuck one is just being....stuck, hehe.

ScrapMetal

· #7 · Jul 6, 2011

I've successfully done the air pressure thing. Just watch your fingers! That thing is gonna fly, hence the towel (I used a bucket to catch it too).

bandit

· #8 · Jul 6, 2011

MechaJubei said:
Thanks Bandit, I will take your advice. I'll snag a G-Clamp on my way home today. Last thing I wanna do is mess up the who kit-n-kaboodle and have to buy a new caliper / piston setup. There doesn't appear to be any rust or anything on the other bore / caliper so hoping the stuck one is just being....stuck, hehe.

you wont be sorry,they are great toys.

good luck and keep us posted.....its a bit of a game,but it will work

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MechaJubei

Discussion Starter · #9 · Jul 6, 2011

ScrapMetal said:
I've successfully done the air pressure thing. Just watch your fingers! That thing is gonna fly, hence the towel (I used a bucket to catch it too).

Wish I had an Air Compressor...I've got a neighbor who needs a piston through his front window. ;-)

bandit

· #10 · Jul 6, 2011

MechaJubei said:
Wish I had an Air Compressor...I've got a neighbor who needs a piston through his front window. ;-)

lol.take it to your local garage,a bottle of vino tinto,it,l take them seconds

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MechaJubei

Discussion Starter · #11 · Jul 10, 2011

Well thanks to everyone's advice I did get the other piston out and cleaned the caliper. Hoorah! So now I need just two of the outer O-Rings the go into the bores. The ineer O-Rings are in great shape for some reason though. Is there any place to get just those outter O-Rings or do I need to buy a whole rebuild kit just to get them?

I've got a pair of replacement organic brake pads on the way but still don't know where to get a braided steel brake cable for the GL500 at. Any suggestions?

Shep

· #12 · Jul 10, 2011

Tip:Wrap some masking tape around the outer part of the G clamp.It helps stop it damaging the caliper outer when you compress the piston in.Also do not compress too far in otherwise it makes it near impossible to get the Dust boot clamp ring back on

.

HTH

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Blue Fox

· #13 · Jul 10, 2011

The outer O rings are actually just a dust seal. Important, but not critical. I doubt that you will find them by themselves, you will probably have to get the complete kit.

Make sure that you clean ALL the crud out of the O ring groove in the caliper. A good, square cross section in this groove helps to retract the pistons from the pads. Before you attempt to slip the pistons back in, lube them with brake fluid to make the job easier. I have not had to resort to a clamp to slide clean pistons back in. If they are aligned correctly, you should be able to push them in with your thumbs.

bandit

· #14 · Jul 10, 2011

MechaJubei said:
Well thanks to everyone's advice I did get the other piston out and cleaned the caliper. Hoorah! So now I need just two of the outer O-Rings the go into the bores. The ineer O-Rings are in great shape for some reason though. Is there any place to get just those outter O-Rings or do I need to buy a whole rebuild kit just to get them?

I've got a pair of replacement organic brake pads on the way but still don't know where to get a braided steel brake cable for the GL500 at. Any suggestions?

while the piston is out,buy the seals as a pair,seal inner and protector[dust seal].what if the inner seal fails a month down the line?you,l shed a tear.

they do not cost a lot.

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ramprat06

· #15 · Jul 10, 2011

http://ofapars-.webs.com/twinpots.htm This link is a nice write up on a brake rebuild.

Stainless Steel Brake Lines - U.S. Source

JDA Enterprises http://www.jdaent.com/

Email ([email protected]) or Call (530-365-8400) Craig Raudman

Craig has templates for almost all of the CX/GL models, so just mention our forum.

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MechaJubei

Discussion Starter · #16 · Jul 10, 2011

Just wanted to thank everyone again for all the help. I used the G-Clamp and about a billion times bleeding the line and got both pistons out. They weren't in too bad of shape so cleaned em' up and am now just waiting for the pads. Thanks guys, and look forward to many more simple solution questions from me, haha!

Just to wrap this up with one more dumb question to close out the thread...

How important are those dust rings? It looks like maybe someone rebuilt the caliper once because all the other rubber rings are in excellent condition. Do I REALLY need them? I can think of other things for the bike (like a braided brake cable) I'd rather spend the $30-$40 on instead of a rebuilt kit just to get those dust rings.....

bandit

· #17 · Jul 11, 2011

MechaJubei said:
Just wanted to thank everyone again for all the help. I used the G-Clamp and about a billion times bleeding the line and got both pistons out. They weren't in too bad of shape so cleaned em' up and am now just waiting for the pads. Thanks guys, and look forward to many more simple solution questions from me, haha!

Just to wrap this up with one more dumb question to close out the thread...

How important are those dust rings? It looks like maybe someone rebuilt the caliper once because all the other rubber rings are in excellent condition. Do I REALLY need them? I can think of other things for the bike (like a braided brake cable) I'd rather spend the $30-$40 on instead of a rebuilt kit just to get those dust rings.....

odd.

just rebuilt sunflowers,the pack contained both seals and was 5 ukp,what is that maybe 7 bucks

..http://www.wemoto.com/parts/brake_caliper_seal_kit/page6_10/

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MechaJubei

Discussion Starter · #18 · Jul 12, 2011

Well damn Bandit, the cheapeast one I found on eBay was $24.95 plus shipping. I wonder if that place you linked to ships to the US...I'll find out. Which size did you get?

bandit

· #19 · Jul 12, 2011

MechaJubei said:
Well damn Bandit, the cheapeast one I found on eBay was $24.95 plus shipping. I wonder if that place you linked to ships to the US...I'll find out. Which size did you get?

great company,good reputation.will ship anywhere.good prices.

as far as size goes,i had an issue.so ended up matching up to the piston size.

hth

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DanCX500

· #20 · Jul 12, 2011

MechaJubei said:
Just wanted to thank everyone again for all the help. I used the G-Clamp and about a billion times bleeding the line and got both pistons out. They weren't in too bad of shape so cleaned em' up and am now just waiting for the pads. Thanks guys, and look forward to many more simple solution questions from me, haha!

Just to wrap this up with one more dumb question to close out the thread...

How important are those dust rings? It looks like maybe someone rebuilt the caliper once because all the other rubber rings are in excellent condition. Do I REALLY need them? I can think of other things for the bike (like a braided brake cable) I'd rather spend the $30-$40 on instead of a rebuilt kit just to get those dust rings.....

Great job on getting the pistons out of the caliper! I know those can be a bugger at times!

I just wanted to point out a little something here. I see you are calling the item that goes fromt the master cylinder to the caliper a 'cable'. This is a hose.......this might help you out down the road.

Another note....I see that you used WD40 to get the pistons out. This in it's self isn't bad and probably helped a lot. However, you did mention reusing the piston seals and I wouldn't do this because the WD40 may have weakened the rubber.....

The dust boots on the outside of each piston will help keep your caliper woking trouble free for years to come. They keep road grime and such out.

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