front brake dillema

[Ed500]

Well I was going to try and get some riding practice this morning when I noticed that the front brake  has  barely any stopping power. The break handle touches the throttle handle all the way and theres very little stopping power at lower speeds. I bled the lines and replaced it with clear liquid again and that didnt solve the problem. from what I can tell, the rotor doesn't seem to be bent and the pads still look very good (deep ridges), it bends the rotor slightly as it grabs the rotor . I've tried the search feature but didn't have any luck. any words of wisdom?
thanks

Ed

[drincruz]

wow even after you bled the breaks still having an issue? and i assume, that proper brake fluid was used?

when you were troubleshooting, did you take the break caliper off? when i do, i usually have to pump the break lever a few good times til i get it back to the correct tension.

not sure. i'm sure someone will ring in with more feedback.

cheers,
~drin

[Dr.Sparkie]

, it bends the rotor slightly as it grabs the rotor . I've tried the search feature but didn't have any luck. any words of wisdom?

pull the caliper off and unseize stuff. I think the factory brake is dual opposed piston (but i dont know, ive never owned one) and it may be that one of your pistons is stuck, therefore you're only brake on half the front brake, and its trying desperatly to warp your super expensive front rotor because the transverse force isnt balanced.

[Ed500]

wow even after you bled the breaks still having an issue? and i assume, that proper brake fluid was used?

when you were troubleshooting, did you take the break caliper off? when i do, i usually have to pump the break lever a few good times til i get it back to the correct tension.

not sure. i'm sure someone will ring in with more feedback.

cheers,
~drin

no sir, I did not take the caliper of.

[Ed500]

, it bends the rotor slightly as it grabs the rotor . I've tried the search feature but didn't have any luck. any words of wisdom?

pull the caliper off and unseize stuff. I think the factory brake is dual opposed piston (but i dont know, ive never owned one) and it may be that one of your pistons is stuck, therefore you're only brake on half the front brake, and its trying desperatly to warp your super expensive front rotor because the transverse force isnt balanced.

what do you mean by "unseize stuff"? the caliper mig be at fault because, and I don't know if this is normal, but when I squeeze the front brake and let off, I can hear a double click comming from the caliper area.

tanks for the info.

[intergalactic]

Sounds like air in the lines to me.

Your fluid might have been low, then you bled it, then you topped up. Which moved air down to the caliper.

Just a guess, but that is easy to do.

Well I was going to try and get some riding practice this morning when I noticed that the front brake  has  barely any stopping power. The break handle touches the throttle handle all the way and theres very little stopping power at lower speeds. I bled the lines and replaced it with clear liquid again and that didnt solve the problem. from what I can tell, the rotor doesn't seem to be bent and the pads still look very good (deep ridges), it bends the rotor slightly as it grabs the rotor . I've tried the search feature but didn't have any luck. any words of wisdom?
thanks

Ed

[Dr.Sparkie]

if the rotor is bending, then its not being clamped, its being pushed. this would occur in a dual opposed piston system if one of the pistons was seized. it occurrs commonly on car brakes with are floating caliper single piston systems, and its a results of the slider pins becoming stuck in the caliper. if the gs uses slider pins, given them a good coat of high temp grease or anti-sieze, and make sure that both pistons move freely in and out of the caliper.

dont remove the caliper and then squeeze the brake lever, the pistons will pop out of the caliper and you will need to bleed the system. just push one piston in a little, and the other should pop out a little. then use two pairs of pliers to squeeze both pistons in to prove they move, inspect your front brakes and re-assemble.

[Dr.Sparkie]

and now i feel like a wanker cause i thought that the front brake was like the back brake (dual opposed piston)
but ron ayers fiche is telling me that its floating caliper
http://fiche.ronayers.com/Index.cfm/Module/Main/TypeID/26/Type/Motorcycle/MakeID/2/Make/Suzuki/YearID/30/Year/1989/ModelID/6312/Model/GS500E/GroupID/259233/Group/FRONT_CALIPER_1996

so lube those pins, and check the pistons too, though the pins are likely the culprit.

[Ed500]

thanks for the info fellas. I shall investigate further when I get off work. 

[gsJack]

Yes it's a floating caliper type with both pistons on the same side and it does sound like a sticking pin slider but it may not be just a case of lubing the pin sliders to fix, it may be a problem of the pin sliders having already been lubed with the wrong lube.  I was out of brake grease once and put a little cup grease on the pins when replacing pads and the grease caused the rubber bushing on the one end to swell up and bind the the slider pin.  Other pin works in the casting w/o a bushing.  My pads only lasted a couple thousand miles with that stuck caliper.  I've got a big can of brake grease now.   

More recently my brake lever got too close to the grip and I bled and bled it with no improvement until I just happened to notice someone readjusted my adjustable brake lever to the min #1 setting, I reset it to #4 and it was right back where it belonged.     Check your lever adjustment too, kids love to play with those things in mall parking lots, etc.

[bill14224]

I had my floating front caliper apart before this riding season and I don't see any way the caliper won't clamp the rotor on both sides at the same time unless the pins are sticking.  GSJack is on top of things once again.  Get that corrosion off the caliper pins and get some brake grease on them.  This would be consistent if my supposition is correct that the brakes worked OK before but you let it sit for a period of time then began riding again and encountered the problem.  The pins got rusty in the interim.

I'm going to guess you have two problems, corroded, un-greased caliper pins and a leaky seal, either a caliper piston and/or master cylinder seal.  You said your lever was going all the way to the grip before you serviced it.  That would indicate air in the lines or not enough fluid.  The only way that can happen is with a leaky caliper seal or worn M/C seal, assuming your banjos are tight and not leaking.

I know it's not always possible, but keeping your bike in a dry place will stop caliper pins and such from corroding.  I've known people who stored their bikes covered outside, the cover trapped moisture, and their bikes rusted anyway.  Gotta get it out of the weather.  Also riding it regularly generally keeps that stuff from happening too, so ride more!  

[Ed500]

I'd love to start riding it, but I've actually never ridden this bike before. I bought it a few weeks back (original owner dropped it on the right side) and just got done now fixing it and wanted to start practicing riding. when I just got it it was leaking at the bottom of the brake line, but that was fixed easily by tightening the bolt that holds the brake line to the caliper. Also, I don't see any leaking anywhere since I bled the lines a couple of weeks ago )the fluid level indicates no fluid loss as well.
thanks

Ed

[bill14224]

OK, Ed, that's good news.  In that case I'd clean and grease the caliper pins and bleed the brakes of any air that was let in by the loose banjo.  Good luck and have fun!

[Ed500]

there isn't a way to disassemble the master cylinder on this bike is there?   long story short; I've followed the steps you fellas gave me and it didn't help. so out of curiosity I disconnected the upper brake line and squeezed the break handle. guess what, there was barely any pressure, the liquid dripped rather than squirting. I couldn't find any bolts that held the construction together so I'm assuming I have to buy a new master cylinder/brake fluid container  

edit: just found the little washer looking clip that held the spring in place. the 2 round rubbers inside looked very spongy and soft which might have caused the low pressure. so is there like a rebuilt kit I can purchase or do I need to buy the whole master cylinder/front brake "box"?

[gsJack]

Hard to believe there's anything wrong with the master cylinder seals unless somebody put something in it like engine oil to screw it up.  Looked back to your first posts and that's a 05 GS500F that you converted to a naked bike and it only has 3700 miles on it.  Shouldn't have needed any brake work yet if milage is correct.  You can buy oem master cylinder parts seperately so it's not necessary to buy complete assembly which is about $113 at Ron Ayers or a piston,cup set for less than $20 to replace the seals.

http://fiche.ronayers.com/Index.cfm/Module/Main/TypeID/26/Type/Motorcycle/MakeID/2/Make/Suzuki/YearID/45/Year/2004/ModelID/6807/Model/GS500F/GroupID/290251/Group/FRONT_MASTER_CYLINDER_GS500FK4

I'm starting to think you have an air problem and haven't got it all bled out yet, you found a loose connection leaking fluid that you didn't mention in your first post.  If it's leaking fluid out it's sucking air back in.  Try putting your master cylinder back together and fill it and bleed it without connecting the line.  Just fill it and hold a finger over the outlet to act as a check valve and pump the lever slowly to see if you can expel air and build up pressure and start squarting pressurized fluid out past your finger.  Be sure to fill master cyl every few strokes so you don't suck air and have to start over.  If you get pressure you can't hold back with your finger the master cyl should be OK.

Then attach brake hose and bleed the line by opening the bleeder screw on the caliper and holding a finger over it lightly while stroking the lever until air is expelled and fluid comes out.  Be sure to close bleeder every few strokes and check master cyl fluid.  When you get fluid to the caliper you can finish bleeding in the conventional manner.  Build pressure, open bleeder, close bleeder, and repeat until you get only fluid without air and don't forget to keep checking the master cyl fluid level.

[Ed500]

the bottom screw of the brake line was the one that was leaking. that went away after I tightened it and there was no leaking anywhere. this being my first motorcycle I was inexperienced and didn't really know how hard/soft the brake handle was supposed to be. I was tinkering around and put a small rubber O ring in front of the middle rubber piece inside the master cylinder. re-connected everything and bled the lines and got the air out . after numerous pumps of the break handle the handle started to feel stiffer mid range. not safe enough to be ridden, but quite a bit stiffer then earlier. I was surprised as well that the master cylinder could be at fault since it's quite a new bike with not many miles, but thought that the previous owners accident might have contributed to the master cylinders break (when the bike fell it broke the end of the break handle so I had to replace it). sir, thank you for the links