brake troubles

[kurt12345]

ok i have a 81 gs1100ex with 25k on her and i just bought this bike and seen the brake fluid was full of gunk so i went cleaned out everything the front calipers, lines everything, then i decided to rebuild the master cylinder with the cup seal kit, then filled it with fluid pumped the fluid bleed the brakes all the stuff your post to do, know here is my problem i pump the brakes about 2 to 4 times and i get my pressure then wait a few seconds then all my prssure is gone, i went threw a bottle of brake fluid bleeding to make sure there was no air in it anywhere, iam thinking its a master cylinder problem but i dont know the brake worked ok before but yeah they feel much stronger when i pump up the pressure but i lose it all after a few seocnds then i half to pump them 2 or 4 more times to get my pressure back, what do you guys think??????

 

[Guest]

Maybe one of your brake copper washers are gone. Did you replace the o-ring on the bottom of the fluid reservoir? You don't see any leaks anywhere?
Pump up your brakes and put a clean piece of cardboard under the front of the bike and see if you have any drips. Wipe everything down first.

 

[SqDancerLynn1]

Are you sure you put the master back together properly ??

 

[kurt12345]

there is no leaks anywhere, its weird you pump the brakes up and get pressure and it will hold the the pressure if you keep your hand on it so its not loosing pressure under load but when you release it and let it sit for a few seconds and try to hit the brakes again yo half to pump it up again to get pressure.

 

[foghog]

Sounds like there may still be some air bubbles in the system.

 

[kurt12345]

ok so far ive took the master cyclinder apart twice to make sure i didnt put anything in wrong, ive bleed the brakes allot, did the the screw driver trick with the plunger and did the banjo bolt bleed thing up top, i have some braking power but i can mash the handle all the way and it just slows me down, i have no leeks theres no air in the system, iam still back to square one any advice?????

 

[kurt12345]

o and yes i did replace the o ring on the bottom of the resorvior and whats the brake copper washer thing chef1366 is talking about??

 

[tomo]

The copper washers should be fitted at all connections between the lines and the calipers, splitter and resevoir. At the ends of the lines, the metal connectors through which the bolt goes should have a copper washer each side. Its always best to replace them when working on brakes, you can get away with refitting the old ones, but for the sake of a few quid (sorry, dollars !) its not worth the risk. Hope you get it sorted, brakes can be frustrating thats for sure !.

 

[Suzuki mad]

Sound like air in the system. You didn't shake the bottle before using the fluid?

Do you have the anti-dive units fitted to the front of the fork leg?
If so these have a habit of being softer than normal units. They also are a s*d to blead as they have to be done in a set patern so the air in the link pipe between the units can be removed. Its higher than any of the bleed nipples.

Did you change piston seals with all this junk in the fluids?

I know your post doesn't say anything about touching these but where the brakes bolt to the stantions there are two similar bolts that the units slide on. Each has a small rubber boot covering up the bolt. These have a habit of seizing up not allowing the brakes to slide over into full contact with the disc's. Have a quick look to see if these are helping cause a problem.

If not it does still sound like air in the system.

Suzuki mad

1981 GS1000ET
1983 GS(X)1100ESD
2002 GSF1200K1

 

[madjack57754]

Absolutely, you have air trapped in the system. Try this, Crack the banjo bolt at the master until you can get fluid to push past the washers. then WITH the lever compressed Tighten the bolt. That takes care of air in the master.Be sure that you are not pumping the lever in and out with the bleeder open, as that just pulls air back into the system. Use the Pressure on lever, crack bleeder,tighten bleeder, release pressure on lever technique, Repeat multiple times. Also pay attention to where the bleeder screws are located. If they are not at the absolute highest spot in the caliper they can trap air. If all else fails use the system that a bike shop would use to bleed your brakes. Its called a Mightyvac. A hand operated pump system that will pull (or push) fluid from the caliper bleed screws to remove air. My local Checker has one that can be borrowed (with a large deposit).

 

[kurt12345]

there is no air in my system, ive went threw 2 bottles of fluid all ready, i know how to bleed brakes, did the banjo bolt thing at the master cylinder ive done everything everybody has said. no change

 

[GS850_Coug]

There IS air in your system, or you put the cup seal in backwards. Those are the ONLY options if they were good before and are not now after opening the system. No one is questioning whether you know how to do it. You came on here asking for ideas and these are the only possibilities for your problem. Hydraulics are not complicated. Apply pressure-if it holds, then all is good-if it doesn't hold, you have either #1: air in the system (air compresses, fluid does not) OR #2: fluid is leaking somewhere (externally-oil leak or internally-bad/incorrectly installed seals).

If you don't like the answer, you'll just have to live with the problem, because THERE IS NO OTHER POSSIBILITY.

 

[Suzuki mad]

The only other suggestion is that you are running original pipes and they have started to fail.

After that there are no more suggestions.

No one has questioned your ability as a mechanic or being able to sort your own machinery. Our advice/experience is personally gained by owning these types of machine's.

Did the brakes work OK before you stripped them down due to the gunk? Why did you decide to replace the master cylinder internals? Poor brake performance? What DOT grade brake fluid have you used, synthetic or normal?

Suzuki workshop manual for the GS(X)1100E-SZ including EX states:-
Insufficient brake power.
1/Leakage of brake fluid from hydraulic system.
2/Worn pads.
3/Oil adhesion on engaging surface of pads.
4/Worn disc.
5/Air entering into hydraulic system.

If you checked them you should have brakes.

Suzuki mad.

 

[denydog]

there is no air in my system, ive went threw 2 bottles of fluid all ready, i know how to bleed brakes, did the banjo bolt thing at the master cylinder ive done everything everybody has said. no change

I know your frustration. Friday I bled my brakes for the 6th time over the last two months, following the rebuilding of my front calipers. I just couldn't seem to get them as firm as they were after I rebuilt the master cyclinder.

Happy to report that I think I may have finally got it. Oh ya, I've been going through the quart size bottles of brake fluid, not those whimpy little pint bottles. Keep at it and good luck!

 

[kurt12345]

well so far i replaced my front pads that helped allot, bled one more the pedal is still a little mushy but know i can make the front tire chirp when iam slowing down so its ok i guess

 

[J_C]

I'm in a similar situation with mine right now. The only difference is that my master cylinder resevoir leaked a bit onto the Master cylinder body... so much for my pretty master cylinder paint job

To all those who offered such great advice, any chance these scenarios might be caused by old flexing brake lines?