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I've Had it!

  • Thread starter Thread starter Burk Ferden
  • Start date Start date
B

Burk Ferden

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I rebuilt the front master cylinder on my 1980 GS 850 GT and the thing will not prime. I rebuilt the calipers and even installed new stainless lines so there are no clogs or anything and when I pump it won't prime. I even tried pulling the leave back and letting it sit over night with the bleeders open hoping to get it to fill and nothing has left the reservoir. I tried cracking open the banjo fitting at the cylinder. I removed the reservoir and made sure the 2 small holes are cleared and NOTHING WORKS. I was considering getting a new front master cylinder but I am afraid of having the same problem. I honestly don't get what the trick is. Hopefully its something that I am doing (or not doing) thats one of those, OH well Duh, moments. Here's hoping anyone can help.

Thanks!
Justin
 
Have you bled the master cylinder first?

Take out the banjo bolt, stick your finger over the hole and pull in the lever. Air should squirt out past your finger (you will have to slightly release the pressure on your finger to 'allow' the air out). Release the lever without allowing any air to get back in past your finger. Pump the lever until only brake fluid squirts out (have plenty of rags thrown over the bike). Refit the brake hose and banjo bolt and try bleeding it again.
 
And just double checking - do you have two seals on the master cylinder piston? Both seals should have their wider ends facing towards the spring at the end of the piston.
 
I'll give that a shot. I've really been trying everything, and for a long period of time. It really is taking forever. and its been driving me crazy. The rear brake went easy. The front system makes me want to rip the brake lines off and hang myself from them.
 
Pennsylvania, outside Allentown. I got a great guide from BassCliff. His site was a huge help, he had the suzuki shop manual. With the exploded view in there I was able to verify I have the cylinder assembled correctly. If anyone wants to come out, we have some great rides in the area for both easy street and adventure sport rides.

Justin
 
On some bikes you just seem to get too much air in the system to start bleeding. Here's my trick when that happens:

Disconnect the banjo from the master cylinder and pump the brake a few times with your thumb over the fluid hole (CARE - brake fluid squirts out under pressure as a spray so cover everything).

Then connect up the top hose, first section only. repeat the same (but pinch the banjo between thumb and finger).

Then connect the splitter and bottom hoses and repeat.

Then connect the bottom hoses to the calipers and finish bleeding properly.

Bleeding a section at a time speeds the whole thing up and you know you're getting somewhere each time a section is full.
 
Wire Wheel Katman said:
Have you bled the master cylinder first?

Take out the banjo bolt, stick your finger over the hole and pull in the lever. Air should squirt out past your finger (you will have to slightly release the pressure on your finger to 'allow' the air out). Release the lever without allowing any air to get back in past your finger. Pump the lever until only brake fluid squirts out (have plenty of rags thrown over the bike). Refit the brake hose and banjo bolt and try bleeding it again.
Click to expand...
This method worked for me on my Rear master.really well. You have to get fluid in there, and it may even help to PUT a lil bit in there to assist in pushing the air out.
 
Put a hose on the caliper bleeder and suck on it with your mouth. The vacuum will draw fluid down out of the reservior and prime the master.
 
Use a vacuum pump on the caliper nipple. The job will be done in 5 mins.
 
Take the calipers off but leave them connected to the master cylinder, shim between the pads & hold them above the height of the master then bleed as normal till you get some pressure

if this fails tie the lever back over night with the calipers up & the bleeds open & try again in the morning

make sure you are bleeding in the corect manner & be patient :-D
 
You have had so many replies, but here is what I have done in a similar situation. The front master cylinder is above the pipes and calipers, thus the air bubble or airlock at the top makes it difficult for the M/C to prime itself.

Just undo the banjo bolt and fit a piece of clear plastic pipe in the hole in the M/C (make sure it is tight, maybe use an old banjo bolt) Now give it a nice long loop upwards and pointing back into the M/C with the cover off.
Pour a some brakefluid in the pipe and let it run to the banjo connection. Pump carerfully and air should start moving through the brake fluid in the pipe. Once all air is gone and each pump pushes out clean brake fluid, connect up your brakeline and bleed in the normal way.
 
Has anyone tried injecting brake fluid from the caliper up to the master cylinder? I've seen this procedure used on bicycle disc brakes with high success. Basically you get a big syringe full of brake fluid, connect to the open bleeder nipple on the caliper, and swuirt the fluid in from the botom of the system to the top, pushing all the air out as it rises. Leave the master cylinder top off and watch the level rise. Once you're full to the brim you should be done....
 
Smokinapankake said:
Has anyone tried injecting brake fluid from the caliper up to the master cylinder? I've seen this procedure used on bicycle disc brakes with high success. Basically you get a big syringe full of brake fluid, connect to the open bleeder nipple on the caliper, and swuirt the fluid in from the botom of the system to the top, pushing all the air out as it rises. Leave the master cylinder top off and watch the level rise. Once you're full to the brim you should be done....
Click to expand...


I've done fluid changes on 5 different bikes that way and only on one was I unsuccessful.
 
I'm glad I'm not the only one having trouble bleeding the front brake on my GS. I'm gonnna try some of the tricks and tips here and see if I can get it. Thanks!
 
I have had this problem always.. pump like crazy and they just wont pump up.. I went to the auto parts store and bought a cheap power bleeder for cars for around 45 bucks. The clear line doesnt fit motorycle bleeder valves as cycle ones seem a bit smaller than cars.. So heres what you do.. get the power bleeder and just buy regular black vacuum hose that will fit snuggly on the bikes bleeders.. assemble and it works every time..
 
I had the same problem, I had to draw the break fluid from the bottom up with a vacuum pump. It would not cooperate the other way, and this was with new Russell SS lines, after everything was rebuilt, calipers and master cylinder.
 
I think I might have a similar problem? I have just rebuilt the MC completely, installed new SS brake lines, and opened the calipers and cleaned them. I've bled the system for at least 3 hours, and I get a stream of fluid without air now. I am 99% sure that the two holes in the MC are unclogged and clear. But it seems like the calipers aren't fully "retracting"? I can still push the bike, but it seems like they are rubbing some. I haven't really riden it yet, so is this normal? (I hope so, brakes are so annoying to work with)

Thanks
Kev

P.S. Burk I live in downingtown. It's good to hear someone kinda close is one these forums.
 
coolksprt said:
I think I might have a similar problem? I have just rebuilt the MC completely, installed new SS brake lines, and opened the calipers and cleaned them. I've bled the system for at least 3 hours, and I get a stream of fluid without air now. I am 99% sure that the two holes in the MC are unclogged and clear. But it seems like the calipers aren't fully "retracting"? I can still push the bike, but it seems like they are rubbing some. I haven't really riden it yet, so is this normal? (I hope so, brakes are so annoying to work with)

Thanks
Kev

P.S. Burk I live in downingtown. It's good to hear someone kinda close is one these forums.
Click to expand...

It's normal for the pads to ever so slightly kiss the rotor but if there is any noticeable drag, something is wrong.
 
Get a Mityvac. I believe they are around $20.
I "believe" you can make it also push fluid from the bottom with this tool if you're really in trouble.
It's great for not only brakes, but also for fork fluid. When you do your forks you put in too much fluid and then mark your tube on your Mityvac for 6" and suck away the excess. Very quick and more accurate than trying to match exact ccs on each side.
 
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