FJR Master Brake and Clutch cylinder questions

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ah rubber boot ok. i don't think its there, but either way if it was plastic it migh thelp but def not rubber.

The rubber boot is attached to the body of the master cylinder. All it does is keep dirt from getting in and damaging the piston. The piston is what does the hydraulic work. The pin is what acutates the piston. The pin sits directly in the "cup" built into the brake lever. It passes through the rubber boot (the part you thought was the "cap") and goes into the bore and pushes the piston. The rubber has no effect on lever feel, its just a barrier for debris.

 

[gamorg02]

The rubber boot is attached to the body of the master cylinder. All it does is keep dirt from getting in and damaging the piston. The piston is what does the hydraulic work. The pin is what acutates the piston. The pin sits directly in the "cup" built into the brake lever. It passes through the rubber boot (the part you thought was the "cap") and goes into the bore and pushes the piston. The rubber has no effect on lever feel, its just a barrier for debris.

oh oh ok. so it doesn't sit in the 'cup'. its like halfway down the piston.

 

[RagingMain]

ah rubber boot ok. i don't think its there, but either way if it was plastic it migh thelp but def not rubber.

i'll try re-bleeding and reporting back. speed bleeders make that an easy job. maybe try bleeding both calipers at the same time. also could try pushing the pistons back in like u mentioned mike. that way the calipers re-bed sort of.



which year you running for your masters fargo?

Ahh **** you would have to ask that Garrett. I want to say the 2003 off the top of my head, which ever ones they are the Brake master didnt have a hole for the mirrors, had to drill and tap.

 

[[email protected]]

oh oh ok. so it doesn't sit in the 'cup'. its like halfway down the piston.

Correct. It does not sit in the cup of the lever. It is pressed into the body of the master. Then you insert the pin. The pin sits between the lever and the piston. Yes, it is halfway down the pin. If you look at the parts diagram you can see some ridges in the pin. These ridges help to locate the pin in the rubber boot and help form a tight seal against the rubber.

Your issues sound opposite of what *should* happen. If you go smaller in bore diameter you get a softer lever, more lever travel to move the fluid, less fluid volume moved, more fluid pressure.

If you go larger (which you did by .005" so in effect, not much at all) you typically get a firmer lever, less lever travel to move the the fluid, more fluid volume, less fluid pressure.

Doesn't really make sense that the lever would take more travel and feel softer if the MC bore is larger by such a small amount. I would lean toward air in the system. Could be residual air from having a totally empty MC to start with, could be some sneaking in past the threads of the speed bleeders during the bleeding operation ( i have heard some people mention this), could be some air leaking in past the seals in either the calipers, or MC (doubtful but possible, they typically last a LONG time).

If you have a might vac, give that a shot, if not, and your using the speed bleeders try putting a little bit of grease or some sealant on the threads of them.

 

[gamorg02]

Ahh **** you would have to ask that Garrett. I want to say the 2003 off the top of my head, which ever ones they are the Brake master didnt have a hole for the mirrors, had to drill and tap.

hmm no tsure. my '05 ABS ones are not drilled in the boss

Correct. It does not sit in the cup of the lever. It is pressed into the body of the master. Then you insert the pin. The pin sits between the lever and the piston. Yes, it is halfway down the pin. If you look at the parts diagram you can see some ridges in the pin. These ridges help to locate the pin in the rubber boot and help form a tight seal against the rubber.

Your issues sound opposite of what *should* happen. If you go smaller in bore diameter you get a softer lever, more lever travel to move the fluid, less fluid volume moved, more fluid pressure.

If you go larger (which you did by .005" so in effect, not much at all) you typically get a firmer lever, less lever travel to move the the fluid, more fluid volume, less fluid pressure.

Doesn't really make sense that the lever would take more travel and feel softer if the MC bore is larger by such a small amount. I would lean toward air in the system. Could be residual air from having a totally empty MC to start with, could be some sneaking in past the threads of the speed bleeders during the bleeding operation ( i have heard some people mention this), could be some air leaking in past the seals in either the calipers, or MC (doubtful but possible, they typically last a LONG time).

If you have a might vac, give that a shot, if not, and your using the speed bleeders try putting a little bit of grease or some sealant on the threads of them.

i used a mityvac to pull the initial fluid thru to the calipers on the dry line then used the speed bleeders as it displaces a lot more fluid than the mityvac does.

i can definitely try again. no air getting thru speedbleeders as they have a sealing compound on them that was one of the reason i wanted them.

i am 100% with you on the bore size shouldn't matter. altho with my old M/C and lever (thinking it might have had to do with the lever) the more fluid i had in the m/c the less 'free play' there was in the lever. also changed with temperature. one of the reasons I wanted to go with SS lines.

 

[gamorg02]

finally got to mess with this. i re-bleed a bunch and it helped a bit. still not 'perfect' but may very well be OK. i heard a trick that you leave your brake lever depressed and it will allow air to come up out of the system if it is still in there, so left the brake lever depressed for a couple hours today and then overnight tonight. only problem is the pads are dragging now but i think that will clear once the tire gets to spin a bit. otherwise i have another whole set of problems..

anyways, the pads are still kind of sticking but here is the current free play which is noticable and then the pull

http://www.youtube.com/watch?v=vQuKgPhwy-Q

let me know your guys thoughts. still not great in my mind but better. this is on the exact middle of the adjustment of the lever.

 

[Nicki66]

Garrett, when I changed my master a few months ago, I had similiar problems. I found that taking the handle of a screwdriver and tapping the brake line and working the air bubbles up into the master. Also "tapping of flicking" the brake lever. With the master cover off, you can see the very tiny bubbles coming out.
I was still not impressed with the lever action and with advice from here, I was given the suggestion to attach a small hose to each bleeder and put them into a container higher them the master. Bleed both sides normally to put fluid into the hoses (1-2 ft) and them open both bleeders and pump the lever. this gives the fluid a chance to move into and expel the trapped air.

 

[gamorg02]

Garrett, when I changed my master a few months ago, I had similiar problems. I found that taking the handle of a screwdriver and tapping the brake line and working the air bubbles up into the master. Also "tapping of flicking" the brake lever. With the master cover off, you can see the very tiny bubbles coming out.
I was still not impressed with the lever action and with advice from here, I was given the suggestion to attach a small hose to each bleeder and put them into a container higher them the master. Bleed both sides normally to put fluid into the hoses (1-2 ft) and them open both bleeders and pump the lever. this gives the fluid a chance to move into and expel the trapped air.

thanks for the heads up. i'll try that today. now any reason to do them at the same time? i've heard that as well. i have a mityvac and can work one at a time pretty easily as i even have some extra hose

 

[tugla]

garrett when i rebuilt my slave cly and then had to bleed, had tons of air, just kept working it, tapping it lightly watched tons of air bubbles comming up. lightly touched the lever and it did let more bubbles come up. took like a hour or more to get clutch feel in the lever. after i figured it was good, just for good measure i left the bleed screw open over night hose in container and seem to be good. havent started it yet but feels better then befor.

 

[gamorg02]

garrett when i rebuilt my slave cly and then had to bleed, had tons of air, just kept working it, tapping it lightly watched tons of air bubbles comming up. lightly touched the lever and it did let more bubbles come up. took like a hour or more to get clutch feel in the lever. after i figured it was good, just for good measure i left the bleed screw open over night hose in container and seem to be good. havent started it yet but feels better then befor.

no air bubbles came up yesterday after a while and when they did it was only 1 or 2 small ones. so i don't think its a massive air thing. i wonder if thats just the free play of the lever itself? does that look like too much play in the lever to u guys?

i might also try cleaning of my caliper pistons and pushing them all the way in and bleeding. less volume for air to hide in.

 

[veebooster]

You can try reverse bleeding.....from the brakes to the master via a syringe.
Just don't overflow the master.

Dale #2592

 

[tugla]

ya , reverse bleeding might be the a best solution here, you try hitting the calipers also with a rubber hammer, to help move the air bubbles out.

 

[gamorg02]

hey thanks everyone for help. feels a lot better now but only way to tell will be out on the road we'll see how she handles then.

still not 'perfect' but we'll see., there were no bubbles whatsoever coming out anymore so i think i cleared as much as i could.

 

[[email protected]]

Hopefully you get it all sorted Garrett.

For those of you who can bleed an empty system in your sleep, I have some stupid questions for you. I'm terrible with bleeding, I always have issues and make a mess. Anyone have some detailed pointers on their bleeding procedure and how they keep things clean. Specifically after replacing or rebuilding components?

Also, when doing the reverse bleed how are you pumping more than one syringe of fluid in there without having issues? I can see the first one, no problem. But, when you have to remove the syringe and fill it back up again how are you doing that without introducing air into the system?

 

[vmax2extreme]

I'm chiming in here too....I just replaced my stock lines with the galfer SS lines and need to bleed them soon too. What size syringe and where do you get them with tubing?

 

[gamorg02]

Hopefully you get it all sorted Garrett.

For those of you who can bleed an empty system in your sleep, I have some stupid questions for you. I'm terrible with bleeding, I always have issues and make a mess. Anyone have some detailed pointers on their bleeding procedure and how they keep things clean. Specifically after replacing or rebuilding components?

Also, when doing the reverse bleed how are you pumping more than one syringe of fluid in there without having issues? I can see the first one, no problem. But, when you have to remove the syringe and fill it back up again how are you doing that without introducing air into the system?

great question. what if you keep the tubing attached and before it goes empty leave the tube mostly full right? close the valve, unattach the syringe and fill it back up. the tiny bit of air in the tube then once you attach the syringe should bubble up to the top of the syringe? then open the valve and push in again?

I'm chiming in here too....I just replaced my stock lines with the galfer SS lines and need to bleed them soon too. What size syringe and where do you get them with tubing?

any auto parts store. mityvac will work as well.

 

[vmax2extreme]

I do have a mighty vac. I will have to play with that then.

Thanks again,

Mike

 

[gamorg02]

I do have a mighty vac. I will have to play with that then.

Thanks again,

Mike

use ksnicks method and get some like 3' tubing so that you can hold the mityvac higher than the master cylinder so it is easier for it to pull air out.

 

[vmax2extreme]

Do you have a link to ksnicks method on here?

 

[gamorg02]

post #27 in this thread.