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brake woes


steveg

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just picked up a 2000 r1100rt and I had to  replace a bleeder on the front rt caliper. The one that was on there was a cylindrical looking thing with an allen in the middle that stripped out quickly ordered a standard bleeder from bmw in doing so I allowed all the fluid to leak out so when I got the new bleeder I bled all the air out of the abs unit and the 2 calipers several times . cant maintain pressure on the lever, it pumps up fine but when I close the bleeder and re apply the lever there's no pressure. have to pump several times to get a hard lever

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Someone a lot more mechanical than i will chime in soon. One thing I do know is if your RT still has the original rubber brake lines, they degrade from the inside out. You would be wise to go ahead and swap to stainless steel lines or you are chasing your tail. Expensive? Yes but it is your brakes. They are a good thing to have. 😳

 

 

https://galferusa.com/

 

 

https://spieglerusa.com/

 

 

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Michaelr11

You have air trapped in the line. If the line held pressure before you changed the bleeder, it’s probably not a problem with the master cylinder. Fill up a bleed bag with DOT4 brake fluid and connect it to the bleeder. Open the bleeder and push brake fluid into the caliper until the master cylinder starts to fill up with brake fluid..  You should have the air out.  Close everything and pump the lever so it is firm. Tie up the lever with some rubber bands and leave it squeezed like that overnight. In the morning remove the rubber bands and you should have a firm brake lever.

 

Yes, if you still have the original rubber brake hoses, replace them.

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szurszewski

Basically a baggie/IV bag type of thing that has a fitting to attach to bleeder or bleed port and allows you to push fluid “up” into the system from the caliper. Hopefully freeing the air from the system. 
 

Another idea is zip tie the brake lever to the grip overnight with the MC open/full. If you’re lucky this will allow air to migrate up. Probably won’t be much help if the air is caught up in the abs unit. 

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12 hours ago, steveg said:

just picked up a 2000 r1100rt and I had to  replace a bleeder on the front rt caliper. The one that was on there was a cylindrical looking thing with an allen in the middle that stripped out quickly ordered a standard bleeder from bmw in doing so I allowed all the fluid to leak out so when I got the new bleeder I bled all the air out of the abs unit and the 2 calipers several times . cant maintain pressure on the lever, it pumps up fine but when I close the bleeder and re apply the lever there's no pressure. have to pump several times to get a hard lever

Morning  steveg

 

 

Definitely try again to get more air out, sometimes pumping the lever until you get some pressure build then allowing the lever to snap back (don't slowly release but allow it to snap back)  will dislodge trapped air & allow the air to move up on the fluid & back into the master cylinder reservoir.   

 

It also helps to set the lever adjuster to max travel.

 

But, if you are sure that you have all the air out then don't discount a damaged master cylinder piston cup. (a damaged piston cup can act just like what you are seeing).  

 

On older motorcycles the master cylinder piston is usually only stroked so far for normal braking, that allows a build up of crud in the lower portion of the master cylinder bore.  

 

When you bled that system  you probably  stroked that master cylinder full travel so if there was a crud build up in the bore  that could have damage the piston cup. 

 

Not saying that is what you have,  just saying if you have all of the air out then that is a valid possibility. 

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thanks guys , I have the system pumped up and zip tied the lever, I'll see what that does, didnt think of the master cylinder cup being damaged because the system was fine before I touched it to do a fluid flush

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10 hours ago, dirtrider said:

Morning  steveg

 

 

Definitely try again to get more air out, sometimes pumping the lever until you get some pressure build then allowing the lever to snap back (don't slowly release but allow it to snap back)  will dislodge trapped air & allow the air to move up on the fluid & back into the master cylinder reservoir.   

 

It also helps to set the lever adjuster to max travel.

 

But, if you are sure that you have all the air out then don't discount a damaged master cylinder piston cup. (a damaged piston cup can act just like what you are seeing).  

 

On older motorcycles the master cylinder piston is usually only stroked so far for normal braking, that allows a build up of crud in the lower portion of the master cylinder bore.  

 

When you bled that system  you probably  stroked that master cylinder full travel so if there was a crud build up in the bore  that could have damage the piston cup. 

 

Not saying that is what you have,  just saying if you have all of the air out then that is a valid possibility. 

 

I had a similar situation, turned out I damaged the master cylinder piston/seals as you reference here.  Pulling the brake lever all the way in in attempts to bleed the circuit caused this damage.  Scored the cylinder bore, seals etc.

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Last fall, my front brake hose failed internally while at speed and I had to use the rear brake and the road shoulder to stop. Do replace the brake hoses if they are stock. 

 

I replaced mine with Galfer SS lines and did multiple brake bleeds to get strong resistance at the brake lever and foot pedal. Also, in between brake bleeds, I got the ABS to activate a few times independently on both the front and rear in order to have some fluid movement. I also did a complete caliper rebuild and master cylinder rebuild to get any gunk out from over the years.

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  • 2 weeks later...

I developed a leak on the front brake line so I ordered the galfer lineset when it comes I will start from scratch, also had a seized caliper in the front

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