Advice on R1200rt front brake problem

[majaem]

Hi.

Just been to see an R1200Rt on an 07 plate with 34000miles on the clock.
Bike starts fine and runs with no unusual noises so pleased on that score however when I pulled the front brake on it initially felt fine and I let go of the lever and pulled on again and the lever puller back until it touched the throttle. I let go, pulled it back on and I then felt pressure on it as normal which left a gap between lever and throttle. I let the brake lever go, pulled it back on and again the lever came all the way back to touch the throttle.

I can't see any leakage of fluid and the front brake master cylinder was full to the correct level in the eye sight circle.

Any ideas?

Mark

 

[steadysteve]

Problem

Sounds like air in the system.

No such problem on my RT that's for sale- brake fluid been changed by the main dealer. Just sayin like.....

 

[mrjim130]

Could be a faulty master cyl seal.

 

[chopper_harris]

07 was the transition year from the wretched servo brake module to the electrical assist ABS.

Do your hear a low pitched whining noise when you pull the brake lever with the ignition on ?
On the earlier servo system, the circuits from the master cylinders are connected to servo actuators, not directly to the calipers.

You have four circuits to bleed - you need to remove the tank covers and use a magic screw-in funnel to do it - not trivial


On post-07 bikes, it is good practice to operate the ABS pump via GS-911 whilst bleeding the brake circuits, to ensure that no residual air remains.

 

[busy builder]

Best is just ignore it and get on, it's just the way they live their lives, don't let it bother you.

 

[Myke Rocks]

Hi.

Just been to see an R1200Rt on an 07 plate with 34000miles on the clock.
Bike starts fine and runs with no unusual noises so pleased on that score however when I pulled the front brake on it initially felt fine and I let go of the lever and pulled on again and the lever puller back until it touched the throttle. I let go, pulled it back on and I then felt pressure on it as normal which left a gap between lever and throttle. I let the brake lever go, pulled it back on and again the lever came all the way back to touch the throttle.

I can't see any leakage of fluid and the front brake master cylinder was full to the correct level in the eye sight circle.

Any ideas?

Mark

You do not say how you pulled in the lever. If you give it a sudden, sharp pull and it does not sink, or maybe you pull it in gently and it does sink.
If the two scenarios above fit the bill, you have a seal passing fluid.
When you pull the lever in suddenly and hard, it expands the seals. A gentle pull, and the seals do not expand, so the lever goes all the way in.
If this is the case, you now have to determine where the leaking seal is. It is most likely in the handlebar Master cylinder, and the easiest way to prove it is to replace the seals.
Myke