Help - Braking problems with 05 1200GS

[Bikerbuk]

I'm new here so please be gentle.

I'm having problems with the front brake on my 05 plate GS. Every so often the front lever goes completely limp. It only happens when i'm feathering the brakes for example on approach to a roundabout behind queuing traffic. If I let the lever go and reapply the brake it works fine. Any time I need the brakes they are there and work fine its just when I apply the front brake very lightly, the lever comes all the way to the bar. I've had it into the local dealer who checked it on the diagnostics and everything is showing up fine. All pressures etc are perfect and it shows no faults what so ever. The servos are whining away and everything appears to be functioning as it should. I suspect it is something mechanical rather than electrical within the ABS system. All fluid levels are fine, pads are relatively new with plenty of wear left and there are no leaks. The brakes don't need bled and there's no air in the system. Yet every so often I get this problem. I can also induce this fault with the bike switched off which again leads me to believe its something mechanical. I'm new to the world of he GS and I love the bike, don't ask me why but I do. I'm very concerned that this turns out to be an expensive repair. Anyone ever heard of this before? All advice greatfully received.

 

[Spike]

Sorry I cannot help you on your problem but with brakes i donot fook about.
You say it only happens when feathering the brake, whats to say it will not happen when applying the brakes normally, I do not mean to concern you too much but if it was me I would not stop till I founfd the problem, it could be the difference between stopping and not.

spike

 

[Popell]

Sorry I cannot help you on your problem but with brakes i donot fook about.
You say it only happens when feathering the brake, whats to say it will not happen when applying the brakes normally, I do not mean to concern you too much but if it was me I would not stop till I founfd the problem, it could be the difference between stopping and not.

spike

+1 Sound advice, sounds worrying.

Would be interested to find out what it is when you find the solution as I have same bike and fore-warned is fore-armed

Best of luck find the problem

 

[billynomates]

A mate had a similair problem on his 1150ADV with the back brake BMW recon'nd it was the servo unit with astronomical quote to replace so he got Steptoe to remove it completely and return it to standard non ABS/Servo.

 

[Wapping]

the front lever goes completely limp.

I can also induce this fault with the bike switched off

Are you saying that when the bike is on its stand, ignition off, the front brake lever pulls right back to the bar grip, completely limply, with no resistance?

And that you can do this each and every time, at will?

When doing this, does the lever spring back into place when you release it? If not, what does the lever do when it returns to its original position? Or do you have to push it back?

 

[Bikerbuk]

Thanks for the replies so far guys. The bike is booked in again on Tuesday so i'll let you know whats happening.

Wapping - Yes thats exactly whats happening. With the bike switched off, on its stand, If I pull the lever slowly it comes right back to the bar with no pressure. If I apply it as per normal braking it works fine.

When it goes limp the lever is slow to return to normal position, very little spring action if you know what I mean. Otherwise its completely normal.

 

[Pukmeister]

It sounds to me like a problem with the master cylinder on the handlebar passing fluid internally past the seals: A firm grab forces the fluid hard enough, triggering the servo before the primary hydraulic circuit has a chance to lose pressure. The servo (secondary hydraulic circuit) then does the work for you.

If you grab the front brake and keep it pulled, do the brakes stay firm over time or do they slowly ease off ???

Did the dealers test the operation slowly, or did you just leave it with them ?

 

[Bikerbuk]

I left the bike with them and they found a fault with the brake light, fitted a new bulb and ran the diagnostics. Everything came out fine.

Thanks Pukmeister. If i grab the brakes they stay firm for as long as I can be bothered holding them, however I've tried the old cable tie overnight trick and they ease off after some time. The master cylinder theory sounds very possible. I spoke to a bike mechanic friend who also believes it to be fluid being passed internally so thats a great place to start - Thanks!

When i'm in on Tuesday i intend to speak to the Tech and show him the problem as he obviously just relied on the diagnostics last time.

 

[Bikerbuk]

It sounds to me like a problem with the master cylinder on the handlebar passing fluid internally past the seals: A firm grab forces the fluid hard enough, triggering the servo before the primary hydraulic circuit has a chance to lose pressure. The servo (secondary hydraulic circuit) then does the work for you.

If you grab the front brake and keep it pulled, do the brakes stay firm over time or do they slowly ease off ???

Did the dealers test the operation slowly, or did you just leave it with them ?

Just a quick update on the braking problem. I had it checked over again today and I asked to speak to the tech so I could show him the problem. He was able to see it for himself and his initial diagnosis confirms Pukmeisters suggestion that the seals are gone in the master cylinder. Unfortunately BMW don't list a master cylinder repair kit and BMW want £200 for a complete assembly. However, I've managed to source (with dealer assistance) a suitable replacement part for £105 which the dealer has offered to fit for free during the 18k service which it is booked in for on Thursday as they will be renewing the brake fluid anyway and it only takes 10 mins to fit. So here's hoping.

 

[Demongroover]

Unfortunately BMW don't list a master cylinder repair kit and BMW want £200 for a complete assembly. .

I was told by Pidcocks that they'll sell you a seal kit, but they won't replace them for you because of liability issues. Thus the big price tag, same with final drives. You can buy the bits but they won't repair them for you.
Personally speaking, I would get kit and replace myself.

 

[Pukmeister]

Personally speaking, I would get kit and replace myself.

So would I, for two reasons:

1) I would be able to tell if the old seals were shot, and know the new ones were installed properly for peace of mind/self-preservation.
2) The money I saved in DIY might be needed later to pay towards a new ABS Servo unit if that is fecked anyway.

 

[Deleted account 190920001]

So would I, for two reasons:

1) I would be able to tell if the old seals were shot, and know the new ones were installed properly for peace of mind/self-preservation.
2) The money I saved in DIY might be needed later to pay towards a new ABS Servo unit if that is fecked anyway.

Is a fair point, is there seals at the servo end as well? If there is then in theory it could be either end.

 

[Bikerbuk]

Thanks for all the replies and advice. Brakes now fixed and working perfect! The seals in the master cylinder were well shot!

 

[Pukmeister]

Thanks for all the replies and advice. Brakes now fixed and working perfect! The seals in the master cylinder were well shot!

Damn, I'm good.

Glad you're now sorted and your brakes are safe.

 

[Bikerbuk]

Damn, I'm good.

Glad you're now sorted and your brakes are safe.

Pukmeister ........... You D Man!