Yet another brake system problem R1150GS 1999

nunesaf

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Ok guys, so here it goes my half an year saga. I am quite irritated now, but so very understandably.

Problem: brake lever very spongy

Done:
1) replaced the master cylinder piston
2) checked brake calipers pistons - all move really freely
3) changed the brake lines to braided steel
4) bleed the system 23,458 times (rougthly :spitfire:eek::D)
5) for the more fundamentalists (though I respect their knowledge... iykwm) bleed the abs controller 23,409 times only
6) used a vacuum pump
7) praid (oh Lord, if I praid)

Now, two notes:
1) I have a hedious grub screw
2) the only way to have the system acceptable is to leave it with a strap over 3 days or so


Need to things... please :thedummy
1) What am I missing?
2) HHHEEELLLPPPP!!!


Ta
 
I dont want to sound like im insulting you but it can only be air in the system. I have yet to find a fool proof method to bleed motorbike systems the problem I think lies with the small amount of fluid being force through the system is not enough to move all the air.
Have you tryed caliper pistons pushed right home and wedged so thay cant move then force fluid in through the bleed nipple so it back fills the master cylinder at least that way you would be forcing the air up hill ? Just a thought.
Good luck

If you lived closer I would say pop over and i would give it a go you are more than welcome if you fancy a ride out to Derbyshire.

Steve
 
Mech said:
I dont want to sound like im insulting you but it can only be air in the system. I have yet to find a fool proof method to bleed motorbike systems the problem I think lies with the small amount of fluid being force through the system is not enough to move all the air.
Have you tried caliper pistons pushed right home and wedged so they cant move then force fluid in through the bleed nipple so it back fills the master cylinder at least that way you would be forcing the air up hill ? Just a thought.
Good luck

If you lived closer I would say pop over and i would give it a go you are more than welcome if you fancy a ride out to Derbyshire.

Steve
Click to expand...


Hi Steve,

Thanks for your message and for volunteering!

I must have used over a liter of oil to bleed the ABS controller, and the same of the callipers. How can air still be there? Though I agree with you: there must be air in the system.

I forgot though to mention that I used a syringe to pump oil up through the system.

I did try to push the pads back and the result was a even spongier feeling. What could the cause be? Any lead to pursue?

Thanks again :thumb
 
I used a lucas easy bleed, it is a piece of clear hose with a rubber end that connects to the nipple,the other end has a one way pressure valve.


connect it,open bleed nipple,start pumping lever and new brake fluid is pumped thru without problems,when finished you just tighten the nipple and viola..........


however.............my GS has never had pin sharp front brakes,I cant pull the lever back to the bar but there is some give as you pull the brakes on.........


some folk seem to go for braided hoses but as long as it stops me I aint that fussy.
 
My mate has a compressor in his garage and whenever I want to bleed brakes/change fluid I go to his place and we suck the fluid through the system from the caliper end. It literally takes just a couple of minutes - he controls the suction and I keep the cylinder topped up - as soon as he sees nice new fluid appearing in the reservoir and no bubbles then that is job done.:D

Do you know anybody with a compressor? :thumb2
 
Boon said:
I used a lucas easy bleed, it is a piece of clear hose with a rubber end that connects to the nipple,the other end has a one way pressure valve.


connect it,open bleed nipple,start pumping lever and new brake fluid is pumped thru without problems,when finished you just tighten the nipple and viola..........


however.............my GS has never had pin sharp front brakes,I cant pull the lever back to the bar but there is some give as you pull the brakes on.........


some folk seem to go for braided hoses but as long as it stops me I aint that fussy.
Click to expand...

Hi Boon,
Thanks for that. And yes, I also done that too :o. I must have air trapped somewhere...

I also had the old rubber hoses but one month ago when leaving the ferry in Dover I have a hose split and drove up here to Leatherhead with no front brakes. I obviously changed to braided lines and was expecting a firm feeling. But oh well, the ABS controller must be the cause of this.

Thanks for your help :thumb2
 
Lord Snooty said:
My mate has a compressor in his garage and whenever I want to bleed brakes/change fluid I go to his place and we suck the fluid through the system from the caliper end. It literally takes just a couple of minutes - he controls the suction and I keep the cylinder topped up - as soon as he sees nice new fluid appearing in the reservoir and no bubbles then that is job done.:D

Do you know anybody with a compressor? :thumb2
Click to expand...

How does that work then, I thought that compressers blow and not suck :aidan
 
Lord Snooty said:
My mate has a compressor in his garage and whenever I want to bleed brakes/change fluid I go to his place and we suck the fluid through the system from the caliper end. It literally takes just a couple of minutes - he controls the suction and I keep the cylinder topped up - as soon as he sees nice new fluid appearing in the reservoir and no bubbles then that is job done.:D

Do you know anybody with a compressor? :thumb2
Click to expand...

Hello,

As a matter of fact, no I don't know anyone with a compressor :(.

But I guess I can do the same with my vacuum pump?

Oh well, I just might have to take her to the dealer. I feel the defeat weight already in my shoulders.

By the way, I want to replace the hideous grub screw - will the 1mmx10mm bleed nipple fit directly there?

Thanks guys!
 
nunesaf said:
Hello,
By the way, I want to replace the hideous grub screw - will the 1mmx10mm bleed nipple fit directly there?
Click to expand...

Yes you can remove that whole bollix of a thing from the calliper and change it to a normal bleed nipple the same as the other side

Did you manage to get the grub screw out and get the ball held down to bleed the right side calliper????

NOTE from memory there is a pink thread lock material on that grub screw housing so plenty of boiling water or a heat gun! to make sure it's softened up or risk damaging the calliper if you just haul it out!

If you clamp the hydraulic lines to each a calliper "One at a Time" does that change the feel of the brake?

Is there a dampness at the rubber boot at the mastercylinder? If so just replace the master cylinder piston AND the boot which they never bloody seem to send!

Getting rid of the fitting in the right calliper seems like a really good idea I don't know what BMW were doin when they fitted that!

I wouldn't go to the dealer just Yet! There's plenty more to do!
 
Hi Jaythro,

See my answers in line with your questions (thank you so much ;))

Jaythro said:
Yes you can remove that whole bollix of a thing from the calliper and change it to a normal bleed nipple the same as the other side

Did you manage to get the grub screw out and get the ball held down to bleed the right side calliper????
I used a different approach - I put a servicing bleeding nipple in the place of the grub screw and bleed it nornmally (though I suspect it is a potential source of air leak)


NOTE from memory there is a pink thread lock material on that grub screw housing so plenty of boiling water or a heat gun! to make sure it's softened up or risk damaging the calliper if you just haul it out!
Thanks for warning me! As I tightened it already because it was leaking (please don't ask why because I don't know :))

If you clamp the hydraulic lines to each a calliper "One at a Time" does that change the feel of the brake?
Sorry for the silly question, but can I clamp braided lines? For some emotional reason I feel reluctant to do so.

Is there a dampness at the rubber boot at the mastercylinder? If so just replace the master cylinder piston AND the boot which they never bloody seem to send!
I don't think so and I replaced 5 months ago the piston without much of improvement (if any).

Getting rid of the fitting in the right calliper seems like a really good idea I don't know what BMW were doin when they fitted that!
The reason why BMW used that thingy is because (so I heard... if any fundamentalist disagrees with this, please accept my apologies) they were filling the system up at the assembly line through there, minimising the bleeding time. Gosh, it must take them one hour to assemble the machine and 3 days to bleed that brake system!
I wouldn't go to the dealer just Yet! There's plenty more to do!
Click to expand...


Thanks :clap
 
Hi Ooops forgot about the braided lines, most definitely not a good idea to clamp them they don't like that!

If you had the rubber boyo's still on it would Identify if you had air trapped in one calliper or not
 
nunesaf said:
Will do sir :bow though I suspect I have been there :)
Click to expand...


if you think you've done everything else - then its the caliper piston seals that need changimg

they swell with age and grab the piston rather than letting it slide

this then pulls the pistons back too much - meaning more lever travel the next time
 
motomartin said:
if you think you've done everything else - then its the caliper piston seals that need changimg

they swell with age and grab the piston rather than letting it slide

this then pulls the pistons back too much - meaning more lever travel the next time
Click to expand...


I would agree with this one, had a similar problem with my sons bike and his girlfriends, both oldish and especially hers we could not get the brakes to work correctly, and that was the seals.
 
I think I bring good news :bounce1.

The brake lever is very firm now and it doesn't reach the handlebar anymore.

I left a strap around it over night after using the bleeding kit. I admit I let a lot of air coming in when using the kit and therefore I was there for ages, but probably by exercising the circuit with the pump, I managed to get rid of the air that trapped somewhere in the ABS modulator for a long time. When I finished the job, the oil was probably with small bubbles (as it has been quite agitated). I learnt that when things go really wrong with the bleeding, you need to wait a couple of hours so the oil stabilises.

I will go for a test ride tonight and if it remains stiff, I will guess I have the problem sorted. I will keep you posted and thanks for your support :thumb2
 
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