Spongy Front Brakes

[Stevewils]

Hi All,

Unfortunately this is a self inflicted injury!

I replaced the brake fluid in the front lines but let the reservoir get too low and now I have some air in the system.
I have bled each caliper several times, and also bled the valve on top of the handlebars several times.
All in all I have put over 1 litre of brake fluid through the brake lines in an attempt to get rid of the air.
I've left it overnight with the brake lever tied back

However I still have spongy brakes and you can pull the brake lever almost as far back as the handlebar.
I have done brakes on many other models and never had a problem.

Am I missing something obvious?
Could anything else cause this?
Is it because of the ABS system?

If anyone has any ideas I would gladly listen.

TIA,

Steve.

 

[alex]

Sounds like the ABS pump needs bleeding. Someone mechanical will be along shortly.

 

[Gaffa22]

Sounds like you have tried most things, and certainly sounds like air in the ABS system
do you have access to a vacuum bleeder ?

The lever tied back overnight usually cures it, had the same problem with my blackbird and that method cured most of it
it then improved over the next couple of days till back to normal.

 

[Stevewils]

Are the front and rear brake lines inside the ABS pump connected? ie would bleeding the rear brakes make any difference?

 

[Gaffa22]

Are the front and rear brake lines inside the ABS pump connected? ie would bleeding the rear brakes make any difference?

Dont have an S1000RR yet, but I believe the brakes are linked so yes bleeding back brake as well might help if the OP has not already done so

 

[DrIoannis]

Air in the system. You will need to go to a BMW service and bleed the ABS pump there or buy a GS911 to do the job.

 

[Stevewils]

Air in the system. You will need to go to a BMW service and bleed the ABS pump there or buy a GS911 to do the job.

The bike is on a Sorn as I currently only use it on the track, so difficult for me to get it to a dealer, hence trying to fix it myself.

Curious to know why you would need a diagnostic tool to bleed the ABS pump? do you have a procedure for this?

 

[mike g]

there is a bleed option on screen when you plug the 911 in - not sure what it does to the pump as haven't used it yet.
I did bleed the back brake through when I first got the bike without using it and it seemed ok, but then again back brake is awful!
Not entirely happy with the fronts on mine (was changed by bmw a while ago, so will probably have a go soon, and post results, (you may have sorted it by then!)

 

[JimmyMac]

Steve I have never bled the brakes on my HP4 but have done it numerous times on my GS's which have ABS also. I always drain the system entirely front and back, draining from the calliper bleed nipples.
Once I am sure it is totally empty I replace the sponge in the reservoir. Then I reverse fill them via the front and rear nipples until the fluid is pushed back through the system filling the ABS pump back up as it goes and when it is at the correct level in both reservoirs I close the nipples, leave the lids loose and put a cable tie round the front lever and hold the rear pedal down overnight.
Next day remove ties and close lids, have done this on many occasions and always been fine. You need a big syringe to do it but I buy them off eBay for a couple of quid.

Don't know if this helps but hope so, I have a GS911 but have never used the bleed function, to be honest I have never even seen it.

JimmyMac

 

[stuartb]

I bled my HP4 brakes with no problems, completely changed my fluid...

 

[Gaffa22]

should not be a problem if you dont get any air in the system, and usually you can bleed the air out if you do