Rear brake pedal right down "Excessive travel"

[GrinningGSer]

As per title , my rear brake pedal goes right down , with very minimal, usually no braking effect. Its happened four times now (One was an MOT failure "Excessive travel ")
(I suspect rear master cylinder failure, but hey, I'm an amateur spanner)
1200GSA. No fluid loss whatsoever ! Always fixed by bleeding both brakes and ABS unit (GS911)
1000 miles later, excessive travel issue starts again
So the bike goes into dealer, who understandably wishes to do their own documented bleed .
HOWEVER , I'm today told that they've "done a software update to give me more pressure "
Is there any way, whatsoever, that software can fix my recurring problem ?
They know that I'm stupid.
Edit : many threads on this similar issue

 

[Bigcats]

Funnily enough mine has just gone in for its MOT and was picked up for having 'excessive travel' on the rear brake (which I must admit was soft but to me bikes are known to have poor back brakes)

£27 later after they bled it and all is good so time will tell

But potentially it could be because its linked to the front brake that is why it goes over time (as the rear pad wears as well)

 

[GB.]

For some reason the LC rear brake seems to need regular bleeding. I also purge it with the gs911 tool, that makes the pedal much firmer.

 

[TIJ650]

This is very common with the linked brakes - especially (like me) if you seldom press rear pedal. It’s easily fixed with a rear brake bleed. I’ve been told by Motorrad to press rear pedal more often, but I opted for the Stahlbus speed bleeder and GS911 for the ABS bleed.
It’s a common fault that the Nazi’s will never admit to


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[Victor c]

There is a technical bulletin for this https://www.tsbsearch.com/BMW-Motorcycle/SIB-34-01-21

 

[GrinningGSer]

Intertesting Victor C, not that I understand much of that technical bulletin : It looks as though there are indeed software pressure set points

 

[Victor c]

Intertesting Victor C, not that I understand much of that technical bulletin : It looks as though there are indeed software pressure set points

My 2016 GS suffered with it, but my 2 subsequent GSAs have not.

 

[TIJ650]

There is a technical bulletin for this https://www.tsbsearch.com/BMW-Motorcycle/SIB-34-01-21

It would seem BMW are aware of this glitch and should repair inside or out the warranty period……….or even as a recall.
I mostly only use the front brake lever anyway (since they’re linked) but have to perform the abs/ rear brake bleed before MOT every 2nd year. Maybe worth taking the bike to Motorrad for MOT and showing them bulletin if any hassle with passing


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[GrinningGSer]

Well, 100 miles since I posted this problem (1200 WC GSA 2014) and after receiving a dealer brake bleed (against my wishes, but understand their need), and after having some mysterious sort of software pressure alteration ...... my rear pedal is now down to the bottom stop again. Bike going back in January . Can anyone explain the mechanics of linked brakes i.e. where decisions are made and how ?
p.s. Dealer commented "We don't see many of these bikes"

 

[TIJ650]

Well, 100 miles since I posted this problem (1200 WC GSA 2014) and after receiving a dealer brake bleed (against my wishes, but understand their need), and after having some mysterious sort of software pressure alteration ...... my rear pedal is now down to the bottom stop again. Bike going back in January . Can anyone explain the mechanics of linked brakes i.e. where decisions are made and how ?
p.s. Dealer commented "We don't see many of these bikes"

I don’t think there’s a permanent cure if your bike has the affliction, just a work around. Like I said, speed bleeder from Santa might be the ticket
PS. Regarding comments - they always say this!


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[Digger john]

One trick i. Was told and it works is secure a heavy weight on the rear brake pedal ,and leave on fo 24 hours it has to be heavy enough to keep the brake depresed

 

[GrinningGSer]

One trick i. Was told and it works is secure a heavy weight on the rear brake pedal ,and leave on fo 24 hours it has to be heavy enough to keep the brake depresed

Yes indeed and I was originally advised to do that myself , “after three of four bleeds “ by the dealer , and I did with superb hard results , but then went downhill again a week later . After which , dealer had a go and now 100 miles later that job has failed .
(It doesn’t need much weight overnight to achieve a good pedal )

 

[Fullchat]

Yes indeed and I was originally advised to do that myself , “after three of four bleeds “ by the dealer , and I did with superb hard results , but then went downhill again a week later . After which , dealer had a go and now 100 miles later that job has failed .
(It doesn’t need much weight overnight to achieve a good pedal )

I did this and then bled. A few bubbles came out of the bleed nipple. A firmer pedal was restored for a while.

 

[GrinningGSer]

Sorry for delay but my excessive travel brake pedal is hopefully now fixed ;
Summary ;
Multiple bleeds only temporary fix
Dealer needed to do their own bleed ; failed yet again after only 100 miles
Dealer not sure what to do so needed advice from BMW Technical support who advised ‘Replace ABS pump’
£1,400 ABS pump + Labour , involving tank removal , re fill and bleed + VAT
Must have been ‘north of ‘ £2k . All covered by my ongoing BMW extended warranty .
My 1200GSA is now known as ‘Trigger’s Broom’, as a result of all the multitude of very expensive parts fitted ( under extended warranty) in the last 12 months and these repairs costs have equalled all of the ‘peace of mind’ premiums that I’ve paid in the last seven years.