Rear brake servo failure

[Motocod]

Nik,

sorry to hear of a potential fault with the bike. Good luck with the 'thrash' idea.
It will be very bad luck to have a pump go at 10,000 miles- fingers crossed for you

Andy

Thanks Andy. Hoping it's not a serious issue - seem like abs pumps don't like sitting unused, and I'll be honest and say there was no way I was riding such a clean bike on salty roads... I'll look it all over tomorrow and see what I find.

Nik

[Motocod]

Well this afternoon I took out the rear wheel speed sensor and cleaned it, and replaced the final drive oil (it was a bit nasty). Sadly the problem persists.

Press the rear brake and the brake light comes on. But no servo whine. The Brake Failure and Warning "triangle" lights come on. Invariably, if I turn the ignition off and on again the problem goes away, then re-appears after a little while.

Starting to think it might be the ABS pump... Anyone else got any other ideas? I can't afford £1200 for a new pump, so if that's what it is I'll have no choice but the split the bike for spares, sadly.

Nik

[slparry]

Well this afternoon I took out the rear wheel speed sensor and cleaned it, and replaced the final drive oil (it was a bit nasty). Sadly the problem persists.

Press the rear brake and the brake light comes on. But no servo whine. The Brake Failure and Warning "triangle" lights come on. Invariably, if I turn the ignition off and on again the problem goes away, then re-appears after a little while.

Starting to think it might be the ABS pump... Anyone else got any other ideas? I can't afford £1200 for a new pump, so if that's what it is I'll have no choice but the split the bike for spares, sadly.

Nik

assuming it's the same pump as the K1200GT they can be repaired as it's just brushes sticking in holders inside the pump.

Peter (Herman) had Alan's fixed on his R1200R recently so could advise who did the work. There was a video on you tube that's now vanished that showed how to do the job but there are several pics etc here
http://www.i-bmw.com/showthread.php?t=41122

Ok they're for the K but it may be the same?

[herrman]

I did indeed have the pump on Alans bike repaired, Think it cost around £300 including shipping and taxes and a 5 yr warranty as against £1400 for a new unit from BMW (and only 1 yr warranty). I'll dig out all the details later and post them up.

Peter.

[herrman]

This is the company I used, Good service with a quick turnround. They don't yet rebuild all BMW ABS pumps but are working to do so. Much cheaper than a new unit and a 5 YR warranty.

http://modulemaster.com/rebuilds/

Peter.

[Motocod]

Thank you Peter, that's fantastic. Really appreciated.

I'll have to look at getting a definitive diagnosis on mine next...

Nik

[citizented]

Hi Nik

I have the same problem on my 2004 R1100S with 10000 miles. It had been garaged over winter with little use. I changed some brake pads recently and then started having problems with the rear brake circuit dropping out. It would sort itself out when switching the bike on and off but gradually got worse and worse. I replaced the brake fluids and they were a very dark colour indicating water and dirt I guess. the fluids had been used for a year and a half with quite a lot of wet weather riding. Replacing the fluids did not improve the problem and the servo motor is permanently inactive now. I suspect the servo motor and will probably have a look at the unit myself. A abs ecu diagnostics would be good, which either means taking the bike to bmw in a trailer (as it is in bits) or if anyone has a gs-911 diagnostics tool in the Bristol or Swindon area. Has anyone used the simple led readers to diagnose abs problems like you can do with the main motronic ecu? If I get it fixed I will change my brake fluids more often and also exercise the abs circuit occasionally.

Bye Ed

[Motocod]

Hi Ed,

Your problem sounds exactly the same as mine. If I remember correctly the brake fluid was changed about a year ago by the previous owner - I seem to recall he had it done before I bought the bike.

Seems weird because like you I've managed to make the problem go away by turning the ignition off and on again. It lasts for a few minutes at the most though. But clearly it's something electrical/electronic that's causing the system to think there's a problem and shut itself down. That's what I'm struggling to understand - what is it specifically that's making the system believe there's a fault (even though it can be rectified by turning the ignition off and on)? In my mind there's either some sort of sensor or electrical issue that's related to either the sevo operation or the operation of the ABS.

I need to get to the bottom of it, as I presently have a bike I can't use and can't trust. It's pretty frustrating.

Any more help or advice would be really appreciated. Unfortunately I just recently lost my job so can't afford to be throwing money at it...

Nik

[Motocod]

Just bumping this one up again... Does anyone else have any ideas?

[Motocod]

Hi people,

Not got anywhere with this - I've recently become unemployed, so can't justify the expense of trying to fix the fault. Now toying with selling the bike as-is with a price to reflect it, as I have neither the time or inclination to fix another faulty motorcycle (I bought this one to replace a pile of crap Multistrada that took up virtually every weekend with some kind of work needing doing).

Really thoroughly fed up that this has happened, and feeling close to chucking it in for now. So if anyone has any ideas I'd love to hear them. Failing that, I'm open to offers on an otherwise really very tidy R1100S...

Nik

[McBoxer]

Is it an option to just fit a non ABS rear master cylinder and brake line? Just thinking out loud and have no experience of this, but if it's do-able I'm sure you could pick up the parts from a breakers or eBay relatively cheaply. In fact there's an ad in the for sale section here from someone who's breaking one I think.

[Motocod]

Nice idea. By some great irony I still have the rear brake assembly from aforementioned Ducati... It had never occurred to me!

Nik

[DaveH]

Hi Ed,
Seems weird because like you I've managed to make the problem go away by turning the ignition off and on again. It lasts for a few minutes at the most though.
Nik

How old is the battery. A dying or under voltage battery can trigger the fault. Could be why it 'resets' for a short time when cycling the ignition, giving the battery chance to recover slightly.

If you get up to Derbyshire, I can drop it on the Diagnostics FOC.

Don't need to scrap the bike if it is terminal - the ABS unit can be removed at little cost. You get great braking feel & power without the anxiety of when it's gonna crap out again !

[Motocod]

I can't tell you the age of the battery, but I can tell you it's in good condition, as it's permanently plugged in to an Optimiser when the bike is parked up.

I may look at the ABS-ectomy route. I guess for the sake of some braided hoses and a day or so with the spanners. Seems a pity to have to remove a system that seems otherwise very effective and extremely worthwhile...

Nik

[bikemad99]

[quote="Motocod"]I can't tell you the age of the battery, but I can tell you it's in good condition, as it's permanently plugged in to an Optimiser when the bike is parked up.

My old battery was permanently plugged into an optimate right up to when it went tits up.New battery fitted everything fine.