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Discussion Starter #1
Well its been a week since my S started having some brake\servo issues
and thought I'd share. First abs/servo failure I've had....ever btw; and I have
4 beemers with either.

Pulling up to a stoplight in town I noticed an increase in pressure at the front brake lever.
( i rarely use the rear anymore)
Tug a little harder, and the ABS lights go on, then the amount of lever pressure
decreases. It seems like the front servo then gets cut out of the circuit (residual mode),
but the rear servos (actuated by front brake) still work.

Since the front end doesn't dive much under braking anyway it's hard to notice
this until you clamp a little harder which induces the rear brake to lock and cycle
the ABS. No issues using the rear brake only. Fluid levels look good.

Simply turning the key off and on clears the fault, but the problem remains
and got so frequent that i took it in saturday.

Before that, I tested and tested some more, I noticed that when lever
effort increased I could still apply the brakes without issue or triggering the fault
if I was careful, but occasionally doing this, the front servo would act like it recognized the
need for assist after the fact and engage suddenly, causing the front wheel to
apply assist.. like NOW, which doesn't make for a smooth stop.

I inferred from the dealer that this has happened before, so just wanted to mention
it and see if anyone else had seen it.

No, I am not soured on the servos because of this. When they were working
they were clearly more powerful than anyone I was running with at the track,
allowing me to blow past those I couldn't outdrag on the preceding straight
into the next corner.

I'll let ya'll know what they find

Best,
 

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brake issues

This one should be on the K1200S forum!
 

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Discussion Starter #3
Got it back after 3 weeks, apparently the wrong part ordered first. Servo
unit itself was bad. Put about 100 miles on it so far

best,
 

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Dug up this thread after my servos failed on my brand new (3 weeks old / 1300km) K1200S. Luckily I was travelling at low speed, as after I pumped the brakes a couple of times, they then LOCKED SOLID! Dropped the bike, with little cosmetic damage, but damage nonetheless and through no fault of my own. And what does the service manager at my dealership tell me? To drive it the 200km for them to have a look at it. He tells me I have no reason to worry about them failing on the drive, but I then take the bike for a 5 minute low-speed cruise around the neighbourhood - 50% of that time with no servos at all. Like hell I'm going to drive it 200km.

I just spent a couple of hours digging around on the internet, and imagine my amazement to discover similar problems reported as far back as late 2004! Wtf is up with that? This is bloody dangerous. If they had locked at highway speed, I would have been a greasy streak on the highway instead of sitting hear complaining!
 

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Discussion Starter #5
My problem was not similar to yours, but i have heard of a like occurrence on the GS board, even along with my failure it is at worst an extremely rare failure. That said i wouldn't ride it there like that.

You may want to check the lever\pedal for free play or binding, and there's a switch in front brake on the bar that must be adjusted correctly. I chalk mine up to early model glitches as its worked great ever since. They are super easy to replace pads on too and as mentioned in my original post there's not much than can outstop it.

HTH
 

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Well, ended up getting BMW Roadside Assistance to tow the bike. However, after running a full set of tests on it, the service manager calls me to say that they can't find anything wrong with it. The computer didn't record any sort of brake failure, and they didn't even get a warning light when they test drove it. He also told me it's impossible for the brake to lock like that. Looks like I'll be kissing a chunk of the riding season good-bye, because I'm not getting back on that bike until someone figures out what went wrong.
 

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I would do two things first call BMW corporate, and write a certified letter stating what happened. I would also take the bike to another dealer, pronto. Good luck
 

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Thanks for the sympathy. I've been digging all over the internet trying to find clues as to what may have gone wrong, and posting on forums to see if anyone else had encountered similar problems.

Other than the initial suggestion that I ride my bike in, the service manager has been cooperative. I understand where he's coming from - if he can't find a problem, he has nothing to fix. After he told me it was impossible for the brake to lock solid, I went back to where it happened, but the skid mark (on a high-traffic hotel parking lot entrance) wasn't visible after 6 days. I ended up speaking with him on the phone for about 20 minutes, hashing over every detail of the incident, and yesterday he was speaking with BMW Canada. They couldn't tell him anything, so they faxed Germany yesterday.

And of course, when they took it for a test ride at the shop, there were no problems. The four-flashes-per-second warning light didn't come on, the servos worked great, and the ABS was engaging.

If this were any of a few dozen other possible faults, I would just take the bike back, suck up the cosmetic damage costs (though I'd be bitter), and keep riding to see if it ever returned. However, with it being the brakes, I keep getting these little mental pictures of what would happen if they locked at highway speed. I'd rather not end up as a greasy streak.
 

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Hi Kevan,

Could it be possible that your brake failure and Eric2's are very similar? What I mean is that Eric2 had a situation where he lost front brake boost, then it suddenly came back.
Unexpected sudden and very strong brake application can easily cause a fall - know that for sure. And I imagine it could feel as if it was total brake lock - even if the wheel didn't fully stop turning.
Wonder if it would be any help to know exactly what had gone wrong inside Eric2's servo unit.

Allen
 

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That's why I originally posted here, because of what seemed like similarities. I wouldn't mind knowing the details of eric2's.

The brake did lock though. As soon as I picked the bike up and walked it out of the way of traffic, I looked back and could clearly see the skid mark from the tire. The only thing I've started questioning is whether it could have been the rear that locked. Immediately after the accident, I was sure it was the front, but everything happened so fast, and I walked the bike away before looking back at the skid mark.
 

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Interesting

First off this is a rare thread. Problems well described by credible reporters. Kudos.

Sounds like a transient signal problem in either the CANBUS (pure electrical signal strength) or the servo chip (bad circuit performance with perhaps heat related variability).

BMW dealers would know nothing. BMW (insert nationality here) would probably also know nothing. They exist to sell and service by the book.

Until BMW Corporate gets suffcient info reported consistently from across the realm, they will note and do nothing. Once the potential downside exceeds the 'do nothing' costs, then they will investigate, test, deny, and perhaps eventually provide minimal fix.

That's the global economy. I am sorry you two have to deal with that. I am glad I do not. But thanks for posting so clearly and warning us so well.
 
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