Brake servo not working.. what to check first? - BMW Luxury Touring Community
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post #1 of 16 Old Apr 9th, 2014, 1:09 pm Thread Starter
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Brake servo not working.. what to check first?

the brake servos stopped working on the LT this morning. (2002)

any suggestions on what to check first?
fuse? brake switches? elect. plug?

not quite sure where it is actually..

I know where the main brake control unit is under the seat...

gonna go sniff around and see if I can find anything obvious...

it was fine when I parked it in the fall.....
but I know that dont mean much.... I am familiar with murphys law..

thanks for any advice....

True Wisdom Only Comes From Pain.


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post #2 of 16 Old Apr 9th, 2014, 1:44 pm Thread Starter
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Re: Brake servo not working.. what to check first?

I just took a quick video

I fear the servo is shot...

All fluids are full

Any ideas??

http://www.youtube.com/watch?v=NIGfYEzsNLo

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post #3 of 16 Old Apr 9th, 2014, 8:50 pm
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Re: Brake servo not working.. what to check first?

OK Two things could be happening based on your video. A failure of the front half of the ABS unit. The other thing is that something is stopping the ABS unit from fully completing the start up self test. With no brakes applied check to see if the brake light comes on when you turn the key. If it does come on find the cause as this could be a stuck brake switch stopping the self test from completing. Might just get lucky.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
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post #4 of 16 Old Apr 10th, 2014, 6:38 pm
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Re: Brake servo not working.. what to check first?

My 2002 will give the fast flash when the ignition is turned on and in a few seconds go to slow flash until the drive away test. It does (as you know) look like it not completing its check.

Chris Ehlbeck
2002 BMW K1200LTE Toscana Green Retired with 85,391 miles
2014 BMW R1200RT Quartz Blue Metallic

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post #5 of 16 Old Apr 13th, 2014, 7:47 am Thread Starter
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Re: Brake servo not working.. what to check first?

Update.

Took the ABS unit out and found a burned chip in the printed circuit board and also the servo motor for the front calipers was dead.

there was a good amount of tarnish and dark brown discoloration inside the unit (on the front brake section) the rear was very clean...

I decided to remove the entire system and run SS lines from the master cylinders to the calipers. (like god intended)

I removed the electrical portion of the unit and insulated it. The speedo and brake lights run through it. so it must be kept.

I removed the ABS relay under the tank.. which stopped the wig wag lights.


Thanks to John Z. and sgroover for help.

probably won't get the SS lines on until next weekend...

I had the stock lines hooked up and bled but the stock rubber hose ruptured at the right caliper...
the lever felt very solid ... before it ruptured..


I think going direct (from master to calipers) applies more pressure... ?
rather than going to the control unit and back.... could have been air in the control unit or lines also... who knows...

I'm just glad to be rid of about 8 lbs. and a maze of brake lines.
Gained some under seat storage room also....

will update when I get her buttoned up and take a good test ride.

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post #6 of 16 Old Apr 28th, 2014, 2:49 pm Thread Starter
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Re: Brake servo not working.. what to check first?

Slight delay in getting my custom lines from Galfer... but lets move on...

The Brake lines fit perfectly ... One line from front master to right caliper, double banjo bolt and another short line over to the left caliper.

Rear is one line from the master to the caliper.

Bleeding was EZ as could be. (speed bleeder bag)

today was my first trip with the bike to work and back... 50 miles round trip. Most of my trip is twisty backroads... the brakes work great.

Not better than the servo assist IMO, but not worse.... I think it's about the same.

In any case, the brakes work great, no warning/fault lights... the brake /tail lights and speedo work as normal.


As far as losing the ABS and linked brakes, Thank God. I hated that crap. I very rarely use the back brake unless it's a slow speed maneuver or holding the bike at a light..... but I used to go through rear pads at the same rate as the front or quicker...


I am very happy I yanked the techno brake system and went back to simple.... and effective.

thanks again john Z and sgroover.

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post #7 of 16 Old Apr 28th, 2014, 3:37 pm
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Re: Brake servo not working.. what to check first?

Glad it is working out OK for you. Enjoy.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

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post #8 of 16 Old Apr 28th, 2014, 10:32 pm
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Re: Brake servo not working.. what to check first?

Some additional reading on ABS if interested.... there's a thread on I-BMW for K12GT slant 4 bikes where they've been repairing the ABS servo motor for "stuck brushes"... and module masters have chimed in there indicating they completely replace the motor brushes with a different type...
not sure if it has any bearing on our LT ABS system or not.. but I guess they'd be pretty similar?

Chris
Sydney, NSW
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post #9 of 16 Old Apr 29th, 2014, 6:33 am
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Re: Brake servo not working.. what to check first?

Quote:
Originally Posted by cws View Post
Some additional reading on ABS if interested.... there's a thread on I-BMW for K12GT slant 4 bikes where they've been repairing the ABS servo motor for "stuck brushes"... and module masters have chimed in there indicating they completely replace the motor brushes with a different type...
not sure if it has any bearing on our LT ABS system or not.. but I guess they'd be pretty similar?
This thread is about another newer ABS modulator installed on all "slant 4" models 2007 and later - this ABS modulator was never installed on the K1200LT.

Early "slant 4", K1200S/K1200GT beginning in 2005/2006, had an ABS-Modulator very similar to the 2nd generation of K1200LT (2005+) with servos. After production of August-2006 (mainly sold as 2007 models in USA), BMW introduced a simpler and lighter ABS modulator on all these models. Although they are simpler to bleed, these have problems with the brushes of the single motor. This is what this thread is about on I-BMW.com

-------------------------------------------------
John (Montreal, CANADA)
K1200RS (2002 IceBlue/Red - 96,000 miles)
-------------------------------------------------
Think twice before you hit [SUBMIT REPLY] - famous quote by another member:
"The value of this board is not founded on dismissing the ideas of others, but by posting to share our experiences and what we've learned from them."
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post #10 of 16 Old Apr 29th, 2014, 8:34 am
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Re: Brake servo not working.. what to check first?

OK, irrelevant info... thx Sailor.... brain is getting confused trying to take in so much extra info lately... :-)

Chris
Sydney, NSW
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post #11 of 16 Old Apr 29th, 2014, 9:59 am
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Re: Brake servo not working.. what to check first?

Those are on some of the later model GS bikes (mine) as well. Stuck brushes well documented.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

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post #12 of 16 Old May 28th, 2014, 2:53 pm
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Re: Brake servo not working.. what to check first?

Quote:
Originally Posted by johnT View Post
Slight delay in getting my custom lines from Galfer... but lets move on...

The Brake lines fit perfectly ... One line from front master to right caliper, double banjo bolt and another short line over to the left caliper.

Rear is one line from the master to the caliper.

Bleeding was EZ as could be. (speed bleeder bag)

today was my first trip with the bike to work and back... 50 miles round trip. Most of my trip is twisty backroads... the brakes work great.

Not better than the servo assist IMO, but not worse.... I think it's about the same.

In any case, the brakes work great, no warning/fault lights... the brake /tail lights and speedo work as normal.


As far as losing the ABS and linked brakes, Thank God. I hated that crap. I very rarely use the back brake unless it's a slow speed maneuver or holding the bike at a light..... but I used to go through rear pads at the same rate as the front or quicker...


I am very happy I yanked the techno brake system and went back to simple.... and effective.

thanks again john Z and sgroover.
Do you happen to have the measurements you used for the custom lines? I think I need to get a set made for my 06 K1200LT
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post #13 of 16 Old May 28th, 2014, 3:08 pm Thread Starter
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Re: Brake servo not working.. what to check first?

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Originally Posted by pricebri View Post
Do you happen to have the measurements you used for the custom lines? I think I need to get a set made for my 06 K1200LT
master to right caliper 40"
caliper to caliper 17"
rear- master to caliper 45"

I would measure twice before you order... not sure if my 2002 is the same as your bike.
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post #14 of 16 Old May 28th, 2014, 4:35 pm
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Re: Brake servo not working.. what to check first?

Thanks so much for the quick response!

I do plan to measure myself, just wanted a baseline so I knew if I was close
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post #15 of 16 Old Aug 21st, 2014, 12:58 pm
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Exclamation Re: Brake servo not working.. what to check first?

John T or any others I need just a little help on this,

Ordering Lines from Galfer. If I could get a former order number and date for these custom lines it would be great. Or the last name of John T. so they (Galfer) can look up the order that way. I want to order the same line configuration for my 2002 LTC. For example the Indexing of the Banjos and the Banjo Type/Angle etc are needed and I would rather not try to guess as some of you have already got them perfect from Galfer.
Your help as always is appreciated,
Mark

Mark D.
Groveland,MA
2002 KLT (JETBLUE)
1993 ST1100 (retired)
1982 GPz 1100 EFI (retired)
1979 750F (retired)
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post #16 of 16 Old Jul 5th, 2015, 4:04 pm
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Re: Brake servo not working.. what to check first?

Quote:
Originally Posted by johnT View Post
master to right caliper 40"
caliper to caliper 17"
rear- master to caliper 45"

I would measure twice before you order... not sure if my 2002 is the same as your bike.
Thank you for posting the details. Want to delete on my 2003 too. Out to the garage
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