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Discussion Starter #1
On my 2003 K1200GT I need to work on the rear brakes. This bike I bought crashed and I know nothing about BMWs so bear with me... The rear brake reservoir line was ripped in the crash so I replaced the line and bled the back brakes but still there is air somewhere.. I have a write up that details all the brake and clutch bleeding and I plan to bleed the control circuit. Looks straight forward (like brakes on the space shuttle) but reading through the whole thing, I don't see where we ever use the front brake reservoir that is co joined to the rear brake reservoir.. I'm just looking forward to when I finally get to doing general maintenance,, right now I just want to make it go and stop
 

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You need the BMW service manual.Service manual with the iABS stuff in it.

Anytime a line is replaced or a reservoir runs dry as per the BMW service manual the reservoir has to be refilled from the brake caliper with the special BMW tool called the "Bubble free injector". Big Syringue with a piece of hose attached.
 

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Discussion Starter #3
Thanks. I have the climer manual and had a great write up on bleeding the RS with ABS3. worked well. but I was asking about the second front brake reservoir that is integral with the rear brake reservoir.
 

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On my 2003 K1200GT I need to work on the rear brakes. This bike I bought crashed and I know nothing about BMWs so bear with me... The rear brake reservoir line was ripped in the crash so I replaced the line and bled the back brakes but still there is air somewhere.. I have a write up that details all the brake and clutch bleeding and I plan to bleed the control circuit. Looks straight forward (like brakes on the space shuttle) but reading through the whole thing, I don't see where we ever use the front brake reservoir that is co joined to the rear brake reservoir.. I'm just looking forward to when I finally get to doing general maintenance,, right now I just want to make it go and stop
I am assuming you are asking about the 2 sections reservoir (DOT4 brake fluid only) located on right side just under the small radiator expansion-tank.

1) The outmost section is for the REAR Brake only (both for "wheel circuit" and "control circuit"). There is a short black hose going from this section to the rear brake master-cylinder.

2) The section that is most inside (toward center of frame) is used when bleeding the FRONT Brake "wheel-circuit". In these iABS system (with servos), the FRONT "Wheel circuit" is between the ABS modulator and the Front Brake Calipers only.

Hence, the fluid level at Front master cylinder (at handlebar) is NOT affected when bleeding this part of the system - neither does the fluid level goes down at handlebar when front brake pads wear. Only the level in the most inside section of the reservoir will vary with front pad wear.

BE CAREFUL when working on brakes as your life depend on it...
Over the years on several BMW forums, many HOW-TO have been written on bleeding these iABS system (with servos). Some of these HOW-TO are missing critical info / details / steps.

ALSO, be aware, that most HOW-TO where written for a normal bleeding procedure. HOWEVER, when one or several brake hoses (or any major component) is replaced, air will be introduced in the system.

In such case the "normal" bleeding method need to be modified with added steps:
As stated to you in the previous post, BMW official shop manual recommend the use of a large Syringue to push fluid from the calipers to the reservoir to refill this section of the system. For such job, the CLYMER manual will NOT help you - although it is a good book for 98% of the maintenance.
 

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Discussion Starter #5
Thanks Sailor. that makes perfect sense. Seems my write up was pretty detailed and accurate saying the iabs pump for wheel circuits but just lever pressure for the control circuits and even tho the fronts are pinching hard I will get to bleeding them just to push fresh fluid through. I'll recheck I guess the write up wasn't very clear on refilling fluid for front control circuit bleeding. Thanks again
 

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Discussion Starter #6
And regarding a reservoir refill through the caliper that is a great process and thanks for that input. but i just filled from the reservoir and normal bleeding with key on and foot control for servo pump bled my wheel circuit.. then I followed up with manual bleed for the control circuit.
 

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Hi GaryS. I have the same 2003 K1200GT bike. I replaced all the brake lines with steel for my own handlebar riser extension project.

That said, I placed air in all the lines everywhere. It was a challenge to get the air out but eventually, I got solid brakes. Keep reading up on the ABS bleeding process. I succeeded by doing the typical normal bleed as if all the lines were already full and just pushed the fluid out the bleeders.

youtube on the k1200RS is the same bike.

is a good video part 1 and part 2

Started with front brake bleeding, full reservoirs in the back inside container and also the handlebar. I had the special $40 funnel with the long neck but you can do with a baby eyedropper to top it off. Front bleeding uses the servo motor.

Rear brake being dry was a problem but when touching the rear pedal, a servo also pumps fluid out the rear caliper along with the master cylinder action on the pedal. They activate together. The rear pedal was limp and wouldn't firm up as expected. That stumped me to the point of buying a replacement master cylinder that I probably didn't need.

Anyway, I moved on to the ABS, starting with the Fill connector. You need a quick bleeder on there. Also, the battery is out to get access and prevents the servo pump from running. You want this a manual process.

Front bleeds are this order with a repeat. F1, F2, F3, F1 bleeds. Had to bend a Menards 7mm box end wrench to get in there. A socket to loosen it and the box end bent 90 degrees at the head to open/close the bleeder while hand pump the front brake to push fluid through. Caution, it squirts brake fluid out the handlebar reservoir if you pump quickly. Gets messy.

Once front done, rear is the R1, R2, R3, R1 again. This uses the rear brake pedal with no battery servo action. Mine was near dry air in there but with slow patience, and steady "open bleeder, press slowly, close bleeder, slow return pedal", after 10 times or so, the rear pedal firmed up and I could see fluid coming out of R1. The rear reservoir tank dropped. Bubbles some. Moving on to R2, lots of bubbles. Moving on to R3, a few more, back to R1, a few bubbles. Ok to repeat the entire Rear brake pattern of R1, R2, R3, R1.

Sounds like you have some experience with repairs and patience. I had no success at using a professional brake pump/vacumm tool to reverse push the fluids through the system. Too many problems clamping hoses to the bleeders, etc.

good luck. The 2003 GT is a nice ride.
 

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Discussion Starter #8
Thanks! I got my brakes working. can you post a picture of your right handlebar control multifunction switch?? Mine is busted and Im wondering if I can use one from an LT.
 

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Right handlebar closeups 2003 K1200GT Manufactured Nov 2002 last 7 digits of vin is ZK00059. I guess that makes it the 59th built in Germany. Go to this link on your vin for some details on your bike.

https://www.realoem.com/bmw/enUS/select

That said, your bike might have changed some during the production year. The GT is based on the RS model about 90%. GT added the heated seat and heated handgrips.

My bike has a small 2 inch riser pulling the grips a little closer to me. It is an add-on none EOM. I don't think an LT will work but not something I searched for. I find my parts on Ebay. Lots of 2003's being parted out these days.

Other non-EOM are foam grips over the stock ones. I think I got those at Pirate's bmw.

Post some pictures of your bike. I would like to see what you had to work with.
Regards John
 

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