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Old 09-22-2008, 11:38 PM   #16
MJS OP
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Servo successfully removed

After returning from my Alaska trip I decided to pull the servo and convert the 12GS to non-servo.

A rear brake pipe from a non-servo bike and a short section on brake tubing and 10mm x 12mm adapter for the front line.
Name:  brake pipe.JPG
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It was a simple job to remove the servo and replace the brake lines. A quick bleed and the brakes were good to go. Definitely a different feel without the servos. Better than residual brakes and with great brake feel, much better than the servos.

The unknown now was the electrical, i.e. canbus system. The brake lights work thru the ZFE so no problem there. However, the speedo and odometer get their signal from the ABS processor thru the canbus. That and the flashing warning lights since the system assumed there was an ABS failure since there was no communication with the now removed ABS unit.

First step was to compare the wiring schematic of a non-abs harness to an ABS harness. The connector on the ABS servo gets direct battery power, front and rear wheel speed sensor data, canbus communication, brake reservoir fluid level, ABS bypass switch and diagnostic port. The non-abs bike connects the rear wheel speed sensor to the ZFE instead of the ABS unit. My goal was to modify the bike in a way that would be easily reversible if I was inclined to replace the servo unit at a later date. That meant no permanent modifications to the original wiring harness.

Some detailed examination and a small screwdriver allowed me to disassemble the connector housings. Unfortunately, the pins in the ZFE connector and the ABS connector are not interchangeable. Hours spent looking at the Mouser and Digikey catalogs and I still wasn't sure of the proper part numbers for the correct pins. Time for another approach. I sourced a main harness from a salvage bike and proceeded to take the connectors apart and salvage the pins I needed. Another benefit was the salvaged connector for the speed sensor.

This allowed me to build a new speed sensor cable and connect it to the ZFE. Some BMW tape to wrap the harness and it looks OEM. I used some small pieces of heat shrink to insulate the unused wires from the original ABS connector and taped them into a small "dead end" branch of the main harness. This was easy to tape back and disappears without the plastic connector body on it. All that's needed is to re-insert the pins into the correct position on the connector body should I ever want re-install the ABS servo.

An appointment with my local dealer was now in order. I had several discussions with the mechanic and service manager about re-programing the bike's systems. At first they thought it would be a 20 minute job. They also wanted to know how the bike was modified (I gave them copies of the schematics) and be sure the brakes worked properly. I don't blame them for that, we were talking about modifying a vital safety system.

Then when they actually started to think about re-programing, they weren't so sure it could be done. Seems the GT1 knows what the bike is supposed to have by the VIN number. Their first try was to request a new vehicle build order from BMW for a non-abs bike. That request was denied by corporate. In the end the were able to successfully modify the vehicle build code themselves. They also updated all of the other processors with the latest software.

Now there are no error codes and no warning lights. And I have re-discovered why I love this bike. It is even more enjoyable with the non-abs brakes. Control feel and feedback is much better than the servo brakes. And while I like the abs functionality, a large amount of my riding is dirt and I don't need or want the abs there. Besides, my other bikes don't have abs and I OK with the braking system on those bikes.

This may not be a modification for everyone but it can be done. This makes financial sense also as the resale value of the bike declines and the cost of a servo replacement climbs above 30% or more of the vehicle's value.
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Old 09-23-2008, 05:57 AM   #17
FrisbeeR1200GS
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Just an FYI: My 03 K1200rs with ABS had a ABS fault light that came on somewhat erratically...and to make a long story short, the rear master cylinder was low on fluid. Simple as that.
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Old 09-23-2008, 05:58 AM   #18
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That is great Mark!

Would you be willing to share your wiring modifications, schematics and the dealer who did the computer updates?

This kind of information would be very usefull, and should be preserved.

Jim
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Old 09-23-2008, 06:19 AM   #19
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Quote:
Originally Posted by JimVonBaden
This kind of information would be very usefull, and should be preserved.

Jim
...... in the GSpot FAQ, for example.

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Old 09-23-2008, 09:12 AM   #20
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Frisbee - this was definitely a servo failure. Bike had no servo brakes, only residual. The servo would not complete the POST. GT! diagnosed with a bad pressure regulator and the problem would reoccur after the ABS fault codes were cleared. New servo unit $2200 plus labor and re-programing. I wasn't able to find a used one and didn't want to put that kind of money into a 60k mile bike.

JVB - I'll pull together the schematics and other info. I didn't take pictures at the time but I will next time I have the tank off. Re-programing should be doable by any dealer who is willing to work "outside the system". After all, this is not a BMW supported repair.
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Old 09-23-2008, 09:14 AM   #21
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Quote:
Originally Posted by MJS
Frisbee - this was definitely a servo failure. Bike had no servo brakes, only residual. The servo would not complete the POST. GT! diagnosed with a bad pressure regulator and the problem would reoccur after the ABS fault codes were cleared. New servo unit $2200 plus labor and re-programing. I wasn't able to find a used one and didn't want to put that kind of money into a 60k mile bike.

JVB - I'll pull together the schematics and other info. I didn't take pictures at the time but I will next time I have the tank off. Re-programing should be doable by any dealer who is willing to work "outside the system". After all, this is not a BMW supported repair.
Sounds great! I would also like to put this on my website, full credit to you of course. I am sure that one would have to find a dealer willing, but it might be easier if your dealer could give the lowdown on how he did it to my dealer, so to speak.

Thanks,

Jim
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Old 09-23-2008, 09:45 AM   #22
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Thumb Worry beads

Quote:
Originally Posted by JimVonBaden
I would also like to put this on my website....

Jim
Are you getting nervous your servo will fail you

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Old 09-23-2008, 12:15 PM   #23
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Quote:
Originally Posted by tagesk
Are you getting nervous your servo will fail you

[TaSK]
Not in the slightest. I figure they fail at a rate no higher than non-servo bikes ABS unit. But I do think it is a good bit of information for if one does fail. Plus, like you, I like to share this kind of wisdom.

HI Task!

Jim
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Old 09-23-2008, 04:16 PM   #24
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Holy shit. Dude is a wizard.
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Old 09-22-2009, 06:06 PM   #25
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Has Anyone Else Tried This??

Im well into this having done the wiring and rerouted the brake lines. I still have the dash lights winking at me and the instruments showing a speed sensor fault. I guess its a trip to the dealer . Has anyone got any clue what I need to tell them? They really have been very helpful in the past.
My guess is they activate the speed sensor terminal on the ZFE and deactivate the ABS connection. Thanks John
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Old 09-22-2009, 07:45 PM   #26
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John,

The dealer needs to get the bike configuration program that is specific to your VIN from BMWNA. The dealer can tell BM that they "lost" your program during an flash upgrade. BM will NOT supply a non-abs program for you bike if the VIN indicates the bike was originally built with ABS. The dealer can modify the program and then upload (download?) the modified program to your bike. I believe they have to answer a series of questions during the upload to the bike and that is when they tell the program there is no ABS. That activates the speed sensor input on the ZFE and gets rid of the flashing light.

Hope that helps.
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Old 09-22-2009, 08:31 PM   #27
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Thanks

That sounds like progress . I'll keep you posted. Oh , Mark , has your conversion proved to be troublefree so far?

Thanks John
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Old 09-23-2009, 12:21 AM   #28
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I've rerouted the brake lines but have not done the reprogramming that Mark has done. My ABS pump was bad and my bike doesn't even know it has ABS according to the dealer. I like not having the servos and haven't had any issues with the hydraulics. I did all the work myself and you don't have to buy any parts for the front and just use one of the old brake lines from the bike to make the rear.

Here's some pics of how I did mine.

Front


Rear
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Old 09-23-2009, 03:24 AM   #29
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Quote:
Originally Posted by peanut_gallery
Here's some pics of how I did mine.
Front

Rear
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Old 09-23-2009, 09:44 AM   #30
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Well crap. Should of just did it this way the first time. Stupid Flickr.

Front



Rear

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