Help! Bleeding servo front brakes on 2006 RT

[Nitronick]

Hi,
Please help, I've realised that bleeding the brakes with the servo is not the same as traditional methods and am wondering what sort of mess I'm in now!
So background is that I replaced both faulty front callipers, disconnected the hoses at the callipers and shut off the ends to prevent loosing fluid.
Fitted the callipers, connected a non return drain to the bleed on the callipers, opened front fluid reservoir (in preparation to top up),ignition on and then operated front brake in the hope that I could get the air out.
Realise now this isn't going to work and indeed, even with bleed nipple removed, brake fluid is not exiting calliper.
Not sure if relevant but with maximum brake lever action I do get minimal braking force (haven't checked but maybe I'll get maximum brake force on back wheel first).
Read things like don't touch servo brakes, take to the dealer and some complex notes involving removing fuel tank ect to access the server (I think) to bleed it here.

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[bieffe]

Maybe this wideo will help, https://www.youtube.com/watch?v=a1ktxY_bgQY, for me was usefull, but be sure, left and right trim panels and tank cover, and reservoir have to go off. :shirty:

[Nitronick]

Thanks for the reply. Had already had a quick look at that video and was worried that I have created a lot of work for myself.
What do you mean when you refer to the 'reservoir' (on the handle bar where the brake lever is?).


I didnt let the fluid in the reservoir on the handle bar run dry, do you still think I need to remove fuel tank and access the servo unit?


Thanks for your help

[David.]

This is not a procedure I've done myself but some research has thrown up the following ideas.

The 2006 R1200RT system may be similar to that on a 2005-2009 K1200LT, https://www.youtube.com/watch?v=WXMNX62sfV4

If this is the case and I've understood it correctly, there are four circuits.
1) Front (handlebar) master cylinder to ABS/Servo unit.
2) ABS/Servo unit to front calipers.
3) Rear (foot pedal) master cylinder to ABS/Servo unit.
4) ABS/Servo unit to rear caliper.

From what has been described, after changing the front calipers, there is now no brake fluid present at the bleed nipples. Perhaps there is no direct fluid connection between the handlebar reservoir and the front calipers. Maybe, the fluid reservoir on the ABS/Servo unit to front calipers circuit has become drained of fluid during the caliper change. Don't forget, the calipers themselves hold a volume of fluid.

This next video shows the location of the ABS/Servo unit on a 2005 RT, https://youtu.be/LaNJjRGrQNo
Looks like there are indeed similar fluid reservoirs to those shown for the K1200LT.

Please remember, I'm no expert on this matter, just trying to help. Any work on brakes is at your own risk.

[David.]

Maybe this video will help, https://www.youtube.com/watch?v=a1ktxY_bgQY

Having looked at this video again, it does indeed show the front and rear calipers being bled from the ABS/Servo unit.

This video is Part 1 of the above, https://www.youtube.com/watch?v=YLM25NYvlas
It shows the four circuits at the start and how to bleed the F&R master cylinders to ABS/Servo unit.

[Nitronick]

Thanks guys for your help.
With your comments and the videos its become clear why I have a 'long peddle' for the front calipers.
Looks like my next task is to find out whats involved in removing the fuel tank!
Any steers to info on this would be greatly appreciated. But I'll have a search myself.

[David.]

Has the bodywork been removed, if not, this video may help, https://www.youtube.com/watch?v=2UHU4ZQ2C_Q

Ok, it's for a Camhead not a Hexhead but there are some similarities.

R1200RT gas tank removal, https://www.bmwsporttouring.com/topic/3 ... k-removal/

[Nitronick]

Thanks again for your help

[Old-Git]

sorry to butt in but does anyone know if LC models are straightforward drain and replace / bleed ? Thanks

[David.]

Does anyone know if LC models are straight forward drain and replace / bleed.

This video shows a guy completing a DIY brake fluid flush on a 2016 Wethead GS, https://www.youtube.com/watch?v=hBE_vDjj4Zs
He uses a GS-911 to flush the ABS pump, don't know if this is the "official" BMW Motorrad procedure.

It has been confirmed by BMW that on a Camhead, the ABS pump flush is not necessary.

[Old-Git]

Thanks, very useful. Now just got to find a way to block the brake lines while the calipers go off to the coaters. Anyone got any tips?

[David.]

Now just got to find a way to block the brake lines while the calipers go off to the coaters. Anyone got any tips?

How about a nut & bolt through the brake hose banjo with a copper crush washer either side.

[Old-Git]

How about a nut & bolt through the brake hose banjo with a copper crush washer either side.

Good idea, thanks

[Nick Evans]

Ask the powder coaters to do it, they have to stop up holes all the time. They will have rubber bungs etc.