Loss of brakes/hydraulic pressure

[pf10015]

I HAD A "NO-SPEED" LAY-DOWN of R11S ONTO THE GRASS ON MACHINE'S RIGHT SIDE. It was at night coming back from store in front of my house, pulled-up on sidewalk, intending to park in front of house but in an absolute idiotic moment I killed all forward velocity, bike started to tip to low side of sidewalk (right side) and as I put my foot down there was of course no sidewalk there, hence a lay-down onto the grass. Bike rested on right cylinder guard but right handle bar was turned under. My son and I lifted bike up I got on it, started it up and the brake failure light flash immediately started flashing and I obviously had no hydraulic pressure. No obvious damage noted to usual lay-down suspects, mirrors, levers, handle bars.

I checked all lines and looked for leaks under good light in garage but see nothing untoward. Bike is equipped with RD Bar-backs.

Can any brethren help with a possible diagnosis? I will move machine to BMW dealer (3-miles) on Friday but brakes will be dicey.

[markjenn]

My guess is that your brake fluid must have been very low, and the tipover introduced air into the line at the master cylinder. Curing the flashing lights will probably require a dealer reset of the ABS computer. But I bet bleeding will be enough to restore normal non-ABS braking.

- Mark

[roger albert]

+1

[Joe the Viking]

I agree with the above.

Easiest way to bleed the master cylinder is to take the lid off the reservoir and push the pistons back into the calipers, this forces fluid up from the calipers through the lines and master cylinder. Usually gives a decent bleed with no mess as long as you don't push them in to the point of overflowing the reservoir.

Make sure you have enough fluid before you ride, you don't want to risk sucking air into the master while on the move. If you do fill it up be VERY sure the level is correct next time you change pads. Filling up with old pads and then changing to new ones will cause the level to rise and this can cause binding.

I hate giving advise on brakes, they're a little to dangerous to be playing around with but riding to the shop with crappy brakes...

[Bob Hancock]

You don't say if you have ABS or if there is any resistance at the lever, but could this be as simple as the light flashing after you start the bike but before you ride the first 10 feet and the system says hello to itself? Others probably have it right but I'd try the simple stuff first.

[pf10015]

(1) UPDATE: Machine is 2002 R1100S with Integral ABS. I had hoped after I righted machine that the flashing light was simply the initial warning that comes as one would energize the ignition, however, no joy after starting-up and riding 0.25 miles to check things out. Most importantly, there was no doubt I had no hydraulic pressure.
(2) QUESTION FOR JOE THE VIKING: Your procedure for bleeding the brakes is that a one man operation that I could do? I assume the sequence would be:
- Place machine on center stand
- Remove resevoir cover
- Ensure fluid is full
- Energize Electrical System
- Place long screw-driver between front (or rear?) rotor and pads & force into caliper until fluid is expelled from resevoir
Is the above sequence correct?
Thanx & Best Regard with a Happy Thanksgiving to all of my R11S friends!

[Joe the Viking]

So you have the servo ABS, that makes it more interesting.

Can you hear the brake booster working when applying the front brake?

Are the brakes completely gone or just very poor?

I'm leaning to wards an electrical problem now actually, does anyone know if the servos will switch themselves off if the break light switch gets busted up or dissconected?

Originally Posted by pf10015

(2) QUESTION FOR JOE THE VIKING: Your procedure for bleeding the brakes is that a one man operation that I could do? I assume the sequence would be:
- Place machine on center stand
- Remove reservoir cover
- Ensure fluid is full
- Energize Electrical System
- Place long screw-driver between front (or rear?) rotor and pads & force into caliper until fluid is expelled from reservoir
Is the above sequence correct?
Thanx & Best Regard with a Happy Thanksgiving to all of my R11S friends!

I haven't actually done this to a bike with your kind of braking system on it but I know how it works and this is what I would do:

- Place machine on center stand
- Remove reservoir cover
- Remove a caliper and use something wider and less sharp than a screwdriver to force pistons into caliper until reservoir fills up all the way. I usually just remove the screws that hold the caliper in place and then I use the brake disk to push the pistons in.

Actually if you're careful you don't even have to remove the reservoir cover. If you don't remove it and push the pistons to far/hard you could end up with enough pressure in the reservoir to pop the seal and get brake fluid everywhere. Still I would do it this way and just be a bit careful.

I don't think you should add any fluid to this system if the level is anywhere near decent, as I recall the system compensates for pad wear and keeps the fluid level constant.

[Dr. Curve]

Just bleed them the traditional way.......you will be OK and the light will go off. Puck backing is alright but you risk overflow at the bar unless someone it there watching.

[pf10015]

UPDATE: No Servo Noise

[SergioK]

Not good. There's no servo fuse, only a relay for the ABS. I doubt that is it though.

[Joe the Viking]

I'm not sure exactly why the servos would switch off, might be due to air in the system but I doubt it.
If your brakes are "kind of usable but really crap" when you pull the lever all the way in to the bars you probably don't have air in there, they feel like that without the servo. If you have very little or no brakes you do have air in there.

Does the brake light work as it should front and rear?

[Mark Estes]

Just a question. Does the 2002 actually have servos? My 2004 does, but I'm not sure what year they started using the servos.

[KMoore]

My August 01 build does.

[tjs]

The brake fluid resevoirs for the wheel circuits are part of the I-ABS unit underneath your gas tank. tjs

[pf10015]

UPDATE: Problem fixed. I called the good folks at Gulf Coast BMW concerning the problem and aforementioned advice before I did anything. The service writer stated that because it was a brake problem she conferred with a technician who asked a few questions and indicated that it was likely an electrical or ABS-computer problem. It turns out with no boost the Brakes would work but poorly, increasing the lead times for stops and they recommended a tow in. My recent abysmal experience the Progreesive Insurance towing program convinced me to see if I could move the machine myself. I again tested the machine and my ability to stop and decided I could handle it. I waited until there was little traffic and then drove my machine the 3+ miles to the shop. As I was advising the service writer, the technician that had fielded the phone call walked out looked under the machine and in a matter of a couple of minutes fixed the problem.

PROBLEM: There is a connector tab extending from the frame/brake system that makes contact with a similar tab underneath the rear pedal. When I laid the bike over on the right side the pedal tab pushed into the machine-mounted brake system tab and bent it inboard. When I started the machine, after righting it, and the brake system went through its diagnostic check and read that the brakes were already depressed hence the computer was waiting for the lever/pedal to be released which was indicated by the rapidly flashing "brake failure" light. Joe the Viking had it right, it was an electrical problem due to a material upset.

FIX: The tech simply bent the frame connector back into contact with the pedal connector and the system was restored with the usual crisp and efficient ABS braking I have come to love and depend on.

QUESTION: I want to understand all I know about the integral ABS system on my bike as opposed to the current system on newer BMW machines. As I understand it, the integral system works proportionally 60/40 from either end in that if you depress the rear brake pedal with no front brake, the ABS computer applies brake 60% rear & 40% front but if you apply the front brake with no rear than the converse is true, ABS computer applies60% front and 40% rear. Is my understanding correct & if so what happens if I apply both? Additionally, what is the difference between my system and newer systems?

Thanks to all for the good and thoughtful advice!