Brake problem ... Servo?

[rbt1548]

Hi All,
Reaching the end of my tether here; got my bike MOT'd last week , (2003 R1150R Rockster), last few yards from home the dreaded general warning light came on along with the flashing ABS light and little braking. Left the bike for a day and went to visit my mother after about 2 miles down the road I noticed it again, and the lack of braking, thank goodness for the engine braking, got home checked the forum, did the usual cleaning of all parts , sensors, slotted discs, etc. and as I was going to be needing a battery soon I got a new one, EX12-19 .Refitted everything and bike started no probs, but after a few mins the warning lights came back on. Also when I pulled the front lever there was no servo sound, I pressed the footbrake servo sounded, then pulled front again servo did sound!, then when I let the levers go the servo continued to sound, 'til I turned ignition switch back off.
Any ideas, pulling what's left of my hair out!,
Thanks, any help much appreciated!

[AndyRR]

Make sure your fluid levels in the ABS unit are up. If it gets low, it'll do that.

[rbt1548]

Make sure your fluid levels in the ABS unit are up. If it gets low, it'll do that.

All fluid levels are fine, right up to levels. It's got to be something fairly simple, but what?

[iowabeakster]

Your brakes work for some amount of time, and then the warning comes on while riding, correct?


A trip to the dealer, who can read the error code, is my only real suggestion.

I've got two guesses (they are only guesses)... if your interested.

1. The wheel sensor (or the wire) for the front wheel is malfunctioning. I don't know of any way to test those sensors.

2. Given your description, it sounds like the pressure might not releasing properly, when the front lever is released. The tiny bleed back hole (the smaller one) in the front handle bar reservoir might be plugged up with a speck of gunk. That hole needs to be clear, in order to release the pressure. Or either the lever's pivot point or the master cylinder piston is sticky. If either isn't returning to its proper resting position, they might be holding some pressure in the system.

background... about guess number 2.

Playing around with my bike a few years back, I discovered that fluid pressure activates the servo on the front brakes. I held the front micro switch closed (it is closed at resting position), then squeezed the lever, the servo would activate and the brake light would light.

It is not simply electrical, as the rears, where the micro switch activates the servo and brake light (if I held the switch closed, pressed the foot pedal, the servo would not activate and brake light would not light).

If either front or rear micro switch was open, the bike would not pass it's initial diagnostic test. The warning would start immediately after turning on the key.

[rbt1548]

[quote="iowabeakster"]Your brakes work for some amount of time, and then the warning comes on while riding, correct?


A trip to the dealer, who can read the error code, is my only real suggestion.

Yes they, work initially then light comes on and no power to the brakes. Also after fitting new battery, I checked the warning lights were doing what they are meant to , ABS slowly flashing and general light going out after a few secs, I then started the bike up and after about 30 secs the general light came on and the abs light started flashing in the fast mode.
Once I get it all together again, (isn't it a pain getting to the battery ?), going to take it out again this morning and see what happens and note everything.
I will try the switches as you suggested, then, if no luck I'll need to bite the bullet and head for the dealers.
Thanks again!
Update ,
Tried all I could think of and things I gleaned from the forum, and I now have some different symptoms, when I initially switch it on it does it's checks and abs light still flashes fast and general light is on.
When I fire the bike it does the same and when I pull front lever there is no servo sound until I also press the rear pedal, then I get the servo sound if I operate either lever.
I took the bike out on the road and went to quiet place with a wee bit gravel on the road and the abs WAS cutting in, but lights still flashing!
Anyway to cut a long story long, as it's the brakes, something I don't want to be worrying about whilst riding, I booked the bike in at the BM place for them to stick on their computer and hopefully fix at not too extravagant a price, to be honest they have been good to me in the past, a few years ago, during a service, they put on brand new cylinder heads, yes heads!, and a new set of forks and discs under warranty on my first R1150R, as they were showing signs of corrosion.
So it'll be the Commando for the next week!
If anyone is interested I'll post their findings and, (hopefully), solution.
Thanks
Robert

[blacklav]

Hi Robert, how did you get on at the bmw garage.
I`m asking as my abs including brakes dissappeared on me on saturday. I was lucky that nothing was on the junction that i went straight over. bmw should get sued for this.
I`m going to get rid of the abs altogether as i dont think i can trust itagain.
Chris r.

[rbt1548]

Hi Robert, how did you get on at the bmw garage.
I`m asking as my abs including brakes dissappeared on me on saturday. I was lucky that nothing was on the junction that i went straight over. bmw should get sued for this.
I`m going to get rid of the abs altogether as i dont think i can trust itagain.
Chris r.

Hi Chris,
It was as I suspected, the ABS control unit, goosed, dead, knackered, etc... need I go on? I saw a read out and one of the systems was reading over 100 bar when they should be in the range of 12-30bar. Fortunately, and I don't know what made me do it, I took out a warranty a while back, so that hopefully should do it. Unable to get it done just now due to me having to go away for about 5 weeks. I don't usually take out a warranty as I do my own bits and pieces, (having a Commando and a 1965 A65 Lightning Clubman you have to!), but luckily I did.
Don't despair though, it might just be dirt on the sensors or a ding in the ABS brake ring, or even a battery slowly going duff, there is a lot on the subject and it's possible causes on this forum, I didn't realise how good it is until I started reading through it.
I would got to the nearest BM dealer and get it diagnosed first, it may after all be something simple, then I would decide the next course of action.
I, like you, was thinking of doing away with it altogether, It's only the second bike I have had with ABS, the first being the R1200ST with which I had no probs! I had a R1150r before with no ABS & servo and was trying to remember what the braking was like, and if I can remember correctly it was good, but as you have just noticed the residual braking without the servo is a grab a big handful affair, I don't know if it would be require so much effort with all the ABS stuff removed. I am not too bothered about the ABS but I like to have decent brakes, it was like trying to brake with the Norton but with 2 1/2 times the engine power!!!!

Could anybody who knows, or who has done the conversion please pass on their opinion on the performance, Thanks!

Hopefully yours will be something simple, but to really find out what it is I think it would need to be diagnosed, ( that is the price we pay for all the modern electrical wizardry on vehicles nowadays, black boxes all over the place!, and the use of the black arts to fix them!!). We can tell if something is not quite right but can't see it to fix it!
At least you have researched the problem and looked at possible solutions so you know the worst that it can be and I fully understand you reasoning to remove it.
Have a chat with the Bm mechanic first and see what advice he can give you then take it from there.
Let us know how you get on.
Cheers
Robert

[sweatmark]

Could anybody who knows, or who has done the conversion please pass on their opinion on the performance, Thanks!

In case you're interested in the conversion of R1150** Integral ABS bike to non-ABS, I have a topic thread over in the Rockster section:

viewtopic.php?f=3&t=13571

To summarize, the braking perfomance of an iABS R1150R converted to non-ABS is nearly identical to the factory non-ABS equivalent. FWIW, my opinion is based on ownership of both types of R1150R bikes.

[rbt1548]

Could anybody who knows, or who has done the conversion please pass on their opinion on the performance, Thanks!

In case you're interested in the conversion of R1150** Integral ABS bike to non-ABS, I have a topic thread over in the Rockster section:

viewtopic.php?f=3&t=13571

To summarize, the braking perfomance of an iABS R1150R converted to non-ABS is nearly identical to the factory non-ABS equivalent. FWIW, my opinion is based on ownership of both types of R1150R bikes.

Hi sweatmark, that certainly is one excellent piece of work!, my hat comes off to you!, I had looked at it before but now you have updated it is even better. I had a quick trawl through the thread looking for the electrical solution and missed it, I'll look in more detail later.
Just one question regarding the new hose splitter you fitted at the headstock, would it not be possible just to get 1 length of hose made up and run it from the master cylinder to the splitter just at the mudguard? Just a thought for ease of routing.
You've got me thinking about whether to get the new module fitted or not now!, probably will go for it as it will be done under warranty, but we'll see, I've a few weeks to think about it.
Cheers

[sweatmark]

I had a quick trawl through the thread looking for the electrical solution and missed it, I'll look in more detail later.
Just one question regarding the new hose splitter you fitted at the headstock, would it not be possible just to get 1 length of hose made up and run it from the master cylinder to the splitter just at the mudguard?

Just updated the plumbing section yesterday, need to update the electrical parts located further down the topic thread. The updates are long overdue, sorry.

Yes, you could try a couple of versions of front brake circuit:

1. brake line from master cylinder (M/C) to the 90-degree splitter located on RHS of fender at Telelever "fork brace";

2. superbike setup like Riceburner's (described in the iABS-ectomy thread), with two lines running from M/C via double banjo bolt, direct to the calipers.

In either case, you need to guarantee adequate clearance for the Telelever's A-arm when handlebar is turned side-to-side.

I can see why BMW chose the OE front brake line routing, but it's certainly not the best option for brake bleeding or parts count.

As for my Rockster, I re-used the OE brake lines and had planned to upgrade in due time...