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AviP

Front brake failed on R1100RT.

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AviP

I have a 2000 R1100RT with about 35K on the odometer. About a month ago, the ABS lights started doing their asymmetric line dance which I ignored as I had no time to deal with it. Last week, the front brake felt like it was binding as I rolled the bike backwards out of the garage. I still ignored it and kept on riding with my kid riding pillion. Yesterday, right after I dropped her off and drove off, somewhere along the ride it felt that the front brake was on. I stopped and investigated and found nothing obvious. Driving on, I was at about 40 mph on local roads and the traffic light changed to red. I pressed the front brake pedal and it went all the way to the handlebar without any resistance. Luckily I was in sissy riding mode and was able to take the shoulder while using the rear pedal. Drove back home without front brakes.

 

So here's the skinny. Brake fluid was changed about 5 years ago and is clear to very light brown in color. Brake fluid level looks good. Brake pads and rotors are not showing any unusual or uneven wear. All 4 pads still have about 10K in them. There are no leaks anywhere along the calipers. I did not check at the ABS module. Battery seems to be good as there is never a problem starting it up. The brake pedal is now responsive but not as firm as before. What should I be looking for?

 

I'm done riding it for the season. I was planning on doing all the fluids, filters and tires this winter.

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szurszewski

Original rubber brake lines? 

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AviP

Yes. Time for SS lines?

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Thomasskin

My ABS failed at 10K. It was in heavy traffic, rush hour and luckily I'm a big guy and could stand on that brake.  I swear the electrical system in these bikes was designed by mice, good luck.  You can send out your ABS and have it rebuilt, way cheaper then new one.

2002 R1150RT

 

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dirtrider
11 hours ago, AviP said:

I have a 2000 R1100RT with about 35K on the odometer. About a month ago, the ABS lights started doing their asymmetric line dance which I ignored as I had no time to deal with it. Last week, the front brake felt like it was binding as I rolled the bike backwards out of the garage. I still ignored it and kept on riding with my kid riding pillion. Yesterday, right after I dropped her off and drove off, somewhere along the ride it felt that the front brake was on. I stopped and investigated and found nothing obvious. Driving on, I was at about 40 mph on local roads and the traffic light changed to red. I pressed the front brake pedal and it went all the way to the handlebar without any resistance. Luckily I was in sissy riding mode and was able to take the shoulder while using the rear pedal. Drove back home without front brakes.

 

So here's the skinny. Brake fluid was changed about 5 years ago and is clear to very light brown in color. Brake fluid level looks good. Brake pads and rotors are not showing any unusual or uneven wear. All 4 pads still have about 10K in them. There are no leaks anywhere along the calipers. I did not check at the ABS module. Battery seems to be good as there is never a problem starting it up. The brake pedal is now responsive but not as firm as before. What should I be looking for?

 

I'm done riding it for the season. I was planning on doing all the fluids, filters and tires this winter.

 

Morning  AviP

 

This is a difficult diagnosis over the internet as you seem to have good brake fluid level in the front master cylinder reservoir. 

 

The things you probably need to look at are:

 

The front master cylinder for the internal piston  fully returning to it's out-stop ring (if the piston isn't fully returning then it can trap fluid in the system & act like the brake  is  sticking on, that also prevents new make-up fluid from entering the cylinder from the reservoir so you can then get a dead lever).

 

Or you could have a crud-plugged take-up port hole in the bottom of the master cylinder reservoir. 

 

This is probably where I would start my diagnosis, especially if you haven't serviced the brake system in 5 years. Start by cleaning the front master cylinder reservoir out then verify that the little fluid hole in the bottom of the reservoir is open & not blocked.

 

Next, would be something wrong with your ABS module. Not very likely but it is possible for the ABS module to dump front brake pressure  (this will be very difficult to test for).

 

Then, you have the possibility of failing front brake hoses, it would have to be a dual failure so that makes it less likely but sure is possible under the right circumstances. You would have to have an internal hose liner failure causing it to act as a check valve (this would cause the front brake to drag due to trapped fluid pressure). Then you would also have to have a very soft degraded hose that bulges as you apply the front brake lever to give you that spongy lever feeling.  You might be able to feel this if you have someone apply the front brake lever as you feel along the front brake hoses for expansion or bulging as the brake lever is applied.  This probably wouldn't put your ABS light on at startup or as you ride away but might put the ABS light on after the first hard stop.

 

One more vey low probability issue,-- any chance that the brake fluid in the front reservoir in on top of the rubber bladder rather than under it???? Not real likely but it is possible to do that. (way more likely on the rear though)

 

If the bike is laid up for this riding season than you might disassemble & clean the front master cylinder including the internal piston & cups. (if internal corrosion is found then replace the master cylinder). You might also just bite the bullet &  proactively replace the rubber brake hoses as your motorcycle is old enough to have degraded brake hoses.  

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dirtrider
8 hours ago, Thomasskin said:

My ABS failed at 10K. It was in heavy traffic, rush hour and luckily I'm a big guy and could stand on that brake.  I swear the electrical system in these bikes was designed by mice, good luck.  You can send out your ABS and have it rebuilt, way cheaper then new one.

2002 R1150RT

 

 

 

Morning Thomasskin

 

You have an 1150 BMW with the I-ABS (EVO) brake system, AviP  has an 1100 BMW with the older ABS-II brake system. The braking systems operate differently as his  1100 doesn't have the Wizzy power assist brakes that your 1150 bike does. 

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AviP

Thanks to all. It will be a while before I get into the brakes, but I will resurrect this thread when I do. I will switch to SS lines, disassemble and clean the entire system and report back any findings. Thanks again.

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RK Ryder

I maybe too anal,  but I change the brake fluid on my K100RT and R1100RT every spring before their first rides of the season.  Five years seems like you might possibly be over extending the fluid's effectiveness. 

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dirtrider
11 minutes ago, RK Ryder said:

I maybe too anal,  but I change the brake fluid on my K100RT and R1100RT every spring before their first rides of the season.  Five years seems like you might possibly be over extending the fluid's effectiveness. 

 

Morning  RK Ryder

 

You might want to give some thought to changing your brake fluid in the fall before storage, contaminated brake fluid actually does more damage during storage than when riding due to the inactivity of the system with no fluid movement.  

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dan cata

I bet it's the screw that links the lever to the piston, nr 7 here

 

image.png.26ffe12e83a182e7857d16f764d59aa8.png

 

It might have tightened or loosened over time, making the brake feel like it is sticking.

 

Dan.

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AviP

Thanks Dan. But I'm pretty sure it's not the screw. There just was no pressure when I pulled in the lever. It moved back (manually) effortlessly without sticking, after I stopped.

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Lowndes

AviP,

 

When you disassemble and clean your brake systems don't neglect cleaning the calipers.  There are drilled passages that collect crud and any decomposing brake line chunks.  These passages cannot be cleaned without removing the pistons and blowing air thru all these passages. 

 

The calipers are at the bottom of the hydraulic system where contaminants and crud will sink to.  Also, the pistons and passages inside the calipers are a "dead end" in the hydraulic system, i.e. if you blow air into the brake line it will "short circuit" out of the bleed nipple port (next to it) and not reach the passages and pistons.

 

There are two ways to to thoroughly clean the internals of the calipers, 1)  the "book" way - removing the pistons one at a time while shimming the other three (to prevent them from extending) and blowing air from the brake line port thru the open cylinder; and 2) split the caliper, remove the pistons, clean and inspect everything, and reassemble. 

 

All the manuals emphasize NOT splitting the calipers but that's what I did.  I'd think it's a liability issue because the calipers are simple as a C clamp; 4 bolts and an O-ring.  Below are the pics of my calipers:

 

chttps://photos.app.goo.gl/kN8PyDxEirl9iVS02

 

 

 

 

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MarinPhil

First things first. Doesn’t matter that it has 35k.  Its 20 yrs old, those rubber brake lines are old, rotting, expanding with pressure, and ready to rupture.  Replace with braided steel lines like the ones from Spiegler.  That done, your problem might be solved.  If not, thats one thing you needed to do anyway. 

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Lowndes
11 hours ago, MarinPhil said:

First things first. Doesn’t matter that it has 35k.  Its 20 yrs old, those rubber brake lines are old, rotting, expanding with pressure, and ready to rupture.  Replace with braided steel lines like the ones from Spiegler.  That done, your problem might be solved.  If not, thats one thing you needed to do anyway. 

 

Heed his words, it's no fun being caught a long way from home with either no brakes or a locked-up wheel.  AMHIK.

 

The brake lines are a well known problem on the old "rubber" lines and it's the AGE, not the miles that destroy them.  And not just on BMW's.

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RK Ryder
On 10/10/2019 at 8:41 AM, dirtrider said:

 

Morning  RK Ryder

 

You might want to give some thought to changing your brake fluid in the fall before storage, contaminated brake fluid actually does more damage during storage than when riding due to the inactivity of the system with no fluid movement.  

Thank you for the advice. My thinking was that at the beginning of riding season would give me the freshest brake oil. Apparently I was wrong and I thank you for bringing this to my attention. If tomorrow's weather holds here in the North, I'll be changing the engine, transmission and rear drive oils on my R and K and parking them for the winter. The brake fluid sometime soon, before Christmas, on the R1100. The K is getting Spielger lines in early January, which is when its' fluid will be changed. The rest of the servicing is scheduled for January.  On the bright side, brake bleeding will be one less task to complete in the spring.

 

Cheers!

 

Paul

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dan cata
On 10/18/2019 at 7:10 PM, AviP said:

Thanks Dan. But I'm pretty sure it's not the screw. There just was no pressure when I pulled in the lever. It moved back (manually) effortlessly without sticking, after I stopped.

 

So what was it in the end? When I was riding my RT trough Serbia, that screw loosened and I had no front brake, figured that out while riding :D and it was pretty scary.

Last night I managed to install metal lines on the bike, I guess it was time after 23 years of service.

 

Dan.

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AviP

So back to resurrecting this thread. I've begun major maintenance on my R1100RT starting with new tires, oils and filters. I've purchased a set of Galfer SS lines and was planning on cleaning the calipers while the brakes are dismantled. Should I be replacing the 20-year old seals on these calipers. I looked for the parts online and pricing seems to be kinda high for the rebuild kit. Do I need 1 or 2 kits for the front calipers? Any alternative suggestions would be appreciated.

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Lowndes

AviP,

 

I found all the "seals" in my '99 R1100S calipers to be in "as new" condition, as opposed the brake lines.  The only "seals" in mine were a square-section O-ring between the caliper halves and two different "piston rings" around each piston.  All of mine were in pristine condition, reinstalled, and still in use.  I would recommend that you do each half of each caliper separately, so as to not get the parts mixed up. There are TWO different size pistons in each caliper half.  I did not remove the seals but left them in place and just wiped them clean.  I never found the torque values for the caliper half bolts but used values from same diameter bolts in aluminum, I forget what values I used.

 

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AviP

Thanks Lowndes. I'd hate to spend a couple of hundred bucks on seals. I'll also try and reverse engineer the torque specs and post them eventually. And your photos are awesome.

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AviP

Some updates. The main front hose line that goes down to the split block had a slight bulge on one side and I'm hoping that was the source of my failed brakes. 

 

I also reverse engineered the torque specs on the front caliper bolts by going upwards from 5, 10, 15, 20, 25 ft-lbs and they are somewhere between 20-25 ft-lbs for each of the 4 bolts. I verified this on 6 out of the 8 bolts on both calipers, while 2 seemed to be inconsistent (loose).

 

I've now completely disassembled and cleaned the calipers. All the seals looked in excellent condition as were the pistons. All the passageways were blown clean. Assembly was done with fresh DOT4 fluid.

 

As I mentioned earlier, I was going with Galfer SS lines. The fuel tank is out as I'm doing the fuel filter as well so I have access to the ABS unit. Can I bleed the ABS unit at home or is this a dealer-only job. What is the process of bleeding the ABS unit?

 

TIA

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dirtrider

Afternoon AviP 

 

Some updates. The main front hose line that goes down to the split block had a slight bulge on one side and I'm hoping that was the source of my failed brakes. -- Could be as a bulge could be indicating an internal hose liner separation therefore forming a sort of soft check valve. 

 

I also reverse engineered the torque specs on the front caliper bolts by going upwards from 5, 10, 15, 20, 25 ft-lbs and they are somewhere between 20-25 ft-lbs for each of the 4 bolts. I verified this on 6 out of the 8 bolts on both calipers, while 2 seemed to be inconsistent (loose).-- This not a reliable way to verify an original bolt torque as the tightened-bolt break-away torque is usually a fair amount higher than the original torque was. Best way is to mark the bolt head for position, then loosen the bolt, THEN retorque the bolt back the original marked position. Now that you have moved all the bolts, -- at reassembly  you might toque to lower spec than you indicated (measured break-away torque)  then allow to sit for a while, then see what the break away torque is to tighten more (probably be higher than you actually torqued to)  

 

I've now completely disassembled and cleaned the calipers. All the seals looked in excellent condition as were the pistons. All the passageways were blown clean. Assembly was done with fresh DOT4 fluid. -- Good, that is now verified.

 

As I mentioned earlier, I was going with Galfer SS lines. The fuel tank is out as I'm doing the fuel filter as well so I have access to the ABS unit. Can I bleed the ABS unit at home or is this a dealer-only job. What is the process of bleeding the ABS unit? -- Pretty easy to bleed at home, just bleed as conventional brakes but also bleed at the ABS module bleeders then go back & re-bleed the system at the calipers again. Your ABS-2 system can sometimes be a bit of a frustration when starting with an empty system but usually an initial bleeding (calipers & ABS module) then riding the bike a bit, then re-bleeding at calipers & ABS module  will get all the air out. 

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AviP

Dirtrider, thanks for the insight on the torque and the ABS brake bleed. I will be patient and diligent.

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Warren Dean
5 hours ago, AviP said:

Some updates. The main front hose line that goes down to the split block had a slight bulge on one side and I'm hoping that was the source of my failed brakes. 

 

 

I spent 26 years as an auto mechanic and have seen brake lines rupture internally and create  a blister like you describe and it held pressure on the caliper. Sounds like that is waht happened to you.  SS line are the fix, I suppose

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