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'97 R1100RT ABS exercising


Warren Dean

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The other morning, I started my scooter and when I took off, I didn't hear the ABS "jingle" and the lights were flashing. It was 29 F outside so I just wrote it off to a low voltage fault from start up. Sure enough, that afternoon when I headed home from work, the lights functioned as normal. No problem. 

Except that it happened again on the next 2 trips to work. The bike lives in a garage, so the temp isn't as cold as outside. I then remembered reading something about exercising the ABS occasionally, ostensibly to keep fluid moved around and not stagnating in one spot. So I initiated a couple of ASB stops, which I had never done on a motorcycle, and the system apparently worked. However, all I heard was a hissing sound and initially thought it was the rear tire sliding. 2 days and no ABS light issues, so i assume that it is "fixed".

 

Is this hiss that i heard the normal sound of an ABS event? Not a big deal but I am curious. All of my experiences with ABS events are car related and were much more pronounced than what I heard and felt on the bike.

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Hard to "hear" what you did with a post, but, yes that seems like a typical ABS2 engagement.  I seriously doubt that it "fixed" your low voltage error.  Only warmer temperatures or a new battery will do that.

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1 hour ago, Warren Dean said:

The other morning, I started my scooter and when I took off, I didn't hear the ABS "jingle" and the lights were flashing. It was 29 F outside so I just wrote it off to a low voltage fault from start up. Sure enough, that afternoon when I headed home from work, the lights functioned as normal. No problem. 

Except that it happened again on the next 2 trips to work. The bike lives in a garage, so the temp isn't as cold as outside. I then remembered reading something about exercising the ABS occasionally, ostensibly to keep fluid moved around and not stagnating in one spot. So I initiated a couple of ASB stops, which I had never done on a motorcycle, and the system apparently worked. However, all I heard was a hissing sound and initially thought it was the rear tire sliding. 2 days and no ABS light issues, so i assume that it is "fixed".

 

Is this hiss that i heard the normal sound of an ABS event? Not a big deal but I am curious. All of my experiences with ABS events are car related and were much more pronounced than what I heard and felt on the bike.

Afternoon Warren

 

Your  BMW 1100 ABS-II system is different than any automobile that you have driven. It is a piston displacement type system so is slow responding, somewhat noisy, & doesn't give the rider much feedback as to what it is doing.  (there is also no pedal kicker with the ABS-II system so no feedback into the foot pedal or hand lever). 

 

As for the noise?-- Depends on what part of the system you heard, when in an ABS event the shaft motor kicks in spinning a shaft, next the displacement piston clutches engage/disengage to allow the spinning shaft to pull on chains to move the pistons therefore controlling the braking pressures (slow reacting system). Pick your noises from all those things.

 

As for exercising the ABS system to move fluid through it. That pretty well happens every time you use the brakes as the ABS-II is a pass-through type system so fluid passed through it when using the brakes. That rurrrrupp that you hear on every few ride-aways is the system re-acquiring the piston positions so it sort of self exercises the internals every few ride-away's.

 

Your exercising the  ABS isn't the reason that your low voltage flashing lights went away, the flashing lights went away due to higher battery voltage during engine starting  (warmer weather, or quicker starting engine, or motorcycle didn't sit as long between starting's, or battery is higher due to riding motorcycle, or ???).  Those flashing lights will probably return during engine starting in colder weather or after the motorcycle sits for while between rides.  

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33 minutes ago, dirtrider said:

 

As for exercising the ABS system to move fluid through it. That pretty well happens every time you use the brakes as the ABS-II is a pass-through type system so fluid passed through it when using the brakes. That rurrrrupp that you hear on every few ride-aways is the system re-acquiring the piston positions so it sort of self exercises the internals every few ride-away's.

 

 

DR,

 

Thanks for that. I was unaware of how the system worked. Now I are smarter.  :) :) 

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9 minutes ago, Warren Dean said:

DR,

 

Thanks for that. I was unaware of how the system worked. Now I are smarter.  :) :) 

Afternoon Warren

 

Don't stop testing the ABS system though as the more you use it the less likely that you will be surprised or startled by it if/when it suddenly kicks in during an emergency situation  stop. 

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DR, way back when ABS systems first came to the auto world....did anyone use a system similar to Warren's & my ABSII ?

I remember ABS in snow country extending my stopping distances while cycling through it's routine. A locked wheel stops pretty quick other than steering (cars) and falling over (bikes). I ask because I once had a bad ABS driveway experience with 3 cars and my garage. Chevy Astro van and clunky snowmobile boots in case you're interested.:4607:

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1 hour ago, dave_a said:

DR, way back when ABS systems first came to the auto world....did anyone use a system similar to Warren's & my ABSII ?

I remember ABS in snow country extending my stopping distances while cycling through it's routine. A locked wheel stops pretty quick other than steering (cars) and falling over (bikes). I ask because I once had a bad ABS driveway experience with 3 cars and my garage. Chevy Astro van and clunky snowmobile boots in case you're interested.:4607:

Evening Dave

 

Not that I am aware of any on  U.S. vehicles, possibly something in Europe tried using that piston system early in the ABS days. 

 

Your early ABS system could have been an early RWAL ABS system that only effected the rear brakes & used a single common wheel speed sensor on the differential. (if either rear wheel locked it released both rear brakes). It basically made you hit whatever you were going to hit front first instead of side first. 

 

ABS has it's place as it can improve stopping on most surfaces for most people but it is sometimes quite lacking on loose surfaces like gravel or somewhat deep snow.  On loose surfaces it does help to keep you pointed straight & allow some directional control but  with no wheel lock-up you loose the piled build-up of gravel or snow in front of the locked tires so the vehicle just skips along as the ABS continually releases the braking to prevent lock-up. Personally I hate motorcycle ABS on loose dirt or gravel as I loose that second (sometimes more important) steering input of braking wheel position control).  

 

Going down a very steep loose-surface hill on a motorcycle with ABS it a real  commitment as there is virtually no braking as  the ABS tries to keep the wheels spinning so no pile of anything in front of tires so it is just a free run-out going down the hill.     

 

 

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13 hours ago, dave_a said:

A locked wheel stops pretty quick other than steering (cars) and falling over (bikes).

 

Sorry Dave, I can't agree with you there. Once a wheel stops rotating and slipping, it is not slowing you down as quickly as a wheel that is retarding you up to the point of skidding. The coefficient of friction reduces so it takes longer to stop.

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15 hours ago, dave_a said:

A locked wheel stops pretty quick other than steering (cars) and falling over (bikes).

Have to agree with Andy on this one.   Locked wheel skidding does not produce the shortest distance to dead stop.

 

Before I had a motorcycle with ABS, I would practice hard (panic) stops several times a year.   I found I would have shorter distances to dead stop with the front tire howling on the edge of skidding but both wheels wheels still rolling. When I would over modulate and lock the wheels up, I would overshoot my shortest distance reference every time.  However, even the slow response of the ABS-II is still better than no ABS because in real life the road surfaces can be variable and it takes a ton of concentration away from actually driving when managing hard braking.

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