Understanding ABS operation - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 22 Old 06-20-2018, 05:00 AM Thread Starter
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Understanding ABS operation

So the majority of us know (or think that we know) about the advantages of ABS, right, and how the bleeding of ABS brake lines can be a major pain in the butt, but how many truely know how ABS works physically and electrically?
My question comes from reading a thread on Strom 650 2017 ABS brakes, where the poster (2017Vrider181) writes: 'Hi stromers, d'like to know if one of you have found a way to disconnect the rear abs brakes, keeping the front abs working. I really don't like the way the rear brakes work in the trails. I'd really like to stop the rear wheel when i'd like to. I know I can remove a fuse in the ABS module and then both front and rear brakes abs disengage. But is there a way to only disconnect the rear abs brakes."
There are a few threads on this site (eg https://www.stromtrooper.com/v-strom-...ff-switch.html) and the VSRI site (eg Proper ABS on/off switch) of mods / ideas to switch off the ABS as a complete unit.
So after looking at a possible solution for switching off ABS to selected wheels, I started by looking at an earlier model DL650A wiring diagram. I saw that the sensors have connectors that could be a possible disconnecting point. Then I thought, since the ABS only activates above 5 mph, the ABS unit may see the disconnection of the connector as a wheel locked and try to pulse the brake caliper, which is not what is being sought.
Reading https://www.vicroads.vic.gov.au/safe...on-motorcycles gives some back ground to ABS purpose, but does not explain everything. Hopefully with your help readers will give a better understanding, that the members can use for future reference?
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post #2 of 22 Old 03-21-2019, 12:34 PM
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I've read on here where if the differential is too large between front and rear wheels, something happens with ABS. Don't remember if it's activate or deactivate. I am going to assume that if there is NO differential, ABS is none the wiser and continues to function normally. I was thinking one method to fool the system would be to install a switch that intercepts and cuts the sensor signal from the rear wheel and replace it with the sensor signal from the front wheel so both receivers would be getting the same signal. Then realized that works until you lock the front brake. The system would then release both brakes. I do think, though, that sensor signal manipulation might allow more alternatives than switching the fuse to disable the entire system.

Does anyone know what differential threshold triggers the ABS to take action?
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post #3 of 22 Old 03-21-2019, 12:54 PM
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On fooling the ABS, or defeating rear brake easing

It is a bad idea to feed the ABS computer's two wheel speed inputs from the same sensor. Doing so will make the ABS non-functional because it relies upon sensing the beginning of lock-up on one wheel, relative to the other, so that it can determine which brake should get reduced pressure. Without that differential appearing when a wheel begins to slow (while the other continues at "full" rotation rate), the ABS will never activate and will be useless.

Disabling the rear brake release actuator might be useful, or not. Most likely not because when that actuator would do something, the rear wheel is slipping and can no longer provide a good reference speed for sensing that the front wheel is slipping. The ABS could become merely useless, or maybe worse. (I would have to know its fault detection algorithm better to decide.)

When the wheel speed differential becomes too great while no brakes are applied, the ABS disables itself and turns on the yellow panel indicator to warn the rider that the ABS is not going to function for the rest of that engine-on cycle.
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post #4 of 22 Old 03-23-2019, 02:56 AM Thread Starter
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The worrying factor about ABS is when is it going to let one down, when a person totally comes to rely on this feature.
I have seen some drivers barrel down to an intersection only to hit the brakes at the last minute. I've noticed witnessed these drivers, a few times, not only here locally, but when I was driving abroad as well.
There have been a few threads posted of ABS pump failure on the V-Strom and other brands. Some say that it is due to the ABS not being activated / tested on a regular bases.
I believe that ABS has it uses, when it doesn't fail, they work well on my cagers. After riding bikes for so many years without ABS, I think that I'll remain with my non-ABS rides for a while longer...
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post #5 of 22 Old 03-23-2019, 09:31 AM
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On my G650GS BMW there is a switch to turn off the ABS for dirt riding. The rear brake is like my 800ST BMW on the street in ABS operation...it feels like a hammering when engaged. Not a good, positive brake feeling. Not sure you'd want the front wheel ABSing in the dirt with the rear locking up.
Different systems on different models, the ABS always felt good on my '01 R1100RT-P
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post #6 of 22 Old 03-28-2019, 01:11 PM
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Quote:
Originally Posted by Gert View Post
The worrying factor about ABS is when is it going to let one down, when a person totally comes to rely on this feature.
I have seen some drivers barrel down to an intersection only to hit the brakes at the last minute. I've noticed witnessed these drivers, a few times, not only here locally, but when I was driving abroad as well.
There have been a few threads posted of ABS pump failure on the V-Strom and other brands. Some say that it is due to the ABS not being activated / tested on a regular bases.
I believe that ABS has it uses, when it doesn't fail, they work well on my cagers. After riding bikes for so many years without ABS, I think that I'll remain with my non-ABS rides for a while longer...

Assuming that there isn't an ABS warning light (on the dash) how would one know if it's functional?

Other than practicing panic stops and deliberately activating the ABS it should never come on in normal riding.

It's been proven over and over that ABS stops a bike faster than even a highly skilled rider can without ABS. Mere mortals definitely benefit from having ABS.
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post #7 of 22 Old 03-28-2019, 01:53 PM
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LOL, we had a rider in our club on his '05 Yamaha R1 that said he could out-brake an ABS-equipped rider every time.
I didnt know that was a contest. Funny, he had more than his share of wrecks than most.

When I attended Subaru ABS training and a BMW motorcycle ABS demo-rides, the emphasis was not on how it braked faster with ABS--the main deal is that a locked wheel can't be steered. By allowing the wheel to be steered with controlled, pulsed braking, steering control was retained.

At Subaru, we went out on a parking lot, rolled out a 100'+ length of vinyl mat and hosed it down, then sprayed dishwashing liquid over the water. As per instruction, I picked up speed in a Legacy sedan to 50 mph, hit the mat an slammed on the brakes. The car went sideways, slid back and forth, finally got it to a stop well beyond the mat. The next Subaru I tried had the then-new Bosch 5.3 ABS system. Same deal, except the car stopped on the mat straight and sure with no drama except for the normal pedal pulsation that occurs during ABS operation.

The main issue people had with ABS was 1) the pedal pulsations freaked them out, to the point where: 2) they let off the pedal, which stopped the ABS operation....and they lost control and crashed.

Yes, ABS cars do stop in a shorter distance, hence possibly quicker, but the main purpose is to allow the operator to maintain steering control.

I'm waiting for the day where, on motorcycles, the ABS unit will activate ABS regardless of brake application in the event of following too closely based on a radar sensor signals, or the operator isnt on the brakes in time to prevent an accident.
My '19 Mazda CX-5, and many more cars these days are so equipped---and twice now I've had the "pleasure" of experiencing this system do its thing.
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Last edited by MAZ4ME; 03-28-2019 at 04:20 PM.
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post #8 of 22 Old 03-28-2019, 03:33 PM
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(I'm not contradicting previous posts on ABS virtues.)

A very important benefit of having a (well designed and working) ABS is that, when brake pressure is high enough to activate the anti-lock easing, it effectively gives the rider very close to the maximum available stopping traction, on each contact patch independently, for the roadway conditions at each contact patch. I am pretty sure that the demos we can see, where some expert rider out-stops an ABS equipped bike, are done on a track with very consistent pavement texture and wetness, and done with the rider having had enough practice under those conditions to know how hard each brake can be applied. This is nothing like what we experience out in the wider world, where some portions of pavement may be slightly oily, some dry faster than others, not-quite-visible debris can be present, often in short stretches, and the pavement changes with rework, application batch, etc.

I practice maximal braking stops without the ABS, to be sure that I remain skilled enough to handle an ABS failure. But when somebody violates my right-of-way and it is time to slow quickly, and my attention is on several things beyond the degree of slide at each contact patch or pavement conditions along my chosen evasion path, I am glad to have a fast-reacting ABS computer giving me nearly all the stopping force that is actually available, even as conditions vary along my slowing path. Add to these complications the fact that I may need to execute a slight turn at the same time, and the benefit increases further. I find it very difficult to believe that such scenarios could be improved upon by a more skilled rider. (And, even if such a super-rider exists, he cannot take my place when my life or limb is in jeopardy.)
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Last edited by Trepidator; 03-28-2019 at 03:33 PM. Reason: spelling
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post #9 of 22 Old 03-28-2019, 09:43 PM
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When I was a younger man I did a advanced driver course, I was the youngest in the group and was fist to be picked on.

I was told drive down the hill, lock the brakes up then steer between the red cones and stop in the box.

It was fully expected I would just skid straight ahead and skittle all the cones.

I did not, after locking the brakes as required and washing off some speed I manoeuvred around the cones and came to a stop in the box.

The instructor asked if it was first time at a driving course ? "yes", who taught to drive ? "my dad" where did I learn to drive ? "in a state forest" BINGO he said....

Learning to drive in the dirt as a young fella had given me skills I never knew I had, a inbuilt ABS.

In the dirt you quickly learn that panic braking will cause more problems than it will solve.

I give a lot of my time to young kids that visit Rolex teaching them to ride and drive, a skill I believe has kept my alive all these years and will help them survive into the future too.
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post #10 of 22 Old 03-29-2019, 06:10 PM
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Quote:
Originally Posted by Gert View Post
The worrying factor about ABS is when is it going to let one down, when a person totally comes to rely on this feature.
I have seen some drivers barrel down to an intersection only to hit the brakes at the last minute. I've noticed witnessed these drivers, a few times, not only here locally, but when I was driving abroad as well.
There have been a few threads posted of ABS pump failure on the V-Strom and other brands. Some say that it is due to the ABS not being activated / tested on a regular bases.
I believe that ABS has it uses, when it doesn't fail, they work well on my cagers. After riding bikes for so many years without ABS, I think that I'll remain with my non-ABS rides for a while longer...
In general, the ABS system will extend your breaking distance. ABS is intended to prevent loss of control by trying to keep the tires rolling instead of sliding.

I thought it was interesting that on Suzuki's website product page for the 2014 DL1000A, the text warning about the increase in stopping distance was 2 to 3 times longer than the text touting its virtues. Even the current lean sensitive ABS still bears a "black box" warning paragraph front and center that is about 1/3 the size of their entire sales pitch...
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Last edited by Grimmer; 03-29-2019 at 06:51 PM.
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