ABS switch: turn off front and rear serparately?

Discussion in 'The Perfect Line and Other Riding Myths' started by glasswave, Jun 18, 2013.

  1. glasswave

    glasswave Been here awhile

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    I am thinking of rigging an abs off switch on my 2012 dl 650 strom. This is done by rigging a switch break the electrical connection near the fuse box. I believe the 2012 has separate fuses for front and back.

    I am wondering about the wisdom or lack thereof in rigging separate switches for both front and back. It seems as tho' most of the complaints with ABS off road are about the back brake losing all effectiveness on a steep down hill.

    Logic seems to say that it may be useful to have the front abs on an the back abs off at times. This way one could lock his rear if needed, w/o being afraid of a front lock up and wash out if he accidentally applied too much front brake.

    Thoughts?
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  2. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Huh and why? The purpose to turn off the ABS off road has to do with loose terrain. ABS works by sensing wheel speed differential during braking. If the surface, like gravel, dirt, mud, can "pile up" in front of a braked tire, the ABS may try to release brake pressure to keep a tire from sliding. But, if the "pile" in front of the tire keeps the wheel sliding, it can trigger a fault in the ABS controller.

    Switiching off one part of the systm likely isn't gonna work. ABS systems work by comparing actual wheel speed against the vehicle "reference" speed. That means the vehicle reference speed is calculated by the ABS controller based on data it gets from each wheel speed sensor. If one speed sensor is not inputting data to the controller, it cannot calculate the refernce speed. The ABS control engages when an individual wheel speed is sensed to be turning slower (by 10 to 20%) than the vehicle reference speed. Newer ABS systems may also integrate wheel speed data with an electronic signal from the speedometer.

    Now, IF the ABS system on your V-Strom also gets an electronic vehicle speed signal from the speedometer, or final drive, or a pulse wheel in the tranny, then it MIGHT work on one or the other wheel speed sensors with the other speed sensor turned off. If the V-strom does not feed the speedometer data into the ABS controller then it probably will not work and you'll generate an ABS fault code when both wheel speeds are not feed into the ABS controller.

    More than likely, if the ABS controller does not get wheel speed info from both sensors it will trigger an ABS fault and shut the whole system down. Also, some faults can only be cleared by the dealer. Some faults, when the signal is regained, will allow the ABS to reactivate.
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  3. duck

    duck Banned

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    I once owned a bike (K100RS4V) where a previous owner had removed the ABS from the rear wheel and replaced the rear modulator with a brake line. Not sure why the PO did it through. Maybe he had slick dirt driveway or something.

    The bike did have both front and rear ABS sensors though.

    I took my K1100RS on a very silty road in The Sierras one day. The result was that the ABS completely disabled both the front and rear brakes and the only way to slow the bike was using engine braking. It was very strange riding a bike that had no brakes.:eek1 (It was a level road and, since I knew I didn't have any brakes, I rode pretty cautiously.)
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  4. Aj Mick

    Aj Mick Been here awhile

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    Illogical if you ask me. But I have yet to operate any vehicle, 2 or 4 wheeled, with ABS.

    A case against ABS, maybe.

    KISS (Keep It Simple, Stupid) tends to be my philosophy, and the bikes (and cars) I have owned have owned have all been quite basic. ABS seems to be just adding complication.
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  5. khager

    khager Long timer

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    I believe the two fuses are for pump & motor, not front & rear. At any rate I think it would be nice to disable the rear only while in the dirt, hell sometimes it would be nice to slide it on the street too.:freaky
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  6. Midnullarbor

    Midnullarbor Been here awhile

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    Fortunately, the Vstrom ABS is simpler and more "resilient" than the K1100's, and will work well as Non-ABS when the electronics have taken a holiday.
    The front ABS is also quite useful, for grip-monitoring purposes ~ newly-rained-upon bitumen [is it wet but grippy, or wet plus slippery film?] or a new stretch of dirt road [is it as dry and as grippy as it appears, or is there more underlying mud than expected?] can be tested to some extent by a dab on the rear brake . . . but the ultimate testing comes from measuring the front wheel's grip : a matter easily & fairly safely assessed by a quick grab of braking up to the point of ABS flutter. Very informative.

    Having a separate, "partial" ABS is a grand idea, if it can be done.

    Does the Dl650 ABS computer require input from each wheel's rotation speed in combination, or separately? Or will it be confused by a locked-up rear wheel?

    If you cannot find a definitive answer to that, then you may well just have to experiment by disconnecting the rear wheel input and seeing whether the front ABS works normally . . . or works with reduced sensitivity/ effectiveness (or not at all).

    Good luck. I'll be interested to hear how it works out.
    As you say, a good system with front-ON / rear-OFF ABS setup would be ideal for *most* riding on very loose surfaces. [Preferably a system that defaults back to both-ON, when you next re-start the bike.]
    .
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  7. viverrid

    viverrid not dead yet

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    On a STEEP downhill (in the dirt) the rear brake already has almost no effectiveness. MY gripe about ABS in the dirt is that in loose material the ABS prevents the FRONT brake from being effective. That's where all the braking power is.

    My 990 Adventure has ABS and I wish it could be turned off more quickly/simply on the fly, for when a hardpack dirt road turns loose. The ABS on the rear could be useful to prevent lockup and stall, if I could turn off one in the dirt on a heavy bike, it might be the front.
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  8. duck

    duck Banned

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    If the ABS control unit on a K1100 takes a shit (faults) then the K1100's brakes just revert to being like non-ABS brakes since a faulted control unit won't cycle the modulators. The problem I had that day was the ABS (which is designed for street use) was working too well.

    I've considered hooking up a switch to cut power to the control unit but, to be honest, it's a street bike so it's not worth the effort IMO.

    One way you could purposefully fault the ABS brain I think is to spin up the rear on gravel with the front brake keeping that wheel locked. That would make the control unit think the front sensor is bad and put it into fault mode.
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  9. viverrid

    viverrid not dead yet

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    When I had a BMW, I was told that an unofficial way to turn off the ABS on the fly was to briefly turn off the key while in motion. When the key was turned back on, the ABS would be unable to initialize with the bike already moving.

    I never tried it, and have not tried it on my KTM either. I have had one occasion on each bike where I was descending a trail covered in small loose rocks, and having the ABS felt like having no brakes at all, I just COULD NOT slow down. In both cases I would have rather had the front work than the back, the back wouldn't have done jack shit anyway.

    On both, I have had several occasions on somewhat loose dirt roads where the ABS definitely reduced braking effectiveness. But nothing as bad as those times on the trail where conditions were both much looser AND much steeper.
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  10. Offcamber

    Offcamber Long timer

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    Most likely the system will shut down completely and revert to a non ABS system if any part of the system is disabled. You can't really look at it as front and rear ABS....its all one system.

    Side note the ABS on my Super Tenere works extremely well on and off road. I ride on ball bearing gravel roads and the ABS is invisible, stops the bike well without that feeling of sliding or slipping brakes. I think Yamaha got it right....
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  11. Lep

    Lep Been here awhile

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    I'm right out of my experience envelope on this subject so be gentle if this sounds stupid. If ABS prevents good braking when descending a steep slope on a loose surface then why not just turn off the ignition until a firmer surface is reached? With few exceptions brakes on bikes are not power assisted so full braking power would be available and since we are talking about a steep descent there would seem to be no need for engine power at that point.

    What am I missing?
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  12. Offcamber

    Offcamber Long timer

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    Engine braking...
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  13. ongrade

    ongrade Been here awhile

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    Still works, in fact even better because you have no combustion event.
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  14. ongrade

    ongrade Been here awhile

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    Rear brake is very useful for steering on steep downhills. If you can lock the wheel.
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  15. viverrid

    viverrid not dead yet

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    In dirt conditions you might want power one second after you needed braking. Lock it up going down this loose rock chute and then gas it over the log across the trail at the bottom, stuff like that. It can even be lock up the rear to "back it in" on this tight corner, and then gas it out (with no elevation change involved). Even when not "backing it in" I might want strong braking going in, and then gas it out a fraction of a second later.

    I wouldn't want to be trying to restart my engine in that short an interval. I think a lot of street riders don't really understand the rapidity of DIFFERENT edge-of-traction-and-beyond maneuvers that can occur in trail riding. (A dirt road is not a trail.)

    But anyhow, I understand the theory of what you are saying but as a practical matter it's not often useable and would leave me stopped and cranking at the bottom instead of having momentum to begin my attack of the other side of the ravine. It's just not a common technique. If there was a looong descent that let out onto a flat you could do it, but that would still leave you behind compared to having your engine already on and powering out as soon as you are able.

    The times I've encountered it, I just rode it out and was on my way before I could have restarted.
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  16. Offcamber

    Offcamber Long timer

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    Not to the same degree...with the engine off your rear tire will most likely lock up on dirt or gravel, with the engine running it would just add drag without the lock up...A lot depends on the bike what gear you use etc....but I'd wouldn't' be in that situation with the engine off on purpose...
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  17. viverrid

    viverrid not dead yet

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    Yup. There are times when you descend just letting the rear be, in the lowest gear available, no brake no throttle. If you turned off the engine the rear would just lock up. Then you'd have to pull the clutch in to let it roll. Then you'd have a "brake" that didn't modulate very well and that's not what you were going for with engine braking to begin with. Engine braking with the engine running, keeps the rear turning but with resistance to further speed increases.

    You are not trying to STOP the rear, you can already lock it up with a touch of the brake pedal. You are trying to keep it turning but with resistance to further speed increases. The front is where the precise speed control is, and that is where I wouldn't want the ABS. Disconnecting rear ABS alone wouldn't be as useful since I'm not using much if any rear brake anyway. I would just rather it was easier to instantly turn off all ABS, or if it was selectable front/rear would go for front turn-off before rear.
    #17