How does ABS affect my bike?

[Warthog]

Firstly, I know what ABS does.

Secondly, I have the 1150 GS ABS, non-servo.

Thirdly, I know this topics been done to death and thats precisely why I'm NOT doing a search as I'd be reading threads all day and still be none the wiser...

What I want to know is what could happen if my ABS failed? Having read about servo failure and residual braking, I started wondering was aI as free from potential probs as I thought in having the ABS only model. Would I simply no longer have the ABS function or would my bikes brakes no longer bite at all if the ABS is fooled into sticking in the on position? Answers in straight forward language, please: I'm not with it today...

Just the facts, man, just the facts...

 

[Steve]

If the ABS fails, you're braking will be exactly the same. The only difference will be that it will be easier to lock the wheels under heavy braking.

I don't think the ABS can be stuck in the "on" position. When the ABS is "on", the brakes are "off", if you see what I mean.

 

[Llama]

My understanding of ABS is that it detects when the wheel locks and releases the brakes to allow it to regain traction.
If the ABS fails it would not detect the wheel locking and as such wouldnt take the brakes off.
So as Steve says you would simply have 'normal' brakes which you can lock.
On my 12 there is the option to turn the ABS off and it doesnt feel any different in normal use. Doesn't yours have this option?

 

[Possu]

You won't notice any difference between ABS & non-ABS bikes in normal use until/unless you skid or slide. With an ABS bike, you should feel a pulsing at the lever if & when the ABS is activated. Should the ABS fail, it will behave just like a non-ABS bike.

If you have a servo equipped bike & the servo fails, then you'll only have the residual braking. I've heard that the early servo bikes had 20% residual braking but that later bikes had 40% - not sure if this is true though??????

On bikes with both servo & ABS: if the servo fails, does the ABS continue to work? If so, is there enough residual braking to lock the wheels on a reasonable surface?

 

[Timolgra]

On bikes with both servo & ABS: if the servo fails, does the ABS continue to work? If so, is there enough residual braking to lock the wheels on a reasonable surface?

Hey? If there was, you would'nt need a servo

 

[jimbo]

Without a servo, the brakes operate just like any other bike. You squeeze the level, displace brake fluid and the fuild will apply pressure to the pads. The difference is that ABS can release the pressure if a wheel lockup is detected.
I'm not too sure how the servo brakes operate. I suspect its like the brakes I have just been de-bugging on my Range rover. Under normal operation, all the brakes do it to modulate pressure built up in a reservoir by an electric motor. So under normal operation none of the braking force is provide by the driver. If the power system fails then a completely separate system comes into play. In the Range Rover this means that only 2 of the 4 pistons on each front brake operate and nothing at the back. Given the weight of the beast that distinctly scarey
I think the term servo is slightly confusing. A car servo 'assists' the effort of the driver by use of the engines vaccuum in the inlet manifold. I think the BMW bike servo is more like the 'fully powered' system of modern cars; in the car world isn't isn't usually called a servo.

 

[Possu]

Without a servo, the brakes operate just like any other bike. You squeeze the level, displace brake fluid and the fuild will apply pressure to the pads. The difference is that ABS can release the pressure if a wheel lockup is detected.
I'm not too sure how the servo brakes operate. I suspect its like the brakes I have just been de-bugging on my Range rover. Under normal operation, all the brakes do it to modulate pressure built up in a reservoir by an electric motor. So under normal operation none of the braking force is provide by the driver. If the power system fails then a completely separate system comes into play. In the Range Rover this means that only 2 of the 4 pistons on each front brake operate and nothing at the back. Given the weight of the beast that distinctly scarey
I think the term servo is slightly confusing. A car servo 'assists' the effort of the driver by use of the engines vaccuum in the inlet manifold. I think the BMW bike servo is more like the 'fully powered' system of modern cars; in the car world isn't isn't usually called a servo.

With the BMW system, you definitely have less braking if there's no servo, hence the term "residual braking"............. Full braking effect is dependent on the ignition being switched on or the engine running (can't remember which?).

Out of the two, I'd rather have the ABS fail on me than the servo because I'd still have 100% braking.

 

[Cullen]

Firstly, I know what ABS does.
What I want to know is what could happen if my ABS failed?

If you brake too hard when the ABS isn't working you'll skid and probably fall off.

 

[Llama]

If you dont brake hard enough.......


....you just might hit what you were trying to avoid

 

[Gonzo]

Aaaaghhh!!

Click here for the type fo quality debate you can expect on this subject!

 

[Cullen]

If you dont brake hard enough.......


....you just might hit what you were trying to avoid

It all seems awful complicated doesn't it...

 

[Warthog]

I don't think the ABS can be stuck in the "on" position. When the ABS is "on", the brakes are "off", if you see what I mean.

That's what I'm worried about. I don't know if this scenario is possible, but as they say: the more complicated the mechanism, the more can go wrong. Normally, the ABS kicks in to avoid a skid by, as you say, doing a on-off-on-off trick on the brakes, but could the ABS sensor somehow shortcircuit or trip so that this on-off-on-off suddenly just becomes "off" with no "on" following it, resulting in no brakes at all?

Paranoid, I know....my bodyguards keep telling me the same thing...

 

[sjwb]

No, absolutely NOT.
The failure mode for ABS is non intervention.
When an FMEA is investigated, as with all safety related systems, the priority is ALWAYS for the safe state. In other words no short or electrical failure will cause ABS to affect (sic) normal braking.
Please note I am not refering to servo or any other assistance.

 

[Cullen]

I think we should get Dr ABS(hole) in to clear all this up for us...

 

[Warthog]

No, absolutely NOT.
The failure mode for ABS is non intervention.
When an FMEA is investigated, as with all safety related systems, the priority is ALWAYS for the safe state. In other words no short or electrical failure will cause ABS to affect (sic) normal braking.
Please note I am not refering to servo or any other assistance.

Phew, glad to hear it.

I think we should get Dr ABS(hole) in to clear all this up for us...

Who he?