Servo & ABS.... I've been thinking

[Wraithwrider]

I've been pondering the whole design issue centrered on the ABS/Servo brakes on my GS.

I haven't got the technical information to back this stuff up so would value any factual input.

It's all a bit chicken and egg really. Now WHY do BMW NEED to have servo brakes?

Let's start with ABS (I said it was chicken and egg). ABS works by sensing when the wheel is about to lock up and then momentarily releasing the brakes.

Fine, so how about making it safer by not, ever releasing all the hydraulic pressure but merely just the servo assistance? That should work.

Okay so we have Servo assistance to allow us to have ABS - (it makes sense to me).

We also need to make sure that the relative efficiency of Servo assisted brakes compared to the the same system without servo assist is large, such that loss of servo assist seems effectively like releasing the brakes.

Ha! Therein it seems lies the problem.

Well that's my take on it anyway, Servo added to enable ABS not to give more powerful brakes, because we know that we don't need servo assist on a bike.

 

[Kropotkin]

That's a very interesting thought. The only thing I can think of is that it might feel VERY weird in the lever, if you see what I mean. Also, there is no guarantee (especially not in an emergency situation, where the rider has just panicked and gone BANG! and grabbed a handful of brakes) that the braking would be any less just because the servo cuts out. It think it would work in most situations, but I would be afraid that paradoxically, it would not work when you need it most, in an emergency situation.

It would be a very elegant solution, though....

David

 

[Wraithwrider]

David

My intended point was that that is what the BMW design team have really done. i.e. introduced the servo as a solution to ABS not as a means of improving braking in itself.

Peter aka

 

[ELIMINATOR]

Does it matter!!!! If as it did with me, the pump dies without warning!

 

[Wraithwrider]

Does it matter?

If it helps understand their thinking process and the reasons for the existing system then, IMHO, yes!

 

[[email protected]]

there is no need for servos for abs braking systems. the honda abs on vfr800 motorbikes comes without servos, but with much better performance.

the 'thinking process' is marketing. they sold a pseudo-innovation.

similar to the SBC brake from mercedes. mercedes will eventually drop SBC brakes, and BMW will definitly drop servos.

it's the same structure: nobody needs SBC oder servo-brakes.

 

[Jimb]

I have ABS on My 52 1150GS but not the servo ones, the version before, so that would lead me to the conclusion its not to do with the ABS.

It was on The RT for a long time before being offered on the GS and I don't remember lots of posts on the subject from the RT riders, maybe it was differnet on that model.

 

[Paul Wakefield]

ABS has been available on BMs for years but servo assistance only for 2/3 years so I don't think this is the reasoning. Interesting thought though.

BTW, there is a K1200 owner in the pipe & slippers mag this month complaining about brake failure.

Paul

 

[CoolCarbon]

ABS has been on BMs since the Eighties.....The first time I rode one on a test track, it was interesting to feel the slight pulsing coming back through the lever and the sensation of the front of the bike lifting back up despite continued pressure on the lever ....

The Servo is, I believe, Bm being Bm....

More to go wrong...IMHO, when I last washed the bike, I put in the garage and noticed that the servo was whinning even though I wasn't on the brakes and the brake light wasn't stuck on...and there was no pressure in the system, I could push it easily!

I put a fan infront of the bike to dry it off overnight....tried again the following day fully expecting to have to get it booked in for some warranty work....it had stopped ...must have been water in something....but it just shows that there is the potential for more to go wrong..

CC

 

[Mouse]

Wraithwrider - interesting thought, but I don't think you're right. Because, as I understand it, there is a seperate ABS pump in the braking system. If ABS was implemented by releasing servo pressure, this pump would not be required.

Of course, I could be wrong

 

[Steptoe]

As others have said - ABS and servo's are two seperate things -

be doing as suggested, cutting off the servo instead of the abs, is just adding more complexity, the abs system doesn't have the problem, its the servo system that is giving all the problems.

Since when the ABS system was first introduced ( 1988), there have never been any problems.

I can't understand people saying " i've never had a problem, so i'm alright " ---- yes you will be . Till you have the problem.

if it was a car having all the reported problems, they would have had to have a recall by now.

After all, its brakes, not a minor problem .

Glad i've got "normal" brakes with ABS, and can just sit and watch the outcome.

 

[[email protected]]

Need a copy...

BTW, there is a K1200 owner in the pipe & slippers mag this month complaining about brake failure. Paul

I would like to get a copy of the article if possible. I do have contact with about 10 drivers (K1200LT) with diffrent brake problems, that cannot be reproduced (no errors in the log).

It might be useful for them to get the attention from BMW.

---> [email protected]

OH

 

[Spanish Bob]

Re: Need a copy...

I would like to get a copy of the article if possible. I do have contact with about 10 drivers (K1200LT) with diffrent brake problems, that cannot be reproduced (no errors in the log).

It might be useful for them to get the attention from BMW.

---> [email protected]

OH

then go to the UK BMW club and ask for one or join the club.

http://www.bmw-club.org.uk/

there you go, another bunch of bikers you can terrorize.