Servo-assisted brakes

[QUOTE=Andy VH;472250] This is especially true on lower speed stops on gravel, when the gravel "piles" in front of the tire and acts as a dam to stop the tire. ABS cannot always respond without some tire slide. Do not put all your faith in ABS. Its also why the GS series bikes have an ON/OFF function for the ABS when riding on loose surfaces.[/QUOTE]

Andy, thanks for explaining the gravel piling in front of the wheel, now I know what to expect when I am in gravel which I have been putting off, just noob jitters and not wanting to drop the bike again, even though I think as any other new rider it is possible. While the damage from the drop was not severe, I really want to get her back to looking new again, but have been cautioned to wait. I'll have to try some gravel next. EVO brakes I still would think would be good for the originator of this thread. -D

Looks like I am in the minority here, but the servo - assisted brakes on my R1150R failed twice on me. I wasn't entirely happy that the fault cured itself, since neither I nor the local dealer could find out why they failed. I understand the subsequent owner encountered a similar failure. Sure the brakes do work in "residual mode", but IMO very, very poorly.

Just last weekend I had a road test on a servo - equipped bike and to my surprise I found that the brakes on my current 2005 R12GS, non - ABS non - servo, required no more pressure to use and certainly had more "feel" than the servo bike.

My understanding too is that there was a change in the manufacturing process for the servo pump during the 2002 model year. Later models are to be preferred.

I think a thorough road test, including a "push test" with the key off and no servo assistance, will be the best way for you to make up your mind. You might be surprised to find how good the less complex system is. Remember as well that some models have integrated, and others partially integrated, brakes. Since you have to deal with the finger issue, a fully integrated system (where the pedal works both wheels) might be of interest to you.

After 43,000 miles on my GS the servo brakes failed once for a short period and based on another recent, ongoing thread ([url]http://www.bmwmoa.org/forum/showthread.php?t=37211[/url]) I now believe it was due to a stuck brake switch, which resulted in inoperative servos following start up. Regardless the flashing brake indicator told me immediately that the servo was non operational and the problem corrected itself.
While I didn't find the lack of servos to be a trip stopper, I will admit if they went out unexpectedly during braking it would be anywhere from scary to catastrophic.

Personally, and this is just me, but I think the servo-assisted brakes are one of the dumbest things BMW ever put on a bike. What possible need is there for power assisted brakes on a bike that can easily be set up for VERY powerful brakes without all the extra complexity of the servo brake system?

Techno for techno sake is not technology of a purpose to me. I have learned to use standard brakes just fine in 37 years of riding. As such, I will never buy any BMW with servo assisted brakes. There simply is no need for it.

But for the sake of the rider who started this post, the servo brakes give him enough assist to perform high effort braking even with limited finger power. So, for his needs the servo brakes make sense.

:thumb :thumb :thumb

This is the 1st BMW that I have ever owned. A 2004 1150 GSA and it has the servo's. While learning how the bike rides and feels brakes included I am not unimpressed with it.

1. It does take some time to get used to the ( in my teams ) quicker response time that the brakes respond.

2. They do grab quicker and start to slow you down faster ( again my terms )

3. I have stopped quicker as I applied pressure to the handle.

Now would I own a bike that has this again.. Hell yes!!

Remember an elephant will get used to how long the chain is on his ankle and will not try go beyond it and we will get used to applying a small amount of force to the brake lever.
Yet I get on the girlfriends bike and grab the lever and remember that I have to apply more force to get it to work.

In the case that this question was asked.....
As long as the pump is maintained.. You should not have an issue and you should be ok..

What some of the other have said about not having the pump working... YES you will have to use all of what you got to get the front to work..
As mentioned roll it around with the bike off and you will see how much force is needed to get the brake to work.
That will let you know if YOU are comfortable with the amount of pressure that is needed to get it to stop.

Happy and safe ridding.

M0rbid.

One of the other issues I have heard of with servo-assisted brakes, is that it is a good idea to practice high effort stops (which is a good idea with ANY bike) that actually engage the ABS system, and make the system work a few ABS cycles, Has something to do with keeping the ABS/servos active.

Not doing so, I have read, can possibly lead to rear servo failures, and non-operative brakes (even in normal mode), and a costly rear servo replacement. Any of the real experts out there want to detail that a bit more?

My 04 R1100s has servo-assisted brakes. I agree with an earlier comment that the downside is using them when the key is off but I got used to that pretty quickly. They've never malfuntioned and do work great with the ABS as I unfortunately T-boned a large dog. The dog was no worse for wear (had some fur missing courtesy of my front tire), lost a fork reflector but the ABS worked great!

My 2005 K1200LT has linked brakes where you get both front and rear brake application whether you want it or not, with either just the handlebar or the brake pedal. I recently dumped it (two up low side) using the rear pedal in a sharp U-turn. Use of any front brake in a sharp turn of course puts a strong roll moment into the bike chassis.

I realized that my other two bikes are not linked and rear brake works well in a U-turn. That's my excuse - and I'm sticking to it.

Can anyone confirm for me the detailed operating characteristics of linked brakes? are they always linked by the same ratio? are they unlinked with the switch off? etc.

I'd have to check the MOM to be sure, but my 05 RT has the servo assisted linked brakes, and my understanding, at least for the rear brake, is that the front brake is not initially actuated. Only with more substantial pressure on the pedal will the front brake work. I've had no trouble in slow speed maneuvers using the rear brake alone, and I'm the king of parking lot tipovers!

[QUOTE=nrpetersen;474266]

Can anyone confirm for me the detailed operating characteristics of linked brakes? are they always linked by the same ratio? are they unlinked with the switch off? etc.[/QUOTE]

Only additional info I can add is my '04 GS has partially linked brakes. Front activates the rear, but the rear always works alone. Not sure if other servo models have partially linked brakes

Not all linked brake systems are equal, in other brands of bikes, but also within the BMW brand.

The R series bikes that had linked brakes are a "partially linked" system. Meaning, application of the front brake will also partially apply the rear brake. But, application of the rear brake alone, applies only the rear brake with no front brake application.

The K-LT (only) has a FULLY linked brake system. Meaning, application of the front brake will also apply the rear brake proportionally. BUT!! Application of the rear brake alone WILL apply some front brake as well. This is key to realize that when doing slow speed manuevers with the handlebar turned, front brake application can have costly and harmful results, so be aware and beware. Also, if you are going across a grassy downhill slope at a rally, and apply the rear brake, you will get some front brake. Another time to be very cautious. Same applies for anytime you are on gravel or any loose surface.

[QUOTE=Andy VH;474345]Not all linked brake systems are equal, in other brands of bikes, but also within the BMW brand.

The R series bikes that had linked brakes are a "partially linked" system. Meaning, application of the front brake will also partially apply the rear brake. But, application of the rear brake alone, applies only the rear brake with no front brake application.

The K-LT (only) has a FULLY linked brake system. Meaning, application of the front brake will also apply the rear brake proportionally. BUT!! Application of the rear brake alone WILL apply some front brake as well. This is key to realize that when doing slow speed manuevers with the handlebar turned, front brake application can have costly and harmful results, so be aware and beware. Also, if you are going across a grassy downhill slope at a rally, and apply the rear brake, you will get some front brake. Another time to be very cautious. Same applies for anytime you are on gravel or any loose surface.[/QUOTE]

I think the brakes were fully linked on the R bikes with the exception of the RT-P models and a few models of the later GS bikes.

My 04' R1150RS is as Andy states, front is linked to the rear only when the front is engaged (or of course both front and rear are engaged). The rear is NOT linked to the front.

I wish someone would state the years and the models of BMWs that came with this terrible system so I and everyone I know can avoid them. My 2004 R1150GS has them and I want to replace the bike with non-assisted bike of the same era. I love everything else about the bike but the lousy seat and these are the worst brakes I have had on any street bike in 30+ years! They have very poor modulation, they grab unexpectedly and force the use of the ABS in limited traction situations. You can't use light braking in a turn without risk - as I have on all my sport and touring bikes. The only redeeming thing is that technically I do have ABS - oh, but that dang ABS failure light keeps coming on - even after multiple expensive, professional flushes...so do I really have ABS when I need it? Ergh! Stupid system... Notice that they stopped providing the system on newer models? Case closed.

[QUOTE=182446;847298] I love everything else about the bike but the lousy seat and these are the worst brakes I have had on any street bike in 30+ years! They have very poor modulation, they grab unexpectedly and force the use of the ABS in limited traction situations. You can't use light braking in a turn without risk....[/QUOTE]

My experience is that a properly functioning system isn't as bad as you make out. I don't love 'em but I don't hate 'em.

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