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Servo-assisted brakes

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!
 
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.

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.
 
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.

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 know what you mean - the servo assisted brakes suck!

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.
 
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....

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.

Insert "My Two Cents" Icon
 
Servo lover here

I had an 04 RT bought new and now ride an 06 RT purchased used. Both have servo assisted brakes and I wouldn't be without them on anything. My 4 wheel vehicles also have "Linked" ABS power brakes and are much appreciated.

One thing: If you have it, USE IT! Learn how the bike reacts to a full on panic stop from fifty or sixty mph. Most people never really use the brake systems to their full advantage due to fear of hurting the system somehow. That is folly. If you don't practice panic stops how on earth will you be able to stop in a panic situation?
 
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.
I think all the boxers and K bikes had servo brakes from 2002 to sometime in 2007. Maybe someone can tell you the exact dates.

I looked at the parts fiche for a couple bikes and it shows the pressure modulator until Aug 2006.
 
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I think all the boxers and K bikes had servo brakes from 2002 to sometime in 2007. Maybe someone can tell you the exact dates.

I looked at the parts fiche for a couple bikes and it shows the pressure modulator until Aug 2006.

RTs stopped using the servo thingy after the 2004 year. I like it, it works great. But then again, I have not had to any $$$$ to deal with a failure yet, knock on wood.
 
RTs stopped using the servo thingy after the 2004 year. I like it, it works great. But then again, I have not had to any $$$$ to deal with a failure yet, knock on wood.

Incorrect: My 06 RT still has them I'm happy to say. Model Yr. 07 didn't get them AFIK.
 
04 1150 RT Braking n a turn

Evo braking.
I've read that these brakes don't work on a turn. Why not?

Peter
 
Evo braking.
I've read that these brakes don't work on a turn. Why not?

Peter

The brakes don't know if you're in a turn or not. Typical of a single track vehicle. They work the same as long as tires have traction, when tires lose all traction brakes are superfluous.
 
Simply amazing what some people post on the net, meaning the comment about Servo-Assist brakes not working in a turn. Now, this is not pointing at the person who posted the comment, but obviously whoever originated that comment did not know anything about motorcycle brakes and physics.

Now, if the comment was made because the originator mistook Servo-Assist brakes for ABS brakes, then yes, there are limitations to what brakes can do in a turn when leaned over and the ABS control is engaged. But the BMW Servo-Assist brakes work at any time, any surface, any lean angle, just like normal cycle brakes. BUT, you do have to aware of the effect of the power assist aspect of the Servo-Assist anytime you are in a position of using too much traction.
 
I had an 04 RT bought new and now ride an 06 RT purchased used. Both have servo assisted brakes and I wouldn't be without them on anything. My 4 wheel vehicles also have "Linked" ABS power brakes and are much appreciated.

One thing: If you have it, USE IT! Learn how the bike reacts to a full on panic stop from fifty or sixty mph. Most people never really use the brake systems to their full advantage due to fear of hurting the system somehow. That is folly. If you don't practice panic stops how on earth will you be able to stop in a panic situation?

You are just the guy I need to talk with, because I am negotiating on an '03 R1150RT that has the servo-assisted linked brakes. ALL my riding experience has been with conventional brakes and non-integrated, non-assisted ABS. The idea of coming to a stop at the bottom of a dirt / gravel road, on which I would normally NOT use any front brake (light & gradual rear, only), and having the front caliper activated sounds like an opportunity for the front end to "dish out" and land me and my expensive bike bodywork on the ground.
Likewise, I took the "Ride Like a Pro" course (ALL low speed) which involved offset cone weaves, the "iron cross" (4-consecutive U-turns) and a low-speed slolum on my Super Glide, and modulated the clutch, throttle and rear brake (no front brake), passing the course with flying colors. In the June, '01, Cycle World, Don Canet, professional test rider and veteran of thousands of U-turns for photo shoots, dumped the 1150RT in the middle of a U-turn, because he "feathered" the rear brake.
I've got ABS on my FJR1300, but the brakes are not linked. I'm thinking of backing away from the '03, despite its pristine condition and low (29K) mileage. BTW, I do practice panic stops. It's the low speed and poor surface stuff that worries me.
Thanks!
 
I've ridden my oilhead for 6 years with servo assisted brakes. I don't even think about them because they do their job without fanfare. I also have an airhead with conventional brakes and a maxi-scooter where the rear brake is on the left hand lever. I go from one to the other automatically without thinking. The oilhead brakes takes far less effort and I don't have to wonder if I am using the rear brake enough or too much on the others.
 
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