MCN Comment on Power Assisted Brakes

[Exploreinman]

In the letters to the editor of the August edition Dave Searle makes the comment: "Lock up was not a problem with the Integral power-assisted ABS, but rather a non-linear feel at the lever and the potential for sudden loss of power assist (and count yourself lucky that you've never experienced that)."

 

Now I agree with the comment on the "non-linear feel", but I have 15,000 miles on my '05 RT and I've never had a loss of power assist on the brakes. His comment makes it sound like it happens all the time. Any thoughts? Anyone have any statistics on this?

[FrankBrown]

I have 82,200 miles on my 05 1200 RT and really love the servo (power) assist breaks. Have never lost the assist. I'm sorry they're no longer available.

[MadDuck]

This is very rare, fewer than 1% of the 2005 motorcycles had this type of failure, but it would occur more than once on the affected motorcycles. There were several "causes" all covered by warranty and recall. The replacement system seen in 2007 was being worked on in fall of 2005 as BMW believed the system would not be up to their expected standard of performance over the life of the vehicle. None of this is "official" but knowledgable people have shared info with me as I tried to sort out my problem. When running correctly the power braking system available on the 2005 and 2006 RT's was the most capable braking system ever tested. The system complexity led to some significant issues which altho affecting relatively few motorcycles could be catastrophic in nature. My bikes new owner loves it and I know he looked at the 07 before he bought my used one. I went back to a Harley and will probably never buy another ABS equipped motorcycle again.

[John Bentall]

Would you buy an ABS-equippped Harley provided it did not have electric servo-assistance for the brakes like the 1200RT?

[MadDuck]

Short answer is no. I am planning on hauling the bike to colorado or wyoming in the back of my F150 and it does have ABS tho. Arthritis has limited my long days in the saddle so I will be going for quality rather than volume.

 

Harleys really do load better than a top heavy BMW. Much easier to trailer.

[Dave_in_TX]

I have 82,200 miles on my 05 1200 RT and really love the servo (power) assist breaks. Have never lost the assist. I'm sorry they're no longer available.

 

I'm quite happy they're no longer available. I have an 07 RT without the power assisted brakes. I took extended test rides on an 06 with the power assists brakes. While the power assist didn't cause any problems, it provided absolutely no benefit over the non assist. The power assist was a solution looking for a problem. All it did was add complexity. I'm very happy with my non power assist brakes.

[CruisinCruzan]

I have an '06 RT and I have never had a loss of the power assist, but I'm sure that it would be quite the pucker factor if it happened. I agree that it was a solution looking for a problem. An unnecessary complication. I have ESA on my bike (I ride 50/50 with my wife so it was something I welcomed) but when it locked in the 2 up position I was annoyed at its complexity. You pay your money and take your chances I guess.

[JayW]

I have 82,200 miles on my 05 1200 RT and really love the servo (power) assist breaks. Have never lost the assist. I'm sorry they're no longer available.

 

Caution - hijack ensuing...

 

Congratulations on all those miles. I have yet to hear of any RT odometers "turning over" to 100K yet, so in a few months you may be the first .

 

Jay

[CruisinCruzan]

No hijack intended, just the point that the more things we have the more can go wrong. BTW, has anyone ever read anything as to why BMW chose to have power assist in the first place? I wonder if it was a case of "This will make us unique", instead of a real difference in braking ability.

[Lawman]

I believe there is a real difference in braking ability..Seems to me braking would start with more force and sooner when first applying brakes.

[ShovelStrokeEd]

BMW did a survey on the braking abilities of a number of riders and they found that with the exception of a few "expert" riders, most could not or would not apply the brakes with sufficient force or rapidity of force buildup to take advantage of the traction available from the front tire. In other words, they were not braking anywhere near the capabilities of the bike.

 

The power assisted brakes were a solution to that as they required much less hand strength to give full braking power and had some "force multiplier" built in that gave a non-linear response to applied force. This, coupled with the ABS to keep the novice and not so novice rider out of trouble resulted in a bike which could more quickly be brought to the level of threshold braking. Those more used to conventional brakes found the system over sensitive and somewhat awkward to use in slow speed applications, mostly because of the built in linking system, another result of the survey, in which it was found that most riders were not effectively using both brakes to bring the bike to a halt, either eschewing the use of the rear or the front brake or improperly applying the correct ratio of both.

 

It was a valiant effort, flawed, IMHO, in execution, due to the complexity of the system and the inability to defeat the linking for those who so wished.

[JayW]

Loud brakes save lives!!

 

Jay

[Don_Eilenberger]

I believe there is a real difference in braking ability..Seems to me braking would start with more force and sooner when first applying brakes.

Having owned both - the non-assisted brakes not only feel more linear - they feel more powerful. THAT is the difference.. but bet there is no different in "ability" - if you can lock the wheel or get it into ABS ratcheting - that's as much brake as the bike can apply. Power/no-power - doesn't really matter.

 

I didn't have a problem with the servo brakes (the former owner of that bike did - which is why he traded it in..) but I greatly prefer the non-servo. Simpler, lighter, less costly to maintain and stop just as well.

[Exploreinman]

BTW, has anyone ever read anything as to why BMW chose to have power assist in the first place?

 

I thought it was an effort to reduce stopping distances.

 

My main point of bringing up this thread was that Dave Searle's comment was very unprofessional. His comment suggests that most bikes with the power assisted brakes experience failures. In doing so he cites no valid statistics or research. As an owner of an '05 model I can live with the non-linear feel of the brakes, but if there were a frequent problem with power loss in the brake system I would think the lawyers would be lining up by the dozens to take on BMW.

[David]

BTW, has anyone ever read anything as to why BMW chose to have power assist in the first place?

 

I thought it was an effort to reduce stopping distances.

 

My main point of bringing up this thread was that Dave Searle's comment was very unprofessional. His comment suggests that most bikes with the power assisted brakes experience failures. In doing so he cites no valid statistics or research. As an owner of an '05 model I can live with the non-linear feel of the brakes, but if there were a frequent problem with power loss in the brake system I would think the lawyers would be lining up by the dozens to take on BMW.

 

"Most"? That's not at all the impression you gave when you started this thread. Did he really say that, or did he say there had been some failure? If the latter, he's right.

[motoguy128]

I just bought a '07RT. For not having servo assit, they are incredibly powerful if not a little grabby (might be the linked brakes). Most powerful system on any bike I've ever owned including a R1150R(non ABS), ZX9R, CBR600F4i (with HH pads & SS lines).

 

My CBR still most likely had the shortest stopping distance, but with a passenger and luggage, the RT is king.

 

I like most the fact that I have brakes when moving the bike around unpowered or if there is a ABS failure.

[Eschelon1]

I have an 1150RT with the servos and fully integrated braking. 17K and no failures to report. I'd have to agree on the non-linear feel and I could do without the linked brakes, but it does stop very well!

 

[Exploreinman]

Most"? That's not at all the impression you gave when you started this thread. Did he really say that, or did he say there had been some failure?

 

His comment was, "count yourself lucky that you've never experienced that," referring to the loss of power in the brake system. To me this comment suggests that the failure happens frequently and that the owner of such a bike is resting on luck for full braking power. How do you interprete such a comment?

[David]

Most"? That's not at all the impression you gave when you started this thread. Did he really say that, or did he say there had been some failure?

 

His comment was, "count yourself lucky that you've never experienced that," referring to the loss of power in the brake system. To me this comment suggests that the failure happens frequently and that the owner of such a bike is resting on luck for full braking power. How do you interprete such a comment?

 

I wouldn't assume he was making a mathematical statement.

 

If I say I consider myself grateful that I've avoided something, it may or may not make some implication about how frequently it occurs. I just think you're reading too much into it.

[BeemerLover]

I am currently considering the purchase of an RT after many years on a R1200C. I was at the local dealer recently and was able to test drive both the 1150 and 1200 RT's. I also rented an 1150 in Europe for a week. In my mind the servo assisted bikes are a real hazard at very low speeds. Above maybe 15 mph there seems to be little difference. Below that speed the "grabbiness" of the servo assisted linked brakes along with the front wheel geometry makes it want to go down. Two people in my BMW MOA have had to purchase +-$900 of tupperware due to this. We had one go down on the European trip as we went down an incline into a parking garage. Slow speed, brakes needed, too grabby, bike on its side.

 

In my test drive the 2007 RT with unlinked, non-servo brakes was better, IMHO. It may actually save me money if I don't have to pay for new tupperware!

 

Can't afford a new 2007 RT, will wait until winter to see what comes available - new models will be out and prices on good used ones will be in my price range. Can hardly wait!

[Mike]

Ed pretty much nailed it. I've got the partially linked, servo-assisted brakes on my R12ST and I've gotten used to them. All things being equal, however, I'd opt for no servo-assist.

 

However, the bottom line is that BMW was trying to maximize safety by engineering a braking system that provided maximum braking force quickly in an emergency situation. They did that really well, though there were some negatives: as others have noted, braking feel is not great with servo assist (though you do get used to it), and if your servos ever fail, you need to apply a lot more force to brake effectively.

 

On the plus side, the system does offer the average panicked rider a stopping distance that will likely be shorter by several feet than a similarly equipped bike without servo assist. In those circumstances, it could mean the difference between soiled drawers and being hauled off in an ambulance. It was not an altogether frivolous engineering exercise.

[blkvelvt]

Mike, I agree. I would like to stop short of an impact if the option was there. I have got used to the feel of no feel with the system. Worse case scenario is I stop short at lights at slow speed and sometimes have to inch up. At least the rear end stays on the ground. I rode a buddies "Rice Burner" and grabbed a tad too much front. Woooohooo. What a stop. (and drop the rear back down again)

[BeemerBerg]

The ABS on my '05 R1200RT routinely "go out" if I'm stuck in stop and go traffic . The "Brake Failure" begins flashing slowly (indicating a partial loss of ABS), then after awhile, it does the "quick flash", at which point I know that all ABS and "link" is kaput. Could it be due to not providing the battery with enought charge? It can be reset if I get out of traffic, let the battery voltage build up for awhile, shut down the bike, pray, and restart. Sometime will reset, sometimes no.

Suggestions?

[Mike]

It could be low voltage, but that typically occurs on startup, not when the bike is already running and there's been no prior fault message. My guess would be that you've got a sensor problem.

[Exploreinman]

It's possible that I'm reading too much into Dave Searle's comments, but my remarks communicate how I understood them. I don't know if there are any reliable statistics available, but it would be interesting to know how often the power loss happens.

[RoyTemple]

Only 13K miles on my 05 RT so far but no issues with the power assist. I had the R1100T before, not power assist or linked brakes and I thought they were fine. I wanted the 05 RT and the only way it came was with power assist. As I recall, I test rode it a few times (5 I think as well as the the 04 GS with power assist). I found them a bit grabby at low speeds but decided I could live with it. I now find I don't notice or even think about the power assist. Maybe I have learned to apply the breaks such that the grabbyness does not normally occur. Occasionally I notice the whine which reminds me that I have power assist.

 

Power assist would not prevent me from buying an 05 or 06 RT. The fully linked brakes on the earlier R1150RTs would, power assisted or not.

[Mike]

It's possible that I'm reading too much into Dave Searle's comments, but my remarks communicate how I understood them. I don't know if there are any reliable statistics available, but it would be interesting to know how often the power loss happens.

 

I don't know if any such statistics are available. There have been a couple of reports here, so it does happen occasionally. However, it's by no means a regular occurrence. Nonetheless, if you have servo-assisted brakes it would be wise to occasionally practice power-off braking occasionally. It takes much more braking input to achieve anything close to the level of braking that's easily achieved with operational servos.

[jimswms]

There were several "causes" all covered by warranty and recall.

I'm interested in the causes and warranty/recall info. My 05 has lost brakes twice, my dealer has no solution and I'm about to leave BMW forever on this issue. I'd love to find a solution, if one exists.

 

thanks

[LuckyLeif]

There were several "causes" all covered by warranty and recall.

I'm interested in the causes and warranty/recall info. My 05 has lost brakes twice, my dealer has no solution and I'm about to leave BMW forever on this issue. I'd love to find a solution, if one exists.

 

thanks

 

Not trying to be a smart azz, but trading for an 07 or 08 is a high cost solution the problem (if you want to stay with BMW). Although I personally never experienced loss of braking assist on my prior bike (05 GS), people I trust implicitly did experience occasional failures. Coincidently, I recently rode a rented 06 GS 1400 miles and did have one episode with lost braking assist. It occured during start-up in a parking lot and I noticed its loss only when slowing at the stop sign on the lot perimeter prior to entering the road. From that point on I paid close attention to the brake failure panel light and/or tested the system by applying the front brake at every subsequent engine start. Only happened that one time - maybe a fluke, but made me glad that my RT is a non-servo bike.

[samtheeagle]

I skipped most of the thread but wanted to add that I have lost the power brakes on my 05 GS and in the camp of those who want to get a non-power assist model. I'm hoping to get an 07 GS.

- Sam

[vincentbob]

I recently traded my 2005 RT for a 2007 RT non servo model, I find the new system feels much more progressive, equally powerful, and less grabby at manovering speeds.

I had two occurances of servo loss which both occured without warning and when travelling at high speed. It took two attempts to solve the problem and was finally diagnosed as water ingress into one of the loom connectors causing ECU interference and software crash. I was pretty unhappy at the time as BMW simply relied on the "residual braking" clause, they were not convinced with my arguments that braking power should not be dependant on software operation.

I'm glad I wasn't two up with luggage when it happened.

I put 12,000 miles on the bike with no further problems other than two sets of front brake discs.

These are my first BMW's, and are the best bikes I have owned. In the end I regained confidence with the 2005 and probably would have kept it, but I was offered an excellent trade in deal.

[jimswms]

I had two occurances of servo loss which both occured without warning and when travelling at high speed. It took two attempts to solve the problem and was finally diagnosed as water ingress into one of the loom connectors causing ECU interference and software crash. I was pretty unhappy at the time as BMW simply relied on the "residual braking" clause, they were not convinced with my arguments that braking power should not be dependant on software operation.

and, therin lies my problem with BMW. It is a faulty system, they know it, which is why they changed it, but, they find it acceptable to keep these bikes on the road. You've gotten a better explanation than the "yeah, they can do that" I got. I find it unacceptable, and, will vote with my dollars.

[MadDuck]

My, admitadly biased, opinion is that the system is extremely sensitive to voltage loss. When the ECU sees values fall much below 12 volts the system can behave errratically. So chafed wires, water in connectors and a hundred other "gremlins" can shut the brakes off. You may or may not have residual braking when this occurs. The causes are extremely rare and are not common amongst bikes. Mine was bad rear brake sensors/connector?? When the ECU is "confused" it seemed to make the braking situation dramatically worse. When the dealer "flashed" my ECU to the current version while doing the banjo bolt recall, a lot of the sensitivity to battery charge went away and brake feel improved dramatically including low speed braking. My guess is that if an 05 has had steady dealer service that the few issues no longer exist. Maintaining it on the BMW charger constantly also seemed to help, but that may have been wishful thinking.