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2002 1150RT Braking vs 03 and 04


bahetrick

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I've read many posts over the last couple of days about the brakes on the 1150RT's. Some hate'em and some like'em.

 

Can someone tell me if the brakes are less sensitive on the 03 or 04 compared to a 2002? I rode a 2002 and first impression of the brakes was not favorable and I'm not sure I would ever get used to how grabby they are.

 

I understand that the brakes on the 1100's are very good so I'll be looking to test ride one of those as well.

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Supposedly, the brakes on the 2004 are less "grabby" or less sensitive than the 2002 RT. I've riden both and can't tell much difference. You can get used to them, though. The first time I rode my '02 RT, I thought I would fly over the windshield.

 

The biggest problem is not being able to independently use the rear brake since they're linked both ways. This makes slow turns difficult and easy to dump the bike. ( you can't trail brake with just the rear brake ). My '04 1150R has an independent rear brake, but I don't recall if the '04 RT is the same. Still, the brake is grabby and difficult for me to use effectively in slow turns.

 

Al

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i believe that the '02 and '03 rt have fully linked brakes, and in '04 they are only partially linked. I have ridden both years and they seem to have the same feel as each other.

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i believe that the '02 and '03 rt have fully linked brakes, and in '04 they are only partially linked. I have ridden both years and they seem to have the same feel as each other.

 

All the R1150RTs have linked brakes. The sensitivity, especially the rear brake pedal, has been gradually reduced over the years. You do get used to them, I still don't like the rear to front linkage but it is not a deal killer for me.

 

Andy

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Francois_Dumas

I ONLY use the brake pedal on low-speed manouevering rather than the front brake handle. It is still 'sensitive' but not as much as the brake handle.

 

It certainly is something to be aware of and get used to I guess...... but not a problem once mastered.

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I have an 05 R1150RT, and for the first 1000 miles or so, I found the brakes a little grabby. Rode a an R1100S for the previous 6 years. Now that I am used to them, the brakes seem great, though I have noticed that I rarely brake with the foot pedal anymore - seems redundant now.

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The '02 and '04 brakes are both fully integrated. I had RTs from both years. I thought the '02 brakes were more sensitive than the '04. When I first got the '02, my wife's helmet would hit the back of my helmet on a regular basis when stopping. I got used to them fairly quickly though. You just have to use a lighter touch when stopping with them under normal conditions. I now have an '05 RT I just bought in March of this year. The biggest difference between the '04 and '05 is that the '05 has partially integrated brakes with an independent rear brake which is really nice.

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One quick note about the 02 model year. About half way through production (don't have VIN numbers to refer to here, but you can look it up), they modified the sensitivity of the Integral Brake System, making it a bit less touchy. So if you have a problem with the 02, you may want to see when it was produced in that model year. I think the cut off for that change was around February-March of 02 (the bike would have been out almost a year by then) - I bought my black 02 R1150RT in April of 02 and it had the modified system.

 

Just a heads up.

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One quick note about the 02 model year. About half way through production (don't have VIN numbers to refer to here, but you can look it up), they modified the sensitivity of the Integral Brake System, making it a bit less touchy. So if you have a problem with the 02, you may want to see when it was produced in that model year. I think the cut off for that change was around February-March of 02 (the bike would have been out almost a year by then) - I bought my black 02 R1150RT in April of 02 and it had the modified system.

 

Just a heads up.

Also on the early '02s there are a couple of thinks you can do to reduce the sensitivity at least a bit. Most notable a full flush & bleed and lowering the rear pedal adjustment.
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ashleybiker

I have an early 2002 model rt. I had heard about the concerns many riders had about the "grabby" brakes. Before my first ride on one, the dealer explained the braking system and cautioned me about the sensitivity. I could easily understand the concerns . No doubt, if you are new to that model and have not been coached about the sensitive brakes, it could be ugly the first time you go to stop.

 

However, like the others have said, once you become accustomed to the sensitivity of the brakes it will probably no longer be of concern.

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I've owned both model years of the 2002 and a 2004.

On the 2002, it was the unpredictability of the rear brake at low speed that was the nuisance. Usually it was a smooth grab but occasionally it was a sudden bite. It was much less of an issue as I got used to it.

The 2004 RT on the other hand, always gives a predictable response.

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Well, I bought the 2002 the other night and couldn't stop smiling the entire way home. By the time I got it to the house, about a 30 minute ride with mutiple stop lights, the brakes didn't feel so bad. I just needed a little time to get a feel for the bike and I think all will be OK. I love how easily it goes down the road. Can't wait to get some miles on it after I get back from vacation. Thanks to everyone for the input and all the information that I found on the forum. This is a great site.

 

Brent

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By the time I got it to the house ... the brakes didn't feel so bad.

You'll have no issues if you're aware of the behaviour of the rear brake. You and the bike will get to know each other very quickly. grin.gif

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Is the year 2002, the first year of the linked braking system?? Since I am just getting ready to buy, I have heard heated debates on this linked system. I rode a 2000 and a 2002 and didn't notice any difference. Is there any reason, having not had either yet, that I should or should not consider the linked system??

 

Basicially my beemer pals told me to buy the newest bike that I could afford. It seems that will be around a 2002. Are all brakes linked on the RT models from that year forward?

 

Thanks,

donna

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The newer systems are more efficient at stopping in emergency stops given most rider's skill sets are not that great when the sudden stress of impending diaster looms (the ah sh?t factor). The I-ABS (linked) system is reliable and proven. The downside of this is you can expect higher maintenance costs with the I-ABS. There are four independant hydralulic circuits requiring some form of annual service. Wheel circuits annually and control circuits along with wheel circuits everyother year. The service process is not user friendly and to do it properly requires expensive tools, a bleed test at the dealer, and a thorough understanding of the procedures. In other words, for most owners it is smart to plan a dealer visit for this. Plan on being billed 3 to 4 hours shop time for the full bleed / change every other year. If you are good with that I say go for it, it is a great brake system. On that bike purchase make sure the seller has a solid documentation of these services being done. Neglecting this time based service has a lot of bearing on future reliability (interval times start from manufactered date) thumbsup.gif

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Hi Bob,

Evo brakes refers to the changed front brake system on 2002 and later BMWs. Many bikes without I-ABS have EVO Brakes and are flushed/bleed the same as previous bikes(R's, GS, S). Now if you are talking about I-ABS yes it can be done if you follow the service procedures and have tools such as correct caliper piston spacers for front and rear. You also should get a bleed test to insure the job is correct. It can and does detect problems that would not otherwise be noticed. Only dealers have the tester to do this. The piston spacer tool set costs over $700 unless you have access to a machinist who can make a correct set for you. That was my point, It is deffinitely more involved. Put it another way, all BMW tech's were required to attend a three day class to be certified to work on this system in 2002. Yea, I would say it is more tedious. grin.gif

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2wheelterry

Mudman:

 

With the instructions available on this website and others and fabricating the tools per the available instructions at about $10, I was able to do my own brake flush on an early 02 RT. It is much more tedious than any other brake flush I have done, but far from something that would force me to take it to the dealer.

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Terry,

 

Glad to hear you got it done.

 

Next time your bike is in the dealer having any other work done you may want to ask them to do a bleed test. Shouldn't add more than 5 to 10 minutes to the bill and be sure to ask for the printout. The test is the only reliable method to know if there is adequate pressure being generated and maintained in residual mode. No body needs surprises on the road if the unit stopped functioning. This is important enough that BMW requires only certified techs do this and they have to sign the bleed test and file it with the vehicle history file. BMW says this job is that important. No other operation on the bike has the same standards of accountability. An operating unit will mask deficiencies in the bleed when everything is powered up so feel isn't a good indicator.

I hope no one has been using vacuum or pressure to bleed the control circuits, that is prohibited by BMW.

 

Any one have a link to the instructions you are speaking of?

 

Thanks,

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The first article is by far better than the other two articles to follow. There are several issues, but it gets you close.

 

There is a model specific wheel circuit fluid volume that must be followed. This requires a specific spacer thickness between the caliper pistons with the brake pads removed. Fill with too much fluid and you will push fluid out and all over your bike as you ride away with new pads. If you fill referencing new pads the wheel circuit might be filled inadequately when the pads wear thin-no brakes. The fluid level has to be correct to prevent either scenario.

 

Neither article stresses the importance to torquing the caliper mounting bolts (Front 30 NM/Rear 40NM), critical! Both methods intermingle the new fluid with the old too much so the flush won't be as thorough as it could be. None of the articles suggest getting a bleed test afterwards.

 

Two other tips when working on brakes you may find useful. Always have a spray filled with water on hand when working on brakes. Any fluid spill can be quickly flooded with water neutralizing the affect of DOT4 on painted or plastic surfaces. Another nugget for the front brake lever is drop a single sided razor blade in the fluid reservoir prior to pumping the bleed sequence. It will block the geyser of fluid and prevent spills. When done extract with pliers before the cap is installed.

 

Everybody will do as they wish, after all the bike is theirs, not BMW. My motivation to comment is to caution owners when working on a complicated system that apparently very few really understand. Brakes should be subject to critical review, they are too important to guess at. I don’t work for BMW or have any dealer connections, but I have a wide range of experience with this system in a professional role. Of course you know about free advise, it often is worth what you pay for it.

 

 

thumbsup.gif

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My July 02 build/2003 MY RT has the revamped EVO brakes. The rear brake actually has a sweet spot where you can lightly apply the rear brakes when doing a parking lot tango and drag the rear brake.

 

To get used to the rear brakes, my advice would be to go out and ride for a while using ONLY your rear brakes. Try it in a large parking lot first or on some empty side roads before you adventure out a little more. On linked brakes, the harder you press your rear lever the more the system applies the fronts. You will "body learn" your braking system much quicker this way thumbsup.gif.

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Stan Walker

While I know you are trying to make a point, I for one would prefer that it not do so by leaving out some of the facts.

 

Fill with too much fluid and you will push fluid out and all over your bike as you ride away with new pads.

 

Not likely. The servo unit has vent line that dangle down by your right foot. If you replace the pads and push out fluid it will mostly just drip on your garage floor. The heavy flow stops the first time you apply the pads, but a few drips will still fall out for the next day or two. I know, as I did it that way when I changed my front pads.

 

If you fill referencing new pads the wheel circuit might be filled inadequately when the pads wear thin-no brakes.

 

The servo unit has built in level detectors and you should get a brake failure when the fluid level gets low in either circuit. I suspect that most of us fill the reservoirs to the full level with whatever pads happen to be on the bike. In short we over fill, not under fill. Even if one circuit (front or rear) were to become low enough to not function, there will still be brakes available from the other circuit.

 

Stan

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Stan,

While I agree with both of your points they are still a problem that is avoided with a proper filling technique.

Fluid pushed out the vent hose can and does a significant amount of cosmetic damage. Many rear wheels and other painted components have been damaged by brake fluid dribbling out of the vent line while riding. This is recognized enough that BMW tells technicians to be sure to blow out the vent lines and clear any fluid if there is evidence of fluid flowing through the line such as a dropped bike. This avoids customer complaints.

 

On your second point, yes the fluid level should indicate a low fluid level before the pump in the wheel circuit cavitates, but how many riders while on a road ride have the tools and time to remove the tank and top off the wheel fluids. How many riders know what the warning is telling them by identifying the frequency and warning light behavior? Sadly many will continue to ride until they get home. The warning lights do not identify which circuit is low, the low warning is wired in series. This is an un-necessarily dangerous condition no matter how one tries to rationalize.

 

This process is not a secret or mysterious. The correct flushing and bleeding procedure is clearly spelled out in the repair manual/CD. Everytime a shortcut or different procedure is followed there is a consequence. If you want to roll the dice, that is your right to do so. Trying to validate your procedure telling others it is fine, the factory method isn't necessary isn't a good idea. A less informed person may look at your ideas as expert when they are not.

 

Unless you are incrediably insightful and have an intimate knowledge of the system under discussion, one should first consider the material written by the engineers or designers as the first best source of information.

 

If you are skilled and follow the factory procedures with appropriate tools this is a do it yourself service item. So far what I have read doesn't meet the conditions to do a correct service on the I-ABS.

 

Thanks for listening - I don't have anything else to say that would be helpful or productive. Hopefully some good comes from this lively discussion cool.gif

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Man, been there, done that! I had 70K under my butt on a R100RT before I bought my 03RT. I didn't need near the effort to stop that bike. Once I stopped in mid turn going into a parking spot. Down I went!

 

 

Supposedly, the brakes on the 2004 are less "grabby" or less sensitive than the 2002 RT. I've riden both and can't tell much difference. You can get used to them, though. The first time I rode my '02 RT, I thought I would fly over the windshield.

 

The biggest problem is not being able to independently use the rear brake since they're linked both ways. This makes slow turns difficult and easy to dump the bike. ( you can't trail brake with just the rear brake ). My '04 1150R has an independent rear brake, but I don't recall if the '04 RT is the same. Still, the brake is grabby and difficult for me to use effectively in slow turns.

 

Al

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Chuck Hatcher

I had an early-build 2002 R1150RT. I played with the brakes with the bike balanced on the center stand to get a feel for how they worked, and to invalidate some incorrect information I had heard about the fully-linked system. Even a light pull on the front brake lever did apply both brakes as expected. The rear pedal applied the rear brake only with light pressure, and with further pressure applied front brake also. With care it is possible to drag the rear brake when desired. Too heavy an application may result in unintended front braking. It wasn't difficult for me to adjust to the brakes. They were very sensitive, and required a lighter touch than any I had used before, but they definitely worked.

 

I'm currently riding an R1200GS Adventure without ABS (or power assist). The brakes are powerful and don't take much effort to use. While I wouldn't mind having ABS in a less invasive form, preferably unlinked, I can't say I miss the linked power-assisted (so-called "servo" brakes) of the RT. BMW seems to be coming around on this issue on newer models and perhaps on some of the older models for 2007. None of this takes away from the fact that the linked power-assisted brakes, even in the earliest incarnation used on the early '02 RT's, were very good brakes.

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All the R1150RTs have linked brakes. The sensitivity, especially the rear brake pedal, has been gradually reduced over the years. You do get used to them, I still don't like the rear to front linkage but it is not a deal killer for me.

 

Andy

 

I bought my 2002 R1150RT with the understanding that it does NOT have linked brakes; it has servo assist and

ABS on both wheels but front and rear are supposed to be independent. According to the salesman . . . crazy.gif

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All the R1150RTs have linked brakes. The sensitivity, especially the rear brake pedal, has been gradually reduced over the years. You do get used to them, I still don't like the rear to front linkage but it is not a deal killer for me.

 

Andy

 

I bought my 2002 R1150RT with the understanding that it does NOT have linked brakes; it has servo assist and ABS on both wheels but front and rear are supposed to be independent. According to the salesman . . . crazy.gif

Well unless you bought TWEETY BIRD's old bike or another one that's been hacked to the tune of ~$2000.000 on consignment . . . they're linked. Sorry, dude. frown.gif
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I bought my 2002 R1150RT with the understanding that it does NOT have linked brakes; it has servo assist and ABS on both wheels but front and rear are supposed to be independent. According to the salesman . . . crazy.gifWell unless you bought TWEETY BIRD's old bike or another one that's been hacked to the tune of ~$2000.000 on consignment . . . they're linked. Sorry, dude. frown.gif

 

Can it be? To investigate I put the bike on the centerstand, and with the brake pedal held down the front wheel spins freely, and with the brake lever pulled in the rear wheel spins freely. So, they don't seem to be linked, unless that happens only when the bike is running and the servo/ABS systems activate. Is that how it works?

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The brakes are not linked in residual mode, there is no way for them to work without a functioning power assist pump.

 

BTW they are not servo brakes, I don't know who started that but the name does not fit. They are hydraulic power assist brakes. I know that doesn't roll off you lips like servo, but the term servo is not accurate in describing what they do.

smile.gifsmile.gifsmile.gif

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Stan Walker

BTW they are not servo brakes, I don't know who started that but the name does not fit.

 

I disagree. The encylopedia I looked in defines servomechanism as:

 

Automatic device for the control of a large power output by means of a small power input or for maintaining correct operating conditions in a mechanism.

 

The clearly describes our Integral Brake Servo.

 

Stan

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Actually, it might be a matter of semantics, but you're both right. Stan, check out this link. While it might be not completely correct in the strictest definition for those in some technical fields (or strict literalists), the term certainly is descriptive enough for lay usage.

 

True, when the power is off, the input from the control circuit does apply some (paltry! tongue.gif ) "residual" braking force which acts similarly to "normal" brakes without a pump, and there is no "feedback loop" but servo (much more so than "EVO") sounds . . . well just so "whizzbang"!! How else could I feel good about paying so much extra for this bike? Heck, cars have had hydraulic power assisted braking systems since at least what . . . the 50's? dopeslap.gifgrin.gif

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I agree servo has a nice sound to it and does sound wizzbang. You bought the device so you certainly have the right to call it what you want grin.gif

 

On your point about residual braking you mentioned paltry brake performance. Try this only if you are confident in your braking skills without ABS!

 

As a safety drill in a controlled environment such as a vacant parking lot try an aggressive stop with the key off (residual). You will not have the safety net of ABS so be judicious! You will find you can slow to the point of locking either the front or rear wheel if needed. It's good to know what to expect in the event of an electrical failure. Sure it is high effort, but the brakes are more than paltry in their effectiveness to the point of exceeding the coefficient of friction. You will also notice the brakes are no longer linked. This is in essence is what the brake bleed test measures. It records the residual generated pressures to determine if the brakes are correctly serviced. thumbsup.gif

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This is in essence is what the brake bleed test measures. It records the residual generated pressures to determine if the brakes are correctly serviced. thumbsup.gif
Interesting, but would that not test only the control circuits? I remember Uli talking about this double check for the control circuits: get the bike up to 30mph or so, shut it off and see if you can lock a wheel. "Paltry" was referring to the amount of apparent braking force available relative to the normal pressure needed to slow the bike, but I agree it is good practice to become familiar with that "residual" feel. It is actually better on the late 2003 models on (the ones that use the newer Mini-Stan's), but especially 2002's and early 2003's feel pretty paltry if you're not expecting it and at first you don't think you've got any brakes at all! dopeslap.gif

 

For the wheel circuits, I seem to remember somewhere in my research that if you happened to get enough air in the wheel circuit portion that the system will fault on start-up if the "servos" (sic) can't spin-up enough pressure during the initialization, non?

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I don't have anything else to say that would be helpful or productive.

. . . but I have a wide range of experience with this system in a professional role.

I'm not so sure about the former based on the latter--you seem to have a lot of intimate knowledge that I'd like to "plumb" a bit more if you don't mind. smile.gif

 

The first article is by far better than the other two articles to follow. There are several issues, but it gets you close.
As the author of "the first article" ( grin.gif ), I'd like to make clear that mine was just a first primitive effort when the EVO brakes were still fairly new. My post was never intended to be complete--just an illustrated walk-through of the service manual procedure. I state clearly in my write up that the service manual is necessary to have on hand to follow (like for torque specs . . . wink.gif ). Someday I'm going to re-write them to incorporate all the good stuff we all have learned and shared about these systems in the intervening three years. This was just my initial attempt to collate the good info discussed here when the procedure was still "mysterious" adding the few tricks that members here figured out and getting people to not be so scared about these double-secret EVO brakes. wink.gif

 

People were being given quotes of $400-$1000 to do this job (along with a bunch of double-speak about required expensive computerized equipment, how the owner is not qualified, just leave your credit card at the counter, etc.). Unfortunately for some people, because of factors like the price of service, proximity of the nearest dealer, and frequency of service intervals: they chose to neglect their brakes entirely--which is a far worse consequence, as I'm sure you'll agree. This is especially true when you consider the price for the components! When a few of us peeked behind the curtain and got a glimpse of "The Great and POWERFUL BMW EVO Brake System" we were understandably underwhelmed and "inspired" to get on the wagon and off the BMW corporate teat.

 

Leslie and I have been bleeding our own brakes every year (wheel, control and clutch . . . just 'cause it's so easy! grin.gif ) since new (2002 and 2003 R1150RT's respectively). I've instructed about 20 bleeds on about as many different bikes and other than a wet thread sealant issue while installing SpeedBleeders, have never had a problem--including those who have subsequently had the computer check done at the dealer. It really is not rocket science: there's either air/crud/water in the brake fluid or not (addressed with regular bleeding), the system's integrity is in tact or it isn't (solved by rebuilding/replacing worn parts), and the computer is happy with what it sees on start-up or it isn't (if it ain't happy you'll get a light show on the dash--go looking--the problem will likely be apparent). From a corporate (or motors agency) liability perspective I know that there is no other option other than BMW's, but for the home wrencher there is no need to be cowed into paying through the nose for brake servicing, and when you learn that it's easy and incredibly cheap (assuming your time has no value! grin.gif ), then you won't put it off causing potentially catastrophic problems down the road--and not just financially! eek.gif

 

Since this sort of thing is what we do here, please indulge me for a bit (since most of this will not be news to you, but is provided for the good of the order) and feel free provide a rebuttal where your experience tells you I'm way off base:

There is a model specific wheel circuit fluid volume that must be followed. This requires a specific spacer thickness between the caliper pistons with the brake pads removed. Fill with too much fluid and you will push fluid out and all over your bike as you ride away with new pads. If you fill referencing new pads the wheel circuit might be filled inadequately when the pads wear thin-no brakes. The fluid level has to be correct to prevent either scenario.
From a corporate perspective that may be true--read: our lawyers say if you don't do it this way, we won't be liable for your funeral costs or other damages--but all that really is required is the presence of enough BF in the reservoir to keep the pump intake covered and hopefully not draw air into the system as the pads wear (or in the case of a tip-over). If you understand how the system works (the pads wear with use, the pistons move further out to make up for the extra space and fluid is drawn down from the reservoir into the calipers behind the pistons), and you carefully monitor the fluid level when bleeding and changing pads NOT in conjunction with a normally scheduled bleed, you should have no problems. If you get a chance to see the newer (post late 2003) ABS reservoirs you'll notice that one of the changes BMW made was a taller front wheel circuit reservoir to be able to hold more BF. Since there are eight pistons in the front wheel circuit (two calipers, each with two pads, each pad with two pistons), the fluid is drawn down into the calipers four times as fast as the rear circuit (with only two pistons). This solves both running out of BF in the reservoir as the pads wear thin and potential overflow issues when replacing pads not in conjunction with a bleed.

 

Example: our pads have lasted about 50-70k miles, but I don't put on 50k miles in a year (and about half are touring miles). My regularly scheduled wheel circuit bleed will therefore come up at least once during the lifetime of a set of pads (we both ride about 33k miles a year). When I bleed the brakes without replacing the pads (say 50% pad wear, for example), I now leave a bit more BF in the Mini-Stan after the bleed is completed, re-install the calipers (torquing appropriately, of course! tongue.gif ), turn on the bike and bed the pads back against the rotors. I then remove the Mini-Stan and adjust the BF level in the reservoir to the max fill line so I have enough BF in the reservoir to cover the rest of the pad wear. Consider that I now have more fluid in the system (reservoir plus more BF behind the pistons) than I did when the pads were new. If I replace the pads with new ones by just pushing the pistons all the way in and putting the new pads in, then yes, I will overflow the BF out the vent and onto the ground by the RH footpeg. However, IF I don't think the remaining pad thickness will make it until the next annual bleed, I'll pull the pads a bit early (say with 30-40% wear remaining) when doing a bleed so I can have new pads when I'm bleeding the system and this problem is alleviated. I also now have a spare set (but not a full thickness set) to swap out if my pads are getting too thin to last on a long trip I've got coming up and I don't want to do the next normal bleed early before I leave. By swapping out the almost gone ones with the "not new, but still serviceable ones", I also avoid having to push the pistons back in too far and thereby overflowing the system. thumbsup.gif

 

Both methods intermingle the new fluid with the old too much so the flush won't be as thorough as it could be. None of the articles suggest getting a bleed test afterwards.
I'm curious as to how my method intermingles old with new, unless leaving the pad "in situ" keeps the pistons from being pushed further into the caliper than without them. I'll have to do a test on this at the next scheduled bleed (God, I think we're due again next month already! eek.gif ). I heartily agree there should be as close to NO mixing of old and new fluid as possible. Instead of holding the pistons at a set position with spacers (presumably leaving some fluid trapped behind them as the end of the brake line is right next to the bleed screw and does not really flow through the caliper), I use wooden construction (framing) shims to push the pads and pistons all the way into the calipers and hold them securely while bleeding the system (which is under pressure from the "servos"). I believe this pushes as much fluid as possible back through the system and into the reservoir where it can be replaced without mixing the old and new almost at all. Also, the BMW instructions say to first draw off all the old fluid from the reservoir, then push the pistons in, then draw out the rest of the fluid pushed back up into the reservoir again (to keep from overflowing the reservoir if the brakes have been serviced without replacing the pads). Some folks here didn't think it was that important to push the pistons in and just emptied the reservoir and bled the lines without messing with the calipers at all. This might be okay if your pads are new (not much fluid behind the pistons), but one experiment we did at one Tech Daze showed that with pads only about 40% worn--between the EIGHT pistons in the front wheel circuit combined--we drew another ~35ml of old brackish fluid out of the reservoir after pushing the pistons in all the way with the tapered wooden shims. As a percentage of the amount of BF in the whole system, that is A LOT of old fluid--filled with dissolved air, water and other crud--that immediately contaminates your new fluid. This not only undoes a good portion of your work, but it sets the clock ticking again on the corrosion of the expensive bits. eek.gif

 

Two other tips when working on brakes you may find useful. Always have a spray filled with water on hand when working on brakes. Any fluid spill can be quickly flooded with water neutralizing the affect of DOT4 on painted or plastic surfaces. Another nugget for the front brake lever is drop a single sided razor blade in the fluid reservoir prior to pumping the bleed sequence. It will block the geyser of fluid and prevent spills. When done extract with pliers before the cap is installed.
Now those two little tricks are slicker than dog snot! smile.gif

 

Another great addition to the collective knowledge base for these bikes, thanks! clap.gif

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Excellent post with many good questions. I will attempt to answer the issues I am familiar with;

 

"Interesting, but would that not test only the control circuits? I remember Uli talking about this double check for the control circuits: get the bike up to 30mph or so, shut it off and see if you can lock a wheel. "

 

The bleed test measures pressures generated and held without leak down in both the control circuit and wheel circuit. The report generated by the tester gives a zero reference readings and then three actual readings of the test performed three times as guided by the procedure. A pass is determined by a minumum pressure generated at the control side by the technician's application of firm brake lever pressure and also records the output pressure to the wheel circuit. A particular pressure ratio must be generated and maintained the three times for a pass. In example the wheel circuit must be in the range of 85 bar which is about 1 1/2 times the pressure needed to lock the front wheel in good dry pavement with good tires. All of this is done in residual mode. The tester disables the electric pumps during the test. You have to be able to maintain the threshold pressures for around five seconds without repumping the lever (that would stop the test). I have seen brakes that felt normal in operational pump mode that failed in the bleed test in residual. My point is the brake feel in normal mode can be misleading if you are trying to determine the brakes are bled adequately. I have seen a caliper pad mounting spring cause a failed bleed test because it was installed incorrectly. The brakes worked, but that spring plate caused a perceptible loss of pressure stability during the test! As stated I know of no way to check all of these critical dynamics without the test.

 

"For the wheel circuits, I seem to remember somewhere in my research that if you happened to get enough air in the wheel circuit portion that the system will fault on start-up if the "servos" (sic) can't spin-up enough pressure during the initialization, non? "

 

I don't believe this is correct. For one thing the initialization sequence only occurs when you have no application of brakes. Because the control circuit is at normalized pressure there is no pressure generated in the wheel circuit when the pumps run. You can test this by putting your bike on the centerstand and turn on the key. Rotate the rear wheel during the period of pump testing and you will feel little or no brake action. The pump running without control pressure delivered by the rider will not apply the brakes so the system has no way to check for pressure loss due to air in the fluid. As long as you have adequate fluid in the wheel circuit and the pumps operated the intialization will pass that part of the sequence.

 

That is saying a mouthful, but hopefully it clears the understanding of some terms and operational design. smile.gifsmile.gifsmile.gif

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This is a huge section to respond to, I will try to answer the questions I have some experience with.grin.gif

 

"I'm not so sure about the former based on the latter--you seem to have a lot of intimate knowledge that I'd like to "plumb" a bit more if you don't mind."

 

I am happy to help. I don't enjoy arguing with some folks over this subject. Sure, semantics like some terms are not particularly important to this group and I have come to understand that. I will try not to assail the egos of some like I have in the past. The thing that really throws me off is the notion held by some of the DIY riders that they know everything thing there is that is important and are quick to lead other inquiring riders along that path. Some are closed minded when it is pointed out some of their procedures are not sound or good for a system that is easily the one of the most safety critical systems on the bikes we ride. I understand the issues of ego and standing in the community, but telling newer members patently incorrect information is not good for anyone. The majority of this group justifiably takes great pride in their safety choices in protective gear, training, and riding skills. The apparent consensus of many of the same riders is they know all they need to know about servicing these critical brakes based on a group consensus. I know many riders that won’t wear proper riding gear and they are still fine. That doesn’t make that poor choice correct. Correct servicing in my view is as important as the gear we choose to wear, the pre-ride safety check, and our riding skills we try to hone, all elements of the safety formula and risk assessment we should use to guide our actions.

rant off dopeslap.gif

 

“People were being given quotes of $400-$1000 to do this job (along with a bunch of double-speak about required expensive computerized equipment, how the owner is not qualified, just leave your credit card at the counter, etc.). Unfortunately for some people, because of factors like the price of service, proximity of the nearest dealer, and frequency of service intervals: they chose to neglect their brakes entirely--which is a far worse consequence, as I'm sure you'll agree.

 

I understand this but I can’t control what dealers are doing. I will tell you that the FRU for a complete flush and bleed is around 36 for a R1150 RT. That is three hours shop time by the book. That is the time BMW has shown a trained and ready Tech will need to do the job from start to end. I don’t know what your shop rate is on an hourly basis, but at that rate most shops would charge around $300.00. Again I don’t know where these figures come from, but I can tell you I wouldn’t pay much more than three hours for the job. Now if they are performing other work and replacing parts or correcting things the owner fouled I can see the price going up. Bottom line there are some things you can’t do correctly as a DIY enthusiast. If you go by the repair manual procedures and use suitable specialized tools you can do this job if you have been coached by a person who has mastered the work. Yes you still have to get a bleed test done, but that cost should be covered by the minimum shop charge. Call it safety certification of a job done right. Beyond this I say this is the cost of ownership when you have an advanced technology machine. We can buy older bikes or different bikes and avoid all of this, but I really appreciate the braking competence of this system. My plan is to do the service myself and schedule a bleed test afterwards. IMHO this is the most prudent action and assures me the brakes are correct.

 

“From a corporate perspective that may be true--read: our lawyers say if you don't do it this way, we won't be liable for your funeral costs or other damages--but all that really is required is the presence of enough BF in the reservoir to keep the pump intake covered and hopefully not draw air into the system as the pads wear (or in the case of a tip-over). If you understand how the system works (the pads wear with use, the pistons move further out to make up for the extra space and fluid is drawn down from the reservoir into the calipers behind the pistons), and you carefully monitor the fluid level when bleeding and changing pads NOT in conjunction with a normally scheduled bleed, you should have no problems. If you get a chance to see the newer (post late 2003) ABS reservoirs you'll notice that one of the changes BMW made was a taller front wheel circuit reservoir to be able to hold more BF. Since there are eight pistons in the front wheel circuit (two calipers, each with two pads, each pad with two pistons), the fluid is drawn down into the calipers four times as fast as the rear circuit (with only two pistons). This solves both running out of BF in the reservoir as the pads wear thin and potential overflow issues when replacing pads not in conjunction with a bleed."

 

The newer design has reduced the risk of too little fluid, but the fact remains there is an optimal fluid level taking into account all brake pad conditions. Getting the correct fluid level you have no concern about changing of the pads in between the annual bleed and there is adequate “slosh room” as the pumps cycle on and off. This correct fill is easily found when you have the correct caliper piston positions held by the spacer tool. In fact the front calipers are not even removed from their mounts during the service, just the pads are removed. Bottom line is the only way to get a correct fill is to set the system to a defined volume and then fill to the mark in the reservoir. Anything different may lead to unfavorable consequences. This is not legal dept or corp speak, this is the word from the engineers that designed the system. How you get there does not matter, but I trust the people who explained the system to me when they said this is critical. There are metering circuits, pressure circuits, and pressure regulation circuits all depending on the correct flow and volume in the system. BMW spent a ton of money to train technicians on the importance of this, that should say something about the importance of procedures. BMW doesn’t make money directly from servicing, that is the realm of dealers.

You have developed a very interesting system of adjusting fluid levels and on the surface it seems sound. The problem I see is most DIY enthusiasts will not follow all the methods you devised. Honestly it seems like a lot of extra work that few home wrenches will understand or follow.

Why not make a group buy of a caliper spacing tool set and loan it out to members that helped pay for it. The individual costs would be low and one tool set could cover at least 50 users. The job is done right. The Harley groups I belonged to before did this for cam tools and it worked out really well. Alternatively some enterprising individual could buy the tools and rent them out with a deposit system. Someone could makeup for high service costs doing this.

 

“I'm curious as to how my method intermingles old with new, unless leaving the pad "in situ" keeps the pistons from being pushed further into the caliper than without them.”

 

The taught method has the caliper spacing tools applied at all three calipers. They are set to fully push the pistons (10 of them) completely into their bores. Next the brake fluid of both wheel circuits is completely pumped out of the system through the bleed screws using the pumps. Yes, you run the pumps dry for a very short times and introduce air into the whole wheel circuit system. Both reservoirs are refilled with fresh fluid and that is pumped out really flushing any additional old fluid out. Next the system is refilled a third time and the clean fluid is circulated from the bleed screw to the reservoir holding pressure on the brake lever. This along with momentary opening and closing of the bleed screws causes hydraulic shocks within the system separating air bubbles from the fluid. After this the caliper spacing tools are set to their model specific setting and brakes are applied to seat the pistons against them. There is no air in the system so we can accurately adjust the reservoir to the marking.

 

In all of this we flushed the brakes very thoroughly with a fresh fluid flush. If the brakes were overdue and required another flush it is very easy to repeat the fresh flush. You should be able to do the entire brake system with less than 32 oz; usually I use around 16 oz.

This is the trained method that clearly provides the best flush and bleed and is accomplished in much less time than it took me to write this summary.

 

Honestly, tapered wooden shims or jamming wood shims between the pads on a removed caliper is neither correct nor efficient. If you want to perform a professional job, a job you can bet you life on you should learn the correct procedures and follow them or entrust the bike to someone who does.

 

Like you, I derive a great deal of satisfaction in knowing my bike and how to work on it. I want my work to be as good as or better than what a good technician is capable of delivering. If you don’t have the skills or can’t follow time honored and proven procedures or can not employ valid tools to do the job you are really better off not doing it. It is a problem compounded by those (including me) that live great distances away from a dealer (my closest dealer is 125 miles away). For me, doing this job incorrectly is not an option.

 

Once I have gathered my brake tools together I would consider contributing by giving a seminar on this subject. Fortunately, I have eleven months to secure my brake tool set.

 

Fewer farkels, more tools thumbsup.gif

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Stan Walker

Next the brake fluid of both wheel circuits is completely pumped out of the system through the bleed screws using the pumps. Yes, you run the pumps dry for a very short times and introduce air into the whole wheel circuit system.

 

Hmmm, who dreamed this up? it's not mentioned in my official BMW service manual. I do have an early copy so perhaps it's been changed. If not, then I for one would resist running the pistons dry, and resist introducing air into the system.

 

 

Honestly, tapered wooden shims or jamming wood shims between the pads on a removed caliper is neither correct nor efficient.

 

Metal tools, wood tools, if it's the right size, it simply doesn't matter. Pushing pistons back into the caliper isn't rocket science. Nor does it matter if you do all three calipers at the same time, or flush fronts and rears separately.

 

Bottom line is the only way to get a correct fill is to set the system to a defined volume and then fill to the mark in the reservoir.

 

The level within the reservoir will vary depending on the wear level of the pads installed from very full with brand new pads to some minimum level with totally worn out pads. Clearly the system is designed to accommodate this change in levels without harm to itself or to the braking function.

 

I do agree that filling the reservoir to the full mark with used pads installed will result in an excess total volumn of fluid and lead to a problem when replacing the pads. My personal experience is that this isn't a big deal.

 

Stan

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Stan Walker

Well, we will just have to NOT see eye to eye on this. You haven't convinced me. So far you have presented many things taught to you by BMWNA but not actually presented any new documentation or even a white paper in support.

 

Until such time as I see something in writing from the factory (not BMWNA) I'll continue to follow the procedure as laid out in the BMW published service manual for my bike. With the exception of how I determine the final fluid level where I will fill it to the full mark using whatever pads are on the bike at the time.

 

Stan

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Mudman,

 

Your obvious in-depth knowledge of the system is a welcome addition here, and I for one thank you for that. Also obvious is your bent to BMWNA's perspective on at least this subject, and that too is fine.

 

But please do not so out-of-hand dismiss the expertise that has been developed, by admittedly DIYers, here and else where in similar forums. Often out of financial necessity, many competent independent mechanics, of which I include myself, in concert have developed a way to successfully service these systems without dire, indeed without even minor, consequences. These independent service procedures work, and the bikes work correctly when complete. Between just Jamie (KMG_365), Stan, and myself alone we have serviced 100s of post-2002 model year EVO brake systems (including on the new "hex-head" series) and those bikes operate 1000s and 1000s of miles/km afterward with no EVO issues. To say nothing of the many, many other people who have done the same themselves following the same procedures. Hardly a track record of the incompetent.

 

BMW/BMWNA procedures are fine, but often, as in this case, are so are DIYer's.

 

Part of the spirit of the "Wrenchin'" forums of this board, and other similar web sites, is the learning tool it provides for the development and dissemination of info about topics such as this. A dismissal of the expertise developed as a result, either within or out of "approved" procedures, is unfair and inaccurate. There are those of us who do know what we are doing, BMWNA aside. Our track record gives evidence of it.

 

All I ask is that a person recognize that both perspectives are valid.

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Ken,

Your points are well taken. I appreciate your viewpoint and have tried to point out the issues of procedure, not personal attack. My thoughts were not on a personal level, but a debate on procedure.

 

It is at times hard to "lurk" and see things explained to others that I know are wrong on something like brakes. Everybody will ultimately choose what they do with their bike. Members asking advice would be well served to hear another side of their request to make an informed decision. You are right, I am pretty much a by the BMW book guy and I won't hide that. I am not an employee or paid representative, but based on personal experience their procedures have worked well for me and those in that business.

 

I understand the desire to be self sufficient and work on your own bike. I have to admit the new systems are making this more difficult all the time. From what I have seen and heard described there are many different ways the brake bleed is being done. Most are pretty close to being correct and a few minor changes would make the process correct without any issues. Some say they are following the factory procedure, but they are really following the part they can do and make up the rest. I was trying to point out the parts that don't follow any recognized procedure. If the consensus is my remarks are not serving a positive purpose I will stop with what has been abrasive to some members.

 

I do enjoy this forum and have learned much from reading the knowledge base the members offer. Hopefully I will be able contribute something from what I have learned as well.

 

Thanks for your kind and thoughtful remarks.

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It is at times hard to "lurk" and see things explained to others that I know are wrong on something like brakes.
Don't you mean, "that I'm not sure are as effective/safe"?

Members asking advice would be well served to hear another side of their request to make an informed decision.
Very true, but you needn't rely on scare tactics and hyperbole to lend your arguments credance. It just undermines any possible value in what you say if it is delivered in such a dogmatic manner.

 

I understand the desire to be self sufficient and work on your own bike. I have to admit the new systems are making this more difficult all the time.
I think BMW has a few more sales to the "self sufficient" types exactly because of places like this. In the last six years that I've been hanging out here sponging up the collective wisdom I can think of MANY people who were on the verge of giving up their BMW's because they couldn't get them to run right or the dealer couldn't do a decent synch (surging), or they quoted $1000.00 for a 24K with annual service. There's absolutely NO way Leslie and I could afford our RT's if we had to pay $90.00/hour for the serving and parts/supplies required for the 65,000 miles a year we ride.

 

We're already hearing the problems with the ESA shocks (and they mostly haven't had to be replaced in large numbers yet), and I can't wait to hear the bellyaching when the new K-motors have to be brought in for a computer to tell you it's time to adjust your valves--and it's 5 hours of labor to do it! eek.gif (In fairness I have no idea what the time is, but removing the radiator and cam shaft, etc can't be a walk in the park.)

 

If the consensus is my remarks are not serving a positive purpose I will stop with what has been abrasive to some members.
Please don't stop sharing your knowledge. It is not the information itself that is abrasive, just the approach. Like this gem:

 

"It was written into service manuals. Trust the force." dopeslap.gif

 

 

That just unnecessarily goes down the wrong road. Then you get the twitchy-kneed among us to fire back with:

 

"Hey, dude! Pass the Kool-Aid!" or "Man I had no idea I've been running with scissors for three years!" . . . and then all rational discussion on the merits of the arguments are lost. frown.gif

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