KDeline Posted January 25, 2009 Share Posted January 25, 2009 I asked this about 8 months ago, did not seem to get a definite answer. Now it's time to bleed. On the 2007 GSA non servo bikes can you just bleed them like the old airheads and the early oilheads? I assume since there are no servos anymore you just put new brake fluid in the reseviors, pump the levers and bleed at the caliper base? Anybody done it yet? Link to comment
Mr_Ed Posted January 25, 2009 Share Posted January 25, 2009 How timely! I've been looking for pictures/video of the procedure myself. On our 07 GSA I know we just have the one circuit so bleeding is supposed to be as simple as it could possible get BUT I've never done it before so I was hoping to find an example of someone executing the procedure. Link to comment
Limecreek Posted January 25, 2009 Share Posted January 25, 2009 I have the new (non servo) system on my GT and will change the brake fluid for the first time this summer. BMW requires a brake fluid change after the first year of service and then every two years going forward. Below is a summary based on the current BMW manual. It is a summary for someone who has experience in bleeding brakes and understands the basic steps in performing maunal brake bleeding/brake fluid replenishment. Brake Fluid Change Summary (Front Brakes) 1. Set the brake lever to maximum span. 2. Remove the reservoir cover and draw off the old fluid. 3. Clean the reservoir. 4. Remove the brake pads from the calipers. 5. Force the caliper pistons back into the bore (bmw tool or shim them like we do). 6. Draw off the fluid in the reservoir. 7. Fill the reservoir with DOT 4 to the Max level. 8. Connect bleeding hose to the bleed screw at the master cylinder--located to the left and below the resevoir, open the screw and begin bleeding the master cylinder. 9. Bleed until clean fluid emerges and close the bleed screw.. Do not let the fluid in the resevoir drop so low that it exposes the replenishment hole (that would be a bad thing). By the way, I am going to use a manual bleeding method vs.vacum extraction. 10. Go to the left caliper and bleed until clean fluid emerges. Again watch the level in the master cylinder as you are bleeding the calipers. Close the bleed screw. 11. Go to the right caliper and bleed until clean fluid emerges. Close the screw. 12. Go back to the master cylinder and bleed it one more time. 13. Top off the master cylinder reservoir. 14. The next step requires that you acquire a special BMW tool or build a suitable replacement. The tool is inserted into the caliper in place of the brake pads. It is the same thickness of a brand new pad. The newer bikes have a brake pad thickness monitoring system. Do you see where this is going? 15. Bed in the brakes with the tool inserted in the caliper. 16. Top off the master cylinder reservoir to the max mark. 17. Remove the tool and install the brake pads. 18. Install the reservoir cover. 19. Bed in the brakes. I'll add the procedure for the rear later today, but it is basically the same as the front with a few minor differences. Next month I am helping a local guy renew the fluid in his '07 RT. We will document the steps with pictures. Link to comment
KDeline Posted January 25, 2009 Author Share Posted January 25, 2009 Wow! Thanks, I will look for it. Link to comment
T__ Posted January 25, 2009 Share Posted January 25, 2009 KDeline, that is a very good question you have brought up.. I haven’t had to do one of the newer partially linked systems yet.. I will have to come up with a solid game plan by the time I have to do mine.. In theory you should be able to bleed just like the old ABS2 systems as that should clean out most of the old fluid.. The catch here being that the new system uses a valve type controller with an accumulator storage.. The basic (below ABS threshold) FRONT brake apply just shoots the fluid straight through an open control valve so it by-passes the electro & accumulator part.. When the dealer does the brake bleed his diagnostic computer system cycles the controller valves to assure all air & old fluid is passed through.. The rear is also different as it uses front brake apply pressure to control the rear electro assist until such a time as rear brake pressure overrides the front apply pressure at which time it supplies the rear brake apply pressure.. How a simple pass through home bleed effects that part of the system I really don’t know.. In my job working in future automotive chassis development I work with some very sophisticated & sometimes strange ABS systems using novel controllers but none like the one on the new BMW R bike.. I am familiar with the newer valve type ABS systems as most of the older piston types have long since disappeared.. The newer electro valve systems are a real bitch to get the air out of if the valves are not cycled while bleeding or after working on the system.. OK, here are my (personal) concerns.. First being- that almost any home bleed won’t completely replace the trapped fluid in parts of the ABS controller.. Will it leave enough to make any difference I can’t say.. Second being- warranty concern from BMW.. If they really want to nit pick you,, a system bleed without cycling the controller valves could be construed as an ineffective bleeding process (just a SWAG on my part here).. My (personal) plans at this point in time baring other info or BMW furnished data is going to be to bleed the system yearly with a 2 part bleed process.. First off,, just bleed as if the system is the older ABS 2 system.. Then take the bike out & run a few front & rear ABS cycles on my dirt road.. Then return & re-bleed hoping that I have cycled the new fluid through the ABS controlled accumulator & rear electro pump.. I see the GS-911 has the ability to read & re-set ABS codes but not sure on it’s ability to cycle the controller valves & electo servo.. This is good (no great) subject to keep going for a while with hopes that we can get some input from may sources & backgrounds involved to try & understand this system when it comes to bleeding & warranty requirements as far as BMWNA is concerned.. Twisty Link to comment
hexairheadbeemerguy Posted January 25, 2009 Share Posted January 25, 2009 You may wish to look at this site jimvonbaden.com. I bought one of his DVDs to learn about servicing my hexhead, it includes bleeding the brakes. He owns a GS and uses it for the dvd video and audio. It is only $30 and imho worth the purchase price. Link to comment
T__ Posted January 25, 2009 Share Posted January 25, 2009 You may wish to look at this site jimvonbaden.com. I bought one of his DVDs to learn about servicing my hexhead, it includes bleeding the brakes. He owns a GS and uses it for the dvd video and audio. It is only $30 and imho worth the purchase price. hexairheadbeemerguy,I don’t see anything from Jim on the newer (gen 2) R1200RT brake system bleeding.. All I see in his listed info - is for the older R1200RT with the IABS power servo brake systems.. I also didn’t see any use of the GS-911 to cycle the ABS controller,, it was just used to read the ABS codes.. If I missed his info on the new (post IABS gen 2) system please point it out for me.. You do realize the newer R1200RT’s use a different brake system then the older R1200RT?. Twisty Link to comment
Limecreek Posted January 25, 2009 Share Posted January 25, 2009 First being- that almost any home bleed won’t completely replace the trapped fluid in parts of the ABS controller.. Will it leave enough to make any difference I can’t say.. I am having a hard time understanding what exactly takes place inside of the pressure modulator after the outlet valve is closed and the intake valve is opened at the end of an ABS cycle. Does the fluid diverted to the the reservoir in the pressue modulator sit there until the next ABS cycle? So far, I cannot find any documentation indicating the valves in the pressure modulator are opened and closed during the bleeding process. Twisty please enlighten us. You have a background in this area based on what you've written. How does the new BMW system work? I'd really like to serice the sytem on my own without concern of fluid trapped in the low pressure reservoir; ultimately leading to a failure or dimished braking capacity. Link to comment
T__ Posted January 25, 2009 Share Posted January 25, 2009 Gregory, lots of holes in what I know about this system but from what I can determine.. Front brake hydraulic pressure from the ft brake lever is delivered directly to the ft calipers through the open ABS controller intake valve.. This allows normal unhindered conventional rider braking control.. Entering impending ABS mode or impending wheel lock up when the ABS controller senses a locking wheel is about to take place (or impending lock up due to very high decel rate) the controller ft intake valve is quickly closed by the controller then that circuit outlet valve is quickly opened.. This then allows fluid pressure to bleed off through the open outlet valve into a storage reservoir (or low pressure accumulator).. This very quickly dumps brake pressure on that circuit to prevent wheel lock up.. I’m not sure on the BMW system but most comparable car systems have the ability to very quickly drop the pressure to almost nothing (the good part about a valve vs a piston system).. In conjunction with the quick pressure dump,, I believe an electric hydro pump comes on to move the fluid back into the control circuit.. When wheel traction returns the outlet valve is probably closed then the intake valve is re-opened putting the system back to rider input control.. If the Gen 2 system is like similar auto systems it will cycle in & out of pressure dump,, accumulation,, & return to driver control as the wheel locks then resumes traction.. (keep in mind some of the above is an educated guess on my part based on similar type systems) … The rear is more complicated as the rear hydro pump comes on with front brake apply & somehow senses front brake pressure vs decel speed as well as rear wheel brake pressure vs rear wheel decel speed then modulates the braking bias & pressure to keep even balanced braking & prevent rear wheel lift (probably circuit pressure vs wheel decel rates) A (quick rear wheel decel rate with little rear brake pressure required probably tells the system that the rear wheel is lifting if the front is still maintaining decent brake pressure without excess wheel slippage (somewhat of a guess on my part here) If more rear bake is used & the rear brake master cylinder pressure exceeds the front proportioned servo pressure the rear system closes some type of crossover valve then takes over braking duties from the servo assist.. If the rear brake is used alone without any front then it has no servo pressure to overcome as the servo motor hasn’t come on so it just operates like a conventional brake until eminent rear wheel lock up is sensed then somehow the rear servo pump comes on to assist fluid transfer & some type of fluid dump must take place like on the front (this part differs from auto type systems so I don’t know exactly how it fully functions).. The above is based on my working knowledge of similar ABS systems & some BMW furnished info from a friend in Germany.. The system more than likely operates pretty close the above info but there could be some errors in the fine details.. Twisty Link to comment
KDeline Posted January 25, 2009 Author Share Posted January 25, 2009 Somehow I think this is not going to be as simple as I thought. Link to comment
T__ Posted January 26, 2009 Share Posted January 26, 2009 Somehow I think this is not going to be as simple as I thought. KDeline, it might be easy,, we just don’t know (well at least I don’t anyhow) .. A conventional brake bleed like on the old ABS 2 system should cover most of the old fluid.. How much of the old fluid is left in the system we really don't know or if it even makes a difference.. People just bled the old ABS 2 system from the master cylinder reservoirs to the calipers & not many problems associated with that.. Thing was if you went a few years then bled at the ABS controller you could see some old skunky fluid come out of the controller that the conventional bleeding process missed.. There were a few ABS controller failures on the ABS 2 system but no way to know if the bleeding process was even part of those failures.. So far I haven’t been able to find a real BMW manual covering the mid 2006 up partial linked gen 2 brake system.. Closest I could find was an authority system that is similar to the gen 2 system.. All that I could find on that system called for hooking the BMW GT-1 to the system prior to bleeding the brakes,, does it actually open the controller valves or cycle the servo pump? I have no idea but kind of think so.. Is it actually required for a proper & thorough bleed? Again I don’t know.. In any case a conventional bleed from reservoir to caliper will be a big help in removing most of the old fluid.. A second bleed after a while & especially after an ABS event would probably help even more.. Hopefully we will get a BMW service manual covering the new brake system but even then I would be willing to bet it says to hook up the BMW Motorrad diagnostic system prior to the bleeding but I will also bet it won’t tell you exactly why or what it’s function is during the bleed.. I’m guessing that if you do a full system bleed from the reservoirs through the calipers yearly that will pretty well move most if not all the old fluid out eventually.. We had a BMW tec appear on the board here from time to time here.. Maybe he can shed some light on what the BMW Motorrad diagnostic system actually does on the gen 2 system during the brake bleed.. Twisty Link to comment
Limecreek Posted January 26, 2009 Share Posted January 26, 2009 Hopefully we will get a BMW service manual covering the new brake system but even then I would be willing to bet it says to hook up the BMW Motorrad diagnostic system prior to the bleeding but I will also bet it won’t tell you exactly why or what it’s function is during the bleed.. I have a BMW repair manual that covers the new ABS system and the old ABS service requirements. The manual does not require the assistance of BMW diagnostic system when bleeding the new system. The only time the diagnostic system is required is after the replacement of the pressure modulator. From what I can tell from the manual, a programming and diagnostics rotine is required with the installation of a new pressure modulator. The repair manual does not require the BMW diagnostic system for the previous generation intergal system either, but I believe BMW uses the system for a leak down check, so perhaps the manual does not reveal the complete procedure. I am out of town next week, but next weekend I'm going to go have a talk with the Lone Star BMW dealer, ask a few question and try to get to the bottom of what is and what is not required. Link to comment
T__ Posted January 26, 2009 Share Posted January 26, 2009 Gregory, I just found that exact info in on of my later BMW repair manuals under pressure modulator replace (gen2) & was about to post it here when I see you already posted it.. It does look like a conventional bleeding is all that is required to purge the system of air so that should also purge it of old fluid.. It also talks of a vacuum bleed followed by a conventional pump the brakes bleed but more than likely the vacuum part is just to quickly purge the new modulator of air.. The pumping part is the final step so that should work for the home bleed process.. Also looks like all that pad resetting tool & pad spacer is to obtain the correct reservoir level at end of dealer level bleeding.. Can’t see where it gains you anything at bleeding time.. Looks like a simple wedge the brake pads back to decrease the caliper volume to minimum will do the trick then let them loose prior to topping off the reservoir.. It does look easier than I first though so the internals of the controller must be set up as a complete flow through (seems strange with a pump & accumulator type system) but the manual doesn’t show a pump or valve cycling sequence & the lines do come out the top of the controller.. Twisty Link to comment
Limecreek Posted January 26, 2009 Share Posted January 26, 2009 Now all we need is a donnor bike, er I mean someone who needs service. Hey Dave in Texas let's try it out on your in a couple of weeks. Link to comment
Koop Posted January 26, 2009 Share Posted January 26, 2009 This is a great topic and I hope the thread evolves as we learn more. Link to comment
T__ Posted January 26, 2009 Share Posted January 26, 2009 Kdeline, OK here is directly from the only manual I have that covers the later (gen 2) mid 06 up RT brakes (full system bleed) .. A lot there & a lot probably not really needed.. I can’t see why you would have to bleed at the master cylinder first if your system has no air in it to begin with & especially to bleed it twice (but it’s there in the manual).. As far a removing the brake pads & using the special piston retraction & holding tools.. Most of us don’t do that but instead just pry the pads back away from the rotors to push the caliper pistons back into the bores then secure there with wooden shims.. Same with all the resetting tool usage,, That seems to be more for obtaining proper master cylinder fluid level than anything else,, probably needed if the fluid level is used for pad wear indication but the RT seems to use a manual rear pad indicator & no front wear indicator (that I can find anyhow).. It does call out a vacuum bleeding process but also says at the end to use manual bleeding if you still don’t have a firm brake lever/pedal so it looks like manual bleeding might be preferred.. Also with the first part saying to re-set the lever to max stroke that points to manual bleeding being used.. My personal opinion is that this won’t get all the old fluid out of the ABS controller but BMW doesn’t seem to care as it isn’t addressed in their bleeding process.. I can see where all the air will come out as the lines are on top of the controller & the fluid should fall to the bottom of the controller forcing the air up & out the top but can’t see how fluid will flow through the internal accumulator or pump during a hand bleed process.. Again in my personal opinion probably not enough fluid left in the system to really matter.. Otherwise it looks straight forward with normal BMW confusing statements in the procedure.. Anybody question this procedure? Lets talk about it (we should maybe start a separate thread to discuss though).. I think for warranty reasons you should document (with pictures if possible) bleeding at the master cylinder & having the brake pads fully retracted along with showing empty then full master cylinders.. Include the mileage & date as well as fluid type & fluid info.. 34 00 010 Change brake fluid in entire system + 34 00 504 Status: (AFTER) 07.2006 Preparatory work Removing seat Core activity (+) Changing brake fluid, front brakes, and bleeding brake system (-) Changing brake fluid, front brakes, and bleeding brake system -------------------------------------------------------------------------------- Note This description applies for the brake filling and bleeding unit with extraction of the brake fluid by partial vacuum. If other devices are used, comply with their manufacturers' instructions. -------------------------------------------------------------------------------- Set the brake lever to maximum span. Remove screws (1) and remove reservoir cap (2) and gasket (3). Draw off the old brake fluid and clean the reservoir. Removing front brake pads Remove retainer (2). Remove screw (3). Remove spring (1). Remove the brake pads. Install piston resetting device (No. 34 1 531) and locator (No. 34 1 532) in the left and right brake calipers. Use the piston resetting device and locators to force the pistons in the left and right brake calipers all the way back and hold them in this position. -------------------------------------------------------------------------------- Draw off the excess brake fluid from the reservoir. -------------------------------------------------------------------------------- Warning Brake fluid is hygroscopic, which means that its boiling point drops once the container has been opened. Use only new brake fluid from freshly opened containers. -------------------------------------------------------------------------------- Top up with fresh brake fluid to the (MAX) mark. Consumables/lubricants DOT4 brake fluid Hydraulic systems 83 13 0 139 895, 83 13 0 139 896, 83 13 0 139 897 Connect the brake bleeding device to bleed screw (4) on the brake master cylinder. Slightly open bleed screw (4). -------------------------------------------------------------------------------- Warning Air can be drawn into the system through the fluid replenishing hole if the fluid level in the reservoir is too low; the system has to be bled again if this happens. During the fluid-change and bleeding procedure, make sure that the fluid replenishing hole is always below the level of the brake fluid. -------------------------------------------------------------------------------- Continue bleeding the brake system until the fresh brake fluid emerges clear and free from bubbles. Close bleed screw (4). Tightening torques Brake fitting bleed screw 3 Nm Connect the brake bleeding device to bleed screw (5) in the left brake caliper. Slightly open bleed screw (5). Continue bleeding the brake system until fresh brake fluid emerges. -------------------------------------------------------------------------------- Warning The brake-bleeding process might have been interrupted even though air remained in the system. On account of the vacuum extraction process, it is not possible to tell whether the brake fluid extracted from the system is free of bubbles. On conclusion of the process, bleed the system manually (without vacuum extraction) until you are sure that the brake fluid expelled from the system is free of bubbles. -------------------------------------------------------------------------------- Close bleed screw (5) of the left brake caliper. Tightening torques Front brake caliper bleed screw 5 Nm Repeat the fluid-change procedure/procedure for bleeding the brakes at the right brake caliper. Top up with fresh brake fluid to the (MAX) mark. Again connect the brake bleeding device to bleed screw (4) on the brake master cylinder. Slightly open bleed screw (4). Continue bleeding the brake system until the fresh brake fluid emerges clear and free from bubbles. Close bleed screw (4). Tightening torques Brake fitting bleed screw 3 Nm Install adapters 22 (No. 34 1 533) in the piston resetting device on left and right and fully compress the piston resetting device. Pull the handbrake lever until the brake pistons are in contact with the piston resetting device. This simulates the thickness of new brake pads and brake discs. Top up the brake fluid level to the (MAX) mark. Expand the piston resetting device on left and right. This forces back the brake pistons so that the brake pads can be installed. Remove the piston resetting device and locators left and right from the brake calipers. Wipe the rim of the reservoir, gasket (3) and cap (2) to remove brake fluid and carefully reassemble the components. Install screws (1). Installing front brake pads -------------------------------------------------------------------------------- Warning Greasing the backing plate can allow grease to make its way onto the friction pad and the brake disc. Take care to grease only the rear and the trailing end face of the backing plate. -------------------------------------------------------------------------------- Grease the rear and the trailing end face of the backing plate. Consumables/lubricants Never Seez compound Protective grease 83 23 9 407 830 Install the brake pads. Install spring (1) with the arrow pointing in the forward direction of travel. Install screw (3). Install retainer (2). Tightening torques Grubscrew, brake pads 7 Nm Bedding in brake pads -------------------------------------------------------------------------------- Warning Braking efficiency is impaired if the brake pads are not correctly bedded against the discs. Before riding off, always check that the brakes bite as soon as the brake lever is pulled or the brake pedal depressed. -------------------------------------------------------------------------------- Operate the brake several times until the brake pads are bedded. Test Check brake pressure by operating the brakes. Result: Low brake pressure Measure: Repeat the brake bleeding procedure without removing the brake pads. (+) Changing brake fluid, rear, and bleeding brake system (-) Changing brake fluid, rear, and bleeding brake system -------------------------------------------------------------------------------- Note This description applies for the brake filling and bleeding unit with extraction of the brake fluid by partial vacuum. If other devices are used, comply with their manufacturers' instructions. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Attention Brake fluid attacks paintwork, plastic and rubber parts. Do not allow brake fluid to come into contact painted plastic parts or rubber parts. -------------------------------------------------------------------------------- Remove reservoir cap with diaphragm. Draw off the brake fluid from the reservoir and clean the reservoir. Removing rear brake pads Remove retainer (1). Drive retaining pin (2) out toward the wheel side. Remove the brake pads. Releasing brake caliper Remove screws (1). -------------------------------------------------------------------------------- Attention The front brake lever also applies the rear brakes (integral brakes). Once the brake calipers and brake pads have been removed, operating a brake lever could result in the pistons being pushed out. Do not operate the brakes with a brake caliper removed. Install the brake caliper with brake pads or insert the piston resetting device. -------------------------------------------------------------------------------- Remove the brake caliper. Using piston resetting device (No. 34 1 531) and adapter (No. 34 1 536) force the pistons of the brake caliper fully back, and secure them in this position. Draw off the brake fluid from the reservoir. -------------------------------------------------------------------------------- Warning Brake fluid is hygroscopic, which means that its boiling point drops once the container has been opened. Use only new brake fluid from freshly opened containers. -------------------------------------------------------------------------------- Top up with fresh brake fluid to the (MAX) mark. Consumables/lubricants DOT4 brake fluid Hydraulic systems 83 13 0 139 895, 83 13 0 139 896, 83 13 0 139 897 Connect the brake bleeding device to bleed screw (1). Slightly open the bleed screw. -------------------------------------------------------------------------------- Warning Air can be drawn into the system through the fluid replenishing hole if the fluid level in the reservoir is too low; the system has to be bled again if this happens. During the fluid-change and bleeding procedure, make sure that the fluid replenishing hole is always below the level of the brake fluid. -------------------------------------------------------------------------------- Continue bleeding the brake system until fresh brake fluid emerges. -------------------------------------------------------------------------------- Warning The brake-bleeding process might have been interrupted even though air remained in the system. On account of the vacuum extraction process, it is not possible to tell whether the brake fluid extracted from the system is free of bubbles. On conclusion of the process, bleed the system manually (without vacuum extraction) until you are sure that the brake fluid expelled from the system is free of bubbles. -------------------------------------------------------------------------------- Close the bleed screw and disconnect the brake bleeding device. Tightening torques Brake caliper, rear, bleed screw 5 Nm Top up the brake fluid level to the (MAX) mark. Tighten up piston resetting device (No. 34 1 531) until it is fully tightened up. Press the footbrake lever until the brake pistons are in contact with the piston resetting device and adapter. This simulates the thickness of new brake pads and brake discs. Top up the brake fluid level to the "MAX" mark. Wipe the rim of the reservoir, the diaphragm and the cap to remove brake fluid, and carefully re-assemble the components. Expand the piston resetting device. This forces back the brake piston so that the brake pads can be installed. Remove the piston resetting device and adapter from the brake caliper. Installing rear brake pads Check that spring (1) is correctly seated and installed right way round. Arrow points in direction of travel. Install the brake pads. Manually install retaining pin (2). Securing rear brake caliper Hold the brake caliper in position and secure with screws (1). Tightening torques Brake caliper, rear, to cover of final drive housing M8 x 25 24 Nm Once the work has been completed, seat the pads against the brake discs and check operation of the brake system. Drive retaining pin (2) all the way into the brake caliper until seated. Install retainer (1). Operate the brake several times until the brake pads are bedded. Test Check brake pressure by operating the brakes. Result: Low brake pressure Measure: Repeat the brake bleeding procedure without removing the brake pads. Finishing work Installing seat Final check of work performed Link to comment
KDeline Posted January 26, 2009 Author Share Posted January 26, 2009 BMW's instructions seem a bit excessive. I have bleed my wifes R1200RS servo brake system, it's about a 5 hour job with all circuits bleed, with only wooden shimes, my hand made brake fluid funnel, and two special BMW tools to reach the recessed bleed valves on the controller. This bike can't be that hard, I hope. Great research guys. Link to comment
T__ Posted January 26, 2009 Share Posted January 26, 2009 BMW's instructions seem a bit excessive. I have bleed my wifes R1200RS servo brake system, it's about a 5 hour job with all circuits bleed, with only wooden shimes, my hand made brake fluid funnel, and two special BMW tools to reach the recessed bleed valves on the controller. This bike can't be that hard, I hope. Great research guys. KDeline, BMW does kind of go to extremes.. You could clip a lot out of that sequence & still get the same results,, I just though I would post the entire procedure so there won’t be anything missed.. Problem is; in that same repair manual the brake procedures are kind of mixed up somewhat due to mistakes in translation but also there are still quite a few references to the old IABS controller in the post 7/06 sections.. In fact I really didn’t know how intermixed they were until your original post here & I started looking at the info & procedures.. Twisty Link to comment
Dave_in_TX Posted January 26, 2009 Share Posted January 26, 2009 Now all we need is a donnor bike, er I mean someone who needs service. Hey Dave in Texas let's try it out on your in a couple of weeks. I think we may be able to arrange that. Link to comment
bmw4latino Posted January 27, 2009 Share Posted January 27, 2009 Thanks for posting that Twisty. I wonder why they don't call for the pistons/seal area on the caliper to be cleaned before the resetting the pistons? Would that eventually damage the seals or introduce contaminants into the fluid? "The brake-bleeding process might have been interrupted even though air remained in the system. On account of the vacuum extraction process, it is not possible to tell whether the brake fluid extracted from the system is free of bubbles. " Why can't one tell that the air is bled (free of bubbles) when using a vacuum extraction process? Link to comment
Boffin Posted January 27, 2009 Share Posted January 27, 2009 Why can't one tell that the air is bled (free of bubbles) when using a vacuum extraction process? Because vacum bleeding often pulls air past the threads of the bleed nipple into the tubing and so it is common to see a fine stream of bubbles in the fluid. A tech might therefore see a fine stream of bubbles and put them down to the vac bleed when they are in fact coming from the brake system. Andy Link to comment
T__ Posted January 27, 2009 Share Posted January 27, 2009 Why can't one tell that the air is bled (free of bubbles) when using a vacuum extraction process? bmw4latino, for a couple of reasons.. The first being that the bleed screws don’t seal very well at the thread area so any negative pressure (that is vacuum to the non engineering people) can draw in small amounts of air at the bleed nipples to caliper threads.. They (the bleed nipples) are designed to ONLY seal when tightened on their seats) Secondly, any air leakage anywhere from bleed hose attachment to who knows what can allow air bubbles in the bleed hose to show up.. If the air is enterng externally but not from inside of the brake system it means little but you can't tell the difference so assume the worst.. Twisty Link to comment
Don_Eilenberger Posted January 27, 2009 Share Posted January 27, 2009 From a brief read - it appears not much different from bleeding any "normal" brake system. Do it with the caliper pistons fully retracted. Bleed until no air appears and fluid is clear. And I'd set the fluid level simply with the pistons fully retracted. I know on the rear brake - they must be fully retracted to get a new set of pads in. Sounds like a piece'a'cake. I was going to do it - I'm approaching the 2 year mark - until I realized - last summer the R12R's were recalled to get brake hoses replaced. Can't replace the hoses without bleeding the system. That means my front has been done. I might do my rear brake just in case it wasn't. Link to comment
KDeline Posted January 27, 2009 Author Share Posted January 27, 2009 Well I'm going the easy route and let you know what happens. We might be over thinking this. Link to comment
Twisties Posted March 8, 2009 Share Posted March 8, 2009 Search is my friend! Great thread guys. My turn to try this next. I got the general idea, but could use some help understanding where all the parts I need to access on the '07 RT are, and how to recognize them. Any pics or diagrams would be superb! Do I need to pull the gas tank to get to the master cylinder... I guess I should just go out and look on the bike before asking, but it's a bit chilly out there right now. What tools are necessary (excluding standard items)? Seems like maybe just some clear hose/tubing to fit on the bleed bibs? Amazingly, the word "flush" doesn't yet appear in this thread, so I didn't find it on my first search. There, now the next person to try searching that way will be in luck. Thanks! Link to comment
Twisties Posted March 8, 2009 Share Posted March 8, 2009 Oh, also, how much fluid should I have on hand for this procedure? Thx Link to comment
Dave_in_TX Posted March 9, 2009 Share Posted March 9, 2009 Oh, also, how much fluid should I have on hand for this procedure? Thx I took two bottles with me to Limecreek's when we did mine and ended up only using one. Link to comment
Recommended Posts
Archived
This topic is now archived and is closed to further replies.