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Brake fluid change on an '04 RT


stonkers441

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$400 dollars?????? Are they nuts???? I'm calm now. Due to my, I can do it nature, I tried to change the fluid on my '04 RT with my trusty Mity Vac. It wouldn't. dopeslap.gif Hence, a call to Foothills BMW in Denver. Nope. You can't do it. There must be a way to change your own fluid without paying for 4 hours labor?? I rode the bike over on Saturday with zero brakes. Well, it had some when I started. At least I saved some dollars by stripping off the body work. It will be ready Wednesday evening. I'm leaving on a 8 day ride Thursday at 6:30. Any ideas for the future? confused.gif

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Has anyone used their mityvac only on the CONTROL Circuits? I realize you wouldn't use it on the wheel circuits.

 

Since those points are bled without energizing the pump, I'm wondering if it would work.

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Has anyone used their mityvac only on the CONTROL Circuits? I realize you wouldn't use it on the wheel circuits.

 

Since those points are bled without energizing the pump, I'm wondering if it would work.

Of course you'll get different opinions, but BMW's specifically advises against using any vacuum bleeding system on any part of the system.

 

Personally, I think they are totally the wrong approach period. Brake systems are designed to work under positive pressure, not negative. When bleeding brakes the goal is to push the air out, not risk pulling it (and dirt) in.

 

Now that being said, someone will jump in here extolling the virtues of them for sure!

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Ken, assuming that pressure is a better approach than vacuum, is system pressure the best option, or is there a good device that provides pressure (similar to the devices that provide vacuum)?

 

Just curious, as brakes are a something I haven't messed with until recently.

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I have a device, sold in the UK as Gunnson Easi-Bleed) that screws onto the reservoir, replacing the cap. It comes with a selection of standard caps but I have made bike-types using spare reservoir covers. The cap has a hose feed from a bottle, which contains clean fluid. The hose extends into the reservoir enough to be below the max mark and reaches to tbe bottom of the fluid bottle. The fluid bottle is pressurised by a hose which has a tyre inflation nozzle, which you connect to a tyre.

 

When you open a bleed nipple, the pressure pushes clean fluid into the reservoir, through the circuit and out of the nipple. Just open the nipple until you get clean fluid and then move to the next.

 

 

Andy

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A wealth of information!! Thanks a bunch. I'll just load up On Any Sunday 1 & 2, fill the fridge with beer, and have a go at it. Next time. This will be one of those jobs done during a cold winter day, in a warm garage. Thanks again.

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The poor man's version of the Gunnson Easi-bleed is to get a spare reservoir cover from a wrecker. Drill a hole in the center and mount a hose barb. Get a <$10 garden sprayer from your favorite home improvement warehouse, remove nozzle, attach hose to reservoir barb. Put a quart of DOT4 in the sprayer, give it a couple of pumps. Open bleeders till fluid runs clean.

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Personally, I think all the doohickeys are making it more complicated than it has to be. Especially on a bike where you can reach both 'ends' at once. Open bleeder, press lever/pedal, close bleeder, repeat.

 

Heck with a handy-dandy hose and catcher bag attached to the bleeder, I rarely even bother with the close bleeder step except on the very last couple of 'pumps.' What little 'back flow' there is at the bleeder as you slowly release the lever/pedal just draws a small amount of fluid back in. To be pushed out, and then some by the next stroke.

 

If a couple of bubbles get drawn back in during the release stroke around the bleeder threads (standard bleeders, not speed bleeders) they also get pushed out with the next pressure stroke.

 

The last couple of strokes I do with open, squeeze, close mid-stroke, release method; to get those last couple of bubbles right at the bleeder out. Then all is fine. YMMV!

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Hi Peter

I had the same reaction when I was quoted $372 at a local SoCal dealership. Luckily I went to a tech day down in San Diego at Jamie's and learned how to do it. A buddy then came over about 4 weeks later and we spent about 4 hours doing it. Final cost- $35 to fabricate the ministan and about $10 for the brake fluid. Hmm. $45 or $372. Let me evaluate my options for maybe a nanosecond. The satisfaction of doing it yourself is great. Besides, I really like working on my own bike.

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Has anyone used their mityvac only on the CONTROL Circuits? I realize you wouldn't use it on the wheel circuits.

 

Since those points are bled without energizing the pump, I'm wondering if it would work.

 

jfremder, I'm not sure why you are so intent on using that My-Ty vac on your brake system.. Those control circuits bleed out so easily with just the hand lever & brake pedal pressure.. A few strokes & you have clean fluid coming out the bleeders.. You don't even have to bend down or stretch as they are right there on top & in the open.. All you need is a hose long enough to get the fluid down & away from the top of the computer & away from the bike.. I have found it much easier to access the control circuit bleeders if I pull the wire harness connector first (just cover that opening with duct tape to keep any fluid out of the computer terminals)..

 

Twisty

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  • 2 weeks later...
Ken, assuming that pressure is a better approach than vacuum, is system pressure the best option, or is there a good device that provides pressure (similar to the devices that provide vacuum)?

 

Just curious, as brakes are a something I haven't messed with until recently.

For all of the standard brakes, I'm not sure there's a difference, but I wouldn't know (having never used either). I know BMW is pretty clear about NOT using these devices on the EVO I-ABS brakes, though again I'm not entirely sure why. If I had to guess it might be because of the valving in the control unit might be affected by the pressure applied by the control levers (for the control circuit) and of course the servos do the work for the wheel circuits already. It might be that for the wheel circuits the actuation of the control circuit opens different channels in the convoluted plumbing of the control unit that might not get flushed otherwise.

 

For the average car which doesn't get the brakes bled but once every ten years or so, the rationale for using either a pressure or vacuum system is that it allows the flushing of fluid (and removal of absorbed air and water) without moving the input pedal into an area of travel that it hasn't seen in the last ten years since the brakes were last bled. In a standard system the pedal actuates a piston with an o-ring that rides inside the master cylinder and this pressure is transmitted to the pistons/pads in the calipers via the brake lines where they squeeze the rotor (or push against the drum) where the friction converts the vehicle's kinetic energy into heat. Brake fluid VERY readily absorbs water vapor from the air and if not regularly flushed, this water in the BF will eventually corrode the inside walls of the cylinder. When you apply your brakes normally the pedal (or lever) only travels a small percentage of the full range before braking occurs. Even under a hard/panic stop it reaches a stopping point and harder application does not move it much further. This is the normal range of the walls of the master cylinder that the piston's o-ring will normally contact and this regular "cleaning" will keep the corrosion to a minimum here. Imagine now what the rest of the travel distance of the cylinder looks like after ten years of saturation with undisturbed dirty old BF: probably a lot like a cheese grater! eek.gif

 

So, you'd ideally like to be able to flush the old BF out without grinding up the piston's o-ring on the (now ruined) walls of the "unused" portion of the master cylinder thereby avoiding causing a leak and necessitating a m/c rebuild (disassembly, honing out the cylinder and replacing the o-ring, etc.). This is one reason why a vacuum/pressure tool is preferred by auto mechanics who work on cars--especially older ones that are neglected. The other is that in a car the bleed nipple is not reachable from inside the car where you'd otherwise need to be sitting to pump the pedal.

 

BMW has solved this problem (and added $$ to dealer's pockets via the service dept.) by:

 

1) recommending annual flushes of the wheel circuits that move the fluid out of the servos (which I assume use some other sort of pump system that travels the entire range but used speed to increase pressure) before they can get too messed up with old wet, and dirty BF.

 

and

 

2) recommending biennial control circuit flushes that move the control circuit input pistons the entire length of the master cylinder thereby not only keeping the fluid drier and cleaner, but also by scraping off any beginnings of corrosion on the cylinder walls before it becomes a cheese grater.

 

Think of it like polishing chrome regularly to keep the teeny dots of rust from becoming huge, deeply pitted patches of rust. The seals and o-rings last longer with regular BF changing and regular exercise over their full range of travel. A simple master cylinder rebuild is not a complex matter, but AFAIK the I-ABS control unit is not rebuildable and I think it is around USD $2000.00 to replace. Plus then the cost of all that labor and another full bleed of all four circuits as well. eek.gif

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