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Issue Bleeding Brakes


MichiganBob

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MichiganBob

Good Evening,

 

This is a 2012 1200rt. I changed my front brake shoes and was bleeding the brakes when the brake level locked up and the wheel won't move. I'm not sure what to do next. Any ideas?

 

Thanks.

 

Bob

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Good Evening,

 

This is a 2012 1200rt. I changed my front brake shoes and was bleeding the brakes when the brake level locked up and the wheel won't move. I'm not sure what to do next. Any ideas?

 

Thanks.

 

Bob

 

Evening Bob

 

A couple of possibilities on your problem.

 

How to go about diagnosis & repair depends on where your brake hand lever is in it position & if it is loose for the first part of it's travel.

 

The 2 usual things that happen is: (1)- the master cylinder piston travels into a part of the bore that is curded up then sticks there holding brake pressure on the calipers. Or (2)- the master cylinder piston doesn't quite return all the way to the out-stop therefore it doesn't uncover the take-up port & allow the trapped fluid pressure to release back into the reservoir.

 

If you can give us more information about how the hand lever is operating then we can probably advise you on how to go about correcting the problem.

 

Sometimes you can use a screwdriver to pry the bake pads back from the brake rotors as that can push the caliper pistons back into their bores and put back pressure on the master cylinder piston and push it back to it's out-stop ring. (that will usually allow wheel rotation once the pressure in the calipers drops off)

 

 

 

 

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MichiganBob

Good evening DR. I tool the calipers off, pushed pistons in, changed pads, installed speedbleeders, assembled back on bike, opened speed bleeder on one side, it was pumping brake fluid into my drain bag just fine, the reservoir never got too low letting in air, then the brake level stopped with about a 1/4 inch of play and the wheel will not move. Yikes.

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Good evening DR. I tool the calipers off, pushed pistons in, changed pads, installed speedbleeders, assembled back on bike, opened speed bleeder on one side, it was pumping brake fluid into my drain bag just fine, the reservoir never got too low letting in air, then the brake level stopped with about a 1/4 inch of play and the wheel will not move. Yikes.

 

Evening Bob

 

With only 1/4" of lever play that sort of points to the take-up port not being uncovered at lever release.

 

With about 1/4 fluid level in the master cylinder reservoir & cover removed, move the hand lever in the apply direction then release while looking down in the reservoir bottom to see if you get a little squirt of fluid back through the very small hole in the bottom of the reservoir as you release the lever. (careful that you don't move the lever too fast as you don't want to get a stream of fluid to squirt up too high & get brake fluid on your bike's paint or dash).

 

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Evening Bob

 

(it's 8PM) I will be off-line until tomorrow so further discussion will either have to wait until tomorrow or hopefully another member can take over & talk you through this problem. D.R.

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MichiganBob

Nothing happening in the reservoir DR. Pull level to about a quarter inch and that's as far as it will go. Wheel is locked so I guess I need to figure a way to release the pressure that is holding the pads to the disk. Make sense?

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Thanks DR appreciate the help as always.

 

Evening Bob

 

I'm not quite gone yet but just about to leave. (this will be my last posting tonight)

 

We might be putting the cart before the horse here. Probably the next move is to remove a speed bleeder & let the latent pressure out (careful to catch any fluid so it doesn't drip down on the wheel paint)

 

If the wheel then spins you know your are dealing with retained pressure issue. If the wheel still won't turn then you are fighting a mechanical problem like a tight or poor fitting brake pad or a caliper issue. (this will tell you the direction to pursue on correcting your problem)

 

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Morning Bob

 

I might have misled you in what I posted above--

 

With about 1/4 fluid level in the master cylinder reservoir & cover removed, move the hand lever in the apply direction then release while looking down in the reservoir bottom to see if you get a little squirt of fluid back through the very small hole in the bottom of the reservoir as you release the lever.

 

This won't work on the camhead bikes--

 

The above only works when you can actually see into the bottom of the master cylinder reservoir. I forgot we are working on a camhead bike not a hexhead bike. The camhead has a remote reservoir so you can't look in & see the take-up port in the master cylinder.

 

 

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MichiganBob

Good Morning, I pulled off both speed bleeders and no fluid is coming out of them. The brake lever only moves about .25 inch. I did notice that there is a bleeder valve on the master cylinder itself. Can this have a role in what is happening? I'm not sure what that valve does?

 

Thanks.

 

Bob

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Good Morning, I pulled off both speed bleeders and no fluid is coming out of them. The brake lever only moves about .25 inch. I did notice that there is a bleeder valve on the master cylinder itself. Can this have a role in what is happening? I'm not sure what that valve does?

 

Thanks.

 

Bob

 

 

Morning Bob

 

That bleeder on the master cylinder is for pre bleeding the master cylinder (you don't need to mess with that unless you run the master cylinder out of fluid).

 

That "no fluid coming out" is kind of puzzling -- a person would think that if the system had enough residual pressure to keep the front wheel from turning that you would have had fluid gushing out when you removed the speed bleeders.

 

Can you now turn the front wheel with the speed bleeders removed?

 

If you can't turn the front wheel with the speed bleeders removed then try gently prying the front bake pads off the rotors then see if you can turn the wheel (caution: pry only on the metal of the brake pads not the fiber friction surface).

 

You might also try re-installing the speed bleeders then turning the key on & pumping the brake lever (maybe the ABS system has the accumulator valve shut but even that should have shown fluid run out when you removed the speed bleeders--(puzzling for sure).

 

Your problem initially sounds/sounded like remaining pressure in the front brake system but the no-fluid coming out when removing the speed bleeders kind of points to a mechanical lock-up (like poor fitting pads, or too thick pads, or something in the caliper/brake pad match up)

 

 

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MichiganBob

Thanks DR. I'll try your suggestions. It was weird when I started bleeding the first side that with the speed bleeder open, fluid was coming out fine and then pressure build up and the system locked. I was thinking that maybe the check valve closed on the bleeder but I now have the stock bleeders back in and can't get any fluid to come out of them.. What if I actually removed the calipers from the disks to free the wheel?

 

Bob

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Thanks DR. I'll try your suggestions. It was weird when I started bleeding the first side that with the speed bleeder open, fluid was coming out fine and then pressure build up and the system locked. I was thinking that maybe the check valve closed on the bleeder but I now have the stock bleeders back in and can't get any fluid to come out of them.. What if I actually removed the calipers from the disks to free the wheel?

 

Bob

 

Morning Bob

 

You could do that but probably no gain over just prying the pads back off the rotors.

 

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MichiganBob

Good afternoon. That was dumb. I thought the wheel was off the garage floor enough on the centerstand to move. I lifted it a tad and the wheel turns. So now I'm back to where I started. There is fluid in the reservoir but only slight lever travel. I put the stock bleeders back on. No fluid gushing out. I'll try tonight with the bleeder open and running if you think that it might make a difference I,m thinking of attaching a mighty vac to see if I can such fluid down the brake line. Make sense?

 

 

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MichiganBob

I;m heading out the door and figure I would give the handle one more try and it felt like something unstuck and now I have handle again. I'm thinking of either speed bleeders again and bleed or stock bleeders and mighty vac. Recommendations?

 

Thanks.

 

Bob

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MichiganBob

Good afternoon, brakes are bled, haven't taken for test ride but will when it stops raining. It does seem that the master cylinder piston may occasionally be stuck and then releases. This is intermittent rather than continual. What can be done to remedy that other than a high high ticket replacement of the cylinder? Can it be disassembled and inspected without to much complexity?

 

Thanks.

 

Bob

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Good afternoon, brakes are bled, haven't taken for test ride but will when it stops raining. It does seem that the master cylinder piston may occasionally be stuck and then releases. This is intermittent rather than continual. What can be done to remedy that other than a high high ticket replacement of the cylinder? Can it be disassembled and inspected without to much complexity?

 

Thanks.

 

Bob

 

Afternoon Bob

 

Darn good question.

 

I haven't ever been into a 2010-up front master cylinder. The piston might come out easily or might be problem, I just don't know. I don't see any internal parts available for the 2010-up master cylinders (at least from BMW) so I'm not sure what you will encounter trying to take it apart.

 

If it wasn't hanging up before the latest work & is now free then you might try (carefully) riding the bike as the problem might not be an issue with normal brake usage. Do be very careful until you are sure it will always work.

 

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MichiganBob

Top Of The Day,

 

Will test as soon as it stops raining. Flash back to post last Fall when twice I pulled the lever and there was no brakes and quickly pulled again and there they were. We agreed to start with a good brake bleed which I just did. Not sure if that event and the recent one is related in any way. I'll ride in places where I can safely stop with just the rear brake (if necessary). Stay tuned.

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MichiganBob

Good Evening,

 

Test ride and brakes worked well. I have a trip down to Lexington first weekend of June (Red Mile Flat Track -- yahoo!!!) so will get in a good test on the 800 mile round trip. Something else though DR that I wanted to pick your brain about. When the bike starts, it's idling at 1600 which seems and feels high. It is almost too fast in first for my crappy dirt road to the pavement. Once warmed, it drops to 1100. Maybe somethings hung up so I will check the throttle bodies. Other than that, I'm thinking that the idle is computer controlled rather than the good old days when there was an idle screw. So does the 1600 and then 1100 seem out of specs for a 2012 1200RT, and if so, what's the fix. Thanks as always.

 

Bob

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Good Evening,

 

Test ride and brakes worked well. I have a trip down to Lexington first weekend of June (Red Mile Flat Track -- yahoo!!!) so will get in a good test on the 800 mile round trip. Something else though DR that I wanted to pick your brain about. When the bike starts, it's idling at 1600 which seems and feels high. It is almost too fast in first for my crappy dirt road to the pavement. Once warmed, it drops to 1100. Maybe somethings hung up so I will check the throttle bodies. Other than that, I'm thinking that the idle is computer controlled rather than the good old days when there was an idle screw. So does the 1600 and then 1100 seem out of specs for a 2012 1200RT, and if so, what's the fix. Thanks as always.

 

Bob

 

Morning Bob

 

 

BMW doesn't furnish a specific cold fast idle spec as it is computer controlled (using stepper motors) & is dependent on many things, like ambient temperature & oil temperature, battery voltage after start-up, & emission performance programming.

 

They do tend to idle a little high after cold start as that assures that the alternator starts charging right away, it also helps to quickly heat the catalytic converter so it starts working quicker (part of the new emission regulations), but it shouldn't fast idle fast for long.

 

As for the hot curb idle, it is also computer controlled using the stepper motors based on engine temperature, battery voltage, engine load, stored adaptives, o2 sensor input, etc.

 

Not much you can do with either fast idle or curb idle as neither are adjustable.

 

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