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#998201 - 10/02/17 03:57 AM Loss of pressure front brake handle  
Joined: Apr 2003
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MichiganBob Offline
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MichiganBob  Offline
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Joined: Apr 2003
Posts: 473
Southwest Michigan
Good Evening,

Just got back from a 700 mile ride this weekend. Bike ran great ... but ... three times over the weekend, I grabbed the front brake and there was no pressure. This loss of pressure would happen only once and when I grabbed it quickly a second time, it was fine. But it happened three times and that is a little troubling. Any notion on why this might occur on my 2012 1200RT? Thanks for your input.

Wishing you a safe ride.

Bob

#998203 - 10/02/17 11:05 AM Re: Loss of pressure front brake handle [Re: MichiganBob]  
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dirtrider Offline
The Oracle
dirtrider  Offline
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Ohio
Originally Posted by MichiganBob
Good Evening,

Just got back from a 700 mile ride this weekend. Bike ran great ... but ... three times over the weekend, I grabbed the front brake and there was no pressure. This loss of pressure would happen only once and when I grabbed it quickly a second time, it was fine. But it happened three times and that is a little troubling. Any notion on why this might occur on my 2012 1200RT? Thanks for your input.

Wishing you a safe ride.


Morning Bob

There are a some possibilities on this one--

Possibly a failing master cylinder or failing master cylinder piston cup. Maybe some reason that the front master cylinder is taking air into the cylinder bore while riding.

Or, possibly something wrong inside, or with, the ABS controller itself.

Or, possibly the front brake rotors are kicking the front brake pads back into the calipers enough to need one cycle to extend them before braking can begin. (this could be due to a loose front wheel on the axle, or failing wheel bearings, (or something wrong at the front wheel area)

This is a serious condition & needs to be found & addressed quickly.

How far did you need to ride before the problem re-occurred & how far had you ridden since the previous pressure loss occurrence?

Any rough road riding just before the brake pressure loss?

Is the front brake rotor color normal or are they bluish/purple looking?


D.R. ___
Sent from my rotory dial wall phone!
#998213 - 10/02/17 02:28 PM Re: Loss of pressure front brake handle [Re: dirtrider]  
Joined: Apr 2003
Posts: 473
MichiganBob Offline
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MichiganBob  Offline
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Joined: Apr 2003
Posts: 473
Southwest Michigan
Good Morning DR,

I'll check everything you suggest this week. I was looking for a pattern but three data points over 700 miles is an insufficient sample. I happened once going into a corner (that was puckering) and twice just turning into the hotel and the gas station. It's just for a second, nothing and then normal. My inclination is the seal on the master cylinder but the infrequency is odd and the fact that I can't replicate the failure. My fear is that this is not testable, an error code would not come up with a scan. If I bring it to the dealer, they will have no choice but to start replacing components starting with the master cylinder I expect and proceed using the logic of elimination. I'm trying to think about what condition would allow something like this to act in an isolated rather than patterned way?

I agree, it's serious business. I replaced rear pads before I left but I'm thinking that my 2012 systems (as compared to my 03RT) is independent. Once should not have an effect on the other.

Take care.

Bob

#998270 - 10/03/17 12:20 PM Re: Loss of pressure front brake handle [Re: MichiganBob]  
Joined: Sep 2009
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David R Offline
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David R  Offline
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Posts: 747
Western NY
A real light continuous pressure on the front brake lever may show a master cylinder cup that is failing.

The rubber gets old and does not always push out against the bore. Under normal or quick pressure it may work just fine.

Push ever so gently, as light as can be S L O W L Y add a little more pressure (travel) and see if the lever moves. If you can get it to move without building pressure, its the master cylinder. This should take a minute or more with minimal pressure on the lever, almost none, Just enough to move the lever a fraction of an inch at a time.

I think I understand you have brakes on the second application?

Have you had the cover off the master cylinder and look in there? Do you see mud? If the fluid level proper?

Best of luck, I am interested in what you find.

David


'76 R75/6 67,000 miles
2000 R1100RT 137,000 miles. (retired)
11 Versys 11,000 miles
12 R1200R!
#998303 - 10/03/17 10:41 PM Re: Loss of pressure front brake handle [Re: David R]  
Joined: Apr 2003
Posts: 473
MichiganBob Offline
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MichiganBob  Offline
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Posts: 473
Southwest Michigan
Thanks David ... I'll give that a try. Stopped at my dealer today for a chat. The mechanic suggested that the first thing I do is bleed the breaks. He wonders if there is an air bubble in the system. Also suggested that I keep on kickstand and cock wheel as far as i can to the left so that front reservoir is as high as it could be and see if I can make this condition occur. Hmmmm!

Bob


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