Re: Bleeding dual cct brakes

[jack@domain.elided (Jack Hagerty)]

>From: "Graham Hilder" <graham.hilder@domain.elided>

>In Digest 916, Jack described an even easier method, which I believe in 
>books is known as the gravity bleed...... i.e. just open the bleed screws 
>and let the fluid run out of its own accord until clean. I have tried this 
>method but have found the fluid seems to flow so slowly that I get tired 
>of waiting for it to run clear and usually give up. I must try it again 
>some time though.

If your only job is to bleed the brakes, then yes, this is probaby not
the best method as it can take up to a half hour or more depending on
the temperature. But as I mentioned, I usually do this as part of a
bigger service so I have plenty of time to let it work while doing other
tasks.

>I would heartily agree with Jack's recommendation of substantiallly 
>emptying the old fluid from the reservoir before adding your new fluid. 
>The emptier the reservoir to begin with, the sooner you'lll see for sure 
>that the emerging fluid is all new. Jack suggested taking a turkey baster 
>and sucking out the old fluid. But even simpler (and with no risk of nasty 
>fluid spillage if you should fumble!), I just open the bleed screws and 
>pedal-pump out the old fluid via the brake system itself, into the tubes 
>& jars.  Just watch that reservoir level like a hawk while you're doing 
>this though....!!!!!

I used to do it this way but stopped because 1) it just didn't feel right
forcing all of the dirty old fluid (with whatever contaminants it might
contain) through my M/C seals and entire brake system, and 2) I once *didn't*
watch it closely enough and wound up sucking a huge air bubble into the
system that was a royal PITA to get out.

As for spillage, I usually treat the engine compartment to a wash out at
the local coin-op after every operation that involves brake fluid.

- - Jack

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| Jack Hagerty                |    "If this rocket stuff is so important    |
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| Livermore, CA		      |    don't blow yourself up. I suppose there  |
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