bleeding maguras?

unicyclepa said:

water is good aslong and it dosint get below 32 degrees where you live.

If this applies, add antifreeze. Some trials riders swear by a mix of
water, antifreeze, and mineral oil.

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Is water more or less compressible that mineral oil (Magura blood or
Finish Line Shock Oil)?

I believe water is more compressible, but I'm not sure by how much.
Wouldn't that make water less desirable to use as a brake fluid? Sure,
it's thinner (less viscous) which means the brake pads and brake lever
will be more snappy and quick. But when you squeeze the brake lever
tight the water would compress more and it might feel a little more
spongy.

And would antifreeze be a good thing for the internal seals inside the
brake? Might it cause the seals to deteriorate faster?

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After ripping my crossover line at CMW, I had to replace line and oil.
It was much simpler than I expected it to be.

I tried to find Finish Line 5wt, but none of the LBSs in town carried
it (nor did the motorcycle shops). I spoke to a mechanic I trust, who
ran HS33s for several years on his bike in the late 90s, and he
recommended sewing machine oil as a substitute. It's very light mineral
oil (looks almost like water), and cost less than $2 for something like
6oz.

I had some spare Magura parts and some old tubing from an aquarium's
air pump, and bought a big plastic syringe from my local feed store (a
syringe turkey baster would also work fine). I stuck the appropriate
fittings on the tubing, then stuck that on the syringe, opened up the
bleed port on the brake lever, and pushed the fluid through. I had a
second fitting with a tube hooked to the bleed port, and attached that
tube to a second bottle to collect the oil again. It took maybe 15
minutes total.

I would recommend reading up a little on the procedure at that
execulink site somebody already linked to earlier. The important thing
is to back out the TPC and before bleeding, and the guides on that site
tell all about how to do that. It's not a difficult procedure at all,
and was actually kind of fun. I figure that, for a cost of maybe $5 out
of pocket, I learned how to take care of my brakes, and if it had been
a complete disaster, there were always LBSs that would be happy to fix
it for me.

--
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*========
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Chico, CA
========*
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john_childs said:

And would antifreeze be a good thing for the internal seals inside the
brake? Might it cause the seals to deteriorate faster?

yes, no

antifreeze dosent just change the freezing/boiling point of your
coolant, it also lubricates the seals in your waterpump.

the rear brake on my bike is pretty solid,the only flex I feel (very
minimal) comes from the pads and frame. Since when do liquids ever
compress?

--
onetrack

"People over here have a dangerous habit of adding quotes to signature
lines."
-Klaas Bil

I pulled a sick trey varial hickflip over an 8 set yesterday, but
unfortunately it was supposed to be seat in to seat out. I've named it
the dioflip
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sorry but i'm a real noob with hydraulic brakes.

would it work if you got a big tub full of the stuff you are doing, put
all the stuff in the liquid, wait for the lquid to fill up into all the
neccesary parts, then assemble it all in the liquid?

would that work cause there's no air that can get in the line?

i assume this would only work with water cause the other stuff is
probably expensive and would cost A LOt to do this.

--
iridemymuni

munipsycho said:

Just a bit of advice: never vomit while wearing a full-face helmet.

irvinegr said:

haha i just thaught it was funny the title is "3th movie"

pixystix6 said:

oo give him and intising lap dance while he rubs pasteries all over you

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haha, that's what I do.

Small bubbles can stick to the side of the hose, so I submerge the
lever and use the syringe like a plunger to get all those out.
foolproof bleed

--
onetrack

"People over here have a dangerous habit of adding quotes to signature
lines."
-Klaas Bil

I pulled a sick trey varial hickflip over an 8 set yesterday, but
unfortunately it was supposed to be seat in to seat out. I've named it
the dioflip
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onetrack said:

the rear brake on my bike is pretty solid,the only flex I feel (very
minimal) comes from the pads and frame. Since when do liquids ever
compress?

Liquids do compress due to pressure. Different liquids compress
different amounts due to pressure. I don't know if the pressures in a
bicycle hydraulic brake are enough to make a difference.

Here's some 'info about water being compressible'
(http://www.piercecollege.edu/offices/weather/water.html):

Quoted message said:

Water's Compressibility
Brake fluid has such a low compressibility factor that auto makers use
it in brake hydraulic systems. When you hit the brake pedal the brake
fluid compresses so slightly you'd think there was no volumetric change
at all! If water got in your brake lines (which is VERY dangerous!) you
would notice your pedal would feel sluggish and the brakes wouldn't
work very well, and may not work at all! This is because water
compresses much more relative to brake fluid.

As pressure is added to the water, which is trapped in a brake line,
its volume decreases as water molecules are forced closer and closer
together. Water at temperatures common in nature has a compressibility
factor of around 0.0000034, meaning that a hydrostatic pressure of 6.89
kilopascals (1lb/ sq. in) would reduce unit volume by about 0.0000034
of the original volume.

This compressibility of water is so slight we could never actually see
it with our own unaided eyes. We might think water is not compressible.
However, if that were the case then the oceans would be about 30 meters
higher than they are now, and therefore cover an extra 5 million square
kilometers of Earth!

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john_childs <[email hidden]>,
quoting [ http://www.piercecollege.edu/offices/weather/water.html]

Quoted message said:

Quoted message said:

If water got in your brake lines (which is VERY dangerous!) you
would notice your pedal would feel sluggish and the brakes wouldn't
work very well, and may not work at all! This is because water
compresses much more relative to brake fluid.

This quote is misleading. Actually, water has very low
compressibility, with a volume reduction of 1/3% per 1000 PSI
[http://www.hydraulic-systems.com/pages/ref_formulas.htm]. This is
comparable to hydraulic oil (e.g. mineral oil type brake fluid), which
is somewhat more compressible at 1/2% / 1000 PSI. Glycol- and
silicone-based brake fluids are in the same ballpark, and I vaguely
recall reading that one of these is 1/2 as compressible as the other.

To understand what this means, consider that the brake hose on my
bicycle is rated to 4600 PSI. Water, at this maximum pressure will
lose about 1% of its volume. Of course, the brakes are very
responsive and do not require anything close to max pressure to
securely lock wheel.

The biggest problem with water in a brake system is that the water can
boil at which point it is useless. Other issues I'd worry about are
lubrication and corrosion inside the brake mechanisms.

Hope that helps.

Ken

cline said:

This quote is misleading. Actually, water has very low
compressibility, with a volume reduction of 1/3% per 1000 PSI
http://www.hydraulic-systems.com/pages/ref_formulas.htm. This is
comparable to hydraulic oil (e.g. mineral oil type brake fluid), which
is somewhat more compressible at 1/2% / 1000 PSI. Glycol- and
silicone-based brake fluids are in the same ballpark, and I vaguely
recall reading that one of these is 1/2 as compressible as the other.

To understand what this means, consider that the brake hose on my
bicycle is rated to 4600 PSI. Water, at this maximum pressure will
lose about 1% of its volume. Of course, the brakes are very
responsive and do not require anything close to max pressure to
securely lock wheel.

The biggest problem with water in a brake system is that the water can
boil at which point it is useless. Other issues I'd worry about are
lubrication and corrosion inside the brake mechanisms.

Hope that helps.

Ken

Ah, I thought water was more compressible than that. Seems water would
work as a hydraulic brake line fluid for Magura rim brakes. The heat
generated by the brake pads is not an issue for the fluid with the rim
brakes like it would be for disc brakes.

Thanks for the numbers. I was having a hard time finding that info
with Google.

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