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brake bleeding theory
- Thread starter inreb
- Start date
To compress the air out of the master cylinder. But that's only if they did a ****** jobAfter bleeding the front brakes some people say to tie the lever back to the bar overnight for best results. What is the theory behind that
That answer didn't disappoint.
Glad to be of service
It will temporarily deform the rubber seals into a shape where they are "pre-deflected" so it doesn't take as much fluid volume to move them into the position that they take under pressure.
It may temporarily force some of the air into solution in the liquid.
It may temporarily force some of the air into solution in the liquid.
Ok, now I feel better about doing it because the other explanation I saw on the youtube didn't make sense. Thanks.
Assuming it was bled well, helps squeeze the microscopic air bubbles out with a bit of pressure. Give it a try, see if you notice a difference. I leave it overnight and find it does help on the track bike. Thats with a brembo MC and SS lines with motul 660. On the street bike with rubber lines I can't say I notice much difference. The deflection in the rubber and mediocre MC likely negates any benefits.
I have had to do this before. There are certain bikes that will not bleed (without a huge hassle) for whatever reason, a VS800 comes to mind (narrow twin Suzuki cruiser). After fighting with the system for a while I used elastic bands to hold the lever and left it over night. By morning the lever was firm. Don't know why those bike specifically, but it has happened a couple of times over the last bunch of years. It helps to bleed the brakes as well as possible using conventional methods first to prevent the piston from travelling too far in the master. Then tie it off and double check the fluid levels when all complete.
daught
Well-known member
Just thinking about this, the brake fluid applies pressure to all sides of the air bubbles. There is no new net force to push the bubbles up. Actually the bubbles compress and with less volume they travel up slower than they would without pressure on them. Also with pressure fluid viscosity increases, so the bubbles will also move slower because of that. Dunno if it has a considerable effect, but I can't see it helping.
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The service manual for my TR280i Ossa says to use a "syringe" to pump fresh brake fluid from the rear caliper back thru to the tiny reservoir mounted above the footpeg.The reservoir is mounted vertically with a bleed screw at the high point.Anyone ever seen a "syringe" for this purpose?
The service manual for my TR280i Ossa says to use a "syringe" to pump fresh brake fluid from the rear caliper back thru to the tiny reservoir mounted above the footpeg.The reservoir is mounted vertically with a bleed screw at the high point.Anyone ever seen a "syringe" for this purpose?
I have a bleeding set up from a high end HOPE TECH mountain bike brake system. I find the smaller bikes like yours use smaller brake components that are similar to mountain bike stuff. It has a bottle that you connect to your tire for air pressure, then the other tube goes to the master cylinder with a plate made to fit that master. You fill the bottle with brake fluid, and kind like what your saying instead of trying to pump out or suck the air out with a vac, you use air pressure to push the fuild through the system
I tried to bleed without that bleeder setup and I wasnt getting anywhere
I would look at the mountain bike industry, I have seen them use syringes also
I think Magura who also makes motorycle brake components use a syringe to bleed
If you google image "Magura bleeder" you get tons of pictures of syringe bleeding setups
If you just want a syringe without a needle, I get them down the street for like 50 cents each. If you go to the phamacy they may not sell just one, you might have to buy a box of them
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I really only use it on mini motorcycle brakes on little bikes, the brake components are really small but just like big motorcycle components. The theory should work on a bigger setup if you were able to make the correct adapters to mount to your calipers or master cylinder.
Its like Brembo for mini bikes, 6 piston billet caliper with titanium pistons, and a floating wave rotor on a CRF50 LOL
The rear is even harder to bleed there are no nipples to put a hose or vac on, just a set screw to let air out like Wingboy has on his rear master
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Going to visit my local Mtn bike shop.Thanks.
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