Bleeding / Filling a dry system
When filling a drained hydraulic system, I always reverse-fill the system. This virtually eliminates air bubbles getting trapped in the line as it pushes the air out of the system from the bottom up.
- This is how... Materials needed: Mity-Vac, rags, appropriate tools, eye protection
Clutch
- Cover the bike except for the MC so your brake fluid does not eat your paint/discolor your plastic
- Remove the screws form the MC cover and set it loosely on the MC. This is so the brake fluid does not spray out in a 2' fountain. BTDT
- Setup your Mity-Vac as so:
- this will push pressure into the cup, forcing the fluid up and out of the cup into the bleeder valve
Bleeding(2d)filling/Mity-Vac_Reverse_Bleed_Setup.jpg "Mity-Vac_Reverse_Bleed_Setup.jpg")
- Loosen the bleeder valve on the slave cylinder and attach the hose from the Mity-Vac cup.
- Build up pressure in the Mity-Vac. Caution, it takes very little fluid to fill the lines once the slave cylinder is full.
- After the pressure has subsided, check the MC. If it is not full, pressurize the Mity-Vac again. It takes about 1/2 cup to fill the lines - so you want about 3/4 cup of brake fluid.
- Once the MC has some fluid in it, and there is no pressure from the Mity-Vac, close the bleeder valve and remove the hose from the bleeder valve.
- Fill the MC up to the line with brake fluid and you are good to go.
Notes:
You may have to burp the banjo bolt, but it is usually not necessary.
This method can be used to push the old fluid up to the MC, but then you have to periodically remove the fluid from the MC. I've found it's just as fast to bleed the clutch the traditional way. If you're just replacing old fluid with new, I've found it's just as fast to bleed the clutch the traditional way.
Front Brakes
- Cover the bike except for the MC so your brake fluid does not eat your paint/discolor your plastic
- Remove the banjo bolt from the MC and line. Ensure the end of the brake line is the highest point in the hydraulic system. Don't lose the copper crush washers, they will be re-used.
- Brake fluid will come out of the hose so use rags to prevent it spilling on anything.
- Setup your Mity-Vac as so:
- this will push pressure into the cup, forcing the fluid up and out of the cup into the bleeder valve
- Loosen the bleeder valve on one caliper and attach the hose from the Mity-Vac cup.
- Build up pressure in the Mity-Vac. Caution, it takes very little fluid to fill the lines.
- Stop when fluid comes out the top of the brake line.
- When there is no pressure from the Mity-Vac, close the bleeder valve and remove the hose from the bleeder valve.
- Repeat with the other caliper. Use very low pressure. Bubbles may appear at the end of the brake line. Continue filling the brake line with fluid until no bubbles appear or until you are sure the line is full.
- When there is no pressure from the Mity-Vac, close the bleeder valve and remove the hose from the bleeder valve.
- Attach the banjo bolt to the MC - don't forget the crush washers.
- Remove the MC cover and fill with brake fluid up to the line.
- Gently squeeze the brake lever and continue until no more bubbles appear.
- Burp the banjo bolt at the MC and you should be good to go.
Notes:
You may have to burp the 2 banjo bolts at the brake junction between the forks, but it is usually not necessary.
This procedure can be used on 2-line stainless steel brake lines also.
If you're replacing old fluid with new, I've found it's just as fast to bleed the traditional way.