Hi,
Who agrees on this statement:
1. When bleeding brakes the main reason is to remove water/moisture from the hydraulic fluid.
2. The main entrance of moisture/water is at the rubber seals or o-rings.
3. When bleeding the calipers there is a large fluid compartment where the piston is located (back side of piston). The more the brakes are worn the bigger this volume becomes. But the entrance of the fluid and the exit (bleed screw) only make up a very small area/volume of the entire compartment. When bleeding the brakes the fluid passes more or less directly from the entrance to the exit and ONLY VERY LITTLE mixing happens. When bleeding the fluid does not travel across this big compartment but the shortest distance close to the outer zone of said compartment. Almost NO fluid is drawn from the area furthest away from this entrance/exit zone. This is pure physics/fluid dynamics. Due to this natural phenomenon of fluid dynamics (that the fluid travels the path with the least resistance), the fluid in the caliper is hardly changed whereas the fluid in the brake lines is changed 100% for sure. For this reason the water/moisture builds up over time even though the user believes everything is OK and the car is serviced correctly. Therefore rust and corrosion will form on the piston/cylinder walls even though the system was serviced hysterically by bleeding every year. Over time the caliper has to be replaced entirely.
In order to prevent this problem during bleeding, it is necessary to remove the entire caliper and squeeze the piston entirely back. By doing this, the fluid in this compartment is reduced to a minimum. Then one should let the piston move outwards again thus filling the compartment with fresh fluid (something that NEVER happens during a normal bleed process). Once it is out, it can be squeezed back a few more times in a similar fashion in order to reduce the amount of contaminated fluid in the compartment. All this of course requires much more work during bleeding.
The same applies for the brake cylinders with drum brakes: Due to system design the fluid closest to the rubber seals is hardly changed and just increases in moisture content over time.
Who agrees on this statement:
1. When bleeding brakes the main reason is to remove water/moisture from the hydraulic fluid.
2. The main entrance of moisture/water is at the rubber seals or o-rings.
3. When bleeding the calipers there is a large fluid compartment where the piston is located (back side of piston). The more the brakes are worn the bigger this volume becomes. But the entrance of the fluid and the exit (bleed screw) only make up a very small area/volume of the entire compartment. When bleeding the brakes the fluid passes more or less directly from the entrance to the exit and ONLY VERY LITTLE mixing happens. When bleeding the fluid does not travel across this big compartment but the shortest distance close to the outer zone of said compartment. Almost NO fluid is drawn from the area furthest away from this entrance/exit zone. This is pure physics/fluid dynamics. Due to this natural phenomenon of fluid dynamics (that the fluid travels the path with the least resistance), the fluid in the caliper is hardly changed whereas the fluid in the brake lines is changed 100% for sure. For this reason the water/moisture builds up over time even though the user believes everything is OK and the car is serviced correctly. Therefore rust and corrosion will form on the piston/cylinder walls even though the system was serviced hysterically by bleeding every year. Over time the caliper has to be replaced entirely.
In order to prevent this problem during bleeding, it is necessary to remove the entire caliper and squeeze the piston entirely back. By doing this, the fluid in this compartment is reduced to a minimum. Then one should let the piston move outwards again thus filling the compartment with fresh fluid (something that NEVER happens during a normal bleed process). Once it is out, it can be squeezed back a few more times in a similar fashion in order to reduce the amount of contaminated fluid in the compartment. All this of course requires much more work during bleeding.
The same applies for the brake cylinders with drum brakes: Due to system design the fluid closest to the rubber seals is hardly changed and just increases in moisture content over time.