HFS
Well Known Member
Probably already a well known fact, but I'll "throw" it out there, just in case ...
If you need to work on the brake cylinder assembly (Cleveland nomenclature) and have to disconnect the brake line, how can you minimize lost fluid during the procedure?
If you replace the reservoir "vent" with an NPT plug before disconnecting the line (at the cylinder assembly); and, have an end plug ready (37* AN type fitting) to immediately "cap" the open brake line, you may be surprised at how little (none?) brake fluid is lost. By plugging the filler neck, you are creating a "vacuum" at the top of the reservoir which prevents fluid from running out the bottom because you are not allowing any air volume increase at the top of the reservoir - which is required if fluid is lost from the open line. Capping the open end insures a complete seal of remaining fluid.
Think of the old "straw in a glass" trick, where you put a straw in a full glass of water, put your thumb over the top of the straw, and then withdraw the straw - the water in the straw is retained because of the "partial pressure" (read vacuum) produced in the volume above the water column.
The last time I had to remove one of the cylinder assemblies on my Rocket, I didn't lose any fluid; and, after filling the cavity in the cylinder assembly with brake fluid, was able to reconnect the brake line and didn't need to "bleed" any trapped air to produce a "hard" pedal.
YMMV - But this does work ...
HFS
My bad for not being more general, as hgerhardt pointed out - about anything that will seal off the inlet to the reservoir is all that is needed. A plug is one way, but as he pointed out, there are many others - pick one ...
If you need to work on the brake cylinder assembly (Cleveland nomenclature) and have to disconnect the brake line, how can you minimize lost fluid during the procedure?
If you replace the reservoir "vent" with an NPT plug before disconnecting the line (at the cylinder assembly); and, have an end plug ready (37* AN type fitting) to immediately "cap" the open brake line, you may be surprised at how little (none?) brake fluid is lost. By plugging the filler neck, you are creating a "vacuum" at the top of the reservoir which prevents fluid from running out the bottom because you are not allowing any air volume increase at the top of the reservoir - which is required if fluid is lost from the open line. Capping the open end insures a complete seal of remaining fluid.
Think of the old "straw in a glass" trick, where you put a straw in a full glass of water, put your thumb over the top of the straw, and then withdraw the straw - the water in the straw is retained because of the "partial pressure" (read vacuum) produced in the volume above the water column.
The last time I had to remove one of the cylinder assemblies on my Rocket, I didn't lose any fluid; and, after filling the cavity in the cylinder assembly with brake fluid, was able to reconnect the brake line and didn't need to "bleed" any trapped air to produce a "hard" pedal.
YMMV - But this does work ...
HFS
My bad for not being more general, as hgerhardt pointed out - about anything that will seal off the inlet to the reservoir is all that is needed. A plug is one way, but as he pointed out, there are many others - pick one ...
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