RCinNC
Well-Known Member
I would love to see a practical demonstration by an engineer of just how far hydraulic fluid (and any included sediment) moves in a closed hydraulic system when you apply pressure, as you do when pushing brake pistons back into the caliper. I've seen this explanation before, that when you push the pistons into the caliper, the debris inside the caliper gets pushed back up into the ABS module. There's got to be 16-18 inches between the caliper and the ABS module under the seat. Any debris in the caliper is obviously denser than the fluid surrounding is, or else it wouldn't sink to the bottom of the system. How much does the piston move when you compress it? Half an inch? How does that translate into debris moving something like 16-18 inches, against the force of gravity, through a fairly dense fluid?
Every time you compress the brake lever, the pistons move in and out. Not as far as when they're compressed by hand, but still, they move in and out constantly. How is it that this constant compressing of the system doesn't create this movement of debris, yet compressing the piston by hand sends this debris all the way up to the ABS unit?
I suspect that the ABS module is the reason you're not supposed to compress the brake pistons without opening the system first, but not because it sends debris up into the module. It seems like it might be more of a function of the valves in the unit, and that they aren't designed for pressure to be exerted in the opposite direction. Naturally, I don't know the answer, not being well versed in the fields of fluid dynamics and hydraulics, but I'd love to see this theory examined by an actual engineer.
Every time you compress the brake lever, the pistons move in and out. Not as far as when they're compressed by hand, but still, they move in and out constantly. How is it that this constant compressing of the system doesn't create this movement of debris, yet compressing the piston by hand sends this debris all the way up to the ABS unit?
I suspect that the ABS module is the reason you're not supposed to compress the brake pistons without opening the system first, but not because it sends debris up into the module. It seems like it might be more of a function of the valves in the unit, and that they aren't designed for pressure to be exerted in the opposite direction. Naturally, I don't know the answer, not being well versed in the fields of fluid dynamics and hydraulics, but I'd love to see this theory examined by an actual engineer.