Disc brake conversion questions

[pjtoledo]

I open the bleeders to drain whatever old fluid is in the caliper instead of pushing it back up the lines.
I also run a drill bit, by hand, in the calipers slider holes to clean them out.

 

[Ranger850]

I'm going to take the advice I was given and move on.

 

[don4331]

@don4331

I thought residual check valves were a thing of the past. At least that seems to be what I remember from trade school many... many moons ago.

Also if the thought that this 10 psi residual pressure holds the brake shoes close to the drum by overcoming the return spring pressure... how come the pedal travel will increase if the rear shoes are misadjusted?

This must also mean the the caliper square cut seal on the piston has greater then 2 psi force to return the piston so the brakes don't drag.

Have I honestly be thinking wrong for like... ever? Seriously... I'm confused.

@Uncle Gump

I thought about this and....

Bore for rear brake cylinders is 13/16" = ~.518"^2 in area * 10 psi = 5.2 lbs force....OK, the residual force is basically doing squat to hold the shoes against drums.

Disc brakes - Explorer rear - 48mm = 2.8z"^2 * 2 psi = 5.6 lbs force - interesting, force is very close to drums.

Disk brake - Explorer rear - 48mm = 2.8z"^2 * 10 psi = 28 lbs force - 10x force wears pads faster

Stepping on brakes - Explorer rear - 48mm = 2.8z"^2 * 1000 psi = 2800 lbs force!

 

[O No 3.0!]

I was saying that, the guy who taught me to do brakes, the owner of the shop that's been in business for over 30 years and is the MOST reputable brake shop in the area, said that was not the correct way to do it.

It isn't when you are trying to maximize profit. But theres nothing wrong with a pad change if everything is in working order.