Rear brake failure

[timtune]

The problem is air is lighter than brake fluid, so the bleeder needs to be at the highest point in the circuit to allow evacuation. It won’t matter whether you shoot air into the bleeder or the reservoir - the air will still be trapped.

That’s why you can never reverse caliper son a car. They usually fit both sides, but are mirrored so the bleeders are always at the top.

The only solution I see is to bleed the caliper off it’s mount, or raise the bikes front end until the bleeders are it the highest point in the hydraulic circuit.

I don't think so. You force fluid into the bleeder and it forces the air up and out the M/C / resevoir or at least I think that's how it works, regardless it's been working well for me.

 

[GreyGhost]

I don't think so. You force fluid into the bleeder and it forces the air up and out the M/C / resevoir or at least I think that's how it works, regardless it's been working well for me.

Mostly true but if caliper has an air pocket above where you are injecting and above where the hose heads to the caliper, the fluid will happily flow and leave the air pocket untouched.

 

[Mad Mike]

I don't think so. You force fluid into the bleeder and it forces the air up and out the M/C / resevoir or at least I think that's how it works, regardless it's been working well for me.

Yes, as long as the brake line connection is above the air pocket.

If the incoming connection is below the air bubble, injected fluid will compress the air, but it will not displace, the fluid will pass under it.

 

[timtune]

Mostly true but if caliper has an air pocket above where you are injecting and above where the hose heads to the caliper, the fluid will happily flow and leave the air pocket untouched.

No problem. A small bleed job after filling most of the system with fluid.

 

[Relax]

No problem. A small bleed job after filling most of the system with fluid.

But that's exactly the problem - not being able to bled the section where the air is trapped, otherwise you wouldn't be resorting to trying to push from below. The correct way is to orient the system so that air bubble can float to the bleeder.

 

[Mad Mike]

But that's exactly the problem - not being able to bled the section where the air is trapped, otherwise you wouldn't be resorting to trying to push from below. The correct way is to orient the system so that air bubble can float to the bleeder.

Or to the master. Tha allows a push, it will also do a natural bleed ( burp ).

 

[mimico_polak]

Went for a quick boot around the block….wow what a difference to the rear brake.

Very firm and immediate response. Almost shocked me how hard the rear brake activated.