Re: Front Brakes, near Lock-up
Posted: Sun Jun 16, 2013 11:24 am
Thank you for being so patient with me Ken. Here is what I've done (in sequence) to date.
* Removed all hydraulic fluid.
* Opened both holes in the master cylinder reservoir.
* Replenished the hydraulic fluid.
* Bleed the brakes.
I understand that the master cylinder assembly creates hydraulic force. This force is transferred to the brake caliper via brake lines (mine are new steel braided). The calipers moving pistons transfer this force on to the brake pads which clamp the rotating rotor affixed to the front wheel. So, having said all that I feel fairly confident I understand a hydraulic circuit and that's exactly why this problem is confusing the heck out of me.
Yes. If I were to release the bleed screw hydraulic fluid would run out and the system would go back to normal. After a few pumps of the lever (~20) the brakes have locked the front wheel from rotating again. In the past I've experienced the same condition and resolution was achieved once the return port (smaller of the two) in the reservoir was cleared of its obstruction. I thought this was going to be a quick and easy fix just having to clear the port again. But that went out the window when while removing the master cylinder reservoir cover I hear air pressure being released (whoosh). I found no obstruction in either port.
With the system all back together and reservoir cover off I can see bubbles rising through the hydraulic fluid once the lever is released (back stroke). I put the cover on and all works fine until the internal air pressure in the reservoir build up pressure which results in the locked condition.
So, anyway from this I'll take away that a few components need to be rebuilt. I will start with the master cylinder and if that does not solve it, I will rebuild the calipers as well.
Ken
* Removed all hydraulic fluid.
* Opened both holes in the master cylinder reservoir.
* Replenished the hydraulic fluid.
* Bleed the brakes.
I understand that the master cylinder assembly creates hydraulic force. This force is transferred to the brake caliper via brake lines (mine are new steel braided). The calipers moving pistons transfer this force on to the brake pads which clamp the rotating rotor affixed to the front wheel. So, having said all that I feel fairly confident I understand a hydraulic circuit and that's exactly why this problem is confusing the heck out of me.
Yes. If I were to release the bleed screw hydraulic fluid would run out and the system would go back to normal. After a few pumps of the lever (~20) the brakes have locked the front wheel from rotating again. In the past I've experienced the same condition and resolution was achieved once the return port (smaller of the two) in the reservoir was cleared of its obstruction. I thought this was going to be a quick and easy fix just having to clear the port again. But that went out the window when while removing the master cylinder reservoir cover I hear air pressure being released (whoosh). I found no obstruction in either port.
With the system all back together and reservoir cover off I can see bubbles rising through the hydraulic fluid once the lever is released (back stroke). I put the cover on and all works fine until the internal air pressure in the reservoir build up pressure which results in the locked condition.
So, anyway from this I'll take away that a few components need to be rebuilt. I will start with the master cylinder and if that does not solve it, I will rebuild the calipers as well.
Ken