Brake bleeder valve seat profile?

[skinnerd]

Just trying to get an answer over the weekend to a question I have.

I've got some new rear calipers going on the car and one of them is weeping some brake fluid.
Hard to see exactly where it is coming from.
Could be a bleeder valve or possibly a defect in the caliper casting.

I have a question about the brake bleed valve seat.....actually the very bottom where the end of the bleed valve bottoms out.

See pic below:



To me, the correct bottom of the bleed valve seat should be beveled to match the beveled point at the end of the bleed valve....such as the example on the right.

My particular caliper has a seat bottom that is square like the example on the left.
Not only do you get less surface area for the bleed valve to seat against possibly causing a leak even when the bleed valve is closed or tightened up....but if you tighten the bleed valve even a moderate amount, the square bottom will put a nice "step" in the bevel of your bleed valve.
I don't believe that is an optimal situation or even wanted.

Any thoughts or knowledge on this?
I'm thinking I have an incorrectly machined bleed valve seat.
I was thinking about taking a proper sized drill bit and putting a bevel down there, but the angle at the bottom of the bleed valve seat is not the same as the tip of most std drill bits.

[Jerry L]

I have not seen one like "B" and in "A" usually the seat is a few degrees more open / wider to have the point seat more than the entire angle.
Check the angle on a new bleeder screw, you should be able to buy a drill with a 118 & 135 degree point at most any good industrial Hdw store, diameter just under the thread minor dia.

Good luck

[gled49]

Doug, rule out that the column of brake fluid remaining in the bleader isn't causing the leak. U know me, I've been doing this a long time but discovered on my last restoration, fluid leaking down calipers. After much struggling I took paper towels, rolled little pieces, stuck them down the bleader and wicked out remaining fluid, leaks gone. The column of fluid in the bleader, with gravities help, would gown down the bleader tube, out the hole and up the threads and leak down the caliper. I chose wicking over blowing with compressed air, as I fear any brake fluid damage to paint. Gordon