Technical What's the correct brake bleeding sequence for GM master with bleeders?

Yes. Most/all disc/disc masters have large reservoirs that look about equal in size.

 

And, in the end, the bleed out was fine, the problem was mechanical. Here's the final solution:



GM master cylinders of this vintage have two different pistons. One, for manual brakes, has a deep hole for the pushrod. The other, for power brakes, has just a centering divot in the end. The manual pushrod is about 1 1/4" longer than the power pushrod. Other than the depth of the hole, the M/C is the same.

A local muscle car parts shop sells one M/C for both applications, and includes this handy slug that fits in the hole. Take it out for manual, install it for power. A friend hooked me up with one.

Slid the M/C forward, enough for this to clear, got it in place, and put the M/C back. Didn't open the system, so didn't have to bleed it yet again. Now I've got brakes without the excessive pedal travel.

Lessons learned: check everything, even if the part claims to be the right one. NAPA sells this as being the right M/C for a power brake on a 70 Chevelle, along with a bunch of other cars. Not that it won't work, but you'd need the longer "manual" pushrod to make it work correctly.

Now I gotta find out how to dispose of 2.5 gallons of brake fluid.


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