1970 Brake Problems
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
I have a wildwood MC and its very difficult to see any flow "push back", but when there is air in the MC you will see air bubbles start via the holes as soon as I press on the brakes, equal front vs back. Also when I pressurize the MC brakes apply front and rear at the same time. I don't have any tools to measure the actual pressure at the pads so I don't know what the actual force is (proportional or not).
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I am sorry that I did not clarify that when I am looking in and watching the piston of the master cylinder I am dealing with the original design cast iron dual reservoir master cylinder.
As for being able to test the actual pressure at the caliper. This gauge and fittings can be purchased if desired more than likely from Willwood or get one like I did from Master Power Brakes.
DUB
As for being able to test the actual pressure at the caliper. This gauge and fittings can be purchased if desired more than likely from Willwood or get one like I did from Master Power Brakes.
DUB
Pro
Joined: Jun 2014
Posts: 706
Likes: 294
From: New Jersey
I have a wildwood MC and its very difficult to see any flow "push back", but when there is air in the MC you will see air bubbles start via the holes as soon as I press on the brakes, equal front vs back. Also when I pressurize the MC brakes apply front and rear at the same time. I don't have any tools to measure the actual pressure at the pads so I don't know what the actual force is (proportional or not).
To clarify, when looking at the bubbles, do both compensation ports close off at exactly the same time?
It would make sense if they did.
and.......
How does the fluid 'push back" compare to a GM master?
I know from racing m/c, the less push back, the better the feel of the brake lever.
Thread Starter
Advanced
Joined: Mar 2003
Posts: 98
Likes: 3
From: Oglesby Illinois
So last night I plugged the rear port of the MC and left the front port connected to the brake line. The break pedal was rock hard, or really really firm. I assume this means two things, the MC is good, and the front brakes have no air in them. I also assume this means the MC doesn't have any or any significant air in it? So I guess I just somehow got a large amount of air in the rear lines, not sure how, that I will have to somehow remove.
Thread Starter
Advanced
Joined: Mar 2003
Posts: 98
Likes: 3
From: Oglesby Illinois
Turns out the issue was the drivers side rear caliper. It was sealing under pressure and letting air in when it wasn't under pressure. I used some vice grips on the flexible lines to block them off and isolate the problem. Wish I would have done that earlier.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
and that's exactly why mity vacs don't work on lip seal calipers.....found that out the hard way
