Matco Master Cylinder with Cleveland Brakes

I have the Matco master cylinder with Cleveland brakes on my Ercoupe. I have worked through some problems that others are describing here. This is my experience so far:

Bleeding the Brakes
I have tried bleeding the brakes by filling the reservoir from the top and pumping the pedal. I could not get that to work dependably. I found that pumping up from the bottom of each brake cylinder worked well. The attached picture shows the equipment I use.

The pump attaches to the brake bleeding port at the wheel cylinder. The plastic tube with the 90 degree fitting attaches to the top of the brake reservoir. The plastic tube is placed in an overflow cup. I pump into each wheel cylinder until the bubbles quit coming. I do this at least twice per side, alternating.

The only problem I have had using this method is when I did not have the Matco master cylinder fully extended. In my plane, there is friction in the brake linkage caused by the flex tubing to and from the master cylinder and from the mechanical linkage itself. If the Matco master cylinder is not fully extended, it will block the path of the fluid from the wheel cylinder to the reservoir when bleeding using the above method.

I have not had my brakes lock up but I can see that it would be possible if the master cylinder was not fully extended while taxiing. When not fully extended, there is no path to release excess pressure in the brake system which could be caused by expansion of the brake fluid. Expansion of the brake fluid could be caused by extended braking which heats the brake fluid at the wheel cylinders.

Dragging Brakes
I had a problem with my brakes dragging. It only happened with the left brake. When taxiing, the plane would want to steer to the left. This was only a slight pull and for a while I thought it was due to a side slope on the taxiway. This was also inconsistent, sometimes it would be fine. I could push the airplane by hand okay but it did seem heavy.

I finally realized that the problem was that the Matco master cylinder was not extending fully when the brake pedal was released.

I solved this problem by adding an auxiliary spring to the brake pedal arm. After that, the brakes have worked perfectly. This is not an approved part.

Weak or No Braking
After bleeding the brakes as described here, I have never had weak or loss of braking. I have done many full throttle run-ups to check my static RPM. The brakes always hold. I am using a McCauley 7146 and have a static RPM of about 2150. When I press on my brake pedal, it feels like stepping on a rock.

John Earl