Brake Pipes, Brake Flares and Initial Brake Bleeding

This topic was covered in two previous posts:

https://valvechatter.com/?p=14379 and https://valvechatter.com/?p=13973

The time came to bleed the brake system. Bleeding brakes for the first time always seems to be a stressful situation and in our case it was no different. With the Bugeye we are using DOT 5, or silicone, brake fluid. Using silicone fluid can be somewhat controversial, but the real benefit is that it does not damage paint. This was a particular concern with the Bugeye because if the master cylinders or their fittings leak, there’s no way to avoid brake fluid in the pedal box at a minimum.

Bleeding the system began with “bench” bleeding the brake master cylinder. This is done to get any air out of the master cylinder itself before filling all the pipes with fluid. It’s really quite easy to do this and the process is shown in the Bugeye Restoration Video Episode Ninety-seven.

Bleeding the Master Cylinder

Following our successful bleeding of the master cylinder we then used a Gunson Eezibleed kit to fill the system with fluid and begin purging the air from the lines. https://www.gunson.co.uk/product/G4062/Eezibleed-Kit. The kit uses a pressurized fluid bottle connected to the master cylinder. Air pressure is used to move fluid through the system. Air pressure comes from using a tire with pressure reduced to no more than 20 pounds.

Before putting any fluid in the Eezibleed container, we connected the supplied cap for Girling master cylinders and pressurized the system to see if we could hear any air leaks. Hearing none, we filled the container with fluid and pressurize the system.

Unfortunately, we experienced several leaks throughout the car. Most could be remedied by simply tightening the fittings, a little bit more than we had previously. However, in the case of the pipe that is routed from the brake union on the right hand engine bay valance to the rear of the car, we concluded that we had improper pipe flares causing leaks and decided to remake the pipe.

Because we were eager to get the job done, we ordered 3/16″ nickel/copper brake pipe from Amazon. This turned out to be a mistake. The walls of the pipe were thinner than the pipe we had previously ordered from Fedhill. Fedhill is the go-to source for brake pipe and fittings used on vintage British cars. The thinner walls on the Amazon pipe prevented making quality flares. So, we ordered a 25′ roll of pip from Fedhill and waited for delivery by the USPS. For the pipe running from the union to the rear of the car, the flare at the union should be a bubble flare. The flare at the other end of the pipe which connects to the Goodridge flex hose at the axle, requires a double flare. In fact, each of the pipe flares (3) joining with a flex hose require the double flare. All other flares are bubble flares.  Making the pipe flares and installing the new pipe in the car is shown in the Episode Ninety-seven Video.

https://vimeo.com/1087163945/947d5a54b9?ts=0&share=copy

0:00 – Bench bleeding the brake master cylinder

2:10 – Brake pipe purchase information

4:13 – Brake pipe flares: bubble and double flares

We have decided to change gears and install disc brakes on the rear of the car so we will pick up with the completion of the bleeding of the brake system following the installation of the new rear brakes.