Brothers Trucks 1947-1959 Dual Master Cylinder Conversion Installation


Brothers Trucks 1947-1959 Dual Master Cylinder Conversion Installation


If you were to order a bracket, a master cylinder, and an access plug, this is what you’d have on your garage floor a couple of days later. A plug is an option you’ll see the need for later on.

This is the original ’57 single master cylinder. It’s mounted to the frame under the floor and faces backward. The front of the truck is to the right. There’s a two-port fitting at the back of the cylinder feeding lines to the front and to the back wheels. The plugin the floor above it is for access to fill it.

With the cylinder removed, you can see the mounting bracket that’s welded to the frame. Note the two brake lines: the upper one goes to the front, and the lower to the rear. New adapter lines will be made to join these to the new unit.

The new parts above the original master cylinder show a good size and layout comparison. Dotted lines demonstrate how the bracket will mount to the same holes as the original unit, the location of the brake pedal lever pivot bushings, and where the new unit mounts to the bracket.

Here’s the new bracket bolted in place. The pedal pivot pin is locked in place with the original retainer, and the new pushrod is bolted to the pedal lever. It’s a good idea to run a reamer through the pedal pivot bushings to remove paint and burrs since the fit is very close.

Take the master cylinder to your parts house to get the proper fittings, and 18 inches or so of new lines with couplers to mate to the old lines. Believe us, you’ll be glad you have all the right stuff before you start.

With the master cylinder temporarily bolted in place, we used an aluminum welding rod to model the new lines.

Although you can bend brake lines by hand, a bending tool makes a neater job of it.

Always use a good sharp tubing cutter to make your cuts. Any other method won’t flare properly and could result in a leak.

What we’re doing is cutting the new tubing to length per our model, then putting the cut-off fitting onto our end, and re-flaring it with a compound flaring tool.

Here you can see the new lines compared to the model forms. Accuracy isn’t required, since the original lines are plenty flexible.

Looking straight down at the driver’s floor with the mat turned back, you can only see the front edge of the master cylinder. Filling it would be a challenge.

But luckily, we had ordered a new access hole plug with our kit and had the genius idea of cutting another hole behind the original one, using both plugs for much better access.

Here’s the kit completely installed, with the new line extensions in place. You can see how the extra hole in the floor will greatly improve access to filling. Just bleed the system, top off the chambers, and you’re on the road again, with safer stoppers.


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