Replacing a Front Wheel Cylinder on an Early Ford
Springtime in Nebraska brings a mile-long list of maintenance needs for the family hot rods. The old cars that will soon become our daily drivers each get checked, greased, tightened, thumped, aired, bled, oiled, cleaned and polished. During this regularly scheduled inspection, small issues get caught before they become bigger issues.
While working through preventative maintenance on his 1931 Ford Roadster, my dad noticed a splatter pattern of fluid around the inside front tire. This was a telltale sign of a wheel cylinder in need of replacement. A fluid leak in your wheel cylinder can cause loss the brakes.
He removed the wheel, the hub and drum from the spindle and checked the grease seal, which looked good.
At this point, he opened the front floor board to peer into the master cylinder to see how much brake fluid had been lost. Luckily, the master cylinder was plenty full so we wouldn’t have to rebleed the entire system. This also meant he had caught the bad wheel cylinder somewhat early in its failure. Brake fluid is very corrosive. You can see the damage it caused to the powder coat finish on the backing plate.
Early Fords (1939-1948) have unique parts for the wheel cylinders between the left driver side and the right passenger side. Before the technology of self-energizing brakes was developed, the wheel cylinder was designed to put more pressure on the front shoes.
The wheel cylinder has two pistons, one on each side. Each piston has a rubber seal and a shaft that connects the piston with a brake shoe. When brake pressure is applied, brake fluid forces the pistons out and pushes the shoes into contact with the drum, using friction to slow and stop the car. Front brakes do about 60% of the stopping because of the front-end weight.
Replace wheel cylinder:
- Remove old wheel cylinder with wrench.
- The copper washer acts as a seal between the wheel cylinder and the back of the brake hose. Look at the copper washer and replace it if you see a depression where the hex nut was tightened against it. It is a good practice to replace the copper washer every time.
- Place new wheel cylinder with the big side towards the front. Install brake line to cylinder and tighten with wrench. Depending on the placement of your brake line, you may need to remove the line to get everything tightened properly. Luckily, we didn’t have to remove anything else. The line tightened to the wheel cylinder with no problem.
- Install and tighten three bolts to secure wheel cylinder to the backing plate.
Replace brake shoes, drum and hub:
- Install Double D type washer for the bottom of the brake shoes
- Install hold down clips which help hold the brake shoes in place
- Install brake shoes, the primary shoe (the longer one) installs on the front
- If the shoes were soaked with brake fluid, you should replace them.
- Use a screwdriver to turn the plunger upright to properly hold the top of the brake shoe. This part of the brake shoe looks like a bird beak.
- Install anchor pin plate and secure with two cotter pins
- Install spring with a special tool, brake shoe return pliers (shown). A vise grip works too.
- You can de-adjust the brakes to relieve pressure if needed by loosening an 11/16” bolt behind the hub of each shoe. This controls a cam which moves the shoe in or out, relieving pressure on the shoe.
- Grease spindle, such as the LE Almagard Industrial Grease
- Install hub and drum onto spindle
- Repack bearing with grease and re-install
- Install bearing retainer washer and spindle nut (also known as a castle nut).
- Tighten nut as you spin the drum. Tighten and then back off the nut (slightly loosen it) to install the cotter pin. Fold and clip ends of cotter pin.
- Install dust cap
- If the dust cap fits loose, you can bend the inside piece out a bit with pliers
- Most dust caps are in rough shape because they’ve been walloped by the installation process. Take your time and gently move a flat screw driver around the edges to install a little bit at a time.
- Now bleed your brakes, adding brake fluid as needed.
