VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1928 aa and ab brake adjustment Service News

The service and owner manuals are not detailed in the adjusting the front and rear brakes. The VCCA, AACA, and the Chevy Facebook groups did help in guiding me with the repair. Unfortunately, I was offered conflicting information on the brake adjustment on a 1928 AA and AB chevy chassis.
The BEST brake adjustment information is the 1928 Chevrolet Service News. STUDY the figures/diagrams! The 1928 brake adjusting tool comes with no directions.
This tool is used on the AA, which has wooden spoke wheels, and the AB, which has disc wheels. The brake adjusting tool for the 1928 is SPECIFIC for that year so do not order a 1929.
The Chevy service news has 3 sections to adjust the brakes. One is the Chassis Linkage, the second is the Front Brake Rods, and the third is he Rear Brake rods. The front and rear crossover rods is in the Chassis Linkage section.
First, I did not know that the cross over shafts take a total of 4 return springs until I saw the diagram on page 4, figure 4. All 4 were missing on my chassis. No mention of these springs in the service manual.
The brake adjusting process is really understanding the diagrams. Page three shows two diagrams and how the brake adjusting tool with the angled, tapered pin going through the hole on the brake cross shaft linkage.
First, remove all connecting brake adjustment linkages on page 3, figure 2. Next, remove the return springs.
Now, study the left-hand diagram in figure 3. The rear brake cross shaft must have its brake linkage rod face 90 Degrees to the floor. This is the first step in using the brake adjusting tool. You can move the rear brake cross shaft with a small pipe wrench.
Connect the straight connector bar that has the two clevis pins holes in it. One connection is at the rear brake linkage, and the other end connects to the curved arm.
I used a small pipe wrench on the front brake cross over bar and turned it towards the floor until the brake adjusting tool slipped into the hole of brake cross shaft.
The straight connection bar will be at a slight angle facing upward. You have just adjusted the front and rear brake cross over shafts.
Page 4, figure 6, paragraph 7 describes another procedure to the brake adjustment. It is the measurement of the distance between the front and rear brake linkage connections.
I use a 12-inch wooden ruler to measure the 3-5/8ths distance between the clevis pins. I use a light ball peen hammer to tap the rear cross shaft brake linkage to the rear of the chassis until I get the 3-5/8ths measurement.

You are ready to set your brake linkage adjustments in the Chassis linkage section.
I adjusted the rear brakes first. There are about 2 inches of thread on the brake rod. The goal is to turn the clevis down on the threads until the clevis hole lines up with hole in the rear brake activation arm. The clevis pin does not extend very far down the brake linkage threads. Do not move the rear cross over shaft. Its measurements are set correctly.
I attached the two rear brake return springs and checked the rear brake linkage adjustment again
To understand how to adjust the front brakes go to page 5, figure 8 of the Service News. You will need a helper to apply the brake pedal when adjusting the front brakes.
The key adjustment is the front brake rod is to push the adjusting brake rod hard against the brake stop. Hold the brake linkage rod hard against the stop and turn the clevis pin until it connects with the front brake linkage. Nothing in the manual talks about pushing the brake rod hard against the stop.
Just resting the brake adjusting rod against the brake stop will not allow enough back and forth movement of the front brake operating lever, page 9, figure 27.
You will not have enough brake movement to fully apply the brakes. Turn the clevis down on the threads until the hole in the clevis lines up with the hole in the brake arm. Again, the clevis will not be turned far down on the threads. Attach the front brake return springs.
You are ready to adjust the brake cam operating lever by turning the adjusting nut on the cam adjusting lever rod.
There are no directions with the Billy Possum front brake adjustment kit. I have never removed one and recognized I would break the adjusting cam. I called Billy Possum and the owner talked me through the removal and installation process. You will break part of the original brake cam as it is made of pot metal!!
Have your helper press the brake pedal several times while turning the adjustment nut. This action helps center the cam during the adjustment. Turn the adjusting nut until the wheel starts to drag. Press the brake pedal and you have front brakes.
A very important process must be done to get good brake adjustments. Use a good grinder with a heavy-duty cone wire brush to clean out the brake drums and polish them with sandpaper. Any built up dirt, grease or what ever creates excess drag on the wheel drums and do not allow correct adjustments.
Use a tap and die to chase the threads on the end of the brake adjusting rods and clevis pin. Replace any grooved clevis pins.

. The AA is a 1927 Passenger and half ton available with wood spoke or metal disc wheel depending on what body style you ordered and no front brakes. The AB is a 1928 Passenger and half ton available with wood spoke or metal disc wheel depending on what body style you ordered and all have front brakes. .
. According to my parts books, 1928 AB and 1929 AC use brake drum #946505 on Wood wheels and #352319 on disc and wire wheels. I have not attempted to adjust the front brakes on an AB and adjusted the fronts on my LQ over 40 years ago. Pedal pressure was very high. .
. Lou .

pgbaresel, Your post is a very detailed and well written account of how to adjust the brakes on these vehicles.

Thanks!! Dean

Thanks, Dean, for the vote of confidence on my article. I believe that it very important to share information with other car enthusiasts to help keep the hobby alive. Paul

You're welcome, Paul.

I agree and have documented on this site and the Stovebolt site many of the technical challenges I've encountered with my old trucks.

Cheers, Dean