If you have been following my Bendix  Self-Energizing Series, this 51 Chevy 2 door Fleetline is the third and final car in the series. The principles of the Bendix  system have been covered in previous issues and a comparison between Chevy's Huck 1936-1950 to Chevys new-for-51 Bendix  systems can be viewed by visiting our Archives section at www.southernwheels.com.
The linings on all '51 Chevy cars are 2"front and 1 3/4"rear linings x 11"drums. The linings were originally bonded, and used with a single reservoir 1bore master cylinder. Conventional Dot3 brake fluid was used. Our cars problem was that only the left front brake worked. We had bled all of the wheel cylinders and fluid came out of the front two only. Fortunately, our lift was free, so we thought that while the brakes were apart, it would be a good time to do a complete brake rebuild, scrape, clean and lightly undercoat the underside of the car. After inspection it was obvious that everything in the braking system would have to be replaced. All brake lines were checked, disconnected, blown out with air, junction blocks removed and cleaned out with brake cleaner and the brass polished, the wheel cylinders were replaced with new ones, mounting bolts cleaned and painted, new crush washers used at the pipe-to-wheel cylinder connection as well. Most new crush washers are hard and flat on both sides. I wanted the old style that were soft and flat on one side and slightly arched on the other side, and I found multiple sizes of these at Pegasus Auto Racing Supplies.*
As the braking system was dismantled, we took pictures and notes on everything. Sometimes brake drums can become stuck, but all of ours came off easily. We noted that on the left and right back brake drums, there were three Tinnerman nuts on each rear drum. These were used at the factory to hold the rear drums on as the car was being assembled (they are push on speed nuts). The front drums were held on with the hub nut and cotter pin before the wheels went on as the car moved down the assembly line. When we removed the drums, we didnt see anything unusual, just rust and muck. The return springs were on rightyellow to the secondary side (it has the strongest pull). Most new sets dont color code except for some muscle car sets. We removed the front bearings and marked which side they went on, and hand cleaned them (we never wash and blow with air spinning them dry; this scores the bearings), new seals were bought and installed. I bought four new brake drums (front and rear drums are the same). The rear drums just push on the wheel studs, but the front hubs are riveted to the drums with three large rivets. These rivets must be drilled out and hubs removed to put the hubs on the new drums. I didnt have to do this, however, because my original drums were turnable. These originals were really made well, heavy cast iron that have many resurfacings in them. They run true and dont wobble. USAcant beat it! When I had them turned, the machinist that turned them went inward beyond the surface of the lining so there was plenty of lining surface, lessening the chance of brake grabbing. I have such a respect for people who know their craft and do the details that make the project work well.
The Master Cylinder was a little more difficult than the drums and shoes had been. It is mounted on the left side and fluid is added from top side by pulling back the mat/carpet, removing a large rubber plug and filling the master cylinder, located under the drivers feet. It mounts to the frame with two bolts, one long and one short. The unusual thing about these is that the clutch and brake shafts go through bushings at the front of the master cylinder. When the two shafts are in place, there is a brake/clutch shaft lock pin to keep the brake shaft and clutch shafts in place. It is inserted through a grease hole in the front of the master cylinder. These are available new at *Chevs of the 40s part #127875A for 216 manuals (1940-54). The early 1951's (my car) had a pipe plug to cover the grease hole. In late 1951, they were replaced with grease zert.
When installing a new master cylinder, it is best to lay the old/new side by side because you will need parts from the old one: 1) a brass junction block for (2) brake lines, and an eccentric bolt on the front of the old master cylinder that will have to be put on the new one). Also, there is a pipe plug thats on the left side that the original did not have. The supplied pipe plug (new one) is not tapered as most pipe plugs are. The new ones are like a screwthey just keep screwing in! We replaced this with a 1/8tapered brass one. It stopped and only went in about half of its threads, and sealed well.
In our underside cleanup, we cleaned the backing plates using a die grinder with a wire wheel. The plates were stripped, metal-prepped, primed and painted with cast. When spraying cast from a can, keep shaking it or it will come out spotty.
Return Springs. I bought new return springs but I wanted to test their return pull. I have a scale to do this, that goes to a 100 pound pullway more than a '51 Chevy return spring would require. I put on my goggles, put one end of the spring in a vise and attached the other end to the scale and pulled straight back. The secondary (yellow) is the stronger spring and it tested 68 pounds. The primary spring tested at 60 pounds. This is about right. The new springs both tested at 65 pounds. I re-used the old ones.
The brake star adjusters were rusty but I found some NOS GM ones (hard to find). They turn like butter.
The '51 brakes are now ready to assemble. I will finish them in an upcoming article. Enjoy your cars and keep em driving!