Saturday, January 15, 2011

Brakes, Part III: Shoes and Drums

In a drum brake system the shoes are located inside of a drum which spins around an axle and to which the wheel is attached. Pressing the brake pedal forces the outer surface of the shoes--through hydraulic pressure--to contact the inner surface of the drum, slowing rotation of the drum and wheel, and stopping the car. Each time you brake a small amount of the brake shoe is worn away. A smaller amount of the drums (drums are cast iron) is also worn away; usually the wear on the drum is not exactly uniform, so over time the brake shoes need to be relined with new friction material, and the drums (usually) need to be turned, i.e. ground down until the surface is uniform and smooth (actually, not exactly smooth, but uniformly rough in order for the shoes to "grab" it better).

When I removed the drums on my car I got several surprises. First, the brake-shoe return system (the springs and clips that pull the brakes back into the "off" position when you release the brake pedal) was not installed correctly. Also, the shoes and drum were oil-soaked, a result of wheel cylinders that had leaked because of long-time inactivity. This is normal in cars put in storage for long time periods because small amounts of moisture inside the hydraulic (oil) system eventually corrode the metal. The rubber seals also degrade and both of these allow brake fluid to leak out of the system onto the shoes and drums. This does not usually occur if the car is used daily because even if there is a small amount of moisture in the system, braking causes it to move around so it doesn't have the chance to corrode a specific spot.

I knew before buying the car that I would have to replace at least some of the components of the hydraulic system ( I ended up replacing most of it), but after assessing the condition of the brake shoes and drums I realized I would also have to replace the shoes and turn (repair) the drums.


Before: Notice oil-soaked and corroded hardware.

After: Relined shoes, new wheel cylinders, cleaned hardware. The "hardware" is the springs at top and bottom and the two clips on the sides. I de-rested these Evapo-Rust, a very handy product to have on hand!



Hardware before Evapo-Rust





Hardware after Evapo-Rust






Freshly-turned drum. Isn't it pretty? I had Austin_Brake_&_Clutch turn the drums and reline the shoes. They have the proper equipment to turn these old-style front drums.


The threads on the axle were stripped. Here I am re-cutting the threads uing a die.





New tap and die set I bought from Harbor_Freight. The quality of the tools they stock is not as good as Craftsman,which I prefer, but they have a HUGE selection in stock, so you can usually find odd special tools there. I also bought my Evapo-Rust there.


After bleeding the brakes and adjusting the shoes the brake system is now restored and works as new, which was among the best, if not the best, in the industry for 1953. The Jul.-Aug. 1986, #94, issue of Special Interest Autos (now Classic_Car) road tested a 1953 Kaiser and said that "The large, 11-inch drum brakes pull the car down from 60 mph in about 225 feet (the same as a disc-braked modern car of this weight)." Not too bad for a 58-year-old car!






Here are the specifications, including brakes, for the 1953 Kaiser taken from the same issue of Special Interest Autos.

Thursday, January 13, 2011

Brakes, Part II: Wheel Cylinders and Lines

I had planned to do the same thing with the wheel cylinders as I was going to do with the master cylinder, viz. rebuild them. But they were in just as bad condition as the master cylinder, so it ended up that I bought new ones instead of rebuilding the old. It is not always easy finding parts for Kaisers and Frazers now, but there are a number of sources. Kaiser_Willys is a source that specializes in parts for Willys Jeeps. Kaiser-Frazer purchased Willys in 1953, and so they have many parts in common, but they are not always an exact fit. For example, the right front wheel cylinder's bolt holes were in the opposite corners on Kaisers than on Willyses, so I had to drill new holes in the backing plate for that wheel cylinder. All the rest fit perfectly with no drilling.



New wheel cylinder next to the old wheel cylinder. Notice that the old one has a chip, which in and of itself would have made it impossible to rebuild. Even without that chip, each of the old wheel cylinders were in similar condition to the master cylinder, with pits too deep to hone smooth (see previous post).



Drilling holes in the backing plate for the new right front wheel cylinder. Kaiser-Willys sent me a pattern with the new wheel cylinder which I used to mark the points for the new holes.



Here is the backing plate after two new holes were drilled. The old holes are now superfluous, but do not negatively affect the new wheel cylinder.



There was one small section of brake line near the rear left rear wheel that I accidently crimped as I was unscrewing the old fitting that hooks the brake line to the wheel cylinder. In order to make a new one I bought a length of the correct diameter line with fittings, measured the old line, cut the new one to size, bent it to the correct shaped, and flared the end so it would mate to the fitting on the wheel cylinder.


From left to right are the line-cutting tool, flaring tool, and shaping tool. At bottom are new brake lines. They come in common pre-cut sizes with fittings, so if you have a common vehicle, you would only have to shape the lines. But there was no size that fit the Kaiser, so I had to cut it to size and re-flare the (straight) end I had cut so it would seal properly.



New brake line after I had cut it.

Flaring the end of the freshly cut brake line.


Compare my flaring on the left with the flared end that came with theline on the right (it's the extra length of line I cut off to make the line the correct size).

New brake line installed on the car. Also note the new rubber brake line between the frame and suspension in the bakground. There are three of these on the car: two in front and one in the rear--I replaced all three.