Re: Brake drum removal 1948 22nd Series

Posted by Scott On 2014/7/8 1:26:06

Regarding the disagreement about the tapered shaft vs. the key providing the transmission of torque: You're both right. How's that for settling an "argument"?

The very high tension on the drum against the tapered shaft provides substantial friction. Also, the key must shear before rotation occurs and it's function is to act as a "fuse". If rotational forces exceed a design limit determined by the frictional and shear sum, the key will shear, preventing broken axles or other major parts.

Two problems arise. I've once had the threaded portion of an axle snap off while driving. At that point there is little to prevent the wheel and drum from parting company with the vehicle. Without a drum there is total loss of both hydraulic and parking brakes on all wheels. Fortunately I was traveling slow at the time, heard a scraping noise and came to a stop with the drum almost off the axle, but not quite.

Another problem with tapered shafts is galling. Over time metal transfers from one surface to another practically welding them together. Good luck getting them separated. A simple old-time preventive is to coat the clean shaft with Milk of Magnesia (MoM). Plain or flavored is your choice, but I prefer plain. This prevents galling but does not impede the frictional properties.

Scott