The Ford Barn - View Single Post - Rear Axle Taper

hotrodart · 10-02-2020, 02:56 PM

Your skepticism of the axle preload specification is way off base. You have been lucky with only 50 ft-lbs....or maybe you simply "baby" your car.

The taper on the axle is designed by the engineers to make sure the hub and axle rotate as one unit (by pure friction) with the maximum torque of the engine, and maximum resistance from the tires (friction between the tire and road surface)......with some margin of safety added. The key should take no load at all with the proper preload (ft-lbs). The proper preload depends upon the taper angle, materials involved (steel in this case), and total contact area between the axle taper and the hub. I have never seen the design figures that Ford used, but a reasonable guess for automotive applications in the '30s would be about 75% (non-lapped tapers).

10-02-2020, 02:56 PM	#8
hotrodart Senior Member Join Date: May 2010 Location: Shenandoah Valley Virginia Posts: 220	Re: Rear Axle Taper - What It Does Your skepticism of the axle preload specification is way off base. You have been lucky with only 50 ft-lbs....or maybe you simply "baby" your car. The taper on the axle is designed by the engineers to make sure the hub and axle rotate as one unit (by pure friction) with the maximum torque of the engine, and maximum resistance from the tires (friction between the tire and road surface)......with some margin of safety added. The key should take no load at all with the proper preload (ft-lbs). The proper preload depends upon the taper angle, materials involved (steel in this case), and total contact area between the axle taper and the hub. I have never seen the design figures that Ford used, but a reasonable guess for automotive applications in the '30s would be about 75% (non-lapped tapers).