Axle beam and stub axles

A note on front axle kingpins

The majority of pre-war front axles made by Rolls-Royce have kingpins that are manufactured with a very slow taper - 1 in 200 on diameter - that engage in a similarly tapered hole in the eye of the axle beam. The fit of the pin in the eye is critical, and must be an interference fit. Without this the pin will become loose in the eye. In this eventuality the eye of the axle beam will have to be opened up with a special tapered reamer and a pin with an oversize taper selected to give the correct fit.

When fitted, the kingpin must be tight in the taper. As a guide the shoulder on the pin adjacent to the larger end of the taper should be between 0.100" and 0.125" clear of the face of the axle beam when pushed in to the axle eye by hand for a Rolls-Royce. In the case of a Derby Bentley this clearance should be 0.150" - 0.175", allowing for the thickness of the lower dust cover. When finally fitted the pin should be tapped home using a soft (aluminium) drift and hammer. In the case of pins with a flange on the lower end be careful not to hit on the flange; it will crack.

We have in our Tool Stores a range of tapered reamers that we have made to enable us to ream worn axle eyes. We also have oversize kingpins to fit worn axles. Please contact us if you find that your kingpins are loose.