Pin Verses Spline

[Rick Parker]

For the record the spline drive was unique to the British Sports car, primarily with wire wheels such as Austin Healy, Mg Midget, Sprite and AC Bristol from which the 289 Cobra was born in 1962. Originally the wheels were relatively narrow without much negative offset. As horsepower increased so did tire & suspension technology hence wider wheels, fenders and ultimately pin drive wheels. Whe the 289 FIA and USRRC cars were created, the wire wheels were deemed out dated/unsafe and pin drive was standard fare. Previously and shortly after their introduction and while earning their reputation, the 260's & 289's were often equipped with wire wheels at the drag strips, but soon afterward the above applied. Spline drive was standard fare for production 260/289 cars. Race cars and all 427's had pin drive with cast wheels. the few British 427 Bodied cars that had the 289 in them (AC 289) also used spline drive wire wheels. I believe the wheels that were on late Austin Healy 3000's were dimensionally the same as those used on the later 289. Cobra.

[Dan Case]

Shelby's works started retrofitting stock hubs (drill new hole patterns) very early. Early photos clearly show the old vacant holes in hubs. New chassis well into the CSX21xxs still arrived in the USA with stock wire wheels, even some of the cars ordered as race cars from AC. Somewhere in time legend says that both AC and Halibrand made new race hubs drilled only for pin drive to retrofit existing cars. One owner of a works racer found the his rear hubs stamped as being race parts. By the time the cut back door race chassis were made it appears AC installed spline drive hubs that also had six pins installed. The last two Daytona Coupes are shown in factory images with front pin drive hubs without splines. It is hard to tell in pictures but the front axles and hubs in those two cars may have been the first two in the design adopted for 427 Cobras. The stub axles come further out and I don't see holes to install split keys to retain the axle nuts as found in stock Cobra front hubs.

There were (not counting the some design changes in a series or the changes in steel alloys):
Cobra splined hubs
Cobra splined hubs retro fitted with drive pins
Cobra splined hubs without the stock bolt pattern but including pin drive
Cobra race hubs without splines in pin drive
Various 427 Cobra hubs without splines in pin drive
AC 289 Sports hubs for spline drive (Cobra hubs and AC 289 Sports hubs are different, AC 289 Sports hubs are different from late 427 Cobra hubs)

I have found all this very confusing over the years and managed to collect used examples of about half of these variants.