Early "Short" Rear Axle

One of the benefits of working on a number of cars from different countries is that we can see how things are designed and assembled as well as see what component on which car holds up the best. On of the most unnecessarily weak elements of a early Ferrari is the rear axle. This axle had a very short pinion gear and the Ferrari “engineers” used ball bearings to carry it.

They also used plain old ball bearings to support the differential/ring gear carrier. As anyone who has been around this style of gear knows, when the pinion twists and meshes into the ring gear it wants to either push out or suck into the ring gear. The same goes for the ring gear itself, when the pinion gear spins the ring gear wants to deflect to one side or the other. As any engineer knows, ball bearings are designed only to spin and not take up thrust so these axles are short lived and we have repaired of these more of these fragile units that we like to admit.

The Jaguar XK-120 from the same era had a very robust Salsbury axle with tapered roller bearings for both the pinion and the differential carrier. This design holds up so well that the only failure I have seen is an axle that had an oil leak and started to sing, it didn’t break but needed bearings due to overheating. Ferrari axles on the other hand fail just because the bearings cannot locate the gears properly and once there is excess play all hell breaks loose.

In these photos we are digging into yet another early Ferrari short pinion axle that needs a new ring gear, pinion gear and side/spider gears. We also need to make 2 very complicated half round bronze spacers and 2 flat spacers for the side/spider gears as well as all of the necessary machining to adapt the axle to tapered roller bearings. At this time we are not only repairing the axle in the photos but two others, all in with the same needs as describes above. With so many expensive-to-attend driving events both overseas and in the states we want these cars as reliable as possible.