In the early days of hot rodding, with the majority of hot rods being Fords, it stands to reason the ’30s and ’40s Ford “banjo” rearend dominated the scene. It’s still popular today with builders of traditional rods, even with the later 8- and 9-inch Ford axles being the mainstay of the street rod market.

However, those old banjo rears had an Achilles’ heel, and a pretty nasty one at that. Should you be unfortunate enough to break an axle in one of these early Ford rearends, you’d likely lose the remaining part of that snapped axle, the wheel, and the brake drum! Not a pleasant experience, especially at speed. Even early hot rodders tried to come up with ways to keep the drum in place should they break a shaft. Today, Vern Tardel and Speedway Motors sell a simple drum retainer that bolts in place.

When it came to the ’40 Ford rearend in his latest project, Bo Bertilsson wanted to go a few steps farther than just a drum retainer though, wanting to thoroughly modernize the old rearend but maintain its period appearance. A call was put in to Hot Rod Works (HRW) in Indiana for one of their modern axle conversion systems.

Most builders who use the old Ford rearend do so for a traditional appearance, either with or without a quick-change conversion. Adding a quick-change still doesn’t resolve the safety issue, but with the HRW axle kit that’s taken care of. You can now modify the old rearend with new 9-inch Ford axles and the complete rearend will still look like an original banjo axle.

However, there a few choices to make. Do you want to use the original rearend housings and centersection, or a completely new rearend that looks like the Ford? Quick-change or original centersection? What size driveshaft bearings and brakes do you want?

In our case we wanted to make the rearend safer and stronger, but keep the original look. How often do you change the gears in a quick-change anyway? Most rodders set it up once and never change them. Many do it for the look of the polished centersection. We went with the stock-type centersection. Next choice was the brakes, and we plan to use stock ’40 Ford-type brakes, which also include the possibility of ’39 Lincoln-style drums, as they’re a bit more effective. Those can be bought new today too. The choice with the original ’40 Ford bolt pattern for the backing plates makes things a little easier. That way you can use the original Ford housings, though they have to be modified for the later 9-inch-style shafts to fit by machining the bearing housings off the ends.

We sent the two housings to HRW in Indiana to have the work done, although we could have opted for later Ford drums and bolt pattern, which require another bearing size. HRW has so many old Ford rearends in stock that they can sell you all the parts or put a complete rearend together for you. Our ’40 rearend had the housings and ring gear machined, to enable the new axle shafts go through the centersection. Machining the ring gear is not that easy because it is hardened, so it was smart to let the experts at HRW take care of that. The kit includes new axles with big bearings and wheel studs, axle seals, bearing adapters, hardware, and axle gears. The conversion requires the use of 11-tooth spider gears.