A Pinion Seal for Ford’s Torque Tube

If you’re running a banjo and torque tube — especially if your car sits on a rake —  you’ve probably wrestled with the problem of your rear end oil drilling it’s way up the torque tube, starving the banjo and flooding the trans. When this problem resulted in a banjo fry in a friend’s roadster, it was time for some pre-emptive action.

Gary’s roadster has a ’35-’36 banjo and torque tube, with a ’34 driveshaft and 4.11 gears. He was getting ready to switch to 3.54’s, so it was an ideal time to attack the oil migration problem.

It worked out to be three part solution: a machined Insert Sleeve designed to sit in the bell of the torque tube, a simple Ford seal, and a Pinion Collar designed to replace the locknut on the pinion.

The Insert Sleeve slides into the torque tube bell and is fixed by three set-screws that have been drilled and tapped into the tube. Ford didn’t precision-machine these bells – in fact Gary’s was slightly cone shaped – so the sleeve was machined for O-rings to accommodate Ford’s variation. Other year Ford torque tubes bells aren’t even close to being round inside — a fact that keeps a solution like this from becoming a universal product. The sleeve was also notched to match the flow-back hole in the flange, providing a return path for trapped oil to flow back into the banjo.

You can see one of the three set-screws on the torque tube in the photo below. The sleeve is dimpled to accept it.

The seal slides in next, and seats against a shoulder machined into the sleeve.

The Pinion Seal Collar below replaces the original pinion locknut. Gary installed it when he replaced the ring gear, but it could also be done to a banjo that was already buttoned up because the nut that adjusts the preload doesn’t have to be loosened to install this new locknut.

Here’s the collar on the pinion. The collar is shallow enough that it won’t interfere with the driveshaft coupler.

He’s put quite a few miles on this set-up and has had no problems. It’s bone dry on the shop floor under the car, too.

Gary has machined a second set of seals for Mike Wittmann’s car: it’s running a shortened ’40 torque tube. As expected, when compared to Gary’s, the inside bell dimensions were different. In fact, it wasn’t even close to being round. Check it out:

While Gary’s ’36 didn’t require any machining, this ’40 was probably as bad as they get and had to be machined round in order to accept the sleeve.