The crack in the torque tube was discovered on March 14, 2025. It was significant and total.  The car had made an unusual sort of thumpy noise before I parked it on February 23, 2025. I surmised that the cracked tube and the pressure and flex on to the drive shaft it covers was the reason for the thump. This did not sound like an easy fix.  And….. it wasn’t.

The crack in the torque tube extended all the way around the tube.

So why did the tube break? Well, this calls for some investigation on the purpose of torque tubes and how they have evolved.

The reason for a torque tube is a phenomena called “axle wrap”. Which is not at all like Saran or plastic wrap. It is the twisting force forward or backward of the differential upon acceleration and braking.

This diagram shows axle wrap distorting the leaf spring while accelerating. The red arrows show the twist that occurs during acceleration and braking. The torque tube is supposed to relieve the stress but on early cars, failed to do so.

Our Michigan has what is referred to as a “torque tube drive” set-up. However, its implementation was not well engineered. Indeed, if you examine the close-up photo of the crack, you will observe what appears to be grinding marks adjacent to the crack. That is not my doing, but is an early attempt to repair a torque tube failure in the exact same location.  While trying to figure out what steps to take to fix the problem, I called upon Mike Howard in Kalamazoo. Mike is another owner of a 1912 Michigan and two 1913 Michigans. Mike sent photos of the same area of his 1912 car. It appeared to have been repaired at some time prior to Mike owning the car. The break is in the IDENTICAL  location. It is important to note that the differential and drive train for the 1913 car is vastly different.

Differential & torque tube of Mike Howard’s 1912 Michigan showing repaired torque tube.

Mike Howard’s 1913 Michigan had no torque tube, an additional universal joint and most importantly, big heavy radius rods to prevent axle wrap. – Click on photo to enlarge.

I looked at about 9 or 10 other cars of similar vintage from before 1912 and after 1912. In nearly every case, there was a radius rod setup of some sort to prevent axle wrap. Our rear axle and differential were built by Sheldon Spring & Axle Company.  Most of the axles they produced were for heavy trucks. Our Sheldon “Pleasure Axle” was for cars. https://michiganmotorcar.com/nuts-bolts-2/axles-differential/  It is very apparent that their  model No. 201-D, was poorly engineered and defective from the beginning. Our car, Michigan serial number 3531, and Mike Howard’s car serial number 3477, both have repaired torque tubes. The only other operating 1912 Michigan that I am aware of, #3535, has a completely replaced rear end from a Ford Pinto, complete with hydraulic brakes. This leads me to believe that use of the Sheldon 201-D rear end was short-lived and a continuing problem.

Michigan Serial #3535, completely replaced
Ford Pinto rear end.

So, we know a little about the problem- axle wrap.  And we have some knowledge about how others seem to have avoided it. I really dislike the idea of replacing the entire rear-end with something modern. So, what was the extent of the damage to our car and how do we fix it?