It was the dog days of summer following the Second World War. To break the tedium of a lazy Saturday afternoon Bob and his buddy decided to tune up the loose front end on their “cut down T” project. The steering linkage was badly worn so they sorted through the junk pile and found an assortment of parts that appeared to be in pretty good shape. It wasn’t long before the upgrade was complete and it fell to Bob to assess the quality of their workmanship. Everything felt great as he entered the U turn at the end of the block. He was pushing the turn to the limit hoping so slide the back end a little when all of a sudden the wheels straightened the swung violently in the opposite direction. The more he turned left the more the car turned right. Before he knew what had happened the radiator was pressed against the neighbor’s porch and the front tires were sitting in the flower bed. Through the windshield he could see Abner Crawford sitting in his living room reading the paper. Old Man Crawford was so deaf he was unaware of the runaway T at his front door.
Talk to any old time T guy and he will have a similarly exciting story regarding “over center” steering.
For the most part, Model T parts are interchangeable from year to year. Interchangeable does not necessarily mean compatible. For example, the pitman arm, the drag link and the tie rod changed length a number of times to accommodate improvements to the car. The final straw may have been the smaller steering bracket introduced in 1925.
It is possible to combine Model T steering components in such a way that the pitman arm does not stop at the limit of the turn but continues up and around in a full circle, reversing the steering. At the point when the pitman arm crosses center, turning the steering wheel right will turn the car left. Alternatively, mismatched components can also cause the car to steer normally in one direction but have limited steering in the opposite direction.
Listed below are a few of the changes that affect steering linkage geometry.
- The length of the pitman arm was changed at least 3 times.
- In 1911 the early one piece spindle was replaced by the two piece spindle and the tie rod was relocated below the wishbone. The short early pitman arm may have been lengthened to accommodate the change. The ball socket was threaded to the drag link at the column end.
- 1918 The drag link received integral forged ends, replacing the riveted-brazed type used since 1913. The tie rod was changed to the type with the integral left yoke; the adjustment was at the right end and was locked by the ball-retaining nut. This effectively reduced the distance between the tie rod ball and the pitman ball, hence a shorter drag link.
- 1919-20 The spindle arm was bent to place the steering linkage over the new style wishbone that was attached below the axle. The linkage components were changed to accommodate the new location.
- In 1921 a slot was added to the bottom of the steering case to allow a stop pin to be used.
- In 1925 the smaller lower steering bracket was introduced which moved the steering column shaft about ¾” closer to the frame.
- In 1925 the spindles were raised on the spindle body to lower the chassis. Late in 1925 the drag link was shortened by about an inch.
The following combination of parts can result in over-center steering: late style small steering bracket, short pitman arm, short drag link, long tie rod, early steering gear case.
Combining the large steering bracket with the long pitman arm, long drag link and short tie rod results in normal steering one direction and limited steering in the other direction.
|Introduced||Drag Link||Tie Rod||Steering Bracket||Wishbone|
|1909||Threaded ball socket||long||large bracket||below tie rod|
|1911||Threaded ball socket||long||large bracket||above tie rod|
|1913||Ball socket brazed||long||large bracket||above tie rod|
|1914||30.688–30.750″||long||large bracket||above tie rod|
|1914||31.062–31.125″||long||large bracket||above tie rod|
|1917||30.938–31.062″||long||large bracket||above tie rod|
|1919||30.312–30.438″||short||large bracket||below tie rod|
|1925||31.125–31.250″||short||small bracket||below tie rod|
|1925-27||30.812–30.875”||short||small bracket||below tie rod|