Spindle Steering Arm Failure
The weekend of International Model A Day was fun-filled as we and our fellow Model A’ers traveled more
than 630 miles in our Model A Victoria over mountain passes, descending downhill onto two-lane roads with switchbacks and following
streams through narrow canyons in the Colorado Rocky Mountains. It was a scenic, relaxing and enjoyable drive without any problems
until - less than one mile from home - the right spindle steering arm failed. This caused a loss of steering control. Fortunately,
we safely stopped the car without incident. We consider the problem very serious and want to ensure the Model A community is
aware of what happened, and recommend that they check their spindle steering arms for a similar problem.
The Victoria’s original right side spindle steering arm had been replaced with an arm that had the ball machined off, leaving the
˝ inch steel shaft. A stainless steel ball had been welded onto the shaft in the original balls place to connect with the tie
rod end. The failure occurred when the stainless steel ball came off the shaft. This happened when we were traveling 35-40
MPH, on a straight road after we had just transitioned from a downhill grade to level road. At the transition point, where there
is a small “bump” in the road, the car began to shimmy, first a mild shimmy that became much more intense (in seconds), which made
it difficult to maintain control. Fortunately, we were able to stop the car without incident.
After we stopped, I checked the front end and found the right side of the tie rod was resting on the wishbone, and the spindle arm
shaft (post) was still attached to the spindle, the machined shaft was not connected to anything. The stainless steel ball was
securely retained in the tie rod end. The wheel could be moved freely in either direction. There was no problem with the
left side steering assembly, which had allowed limited (very limited!) steering control.
A reputable alignment shop had checked the front-end alignment, including the “toe,” less than two months prior to the failure.
They did not detect any wear or alignment problems with the tie rod assembly or any other steering component. Since then, the
car had been driven approximately 1,000 miles. There was no indication of the steering being loose prior to the ball coming
off the shaft. The car drove fine on the club tour; it did not pull in either direction and there were no shimmy, steering problems
or any other concerns.
The spindle steering arm, stainless steel
ball and tie rod end were inspected after they were removed, with the following results:
1) Spindle Steering Arm
a) Post had
been machined to approximately ˝ in diameter.
b) There were wear marks on the shaft where the ball had turned on the
shaft prior to coming off the shaft.
c) There was a small amount of “welded” material at the top of the shaft.
d) The shaft had not
melted during welding; material had not flowed.
e) The post had no other damage.
2) Stainless Steel Ball
a) The ball
was round, with ˝ inch hole bored through the ball.
b) The hole through the ball had a larger diameter recessed area
(~.020 larger diameter, 1/16 into the ball) on one end, perhaps a
“welding” area.
c) The ball had not melted
during welding; material had not flowed.
A small amount of welded material was visible in the recessed area.
d)
There was no attempt to weld the bottom of the ball to the shaft.
e) There was no other damage to the ball.
3) Tie Rod End
a)
The tie rod end had Teflon bushings installed.
b) The bushings appeared to be tightened to the correct tension.
c) Neither the inside
nor outside bushing had any damage to the Teflon.