Model A

Ford Garage

Dangerous Lug Nuts

Here is one style of reproduction Model A Ford lug nut to watch out for. The minor diameter of this nut was made too large for the 1/2-20 stud size.

What this means is that the nut will still screw on the stud okay, but the amount of surface engagement between the nut thread and the wheel stud is greatly reduced and weakened.

Actually the remaining threadform in the nut is probably stronger than the thread crests on the stud, so as you torque the nut you will deform the threads on the stud and ruin them first. The ridiculous nut should survive just fine!

Moral of the story: A poor quality lug nut ruins the studs of an expensive brake drum and hub assembly, and makes a dangerous wheel attachment.

Here is another common lug nut problem. Original Ford studs are swaged into the drum and have an unthreaded shoulder at the base. The original design lug nut on the left has a corresponding relief in the threads to clear the stud shoulder.

The repro nut on the right has the threads running all the way to the base of the nut and no relief for the stud shoulder.

Many nuts are missing the thread relief, and the nut threads will bottom-out on the stud shoulder before they tighten the wheel. Then people think they should add those fabulous (not!) conical wheel nut washers to take up the slack.

The only thing the conical washers really do is add more mis-fitting interfaces into the joint, and waste valuable thread engagement length of the stud. They make a bad situation much worse. I do not care to ride in any car with conical washers on the wheels.

Moral of the story: Use correct wheel nuts having the proper shoulder relief at the bottom, and throw away the dangerous conical washers.


November 2002