Kingpin Locking Pin

Bruce of MN

Bruce of MN

Well-known member
While helping a friend with his '40 Ford kingpins (same as an A), I discovered that the locking pins wouldn't even start in the hole in the axle. When I reamed the bushings on my A last winter, I had similar problems, but didn't test it first on the bare axle before inserting the kingpin. For that, I had to file and grind the locking pin a lot. Anyway, with the '40, I felt a bit of a burr at the edge of the wedge cuts in the pin and filed them smooth. This wasn't enough to get the pin very deep in the hole, so I filed them all over. This worked and the job went smoothly. I wish that I had filed mine similarly. I used a pretty coarse file, but it wasn't enough to take off a significant amount of metal.
 
The spindle bolts (kingpins) on a '40 are not the same as a Model A's. There is a cavity at the top of the bolt where the brake operating lever connects on a Model A. The '40 had hydraulic brakes and didn't need that cavity. Anyway... I've come across repro spindle bolts where the notch in the side (where the locking pin wedges) was machined in not quite the right location, and it didn't line up with the hole in the axle.
 
You are right about the kingpin style. I meant that the locking pin arrangement was the same and the filing should be useful for A’s, too.
 
The retaining pins for the kingpins on the Model A are a "cylinder." As in the pin body is a section of rod and the hole in the axle is cylindrical to fit.

Without the kingpin, the retaining pins will "fall right through."

What retains the pin (and locates the kingpin) is the key/wedge portion of the retaining pin. And hopefully the matching groove in the kingpin. You put in the retaining pin and a "side thrust" caused by the taper on the retaining pin "wedges" both the kingpin and retaining pin in place. The nut acts as the "keeper."

I've seen where the kingpin groove is "misplaced" - as in you put everything in its proper assembly and the "top" of the kingpin is "at angle" to the brake shaft housing. There is no ready solution to that except to return the kingpin on "quality issue."

I have heard about the "Y-direction" location of the king pin groove is misplaced. Some get past this with washers or shims under the top bearing. I suppose one could "re-cut" the kingpin shoulder to make bearing/washer space for a groove that is too close to the bearing end of the kingpin.

One MAY be able to file or machine the groove, but there isn't a lot of extra material there to make a correction. And I certainly wouldn't build it up with weld and re-cut.

Joe K
 
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