Tuesday, February 22, 2011

Making Radius Arm & Hairpin Frame Brackets

Completed hairpin frame brackets, with tapered holes.

Written as a companion to my earlier post Home-Made Hairpins.

I spent part of Presidents Day completing brackets needed to attach the front hairpins & rear end radius arms to the Model A frame.

Earlier, I flame cut 3" wide strips of 3/8" 1/4" thick steel plate to use as the base to which tapered-hole bungs will be welded.
A lot of hot rodders would stop there, drill holes, and bolt this mount straight down, off the side of the frame.  I'm going for a more finished look, so I'll take it a few steps further.

Keep the mallet close.
...flame has no shadow.

Next, I heated and bent the plate 90°.  Evenly heating a band to a dull red (front & back) just above the vise, made hammering the steel over easy as cake.  I used a Harris #2 Rosebud tip.  From lighting the torch to the completed bend took about one-minute.  Then let the steel air cool off the vise.

After marking the piece, I used my cutting torch this time, to cut off the excess.  Then using the bench grinder to clean it up a bit.  Next I cut & shaped a hole to fit the tapered-hole Speedway 'shock mount'.

Hot rodding books from the 50's told readers to cut off tapered tie-rod eyes from steering arms found on car spindles.  This could still be done today from just about any junk car or truck.  But at $2.99 each from Speedway Motors, it's much cleaner & easier.

After fitting the mount into the bracket (making sure I have the correct side of the mount facing out), and chamfering the hole as a valley for the weld, I set the welder on high.  A nice MIG weld bead, front and back, completes the joining of two pieces.

I took an architectural class in high school.

Some final machine sanding, and the brackets actually look a little too good for a 1950's track car.

(A sketch with measurements is useful when making multiples of something.)

The next thing I have to do is fit the rear radius arms with threaded tube & tie-rod ends.  Then tack these brackets to the underside of the frame rails, after I've 'measured twice'.