aa-fords.com

I'm trying to build a cutting fixture to machine the rear spring pivot pins while still attached to the frame. I need help with some details.
-pivot pin dimensions and wear limits? (couldn't find a reference in the shop manual)
-pivot pin bushing dimensions?
-pivot pin thread size?
-other considerations?
If I am successful in making the cutting fixture, I will see about making up several sets.
John
NNY

This thread has a picture of a cutter to machine the pivot on the frame.
http://forums.aa-fords.com/viewtopic.ph ... ilit=pivot

Bob

I'm rebuilding mine on a29 AA. unworn spots are 1.49 in on mine Mac....

Both my frames were well worn in a saddle shape I think caused by the two bushing system installed prior. Who ever had them after slid in some single full lenght bushings and made little effort to clean up the pivot shafts. I figured them to be 1.5" new as the unworn areas gave me that measurement, and all the wear seemed to be on the bottom. Using a sharpy pen I traced out the low areas and filled them with healthy beads of MIG wire. Made a guage for sizing and ground, filed and sanded til the were damn near perfect. I filled in any spots I missed in the first few passes and filed again. It was tedious, but the new bushings fit like a wrist pin after I was done. After installing the bushings in the top spring hanger they no longer fit and I had to do a bit more work on the shaft and bushings to get them friendly again. In retrospect It was probably easier to take them off, have a machine shop do the work and re-rivet them on. But I never got an award for being smart anyway.

That 1.490 dim. must be pretty accurate. I like your weld build up idea though.

Do you suppose it really makes a huge difference if the spindle is worn a bit as long as the bushing is good, most trucks are past the working for a living days.

The pivot bracket shaft has a thread size of 3/4-16 for the 1928 AA’s. The thread size is 7/8-14 for the 1929-1931 AA’s. The Arnold Read tool was designed so that it could be used on either thread size.

The pivot bracket shaft has a 1-1/2” diameter. I don’t know what the “ware limit” is.

The AA-5790 pivot bushing is 1-3/4” OD x 1-1/2” ID x 2-1/4” long (2 per truck). This is for the 17 leaf rear spring (through early 1928). All other springs use the AA-5790-B pivot bushing which is 1-5/8” OD x 1-1/2” ID x 1” long (4 per truck).

I found that the (3) handles on the tool had to be cut slightly shorter to allow clearance for a frame with the #3 running board brackets.

It would be great if this tool was available. The Arnold Read tool is not available currently since he has moved and does not have a new shop set up.

The article “AA Truck Talk – AA Rear Spring” in the April 2010 club newsletter covers the above and much more. And there is an article in the upcoming 2012 newsletter about servicing the AA rear springs with more trivia to read about .

After looking at Neils tool, I'M thinking a sleeve that fits over the threaded area with a few threads on the end to hold it in place...... A tool holder that rides on the sleeve and is driven with a 1/2 " drill motor. Build up the shaft with weld, grind it down close to the dimension and turn that shaft down..........................sounds good anyway.

Shorthaul:

I've wondered if a guy could simply slap some JB Weld in the worn spot(s), then slide on the bushing and spin it a few times. Next, let remove the bushing and let the JB Weld dry. And, be sure to clean the bushing. You're right, most of us don't haul any loads on these old trucks anyway.

-- Drew

Shorthaul wrote:After looking at Neils tool, I'M thinking a sleeve that fits over the threaded area with a few threads on the end to hold it in place...... A tool holder that rides on the sleeve and is driven with a 1/2 " drill motor. Build up the shaft with weld, grind it down close to the dimension and turn that shaft down..........................sounds good anyway.

I wonder about welding on that pivot, and changing it's strength or brittleness. I know most fractures start at a weld. Just wondering.

Yeah, I don't know how hard that spindle is or if welding on it would cause a problem, How hard is JB weld? I never put a file to it, pretty strong stuff, don't know how it wears.

My spindles are not too bad, one shows some wear in the center bottom area and the other less than what I want to worry about.