Nuts & Bolts: Wandering International HarvesterPosted in How To: Suspension Brakes on October 11, 2015
I have a 1956 IH 3/4-ton 4x4 (factory made, not a conversion) that was converted to 3/4-ton 1975 Dodge axles in the ’80s. The man that did the conversion kept the original spring packs, which are 1 3/4 inches wide, and adapted them to the Dodge 2 1/2-inch spring pads by use of a 1/4-inch shim on either side of the spring pack. This is a good thing because it got rid of the orphan old six-bolt 1-ton wheels and gave me common eight-lug wheels instead. Unfortunately he neglected to give the front axle proper (or even decent) caster. I measure the caster at about 1.5 positive degrees, which by my research should be 3.5 to 5 degrees. There’s a bit of wandering at common road speeds. I chase the steering wheel back and forth as the wheels find their own path through life.
Several websites have given me clues where the caster should be to track properly, and the wheel alignment shop agrees. The amount I’ve found is 4 degrees minimum, 6 max, based on whether it’s a Dana 44 or Dana 60. Mine’s a 44. There are a few 1 3/4-inch-wide shims but a much wider selection in 2 1/2 inch wide shims. I’ve found some steel 2 1/2-inch, 4-degree shims, and there is room under the above mentioned spring side shims that a 2 1/2-inch-wide shim could fit, either to the bottom of the spring pack or to the top of the mounting pad of the axle. Essentially the same place, but removable versus not.
My problem: Do I weld the shim to the mounting pad, or add it to the bottom of the spring pack? The website selling the shims suggests either as a possibility. I’m leaning toward the spring pack, but is there a valid reason to put it on the mounting pad? If they go on the spring pack, the pack would get disassembled and inspected/repaired as needed, which may be reason enough to put them there. My thinking is, in my case, the spring pack is the better option. I’m not planning on doing anything wild enough to spit the shims out. You wouldn’t believe the number of positive comments I’ve had since I bought it! But the old girl has her issues to fix.
You are on the right track to resolving the wandering issues on your classic corn binder. You are also right to prefer steel degree shims over aluminum ones, as aluminum shims tend to crack and work loose. The 1 3/4-inch-wide springs are a little unusual, so it is not surprising that you haven't had much luck finding shims that are the right width. However, it would be easy enough to just buy 2 1/2-inch-wide shims and cut them down, and I would definitely cut them down to the proper width as opposed to running them full width under the skinny springs.
As for placement, you definitely want to attach the shims to the spring pack. The centering pin in the spring pack needs to engage the hole in the spring pad, and if you were to attach (weld) the shims to the spring pad instead, the centering pins wouldn’t have enough engagement. Keep in mind that you are going to need new centering pins when you install the shims on the spring pack.
While it sounds like the way in which the previous owner adapted the skinny springs to the 2 1/2-inch-wide Dodge spring pads worked, it's less than ideal. What is keeping the spacers in place between the springs and the U-bolts? If the spacers were to work loose, you could have an issue with the springs working loose or getting displaced under heavy cornering forces, and that's something you definitely don't want to happen.
In order to really fix it right, you should strongly consider cutting off the original Dodge spring pads and installing new pads that match the width of the springs. By replacing the spring pads, you kill two birds with one stone: You can set the new spring pads to the proper amount of caster and end up with a safer, stronger spring arrangement for the front suspension.