Basically stock Model A front end, with the exception of a Super Bell dropped axle And ‘40 Ford spindles and brakes. The Super Bell has 35” perch centers, but the stock A had 36.5” perch centers. We carefully heated and bent the stock A wishbone yoke to fit the Super Bell axle. Installing the wishbone on the car, it was an extremely tight fit, but it did go together. My questions - I think between the chassis rake, and the tight wishbone, it is taking some caster out of the setup. We have about 3’ of caster now. I know it’s not ideal, but is that enough caster? Could we get by with a wedge on the spring to get a little more caster, or do we need to be shortening the wishbone, so that it’s not such a tight fit? Anyone dealt with this situation before? In case you’re wondering, we’re running the original banger motor, with an AA bellhousing, to accommodate a T5 overdrive transmission. That’s how we’re running the unsplit wishbone. Thanks In advance for any advice you can share!
I would cut the bones from the bottom up, leaving some material at the top. That way you can increase the caster a slight amount, and weld the gap up. I don't see how pinching the front together would affect the caster.
First off I don't understand why you didn't use the Superbell with the right perch width since it is available, the caster is built into the front crossmember. I ran a dropped axle on my avatar with an adapter to attach a stock wishbone to the flathead bellhousing. I don't think the AA bellhousing moves the wishbone attachment point so shouldn't change the caster. I think you created the problem when you bent the wishbone, usually have to put a little upward pressure on the ball to seat it in the socket. When you narrowed the front mounting points you made the wishbone longer which pushed the axle forward.
No, it is not. This is a common, and oft repeated misconception. Caster is not a function of the angle of the crossmember. It is the relationship to the spindle axis to the ground, and is set by altering the wishbone, by cutting and welding it, or moving its pickup point. The spring pad on the center of the front crossmember is at a angle that has nothing whatsoever to do with caster. Viewed from the side, the wishbone swings in an arc. The ends of the spring that are attached to the perches remain in a constant relationship to the axle, on a line perpendicular to that arc, at rest. During compression, that line moves up the arc, toward the line of the spring pad, as the spring compresses. This is done to minimize bind in the spring, NOT SET CASTER! @Marty Strode has kindly shown how caster is set. That's it, aside from moving the pickup point on the chassis.
Thanks for your responses! To clarify - we already had the axle and are just trying to use what we have. As we all know, that sometimes means making more work for ourselves! We carefully tacked the wishbone down, one side at a time, to keep it flat. Then we heated the yoke (since it is forged) one side at a time, and pulled the perch end in .75 on each side. I believe this did lengthen the wishbone overall, when measured from the axle to the cup mount. How much I don’t know. I lost those geometry skills years ago! Do you guys think we can get by with just slicing it? Or do we need to completely cut it to shorten it up slightly? Is there anyway of determining how much we need to adjust it, or is it a guessing game? Do you think we could get by with the 3’ of caster? I’d prefer to be around 6’ to 8’. Thanks again for the help!
Cut your ends as stated above, find your correct caster, then weld them up. Your car will drive alot better with more caster than you have now.
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