My '75 F-250 2wd had toasted I-beams when I bought and towed it home. I found and installed replacements from a '78 f-100. It was an exact fit. But, although the camber is sweet, there is not enough caster for the truck to center - it feels a little like driving on ice. This makes sense because the f-100 sat about 4-6 inches lower than the f-250 does. Every bushing, bearing, seal, even the PS gear box have been replaced and the tires are brand new. The alignment shop told me the only way to increase caster on this truck is to bend the I-beam. That will effect the camber too and I just am not going to have that done - there has to be a better way.

I have found inserts that fit into the lower hole in the radius arm (after enlarging the hole) but they only provide +/- 2 degrees. The alignment shop tech didn't measure it but said he thought there is presently about 0.5 degrees caster and that it should be around 6 or eight. Another option might be to purchase or have someone fabricate drop radius arm brackets for the rear of the arm like I see on the lifted trucks. That might be too costly.

But it seems to me I could achieve the same effect by machining the lower hole in the radius arm into a front-to-back slot the same width as the existing hole, starting with the existing hole and elongating it forward, and then twisting the I-beam mounting rubber a bit by bolting it up with the lower end of the big bolt that goes through both the radius arm and the I-beam pushed all the way forward and shimmed in place.
I have the radius arms out of the f-100 to experiment with. Thoughts?

 

There's very few vehicles that call for that much caster and Ford trucks aren't 1 of them.Your's would be "happy" with 3-4 deg.the more positive;the more stable at higher speeds (why most European cars use 8-up),but it can cause a "heavy" feeling at lower speeds.Bending the I-beams affects camber,but a bend can be put in the radius arm for more caster.What your talking about doing is fine.

 

You can't bend the "I" beans for caster, just camber. I mean anything is possible but I would never consider it. I have used the cams in the spring bolt holes and they work. Don't recall the specs but I don't think it's all that many degrees.

 

Well, I took the radius arms to the machine shop (finally, I know, it's been 7 months) and described what I wanted to do and they refused to do it. On the way back home I stopped at the local wrecking yard and they had just acquired a 78 F-250 camper special which as still intact so I was able to look at the front end all assembled. The tires were showing no sign of uneven wear and the camber appeared similar to the other stock setups I've looked at. It also has the dual-piston brake calipers ( which would be an upgrade) so I bought the I-beams, radius arms, spindles, brakes, springs and anti-sway bar mounts.

To be succint, I'm replacing every bearing, bushing, king pin, caliper, brake line on the front, along with installing the "new" I-beams, radius arms and heavier coil springs, and had to switch out the tie rods. I'm ready to begin reassembly and have a question - How do I install the new I-beam pivot bushings? I'm hoping I can soak them in ice water for an hour, lube the casings and then tap them into the I-beams. Is there a better way to do this? THANKS!