Setting caster when fabricating radius arms

[Wcbmustang]

I’m in the process of building a suspension for my 1988 Bronco. I’m going to be using drop brackets and 4” desolate springs.
I have a frame section but it’s short of the rear radius arm mounts. I could fab the axle brackets off this but am concerned about the tubes hitting the rear mounts at the correct angle. Best I’ve heard is 4-6 degrees caster and am curious to how everyone is going about setting this. I’m trying to fab all I can before having the truck down for install time.


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[ChaseTruck754]

There is some caster built into the beams already, I just forget how much. I want to say it's around 5*. As for how much to run, that's kind of driver and driving style dependent. For dirt only trucks guys go as high as like 16*. I know Geoff at Giant likes 15-16* if I remember right. For street and dirt toys I've heard a bunch of people in the 8-10* range. From what I've read and discussed I haven't found a good reason to keep the caster lower. The tracking and return to center benefit of higher caster helps while bouncing all over the place in the dirt.

As far as fabbing it up, that may be tough or a bit more work with the short frame section. You need to determine ride height and take measurements at that. See what caster you have and build the radius arms to modify from there. This will involve some time with an angle finder. Get this set/figured out on the truck and then try and replicate that with the shortie frame. IE get the truck set on level ground and get a frame angle measurement and height from a known point on the truck frame that you have in your short frame section and built something to hold the frame section at that angle and height.

I'd then try & make the radius arm mounts on the truck and create a fixture or something to hold them in that exact spot on the shorty frame. Maybe a tube that comes from the coil bucket to it? Gonna be tough with how short the frame section looks

[Wcbmustang]

After looking at it in the shop for a day now, I think your right. The frame is too short to get any accurate measurements for the radius arms. Total caster I am shooting for 8-10 degrees. I probably didn’t make that really clear in the post. Sorry about that. I was reading the 4-6 number on the factory arms best I could calculate like you confirmed. At least the brackets are done!

Think I’ll leave the arms like this until I can get ride height set in the actual frame. At least I can go ahead with arm frame brackets. I did get a 24 1/4” ride height number from desolate for hub center to bottom of wheel well on factory fenders that is going to help setting and cycling.


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[ChaseTruck754]

I was going to say ask Desolate if they had an opinion on numbers. Cool they gave you that measurement.

I'd probably do exactly as you are planning and leave the arms like that (you can weld the tubes together for now) and set the final stuff up on the truck and tack the plates there.