Caster Mod for pre 73

[hewittca]

Originally Posted by SuperDuperDoughnuts

So I'll be rebuilding my suspension this weekend and I wanted to do this...

Bought bunch of new parts including new lower control arm shafts (Moog K6147). The new shafts have only a single locating hole--not two--that is 1.25" from the shoulder. The only other person (The Rocknrod) I see who had a single hole, says his were originally at 1.75".

I don't have power steering so I'm not trying to get to 6°+ degrees of caster, just ~4°. Basically confused at what I should drill at to hit my target.

That's interesting that your original hole is in a different spot than what has been previously reported. I would compare that new shaft to the one you take out and go from there. If it's in the same spot as your old shaft, just base your new hole location on that. If the new shaft is different than your original, then maybe they drilled it in the wrong spot? With it being at 1.25 (vs 1.75) that would put the arm in the opposite direction of what you want for this caster mod, so you'd have a really poor handling truck!

[SuperDuperDoughnuts]

Originally Posted by hewittca

That's interesting that your original hole is in a different spot than what has been previously reported. I would compare that new shaft to the one you take out and go from there. If it's in the same spot as your old shaft, just base your new hole location on that. If the new shaft is different than your original, then maybe they drilled it in the wrong spot? With it being at 1.25 (vs 1.75) that would put the arm in the opposite direction of what you want for this caster mod, so you'd have a really poor handling truck!

I did more digging and found this: http://67-72chevytrucks.com/vboard/s...&postcount=209

The critical measuring reference point shouldn't be the shoulder, but rather the end of the shaft. This makes sense given how the control arm and shaft are assembled with the end caps screwing on.

Measuring from the end of the shaft to the center of the existing hole I get 3", which is the same as most other posters (give or take a couple sixteenths). So now I'm debating moving the hole 1/2" or 5/8" towards the center in an attempt to get somewhere near 4° of caster. I really just want a bit more than currently, but not enough that I become Popeye in parking lots.

[SCOTI]

Moving the hole & shifting things forward still requires shims during alignment to dial it in. I'd prob still target the max the hole can be moved w/the minimal amount of clearance related issues.

[SuperDuperDoughnuts]

Originally Posted by SCOTI

Moving the hole & shifting things forward still requires shims during alignment to dial it in. I'd prob still target the max the hole can be moved w/the minimal amount of clearance related issues.

I'm still a bit hesitant to go the full 3/4" because I'm running a manual steering box. While I want improved highway tracking, I also don't want to make parking lots too much worse. I'm trying to find a sweet spot.

It seems that most fellas that go the full 3/4" have power steering.

[hewittca]

That's a good consideration that I did not think about when doing mine. I went the full 3/4" and mine is manual steering as well. It was already a bit of a bear at low speed with a 15" steering wheel. I hope it's not too bad now! I have yet to drive it as I am still in the process of a motor swap.