Switching from stock .830 to .870 bars.
How low can I go with these?

Are those moog problem-solver bushings used solely to compensate for geometry changes when you lower the front end?

If so, can I go low enough with .870s to require these special bushings?

note: it is a 63 2-dr hardtop =~ 2570 pounds

With any T-bars, you can only go as low as the bump stops will allow (unless you modify them). You need at least 3/4" between the LCA bumpstop and the frame contact point, or you will bottom out readily and your suspension will not be useful.

The camber/caster does get a bit worse when you lower things, so the problem solver bushings (with one reversed for best caster increase) are a good idea in any case.

Lou

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Home of Slant6-powered fun machines since 1988

This might help. http://www.ingallseng.com/performance/camberchange.htm