Any guidance on my 1970 Duster plans
, and was thinking autocross seems like something I want to do. Though I also want the car to be able to cruise and do road trips and such. So I'm looking for it to be good at multiple things but not great at one thing I suppose, I'm sure my limitation will be my driving skill instead of the car in the beginning, I'm just something that works and lets me get into it and would be an interesting project to get to my goal.
good to start with a goal. you can have a car that has good street manners and is great on long trips as long as you don't over do it in any one aspect. suspension wise, if you shoot for the upper middle you're not really leaving a lot on the table and set up correctly it'll still be decent at autox for what your skill level may be.
For the rear, I was able to score a new 8.75 rear at Carlisle this past summer to upgrade the previous rear. I was thinking of putting in the Hotchkis geometry corrected leafs.
excellent. great start.
For the front, I was going to do the Firm Feel reinforcement kit for the k-member, reinforce the lower control arms, get the Firm Feel tubular uppers with the big ball joint (if I replace the spindles), and adjustable strut rods. Poly bushings for everything. Also the car has a pretty big front sway bar currently, though I haven't measured it, but I don't think it's original.
fully endorse reinforcing the K & lowers. FF uppers are nice, as are the SPC. if you stay with stock uppers (which are fine, upgrade them using the moog offset bushings for more caster), adjustable strut rods are nice, but not strictly necessary. we'll come back to the bit about the spindles and sway bar
For torsion bars I was thinking 1.08 or 1.12 based on what I'm reading here. However the question is, how do I address the 1" drop from the Hotchkis leafs? Do I get drop spindles or just drop the front using the torsion bars?
i would go with 1.03 or 1.08's and pair them up with some bilstein RCD or hotchkis shocks, do not cheap out on the shocks or it's a waste to get the big bars. don't worry about the 1" drop on the rear leafs. do not get drop spindles, there is no need.
And finally I'll replace the power steering box with a better ratio. Perhaps at some point I'll also add frame rail connectors and torque boxes, but I'd like to get driving down the road first at least.
all the factory stock power boxes are the same ratio 16:1 you can upgrade to a borgsen unit that is quicker at 14:1 for a decent chunk of change. i would suggest the addition of subframe connectors and torque boxes at the start rather than down the road. two fold: one, it's easier while the car is all apart to weld them in; two a flexible chassis is not a tuneable chassis.
back up there you mentioned swapping out the spindles. it appears that you've got factory drums (from the photo up there) so i'm guessing that you're going to go with an aftermarket disc brake set up? let me be the first to tell you to upgrade it to the factory 73~76 style. there are several reasons for this, but some of the biggest involve availability and price: wheels, brakes, parts. besides that, the stuff just flat out works.
on the sway bar: let's see what you've got. you may be able to incorporate it to your new build.
finally: i would try to do ALL of these upgrades before sending the car out to paint.