Any drawback to keeping the drum spindles on my 66 Valiant?
Yes, absolutely true - but isn't is still less width than the 73-76 disk spindle adds? In any case, I'd have to mock-up the hub and wheel to confirm whether the wheel would seat onto a 0.20-0.25" spacer.
Thanks for bouncing these ideas back and forth!
That's a good point, it depends on how much the Wilwood kit adds. I know wilwood says that kit doesn't add any width, but quite honestly I wouldn't depend on that because they never really say what they based that information on. But yes, that probably does still end up being less than what a 73-76 disk spindle adds. So maybe a 225/60/15 might still work. It's close with the 73+ disk spindles with the full 4.25" backspace of the 15x7" cop wheels. The other issue is going to be the spacer, you'll have to have a plain flat spacer for a 1/4". So that will probably mean longer wheel studs than what comes with the wilwood kit. Maybe not, but that's pretty much the upper limit for me for a plain spacer.
And no problem! I get it, it's a lot of money to commit and there are lots of things to consider.
Quite honestly with the way that Moog's quality has been dropping off lately I wouldn't count on their offset bushings being right anymore. Which makes the upgrade to a tubular UCA even more beneficial. And if you do that, the QA1's can be had in either large ball joint (52301) or small ball joint (52303). So you could run the 52303 QA1's and keep your 10" drum spindles and use the Wilwood kit. The wilwood kit will set you back at least $780 for the kit depending on your option, plus another $60 for the brake hoses, so minimum $840 for the wilwoods and you'll need a spacer on top of that and possibly longer wheel studs.
Or you could run the 52301 QA1 UCA's, get the large ball joint, and be able to bolt on DoctorDiff's 10.95" 73+ mopar kit for $470, which includes the stainless hoses at that price. And run the cop wheels with no spacers. Yes, the 73+ kit will end up being like 35 lbs heavier. But you can get all of your parts from the local parts store under a '76 Dart. And have the large ball joint and larger wheel bearings. Not as fancy as the Wilwoods, but more clamp force generated by the calipers.