I'm curious if Holden Commorore calipers (the ones in Tech-Wiki) were used any USA models. Thinking maybe they were in the GM parts bin.

Also are they lighter than the ubiquitous 280ZX boat anchors?

I'm happy with the braking on my car I'm just looking for a low bucks way to cut some weight. Wilwoods are fairly cheap but I'm curious if there's an even cheaper choice.

Tom

Yes, they are alloy GM parts. Produced by PBR Australia. I heard they were fitted to some USA Camaros and the Pontiac GTO, not sure about that. Maybe the new USA Caprice as that is made down under

For the race car i don't think they are a very good option. (depending on your starting point of course).
However, we have not had very good results with wilwood either (too much caliper flex).
I have s4 Rx7 calipers coupled with ferodo DS3000 pads on my circuit racing coupe (296x22mm disc). I would look into pad choice before committing too. I have found this to be critical for racing applications (almost more important then the calipers themselves).
I have melted the dust piston seals on my current calipers, and will only use DBA 4000 discs as i have warped others.
i.e for my application i really need to upgrade to a proper racing setup.
Saving unsprung weight unfortunately comes at a cost. If you find a golden bullet, please let me know, as my next upgrade starts to cost a lot of coin.

Good thing is all the options in the US a very cheap in comparison to AUS. I would look to pick up a second hand set of racing calipers (ex nascar rears or something like that, they seem to go cheap over there).

All the best with the search.

Bryan

Bryan thanks for the input. We used Wilwoods on our old sports racer and in that application they were very good. My Formula 500 uses them as well without issue but you are not the first person I've heard mention caliper flex. On that front on the aforementioned sports race the rear calipers were Yamaha RD 350 units. Rock solid units.

It is possible to shave some more weight of the 280ZX units in out application; you can turn the rotors down and trim a pound or so off and mill some off the carriers but that's not something I'd spend a lot of time on.

Use to run Wilwoods on a Sports Racer and noticed a fair bit of pad taper but I just machine the pads true after each event. Worth noting it was virtually cheaper to replace the caliper than rebuild them with new pistons! Cheap calipers but good value. Most have no dust seals though.
RX7 S4 are great calipers from limited experience and can be cheap to buy. Excellent pad choices.
AP do a budget caliper for circle track guys called SC320, but they are still US$390ea which is cheap by AP standards.