My "new" '74 Duster- or why I need a project like a hole in the head

goldduster318 said

I kind of wanted to do 2 things simulatenously if I did that - get some opposed piston calipers, but keep the 330mm rotor size so my spare will fit, and not spend a ton of money. The craziest calipers that fit this are for an 04-10 VW Toureg or Porsche Cayenne, the 17Z versions are made for a 330mm rotor and are 6 pot brembos. There is an 18Z version that was on the turbo cars that's even bigger at 350mm. You can buy a pair easy for $250 or less on the 17Z. Piston area is about 15% more than a cobra brake set.
17Z
View attachment 1716151826

View attachment 1716151823
18Z

I'm also not sure about getting that to clear varius suspension stuff like the tie rod / strut rod / sway bar. On the original applicaiton they are front mount, however, it seems possible to swap the crossover tube and bleeders side to side on the calipers and do rear mount, so the leading and trailing pistons are still in the proper orientation. Would also need a 32mm wide brake disk with enough offset to clear the wheels.

I could CAD model all this stuff if I had all the dimensions for everything handy already, but I don't.

The Hotchkis arms hit everything on the back unfortunately, you can see the arm is just so low back there and given that this is drooped out, it just crams into it. They'll even hit the stock calipers if they are rear mounted.
View attachment 1716151827

Click to expand...

I wanted to keep a 13" rotor and 17" wheels originally. But both the Mustang and Scat Pack calipers were too big and crashed with the mounting ears on the spindle. I even tried it with drum brake spindles and couldn't make it work. The Porsche/VW caliper does look shallower, so maybe it would work? But with the SP caliper, I had to go up to 14.2" caliper to just barely get them to fit.

In regards to dimensions, I didn't have any initially either. I grabbed images off RockAuto that looked to be close to straight on and then traced them. Then I used the mounting hole distance to scale them. Did the same thing with a brake pad and nested them so I could get a rough idea of how they might relate to the spindle. I did have a good layout of the spindle already from when I did my C5 caliper mounts, so that helped.

This is where I started:



And then the caliper with the spindle:





These are just rough layouts to see if the idea works. I wouldn't create a mounting plate from this. But when I moved up to a 14.2" rotor, I could see that it might work, at which time I bought one caliper and a set of pads so I could take real measurements and start making a true layout.

This doesn't mean there aren't other issue that could come up. I rotated the caliper about as much as I could to get the upper hole to clear the upper spindle hole and was worried that the lower ball joint wouldn't bolt on, which is where the 3D printer came in clutch.



Sure was happy to see the clearance there. At this point, I could still return the caliper and would have only been out the cost of the pads and shipping to return the caliper. But it all seemed to check out so I went forward from there.

This is the process I used to go from no functional dimensions to metal on the table to bolt them up.

In regards to the rotor, the one Dr. Diff uses is a 32mm thick rotor, and it is really deep so it would help with wheel spokes clearing the fixed caliper. But it won't help with clearing the strut rod or sway bar on a front mount, nor the upper control arm on a rear mount.