So somebody else found this little problem.
These are Seville rear brakes.
The cables are normally run over the rear end and pull the opposite way from the way we like to see them on our streetrods.
So what to do??
First do a search for Seville rear brake problems on the internet. Eventually you will get some information on how these work. This will give you the information you will need to work with these brakes. I'd help out but I lost the URLs in a computer crash a while ago.
Take a very close look at what happens when you move the cable arm. You may have two of the same side. There is a left and a right.
I mounted mine so the cables pull from the front, sort of like you have done. Unfortunately this puts them on the wrong side of the rear end.
They don't tell you this in the instructions. BTW, no instructions came with my kit.
I had to do this the hard way.
I took them apart and reversed the gut pieces, left went to the right, right went to the left. I also had to make a minor modification to the arms as a result. I think I reversed the arms too. There was a minor mod done to the brackets too. This made it so when the arms are pulled forward the E brake applies. It's been 10 years so memory is a little short.
You also should get a couple of rebuild kits as you will most likely damage at least one of the o rings. Oh yes these kits can be a bit hard to get.
You will also need a 10 psi residual valve on the rear brakes. These are the only disc brakes requiring this. There is a GM TSB regarding this. If you don't do this you will have low pedal. The reason for this is that the parking brake retracts the piston about .050 instead of .010 so you need to have some residual pressure to keep the pads near the rotor.
When you bleed these it very important to make sure all the air is out of the system. As I recall the last time I serviced mine I removed the caliper and rotated it so the bleeder was straight up. I think one of the GM TSB says to wiggle the caliper around to make the final air bubbles come out. They get caught in the ratchet mechanism. Pressure bleeding will not help. Actually a true vacuum bleeding is the best but it is very hard to do. When I repaired a leak in one of these I bled it on the bench first then again when I installed it on the car. This worked the best. I actually have very high pedal now.
It can be difficult to get the adjustment correctly. If you dig around on the internet you find various methods of doing this. Most say that you need to snap the lever about 30-50 times to get the one way clutch inside to ratchet to the minimum position. It is a real pain. If you are really, really careful you can remove the arm and turn the shaft untill you can just get the arm back on. This will usually cost you and o-ring. BTW I used a small vise grip on the arm when snapping. It makes it easier.
Plan on an all day project if everything works the first time.
Caddy mechanics cussed these everyday.
They actually do work once you get them set up.
Finally you MUST activate the E brake every time to park the car. If you don't the ratchet mechanism will freeze up and the E brake will not work. The pads will wear down and the pedal will get lower and lower as the adjustment is gone.
Don't forget to release the e brake either. The rear brakes will get very hot and the pads will wear down. I've done this at least a dozen times haha
That's it in a nut sack.