More disc brake questions
I had a AAR that I raced and when I changed the torsion bars to the .830 and 90/10's it changed the weight transfer and the rear wheels would lock up on hard braking. Installing a adjustable valve I could make it stop with out locking any wheels on straight stops and when it was set up for corners just turn the knob and it was set up for the stiff suspension.
Don't let anyone talk you out of a adjustable valve.
Unless you don't
need one. 60k+ miles on my Challenger with that brake set up, and with 1.12" torsion bars up front, 275's all the way around and even the 11x2.5" drum brakes out back it would lock the front's slightly before the rears. No adjustable prop valve can change that (they can only reduce the rear pressure), none needed. You only need one if you need to reduce the pressure to the rear brakes. And if you're not constantly swapping suspensions or tires, you only need to set it up once.
some of the 60's heavyweights with front discs did not use a prop valve...like big station wagons.
smaller cars with front disc can tune their brakes without a prop valve using different rear wheel cylinders and bigger or wider rear tires which are harder to lock up.It's trial and error but the the best is using an adjustable valve.
Exactly. There are a lot of factors that determine the brake bias. Tire size, brake size, wheel cylinder and caliper bore size, front/rear weight balance, spring rates, etc. There are a few different rear wheel cylinder bores out there for these cars, but if I needed to back the rears off I would be more apt to install an adjustable prop valve, just makes it easier to tune.
I looked up 78/79 cordoba master cylinder on rockauto. 79 shows aluminum with 1&1/32" bore, the 78 shows a cast iron one with a 1&1/32" bore as well. Both with 11.75" rotors and 2.75" piston calipers. Can i assume that this bore has something to do with power brakes which both year cordobas have as std equipment?
What if i rebuild my power booster and attach this master to it?
Yes the power brakes would make a difference, the linkage for the power brakes actually has an effect on the pedal ratio. A and E bodies didn't even run the same master cylinder bores with power brakes because of that, the A's were actually backward, they ran a 15/16" master with power and 1 1/32" with manual. E's were the other way around, and it sounds like the Cordoba's used the 1-1/32" with power as well.
As for running the power brake master with manual brakes, you will have to check to see if they have the provisions for the manual rod and retainer, they probably don't. The aluminum ones don't, that's one of the things Cass does to modify the later aluminum master cylinders for use with manual brakes.