by ian24ian » Tue Sep 25, 2012 8:12 pm
Im new to vauxhalls, but have built a few mix n match braking systems....
Savanna disc, is approximately the same size as the stock solid disc, I am assuming the Magnum uses the Girling M16 calliper, You can buy a spacer kit from somewhere like Rally design for the calliper,which will save a lot of work.. going this route will not make your brakes any better than stock, other than the vents giving better cooling, you have the same swept pad area, same dia of disc, and the same calliper piston size, you gain nothing other than new discs and pads, However all is not lost, Austin princess Callipers are 4 pot, and use the same bolt pattern as the M16s, these will give you much more pad area and have a similar piston CSA as the M16, so there is no need to change the master cyl, you will need to but a spacer kit, again from Rally design. If you want to keep the appearance of stock brakes but with upgrades, you can use the Mk2 Granada caliper, known as the M18, this was available as a wide calliper. this bolts on gives you more pad area and uses the same piston size as the M16, If the Vauxhall uses the M16 Girling calliper, both these callipers will bolt onto the stub axle.
Pads--- Good pads are really a worthwhile purchase, I have a favorite, EBC Green Stuff, not aggressive to the disc, and dont need warming up like many performance pads like DS22s.
Condition of discs plays a big part in the performance, if your discs are rusty, even slightly, this will clean off the disc, but will embed into the pads, now dosent sound like a problem, but you will not clean this off the pads, all you have done is glazed the pads, which again will glaze the discs,
Tires, your braking is only as good as your tires, as soon as you have locked up, you have lost 90% of your front retardation, good tires are as important as good brakes, Bigger discs dia dose not necessarily give you better brakes for the reason of tires, BUT what they will do is give you a better feel to the brakes, I was running 330mm discs in15" wheels on my last car without a servo, I never locked the brakes on that car no matter how hard I pulled up, but would lock the wheels if I stood on the brakes,
Finally, Servos--- They do not improve you brakes!!!!!!!! what it does is lessen the pedal pressure at your foot. and lessen the pedal feel.
A rotter and a scoundrel, 
