Need some newb advice on an unusual combo

[Sean-m]

Need some help with a car of mine that has poor stopping abilities. Its a 70 Coupe Deville Cadillac that has stock front brakes(with extended length pads), home modded rear brake rotors are from a later model SS Impala (10-11"?) with G-body front calipers.



There is no prop valve currently. The power booster is from a mid 70's GM wagon I think. Have tried a 1 1/8" Corvette master cylinder and a 1" Eldorado master cylinder. Both from 70's model cars with 4-wheel disks. All new parts are being used.

The car just doesn't seem to have enough pressure to lock the wheels no matter how hard you push the pedal. It stops much better with the 1" Eldorado MC but still seems like it shoud do better. It stops straight and drama free. I know it will never stop like a sprots car but it should be better than it is IMO.

Feels like there is insufficient volume but it stops better with the smaller diameter MC. I'm confused

Thanks Sean

[TPI Monte SS]

Locking the wheels is not a good indicator of how well your car stops, it's how much traction your car DOESN'T have while it's stopping. Honestly, if you can haul that much weight down without locking the brakes you're better off. What size wheels/tires do you have on it?

[Sean-m]

Thanks, the wheels and tires are drag oriented. 15X7.5's with 235/70/15 front and 275/60/15 drag radials on the rear. Thought about doing something to make the Caddy handle but decided it would be much easier to make my Mustang handle than the Caddy.