Wilwood brakes

Hey guys, I'm going to ordering front and rear disc brakes for my '70 'cuda street/strip car, 95% (street honestly), the car is a factory disc brake car, was power but I removed the booster and used the manual brake rod years ago. It weighs about 3850, Dana with 11" drums, is a mid-10 N/A car, but going to step it up a little very soon.
My question is, for you guys that have done this swap, did you replace the factory proportioning valve or retained the stock one?, what bore size master cylinder did you use and were happy with when driving?

Thanks!

I have Strange on the front and Wilwoods on the back, no proportioning valve at all. The valve s gutted and used as a T for the fronts, the rear goes straight from the m/c to the rear. My m/c is 15/16”, if it ever goes bad I’ll use a 7/8”. The car is 3350# or so with me in it.

I had heard from someone before about doing that, but didn't know how well it stopped in traffic etc., ..spongy or rock hard.
I talked to a guy at Wilwood, and he told me Mopar two different brake pedals, I told him I'd never seen or heard that, that they had 2 different brake rods, power and manual.

Wilwoods didnt fit on a weld rear wheel.
Had to grind on the caliper to get them to work. They are 15x10s

Strange rears fit perfectly and installation is easier than the Wilwoods.

What back space? Mine clear fine with 3 1/2" back space.

With the normal race calipers using the 1.75" bore, a four caliper with 4 piston all around would use a 1.125" MC. The Wilwoods use a smaller piston 1.375" on some of their stuff for some reason. We got caught with that one time years ago. With a 1.125 MC pedal was hard as a rock and the car wouldn't stop with 2 feet. Figured out what was going on, put an .875 on it and it would put you through the windshield if you wanted. Pedal was a little low for my taste, but it wasn't my car.

Ask Wilwood what they want on it. They will know what parts you're getting.

Modifying the system/replacing OEM parts = ditch the factory prop valves. Some people use an adjustable prop valve, but if the components are matched according to the parts used and application for the car, it ends up being run wide open and useless.

Initially I had a 1 1/16" m/c on mine and it was hard to stop. Also had a adjustable proportioning on it too, now its in a box on the shelf.

I run wilwoods front and rear, I use a Dr Diff master cylinder kit with the smaller piston. I do not have a proportioning valve. The front kit has vented rotors but the rear kit is not vented and the rotors are drilled. The fronts have been on there for 18-20 years and the rears just a year or two. I have been very pleased with them and couldn't imagine something else working much better.

My car is 3550 on the starting line and 4000-4100 on the road for drag week. In 2018 we were up in the hills and mountains and stopping was never a concern.

Thanks everybody for the help and advice, as always the Moparts family comes thru, I will need to ask Wilwood about the calipers not clearing Weld wheels, mine are a 15x10 with 6.5" backspace.

They won't work. They will tell you they work but they don't on certain Welds.
Get Strange rear brakes

If street driven with normal (not skinny) front tires you should use an adjustable valve in the rear line to dial in premature lockup of rear brakes. Makes all the difference in the world for panic stops.
G

I have the Weld Draglites on the rear, I have Strange's spool/axles in the Dana, they built them using a 2.600 offset, so need to see if they offer that brake kit for that.
I have fairly skinny tires up front, a 205/70-15 I believe?, 28" tall, wheels are 3.5" wide.

Wilwoods and Welds, 12.19" rotors, 2.36" offset.

Matching the clamping force of the front & rear brakes by choosing the correct size caliper bores and master cylinder is dramatically better than trying to use an adjustable proportioning valve as a bandaid. 4 wheel disc systems need a distribution block like 4 wheel drum brake cars have. There is no proportioning valve in them.

Experts like Dr Diff or Wilwood's tech guys can steer you to the correct sizing and matching of parts. Make sure you use DOT approved braided lines, which will help you modulate the brake pedal better.

There is also a small device commonly used in race cars that helps cushion the shock wave of a sudden brake application to the rear brakes. It doesn't lower the pressure, but it does soften the spike to reduce the tendency of the rear brakes to lock up during panic like stops/slowing. It's around $100, and it works amazingly well.

Years ago I purchased 4 wheel disc system and had Wilwood spec the entire system, gave them weight of the car 3,400 lbs, and weight bias. They sold me the standard solid rotors with 4 piston calipers in rear and a vented rotor with a little bigger caliper in the front. I plumbed no proportioning valve, brakes are first rate. The only issue I had was the compound of the pads they selected for the rear. They were too aggressive, the rotors showed a lot of grooving and wear after the first season. Called Wilwood they sent me a different compound and all is well. There are sites with the formulas, but if you pick and choose a system your self the surface area of the master cylinder pistons, and the caliper pistons is what is critical in getting a well performing system that is balanced. The pressure needed to operate disc brakes, is a lot more than the pressure to operate drum brakes, that is why you need proportioning valves in a split type system. You also need more volume of fluid for disc brakes as compared to drum brakes.