Typically you will want the brake pads to lightly rub the rotors constantly to keep them clean and ready, but without producing noticable drag.

If you DO NOT keep the brake pads right up against the rotors, you will have a lag time to activate the brakes, and/or a low pedal that needs two strokes or more to bring the brakes back to readiness.
So, once you disble the RP valve inside the MC, you must add one 2-4 lb RP valve in the steel line that goes to the front discs, and one 10-12 lb RP valve in the steel line that goes to the rear brakes.

(You must do this even if you are adding 4 wheel disc brakes. For an explanation of why see our REAR DISC BRAKES Instructions)

 A few disc brake master cylinders will have NO residual pressure valve (on later cars, not Studes, sometimes they put it in the "combo valve"- the junction block on the fender or firewall with all the lines running in). MOST disc brake master cyls for a front disc rear drum vehicle will have a 2-4 lb residual pressure valve near the outlet to the front brakes, and a 10-12 lb "RP" valve at the outlet to the rear line.

This is a close up of the outlets on a DUAL MASTER CYLINDER.

If you use the Stude master cyl, or any SINGLE-chamber MC you must disable the RP valve INSIDE the master cyl.
On a Stude, it is the strange looking round, slightly cone shaped disc with some perforated holes in it. Simply running a small drill bit hole through it will prevent it from holding residual pressure in the system.
This shows the location of the Residual Pressure valve inside a typical SINGLE master cyl.
This is the same location in a Stude master cyl.

You will then need to install an inline 2-4 lb residual pressure valve in the steel line running to the disc brakes, and a 12 lb RP valve in the steel line running to the drum brakes.

($17 at Summit Racing and other rod shops)
 WARNING-- skipping this step of installing the RP valve(s) will result in a low brake pedal that will often need pumping to make them work correctly.

IMPORTANT!! Make sure that ALL existing brake lines, hoses, and cylinders are in excellent working order, and are recently installed.
 Using 10 year old steel lines with hidden corrosion, or 10 year old rubber hoses with simple aging, is unnecessary risk taking. ALL reasonable systems and parts will easily handle a booster and discs, BUT if you have any marginal parts that may be near failure, it may show up now.
Please check the entire system and replace all questionable parts right away.

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Remove the Stude drum from the spindle. Disconnect brake hose. Remove the brake backing plate and thoroughly clean the back side of the spindle paying particular attention to the machined recesses where the mounting bolt washers and nuts were. That is important because those recesses will locate the disc brake brackets.

 Choose the appropriate caliper and mount assembly. Red/Orange/Yellow for the driver side. Blue/Green for the passenger side.

FROM ONE SIDE ONLY- Remove the caliper guide pins, pads etc. from the bracket. Remove the grade 8 mounting bolts. Put the bracket in place on the back side of the spindle I such a way that it will later carry the caliper to the REAR of the kingpin, and just above the steering arm. Push the 4 bolts in the correct holes to enter the spindle and then enter the welded spacers on the brackets. Install the lockwashers and grade 8 nuts on the bolts so the nuts are on the inboard side of the brackets. Only the bolt-heads will show on the rotor-side of the spindle. Use Locktite and tighten very securely! 45-50 Ft Lbs is a good setting if you want to be sure.

ROTOR-- Rotor, bearings, seals are now cleaned, inspected, greased according to accepted methods outlined in shop manuals.
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ROTOR- Install the rotor on the spindle and adjust the castle nut with the usual procedure.

 CALIPER- Caliper and pads are installed in this manner- First, the outboard pad is fitted to the caliper. The TABS on the brake pad are designed to be "tightened" to fit the caliper without rattle or room to wiggle. Simply bend the tabs slightly to provide a rattle-free fit on the caliper. With ONLY the out board pad on the caliper, I like to slide the inboard pad in place between the rotor and the bracket instead of putting it on the caliper. With the inboard pad held in the approximate location, I use one hand to lower the caliper in place on the rotor, and then slide in the two caliper guide pins thru the caliper and use them to hold up the inboard pad. I then push the guide pins in all the way the to final position for tightening. Refer to the OTHER SIDE parts that are still assembled if you have any questions about how the parts are supposed to look when assembled. Install the brake hoses, hook them up, install the residual pressure valves (2-4 Lbs for the front line, and 10-12 lb for the rear line) Check EVERYTHING! You can test to see if you need an adjustable proportioning valve by doing some hard braking on a gravel parking lot. That will tell you if you need to adjust one end or another to reduce any tendency for one or the other to brake harder than desired. I usually find that none is needed.