"Drum to Disc" Conversion FAQ 60-70

[lolife99]

DRUM TO DISC CONVERSIONS 60-62

60-62 truck with:

63-70 Crossmember Installed
1) The 60-62 trucks have a torsion bar front suspension, which requires swapping the entire 63-70 crossmember and all it's components.

2) A better option would be to swap out a complete 71-72 or 73-87 crossmember to take advantage of the factory disc brakes.


Links:
*Replace Your Drums With Discs-Article by Brian McCormick
*Disc brake upgrade- Article by Early Classic Enterprises

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60-62 truck with:

71-72 Crossmember Installed
1) Your truck's donor 71-72 crossmember came from the factory with disc brakes.

2) "Year Specific" 71-72 drop spindles are readily available.

3) All spindles and rotors are the HD version (1-1/4" wide).
* This will require matching HD calipers.

4) Steering linkage contains 11/16" diameter tie rods.
* Inner Tie rods are LH thread.
* Outer Tie rods are RH thread.
* Inner Tie Rods are a "2-year only" tie rods. (71-72 only)
* Outer Tie Rods are a "2-year only" tie rods. (71-72 only)

5) Steering Linkage:
* All 71-72 oem linkage will work with 71-72 "year specific" drop spindles.

6) A-arms have steel bushings.

7) 71-72 crossmembers have the steel brake line connect the rubber brake line on the front side of the crossmember.
* Steel reproduction brake line sets are specific to the 71-72 design.
* There is also a tab welded to the front side of the crossmember, at the location where the steel brake line joins the caliper's rubber brake hose.

8) Rubber brake hoses are a "2-year only" item. (71-72)

9) 6-lug aftermarket rotors are now readily available if you decide you want to keep your 6-lug style wheels on your 60-62 truck.
* Be aware that the oem 15x6.5 steel 6-lug wheels will not clear your new disc brake conversion.
* You will need to use a set of steel wheels found on the later 73-87 4x4 trucks.

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60-62 truck with:

73-87 Crossmember Installed
1) Your trucks 73-87 donor crossmember came from the factory with disc brakes.
* Using the 73-87 crossmember allows for upgrading to 73-87 style rubber bushed a-arms.
* Most replacement parts are more affordable than the "2-year" specific 71-72 model trucks.
* Plus most auto parts stores keep these parts in stock.

2) Drop spindles are readily available,... but there are two versions that must match the two rotor versions below:

3) Rotors: There are two different widths of rotors available on the 73-87 model trucks.
3.1) HD or Heavy Duty rotors: (1-1/4" wide version) available from 73-87
* These will require matching HD bearings and calipers.
3.2) LD or Light Duty rotors: (1" wide version) available from 81-87.
* These will require matching LD bearings and calipers.

4) Steering linkage contains 11/16" diameter tie rods.
* Inner Tie rods are LH thread.
* Outer Tie rods are RH thread.
* Inner Tie Rods are 73-87 specific
* Outer Tie Rods are 73-87 specific

5) All 73-87 oem steering linkage will work with your 73-87 spindles.

6) The 1/2 ton a-arms have rubber bushed cross shafts
* (compared to the steel bushings of the 71-72 a-arms)

7) 73-87 crossmembers have the steel brake line connect the rubber brake hose through a hole originally drilled in the 73-87 frame rail.
* Using these crossmembers in the older trucks will require you to fabricate some or all of your steel brake lines.
* (63-70 brake lines connect on the rear side of the crossmember)
* (71-72 brake lines connect on the front side of the crossmember)
* Steel reproduction brake line sets are specific to the 73-87 design with their proportioning valve mounted on a crossmember in front of the engine opposed to hanging below the master cylinder.

8) 73-87 rubber brake hoses are much longer than either the 63-70 drum brake hose or the 71-72 disc brake hose.

9) 6-lug aftermarket rotors are now readily available if you decide you want to keep your 6-lug style wheels.
* To use the 6-lug rotors you must have the 73-87 HD spindles,... since all aftermarket 6-lug rotors are only available in the 1-1/4" wide version.
* Be aware that the oem 15x6.5 steel 6-lug wheels will not clear your new disc brake conversion.
* You will need to use a set of steel wheels found on the later 73-87 4x4 trucks.

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60-62 truck with:

71-72 Crossmember Not Yet Installed:
1)The 60-62 trucks have a torsion bar front suspension, which requires swapping the entire 71-72 crossmember and all it's components.

2) 60-62 steering linkage use a different centerlink and tie rods, compared to the 71-72 crossmember you will be installing.

3) 60-62 tie rods are 5/8" diameter,... 71-72 tie rods are 11/16" diameter (with the opposite thread direction).
* 60-62 inner tie rods are RH thread vs. 71-72 inner tie rods (that are LH thread).
* 63-62 outer tie rods are LH thread vs 71-72 outer tie rods (that are RH thread).
* It's easiest to just use all of the 71-72 Steering linkage.
* You can also use all of the 73-87 steering linkage, but you will have to change the outer tie rods to the 71-72 version to match the 71-72 spindle.

4) Rubber brake hoses:
* You must change to a disc brake style hose.
* Early Classic Enterprises, and other suspension vendors, make a "conversion" brake hose that will connect the disc brake caliper, to the original 60-62 brake hose steel line location.
* 71-72 hoses is another option. (but I haven't personally confirmed if the steel line connection is the correct size).
* Another option is to use 73-87 hoses, (cheaper to purchase), but they are much longer, and also may need fitting adapters.
* Aftermarket steel braided hoses and AN fittings is another option.
* Most likely there will be a need to fabricate a few, if not all steel brake lines.

5) Some drilling will be required to bolt the 71-72 crossmember in place.

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Links:
*1960-62 Front Suspension Upgrade- by markeb01
*1960-62 GMC to SBC V8 motor & trans mounts- by markeb01
*1960 crossmember swap- by markeb01
*89 3/4T 'burb front-end swap to '66 C20- byHilandr451
*Lowering a '75 Shorty With Performance Online and Belltech- by Classic Trucks
*Disc Brake Upgrade Reference Thread
*CPP Modular Spindle Install

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60-62 Truck With 6-lug Disc Brakes:

6-Lug Drum to 6-Lug Disc Conversions:
1) This 6-lug disc brake swap will include all of the above 5-lug information.

2) The only difference is the use of an aftermarket 6-lug rotor.
* These rotors are new castings.
* These rotors have been drilled with the correct 6x5.5" 6-lug pattern.
* These rotors have the correct 7/16" lug studs that match the original drum brake lug studs.

3) Several aftermarket suspension vendors sell these rotors,... such as:
* ECE (Early Classic Enterprises).
* POL (Performance OnLine).
* CPP (Classic Performance Products).

4) All 60-62 "conversion" stock height and drop spindles will work with these 6-lug rotors.

5) All 71-72 stock oem and drop spindles will work with these 6-lug rotors.

6) If using a 73-87 spindle,... it must be the HD spindle, that works with the 1-1/4" wide rotors.
* The 81-87 LD spindles will not work with these 6-lug rotors.

Links:
*http://www.earlyclassic.com/tech.asp...arly%20Braking
*http://www.earlyclassic.com/tech.asp...h%20And%20Whoa

6-lug Rotors:
*http://67-72chevytrucks.com/vboard/s...ght=Disc+Brake