Convert Front Drums to Disc

Q: Convert Front Drums to Disc

What do I need to convert my front drums to disc brakes?

A: This is one of the best mods you can do to your car. Factory parts are your best bet (unless your shooting for a custom looking setup). Even junkyard special parts work top-notch once cleaned up. The following list of parts will give you the best performance for cost and reliability:

1. Two new GM 1969 spindles (still available from GM) or 1969 – 1974 Nova units for SPC Camaro (or original units if you can find them)

2. Two junkyard caliper brackets from a 1968 – 1978 midsize GM car using a corporate front wheel disc setup

3. Two Nova or Cutlass (corporate) calipers for cores from the local parts store – eat the core charge (if low) to save canvasing the junkyard

4. One new/rebuilt master cylinder (don’t use junkyard units for this) for 1969 SPC Camaro (or for 1969 – 1972 Nova with front disks for places that charge extra when they hear the word Camaro or Firebird)

5. One set of first gen (or Nova) lines, hardware, and adjustible P-valve

6. One powerboster either new or from almost any late ’60s to mid ’70s GM

7. Two rotors – 1969 SPC Camaro or 1969 – 1972 Nova

8. One alignment after swaping

If you keep your eyes peeled, and piece it together, you can probably do the swap for about $100.

A: Tips for the single-piston disc brake setup conversion: the first-gen stocker ’14 rims will NOT work with disks. If you have these, plan to use 15″ rallys or a custom rim. (ADMN NOTE: Actually, it has been determine that Rally II Rim Code “JC” was used on both disc and drum equipped 1968 Firebirds)

use stock parts for a driver! they are over engineered and ultra reliable, not to mention replacable on the road. Keep a record of the year parts you use since there are slight differences between the years.

Of all these parts, only the caliper brackets, proportional valve, and metering valve are parts no longer in production, so make sure you get good ones. remember, the valve stuff can be replaced with an adjustible one, I dont like them, but they are worth a few feet.

use calipers for cores if they’re crap. quality rebuilds of single pistons are cheap!

if rotors are like new (thick and no valley wear) use’em they work fine, else buy new. never mix new and old.

backing plates are a easy to find, even new ones are cheap. if in the junkyard, subsitute a bent one for the best you can bolt up.

rubber lines. DONT REUSE, its not worth it, but take them to match the caliper and bracket ends for the new ones. reuse the caliper bolt washers, old ones seal better then new ones.

line mounting flanges keys are different, plus the mount point is relocated from the drum position, so take’em if they are not the welded type (Chevelle/A-Body)

1969 Camaro/Firebird or ’68-74 Nova/X-Body lines are direct drop-ins, use’em if good. if theyre crap, then use then as guidelines for new ones. swipe the fittings and armco(?) if you make your own.

The ’70(-’71?) camaro rear brake mastercylinder-to-proportional valve line tucks out of the way and looks bitchin compared to the 1969 Camaro/Firebird or ’68-74 Nova/X-Body version.

buy a new high volume master, I recommend the 1967 vette, 1967-1968 Z28, 1967-1968 J52/J56 (all the same) GM “fat-boy” master. The 1969 standard disk master will do, but the fat-boy looks way cooler, and has a bigger bore (if I remember correctly)

when you replace the master (?) make sure the hole depth for the push rod is the same on the new master as the old (since its a rod with manual brakes not a replacable pin)

I recommend a new booster for a 1969, dont waste your time (experience here) to save some bux. masters come needing long or short pins, swipe the correct pin from the junkyard to fit your master/booster combo. do this before install day. 🙂

I also forgot the most important tip: never use a drum-drum prop valve on a disk-drum car, the different front-read balance will result in severe lock up of the rear wheels.

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