Brake Drum - Rear

This procedure covers removal and installation of rear brake drums on a 1966 Chevrolet Corvette with 327ci V8, including inspection of brake hardware and adjustment of brake shoes.

Warnings

Tools required

Parts

• Rear brake drum (left) × 1 — Use OEM specification or quality aftermarket
• Rear brake drum (right) × 1 — Use OEM specification or quality aftermarket
• Drum retaining washers (if equipped) × 2 — Use OEM specification

Preparation

1. Park vehicle on flat, level, solid surface and engage parking brake firmly.
2. Place wheel chocks in front of both front wheels to prevent forward vehicle movement.
3. Loosen rear wheel lug nuts 1/2 turn while vehicle is still on the ground.
4. Raise rear of vehicle with floor jack at rear differential housing or frame rail jack points.
5. Place jack stands under rear axle housing or frame rails rated for vehicle weight. Lower vehicle onto stands.
6. Remove rear wheel lug nuts completely and remove both rear wheels.
7. Release parking brake to relieve tension on brake shoes.

Procedure

1. 1

   Remove drum retaining hardware
   Locate the drum retaining washer on the wheel studs (if equipped - these were sometimes installed at factory or removed during previous service). These are small flat washers with a slot or pressed onto a stud. Remove with pliers or tap off with screwdriver if present. Note that many 1966 Corvettes had these washers for shipping but they may have been discarded during first brake service.
2. 2

   Initial drum removal attempt
   Grasp the brake drum firmly with both hands and pull straight outward off the axle hub. If drum is loose and pulls free easily, proceed to step 5. If drum resists removal, proceed to next step.
3. 3

   Break drum free from corrosion
   If drum will not pull free, it is likely corroded to the axle hub or being held by brake shoe contact. Tap the drum face firmly with a rubber mallet in a circular pattern around the outer edge. Apply penetrating oil around the center hub opening and wait 5-10 minutes. Attempt removal again. If still stuck, proceed to next step.
4. 4

   Back off brake shoe adjustment
   Locate the brake adjuster access hole on the backing plate (may be covered by a rubber plug - remove if present). The access slot is typically at the bottom or rear-bottom of the backing plate. Using a brake spoon or flat screwdriver, rotate the adjuster star wheel to retract the brake shoes. Insert the tool through the access hole, contact the star wheel teeth, and push the tool handle upward (this typically moves the shoes apart and away from drum). You may need to also push the adjuster lever away from the star wheel with a second tool or stiff wire. Rotate star wheel approximately 20-30 clicks to fully retract shoes, then attempt drum removal.
5. 5

   Final drum removal
   If drum still will not release after adjustment backing and mallet tapping, install a brake drum puller with bolts threaded into the two puller holes cast into the drum face (5/16"-18 thread). Tighten puller center screw gradually while tapping drum face with mallet until drum releases from hub. Once drum breaks free, remove completely and set aside on clean surface with friction surface facing up to prevent contamination.
6. 6

   Inspect drum friction surface
   Thoroughly clean the inside friction surface of the drum with brake cleaner spray and wipe with clean shop rags. Inspect for deep grooves (more than 0.060" deep), cracks, heat checking, hard spots (shiny blue or black discolored areas), or out-of-round wear. Measure drum inside diameter with micrometer or drum gauge at multiple points. Maximum diameter specification for 1966 Corvette rear drums is 11.060" (standard new diameter is 11.000"). If drum exceeds maximum diameter, shows cracks, or has grooves deeper than 0.060", drum must be replaced or resurfaced by machine shop. Light surface rust or minor scoring up to 0.030" depth can typically be cleaned up by resurfacing.
7. 7

   Inspect brake shoes and hardware
   With drum removed, visually inspect brake shoes for remaining lining thickness (minimum 1/16" above rivet heads or shoe platform), contamination from oil or grease, glazing, cracking, or uneven wear. Inspect all return springs, hold-down springs, self-adjuster components, and wheel cylinder for leakage or damage. This drum removal procedure does not include brake shoe replacement, but note any components requiring future service. If brake shoes or hardware require replacement, those procedures should be performed before drum reinstallation.
8. 8

   Clean backing plate and hub
   Spray backing plate and exposed brake components with brake cleaner to remove dust and debris (use wet method if asbestos is suspected - do not create airborne dust). Wire brush the axle hub flange surface to remove all rust and corrosion. Clean the hub pilot diameter (center register where drum seats) until bare metal is visible. Any corrosion left on hub will cause drum runout and pulsation.
9. 9

   Prepare drum for installation
   Wire brush any rust from the drum center mounting hole and hub mounting surface. Clean drum friction surface once more with brake cleaner and ensure it is completely free of oil, grease, or fingerprints. Apply a very light coat of anti-seize compound to the drum center pilot hole where it contacts the axle hub (avoid getting any on the friction surface).
10. 10

    Install brake drum
    Align drum with wheel studs and slide drum straight onto hub until it seats fully against the hub flange. Drum should slide on with moderate resistance. If drum will not slide on fully, brake shoes may need further adjustment retraction - remove drum and repeat step 4. If drum slides on but contacts shoes lightly (you can feel slight drag when rotating), this is acceptable as adjustment will be set in next steps.
11. 11

    Reinstall drum retaining hardware
    If drum retaining washers were present during disassembly, reinstall them on one or two wheel studs to hold drum in place during adjustment and wheel installation. These washers are not required for final operation and may be left off if desired.
12. 12

    Adjust brake shoes
    Through the adjuster access hole in the backing plate, use brake spoon to rotate the star wheel adjuster in the tightening direction (opposite of step 4 - typically pushing tool handle downward). Rotate drum by hand while adjusting. Tighten star wheel until drum becomes difficult to turn and shoes drag noticeably. Then back off star wheel 8-10 clicks until drum rotates freely with only very slight drag. Drum should rotate without binding but with slight resistance from shoe contact. Final adjustment will be verified during test drive.
13. 13

    Repeat for opposite side
    Perform steps 1-12 for the opposite rear drum. Both rear brakes must be adjusted to the same specification for balanced braking. Ensure both drums rotate with the same amount of drag resistance.
14. 14

    Reinstall wheels and lower vehicle
    Install rear wheels onto wheel studs. Install lug nuts and hand-tighten in a star pattern. Remove drum retaining washers if they were temporarily installed. With vehicle still on jack stands, torque lug nuts in a star/cross pattern to the factory specification (verify exact value in the GM service manual before final tightening). Raise vehicle slightly with floor jack, remove jack stands, and lower vehicle fully to ground. Re-torque lug nuts to the factory specification once vehicle weight is on wheels.

Reassembly

1. Reassembly is covered in the main procedure steps as this job involves drum removal and reinstallation.
2. Ensure both rear drums are adjusted equally for balanced brake performance.
3. If drum retaining washers were lost or damaged, they are not required for proper operation and may be omitted.

Verification

• With vehicle still raised on jack stands, rotate both rear drums by hand to confirm smooth rotation with only slight drag. Both sides should have similar drag resistance.
• Press brake pedal firmly 10-15 times to seat brake shoes and establish proper pedal height. Pedal should feel firm with normal height (not sinking to floor).
• After lowering vehicle, perform a slow-speed test drive in a safe area. Apply brakes gently at 5-10 mph to verify proper brake engagement without pulling to either side.
• Perform several moderate stops from 20-30 mph to seat brake shoes to drums. Braking should be smooth without pulsation, noise, or vehicle pull.
• After 50-100 miles of driving, re-check rear brake adjustment through access holes and verify drums still rotate freely without excessive drag or looseness.
• If brake pedal is lower than before service or requires pumping, rear brakes may be over-adjusted (too loose star wheel setting) - readjust through access holes.
• Check for any fluid leaks at wheel cylinders after test drive. Any brake fluid leakage requires immediate wheel cylinder service.

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