A typical drum-brake setup...
A typical drum-brake setup is shown. This is the right rear, but it's similar to all four wheels.
Free Mod
In the March '09 issue, we presented a group of low-cost modifications in "30 Low-Buck And No-Buck Mods." One was to adjust the drum brakes to temporarily eliminate drag prior to drag racing. It was temporary because once the Pontiac is put in Reverse and backed up, the self-adjusters take up the slack and the drag returns. Though another choice is to remove the self-adjusters, doing so adds maintenance via required manual adjustments, and braking performance and safety depends heavily upon your maintenance regimen.
The following illustrates a relatively easy method of permanently modifying drum brakes to prevent drag at any time. It's the same for all four wheels, and the self-adjusting feature continues to work normally. Best of all, no parts are required and very little disassembly is needed.
First here's a brief review of the self-adjusting system. While the brake shoes are called "primary" and "secondary," I will refer to them as left or right, as they appear in the photos. For example, the lining/shoe with the orange spring retainer in the lead photo will be called the left shoe.
The self-adjusting feature operates when you apply the brakes while rolling rearward. Both shoes try to also rotate rearward, or counterclockwise in the photo. The anchor pin at the top center, where the brake springs and actuating link are attached, stops the right shoe. If there is any clearance between the shoes and drum, the left shoe tries to pivot outward but is prevented from doing so by the actuating link. The actuating link is the S-shaped heavy link connected between the anchor link and the left shoe just above the top end of the blue spring (the blue spring is mounted on the adjuster lever).
However, as the left shoe is attached by and pivots on the orange retainer assembly, it tends to rotate at the pivot point, thus forcing the lower end of the adjuster lever downward. If there's enough clearance between the shoes and the drum, the adjuster lever will move far enough to turn the adjusting screw star wheel one or two teeth. This expands the adjuster and tightens the brakes.
Unfortunately, the factory design causes the assembly to fit tightly, with the adjuster lever at the top and very close to the adjusting star wheel. Any clearance will cause the system to click the star wheel tighter; then you have "brake drag." Follow along to see how to eliminate it.
Conclusion
Not only does this mod eliminate any brake drag, but also it's much easier to remove brake drums that have noticeable rust or wear ridges on the inside edge since the shoes are not expanded as much. I have run this mod for about 15 years and have never had to adjust the brakes (except during lining replacement), yet they work perfectly.
 The factory setup illustrates...  The factory setup illustrates how high and tight the adjusting lever is to the adjusting wheel, which is under the "6" in the lever's part number. A simple modification is to bend the lower section of the adjuster lever outward such that it doesn't contact the adjusting star wheel until the brake shoe moves further away from the drum. |  To remove the adjusting lever,...  To remove the adjusting lever, release the reddish-colored spring between it and the left shoe as shown in the lead photo. Then take off the orange retaining spring and pin assembly that holds the shoe to the backing plate. Pull the actuating link out slightly and rotate the adjusting lever out of the link. Upon turning the lever over, you'll see that the portion normally visible from the front doesn't contact the star wheel; rather a notch on the rear (shown here) actually makes contact and rotates the star wheel when the linings become worn. |  Modify the lever by bending...  Modify the lever by bending the end diagonally (see the black line) and slightly upwards, about 1/8 inch, so it will be further away from the star wheel. Some trial and error may be required. Now the adjuster lever contacts the star wheel further out towards its perimeter as shown. Note the difference in location as compared to the stock setup-the star wheel is now under the "5" of the lever part number. |