Pontiac Drum Brake Drag Reduction - Low-Drag Brakes = Lower E.T.

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.