Comparing thin-walled plastic bushings and thick-walled bronze bushings

Sometimes, thicker is better — heavy wool socks on a cold day or a thick, juicy steak for dinner come to mind. However, when it comes to plain bushings, thick walled isn’t necessarily better than thin-walled versions.

First, it’s important to understand the basic difference between a thin-walled plastic bushing and a thick-walled bronze bushing. The wall thicknesses of standard bronze bushings range between 0.0625 and 0.156 in. In comparison, plastic bushings have walls typically from 0.0468 to 0.0625-in. thick.

Thin walls offer some advantages that let plastic bushings perform as well as, if not better than, thick-walled bushings. For example, thinner walls are better for heat dissipation. Heat buildup can accelerate wear on a bushing, so it is critical that heat dissipates through the shaft and housing. With thick-walled bronze bushings, heat buildup is much more likely.

Better heat dissipation equates to higher PV (pressure-velocity) values — a measure of performance capability. Higher PV ratings let bushings handle higher speeds and loads.

In addition, thin-walled plastic bushings can hold tighter tolerances and are less likely to deform, which can be common with thicker-walled bushings. Finally, thin-walled plastic bushings are well suited for applications where weight and fuel economy are an issue. Typical examples include racing bikes, snowmobiles, automobiles, and motorcycles. (The accompanying graph compares the weights of different bushing materials.)