|Poly vs. Rubber
We all know what it’s like to suffer from sore joints. Even if you’re in good physical condition, without enough cushioning between your bones, ordinary motions can be difficult. Now, apply that same concept to the suspension on your old car or truck. The bushings found on the control arms, leaf springs and various mounts are like the cartilage between your joints. The manufacturer normally equips a vehicle with rubber bushings, which provide a soft ride. Over time, however, the rubber begins to wear from oil and other contaminants under your vehicle, and the suspension components start to bind. That’s when the automotive equivalent of arthritis sets in, and your vehicle’s performance suffers (not to mention your own level of ride and handling comfort). Worn bushings are one of the major reasons for road wander. Rubber bushings may crush down before the suspension can respond to a bumpy road, allowing for play or wobble.
For more precise handling and firmer control on your resto project vehicle, installing polyurethane bushings can make an enormous difference because they help to maintain the right alignment of caster, camber and toe, even on rough or uneven pavement. Polyurethane bushings can be used in a wide variety of suspension components and also in mounts for the body, engine and transmission. They can be used on virtually any type of vehicle, domestic or import, and despite their small size, they can have a big impact on your resto-mod project.
Another advantage of polyurethane bushings is that they’re virtually impervious to oil and other road contaminants. These units will not crush down or wear out like rubber bushings, and are designed to be free-floating, rotating 360 degrees, so the suspension can articulate fully without binding. In contrast, rubber bushings are often bonded to a metal shell and sleeve, and function with a twisting action that, when pushed to its limit, binds up instead of rotating freely like urethane units. Rubber bushings can even induce wheel hop from the spring-like action of the rubber twisting back and forth.
Tools & Tips
What does it take to install polyurethane bushings? All you need are some common automotive tools and a basic knowledge of auto repair. Polyurethane products usually install just like their rubber counterparts. Depending on the product, it can be installed in as little as a half-hour, but may take as long as four hours in some cases. And, of course, an automotive repair shop can also do the installation as well.
By the way, when a vehicle is raised or lowered beyond its stock specifications, the original rubber suspension bushings are at greater risk of failing. The OEM/stock rubber usually can’t withstand the forces of a vehicle setup at a non-stock riding height. Polyurethane bushings are better suited for the weight transfer and shift characteristics of raised vehicles. Depending on their application, polyurethane bushings can be formulated to a specific “hardness” (known as durometer). By formulating different levels of durometer strength, they can be designed for specific needs, be it a street rod, off-road truck, sport compact, or even a hopping low-rider.
In addition to tightening up the suspension, polyurethane bushings provide improved turn-in and cornering response. Also, polyurethane body mounts can help to reduce body roll, a real plus for lifted trucks. In some applications, they can be used to provide extra clearance for larger off-road tires, with or without adding a suspension lift.
So whatever type of “joints” you have on your vehicle, consider upgrading them with polyurethane bushings—they’re a sure cure for your vehicle’s aches and pains