Suspension and exhaust systems begin with all of the hard parts: hangers, pipes, control arms, struts, shocks, sway bars, and springs. Bushings and insulators are the flexible connections between the hard parts. They serve as shock absorbers and vibration isolators, providing a pivot point on which the hard parts articulate.
Energy Suspension tells us suspension bushings and the like are generally made of steel and rubber. Polyurethane is a form of rubber though we don’t think of it as rubber. Like rubber, this elastomer offers the same kind of flex that enables it to isolate noise, vibration, and harshness (NVR). Polyurethane is a synthetic rubber, as is the soft, black flexible stuff in your Chevy’s factory suspension parts, subframe, and engine mounts.
Black rubber is made from petroleum byproducts as opposed to natural rubber gum that comes from trees. Polyurethane is a reaction polymer created in a thermoset process. What’s more, polyurethane is virtually indestructible and outlasts rubber. Rubber is used to describe factory bushing material and polyurethane is used to describe Hyper-Flex—the proprietary material used by Energy Suspension.
Why is it important to have less flex from our suspension systems? Because flex slows a chassis’ response to input, creating a disconnect among the driver, the chassis, and the road. In tire and suspension testing, professionals do a step and steer test, which involves driving at a constant rate of speed, quickly dialing in a specific steering angle, holding that input, and then measuring the car’s response to that input. Most vehicles will have an initial reaction and then a secondary reaction after everything settles. While some of this “settling” is tire reaction, a great deal of it is suspension deflection, or movement.
The goal is to have a very deliberate initial response and a very minimal secondary response. Soft suspension bushings not only take longer to settle but will deflect more, causing unwanted geometry changes and sloppy handling. The same can be said with subframe and engine/transmission mounts. The engine torques one way under acceleration (positive torque) and the other under deceleration (negative torque).
Energy Suspension tells Chevy High Performance that polyurethane bushing design and manufacturing isn’t as simple as the consumer may think. We check the hardness of polyurethane and other like materials such as rubber using the durometer scale. There are two main scales followed by either A, D, or OO. An average car tire will have a durometer number of 60A while a much harder handtruck wheel is a 50D. These two systems use the same testing procedure of probe pressure into the polyurethane or rubber with an exact force and measuring deflection, however, with different probes and forces.
Energy Suspension focuses primarily on the durometer scale to gauge hardness. Think of a bushing like a mini suspension system for a particular part. There is not only the spring rate, but there is also hysteresis, or the damping of the material. How does it compress, deflect, and spring back? If you have a high spring rate and no damping, you get a car that bounces around and never settles. If you have an overdamped vehicle, you get poor impact absorption.
Bushings work the same way, where the energy is dissipated through heat in the material. One of the few downsides of polyurethane is its coefficient of thermal conductivity, which is not as beneficial as rubber. Energy Suspension gets around this by either making the material stiffer to decrease the amount of movement or by using more material to distribute the energy over a greater area.
Polyurethane bushings last far longer than rubber because they’re resistant to heat, ozone, and harsh chemicals. If you keep polyurethane parts lubricated, and you will rarely have to do this, they will last the life of your vehicle.
What kind of performance improvement can you expect from polyurethane parts? Drag racers can expect to see better 60-foot times. Road racers will see added confidence by improving lap times. Decreased component deflection will deliver better handling as well as decreased tire wear from unwanted geometry changes. CHP
Energy Suspension offers three suspension bushing color choices: red and black, depending upon the part chosen. Their complete suspension bushing kits enable you to upgrade your suspension all in one stop. Leaf spring insulators may call for longer U-bolts to accommodate the thickness on some Chevrolet models.
Here’s the same suspension bushing kit in black. Consumers often ask if there’s a difference between the red and black polyurethane bushings. There isn’t. Color has no effect on hardness.
Control arm bushings are available in different hardnesses.
Here are control arm bushings in red, which has no effect on hardness. Color selection is little more than an aesthetic choice. Hardness is measured by a durometer—similar to the Rockwell Hardness Test for steel. There are three durometer scales: Shore A, Shore D, and Shore OO. The Shore scale is named for Albert Ferdinand Shore who invented the process of measuring the hardness of polymers, elastomers, and rubber.
Polyurethane engine and transmission mounts provide unequalled strength and durability when compared to rubber. They will outlast rubber by a wide margin. They also limit powertrain movement. You will surely feel a difference when you use them.
Polyurethane integrity and performance are rooted in hardness and how much flex there is in a bushing or mount. Factory bushings are made of rubber, a natural material harvested from certain kinds of tropical trees or from petroleum. Rubber bushings are softer than polyurethane, around a 60-65 Shore A rating. Polyurethane bushing hardness usually ranges from just slightly harder than rubber, around 70-80 Shore A rating, to firm, around 80-90 Shore A rating, to very firm, around 95 Shore A to the harder Shore D rating on the durometer scale.
Talk about hardness? This is a very hard polyurethane bushing at 90 Shore A. When bushings are this hard, they flex very little, which is what you want for motorsports, although these tend to be a bit hard for the street. Hardness selection depends on what you want in terms of ride quality and handling. In short, ride quality or competition?
Rubber bushings and mounts offer the best NVH quality. However, rubber also flexes the greatest amount, altering suspension geometry as it goes. Rubber also deteriorates with time, heat, and ozone. It isn’t even in the same universe as polyurethane when it comes to longevity. Polyurethane outlasts rubber by a wide margin.
Bushing dimensions have to be ascertained before ordering them from Energy Suspension. Diameter and length are measured with a micrometer, as shown.
The old bushing is pushed out with a hydraulic press. Stubborn rubber bushings may have to be heated with a torch and driven out.
Here, the new Energy Suspension bushing sleeve is pressed into the upper control arm. Using a good penetrating lubricant makes it easier to drive this sleeve into place.
The bushing sleeve is then pressed into position as shown.
Here is the new Energy Suspension polyurethane bushing being lubed with Formula 5 Pre-Lube, which makes installation easier and bushing function quiet. Both the bushing and the lube will outlast any form of rubber imaginable. Formula 5 Pre-Lube will last 4-5 years depending on how you use your vehicle. The polyurethane bushing will last the life of your vehicle. It is that good.
The contact surfaces are lubed with Formula 5 Pre-Lube. We caution you to wear protective gloves (unlike us) while doing this because Formula 5 Pre-Lube has staying power. It is challenging to wash it off your hands.
The upper control arm shaft nuts are tightened while keeping the shaft centered. You want these locknuts tight, but not so tight they bind.
The upper control arm shaft is properly centered and should look like this. These Energy Suspension bushings will tighten up the front end movement of your Camaro, Chevelle, Nova, or Impala considerably, netting you crisp handling.
You can see here the lower control arm bushings have been installed and are good to go. We like the idea of minimal suspension deflection, which keeps suspension/alignment geometry where it belongs.
The upper (left) and lower (right) control arms have been fitted with new Energy Suspension polyurethane bushings. What this means for handling is significant improvement in handling because they will not deflect. Movement depends directly on hardness. The harder they are the less they will deflect.
Energy Suspension’s polyurethane engine and transmission mounts tighten up driveline damping, minimizing movement during acceleration and deceleration. You will notice a significant difference in NVH compared to rubber, yet a firm, more-confident feel because these guys don’t move.
It takes a full complement of suspension components and serious tire contact patch to complete the path to handling excellence. Polyurethane bushings and insulators, when properly installed, make all the difference because they enable a suspension to hold the line under the toughest of driving conditions. (Photo by Wes Duenkel)
Photos courtesy of the manufacturers