Rubber bushings
2008-08-25

A rubber bushing is a device, primarily used in suspension systems, which separates the faces of two metal objects whilst still allowing a set degree of movement. This movement allows the suspension parts to move freely for example when traveling over a large bump but minimizes transmission of noise and small vibrations through to the chassis of the vehicle. Uses for the rubber bushing include, on anti-roll bar links and mountings, shock absorber mountings and in front wishbone assemblies to name but a few.

 Advantages of using a rubber bushing over a solid bearing system are that less noise and vibration are transmitted through rubber. Rubber also requires little or no lubrication.

Disadvantages of rubber bushings are that they can deteriorate quickly in the presence of oil and that extreme heat and cold can also lead to failure. The flexibility of rubber also introduces an element of play in the suspension system. This may result in camber, caster or toe changes in the wheels of the vehicle during high load conditions (cornering and braking), adversely affecting the vehicle's handling. For this reason a popular aftermarket performance upgrade is the replacement of rubber suspension bushes with bushes made of more rigid materials, such as polyurethane.

Rubber bushings are mainly used for a variety of purposes: They can be used as shock absorbers, vibration insulators, abrasion resistors, and as seals for wires, pipes, tubing, and rods. Bushings come in a variety of different shapes and sizes. The Profile Rubber Corporation manufactures custom rubber bushings to most demanding specifications, ensuring that the precise part for a specific job is received. Similar to bushings, rubber grommets are an essential machine component.

In general, grommets serve as "artificial eyelets" by protecting an existing eyelet from the wear associated with the relative motion of an object passing through it. In addition to limiting wear, many grommets also serve as seals for wires, rods, and pipes that pass through bulkheads, firewalls, and plates. Just as the uses of grommets are varied, so too is our manufacturing of them. 

 The way bushings are made is vital for their durability. During the mixing process the materials will absorb water. Any moisture trapped inside will form bubbles or pockets and weaken the part. So the best manufacturers mix their products in total vacuum. Generally you can say that a rough looking PU is inferior in quality to a smooth one. Best rule of thumb is to buy from a well known manufacturer who gives a warranty on his parts. A suspension rubber bushing of vertical mount type attachable in a suspension assembly with a bushing axis vertically oriented, comprising: an inner sleeve; an outer sleeve disposed about the inner sleeve with a radial spacing therebetween; and a rubber elastic body interposed between and elastically connecting the outer and inner sleeves, wherein the rubber elastic body, as viewed in vertical cross section in a first direction coincident with a direction of prizing force input, has a generally "V" shape overall where a pair of rubber legs, extend approximately straightly with a substantially constant axial wall thickness, from an axially medial portion of the inner sleeve to which proximal ends of the rubber legs are bonded, to opposite axial end portions of the outer sleeve to which distal ends of the rubber legs are bonded so that the pair of rubber legs gradually extend axially outwardly as they move away from the inner sleeve toward the outer sleeve so as to form depressed spaces between axially outer faces of the rubber legs and the inner sleeve to either axial side of the axially medial portion of the inner sleeve, and as viewed in vertical cross section in a second direction approximately orthogonal to the first direction, has a tapered shape overall where a main body rubber portion having an axial wall thickness thicker than the rubber legs and elastically linking the inner sleeve and outer sleeve while extending in the second direction, the main body rubber portion generally increasing in length in an axial direction as it moves away from the outer sleeve toward the inner sleeve.