STI hardened rubber bushings, either sold as a kit or individually, to improve handling, traction, and steering response. Rubber hardness is increased noticeably over stock parts (on all models including STI) but is within the limits for Group N use. Manufactured with the same quality and on the same production line as the OEM bushings.
Usually ships the next business day.
Why doesn't the front control arm rear bushing fit the 2011 and newer STI and is there an uprated bushing available? The diameter of the bushing was increased. STI does not have an uprated rubber bushing available for the newer models. To upgrade you will need to look at one of the aftermarket companies or the spherical bearing conversion that STI offers.
How do these bushings compare to urethane bushings? These are rubber bushings with a higher durometer than the factory ones. In terms of hardness they are comparable to most aftermarket urethane bushings. However, urethane and rubber bushings operate differently. Urethane bushings rotate in a sliding motion around the center sleeve and require lubrication. If the lubrication washes out or dries up the bushing may begin to make noise and can wear prematurely. A rubber bushing, on the other hand, has no sliding motion under normal conditions, but instead the material twists or distorts around the center sleeve to allow the suspension arm to articulate. A rubber bushing will not wear unless the material deteriorates. Exposure to heat, chemicals, ozone, UV light, etc. can break down the rubber.
How difficult are they to install? Installation requires the use of a hydraulic press. Some bushings use an outer metal sleeve that may need to be split in order to press the bushing out of its bore. Installing the new bushings without damaging them may require the fabrication of special tools. It is a job best left to a skilled professional.