This week’s featured service is control arm bushing replacement performed on a 2006 Subaru Outback.
Control arm bushing replacement is becoming a frequent service at our shop. The increased wear seems to center around the design of the bushing which has changed over the past 10 or 15 years.
A bushing, in case you were wondering, is a flexible coupler. They are used in many areas of the automobile and are always found in the suspension system. A control arm bushing connects the control arm to the vehicle frame. Depending on the design of the control arm there can be up to 2 bushings. The other end of the control arm connects to the wheel hub, essentially the area where the wheel bolts on.
There are many different shapes and designs of bushings but all of them have the same basic components: an outer metal sleeve and an inner metal sleeve coupled together by a piece of rubber. The rubber is designed to flex and twist which is essential for proper suspension operation.
As you might guess the flexing rubber can only happen for so long before it breaks, and that is exactly why these bushing need replacement.
As I eluded to earlier there have been design changes in bushings and some of these are more susceptible to wear. The high wearing bushings are generally vertically installed and feature a rubber section that has some air gaps. My guess as to why this design is used is to allow more flexibility in the suspension.
Looking at our featured Subaru Outback this model year has this vertical bushing on the rear of the control arm and seems to wear out by around 100,000 kilometers. The previous generations of Outbacks used a different bushing design that is much more robust. I own a 2001 Outback with well over 200,000 kilometers and control arm bushings are still solid. It is unfortunate to see this very reliable design being replaced by something less reliable; though I guess I shouldn’t complain because it does benefit our business.
How would you know that your control arm bushings are worn? When they are badly worn you will hear clunks and creaks when you go over bumps. We recently serviced a Nissan Murano that had a very distinct clunk and pulling when the brakes were applied. Ideally it is best to replace them before this point. Routine inspections and service are the best way to find worn bushings. The good news is that these parts will not fail to the point of your wheel falling or breaking off, unless they are worn and clunking for years, which would probably be intolerable.
For more about the Subaru Outback click here https://en.wikipedia.org/wiki/Subaru_Outback
For more about bushings click here https://en.wikipedia.org/wiki/Bushing_%28isolator%29