Ride quality and comfort are created in part with bushings, the flex points within the suspension that ensure road noise and vibration are not transferred to the occupants. On a race car however, this leads to inconsistency and and slower lap times as the wheel alignment flexes in and out of spec. This problem is amplified when the factory bushings are worn out and need to be replaced, and can lead to many other issues even on a street car. When bushings need to be replaced, tires will wear inconsistently, knocking and clunking can be heard from the suspension parts, and your car will simply not handle very well. A little voice in the distance was whispering “Powerflex Bushings“.
The solution for anyone seeking extra performance as well as longevity is to install polyurethane bushings, and for our Saab 9-5 race car that meant installing the Powerflex bushings (Black Series) for maximum performance. Installing the bushings isn’t difficult, but does take some experience and specific tools. Don’t discount spending a weekend on a project like this if you’re new to the poly scene. On the 9-5, the front sub frame is what takes the most time to remove and re-fit. Once the sub frame is removed, the control arms and the transmission torque arm can be unbolted. The control arm rear bushings simply pull off once the nut is removed, a socket extension can be used to rotate the bushing housing if it seems stuck.
For the remainder, either a press or threaded rod assembly is required to remove and fit the bushings. If you are feeling saucy this can also be done by holesawing out the center of the sub frame bushings, and then gently using a reciprocating saw to finish cutting the races out. Once all bushings have been removed from the subframe and control arms, now is a great time to check them over for rust and clean them up as needed. On the subframe, the welds seem to be the biggest source of rust (and if you live in a rust belt area, good luck to you); an angle grinder with a wire wheel and some quality rust proof paint are the best way to keep it at bay.
Most Powerflex bushings are manufactured in two pieces, making install very easy (check to see if yours are). Insert both sides using the provided PTFE lubricant, and fit the inner sleeve to keep them in place. Some may require you to hammer in or press in the sleeve as its intended to be a very tight fit. We selected the ProParts polyurethane for the sub frame bushings which came in one piece: these must be pressed into the sub frame. It’s possible to do these by using a floor jack to pop them in one by one, just make sure they are nice and greased up. Remember the big washer goes on top, not on the bottom.
In total we replaced the control arm bushings, torque arm bushings, steering rack bushings, and sub frame bushings. We didn’t get an opportunity to replace the sway bar bushings but they are next on the list, to ensure we get the most out of the car this season.
The suspension feels much tighter, and with the appropriate tires our steering response was significantly better. Now that we know our alignment will hold itself on the track, we’ll be replacing some parts to help us obtain the exact alignment spec we want! Adjustable rear cross-stays and front camber bolts will help us set the car up for a more aggressive alignment to bring our lap times down even further!