Who knows how many times a broken ball joint or worn-out bushing has cost a racer a good finish. Bushings definitely fall under the "mundane" category, but things can quickly get exciting if they are not doing their job.
The number one goal for a racer is to have his ball joints and bushings tight, greased, and free from crash damage. If these are in check, the suspension will be able to do its job. After every race, the suspension should be cleaned with the rest of the car and the parts inspected. Mangled parts should be replaced. If you don't have the money to replace them, why bother going to the track and risking a failure that costs you even more? Get the right parts and take care of them.
Advanced racers will be able to tune their suspension with some of the more intricate parts like adjustable-height ball joints (for camber gain), different ball joints than stock (by using a reamer to change the taper in the spindle), and more. If you don't understand that stuff, check with the suppliers listed at the end of this article. For now, making sure everything is hunky-dory in bushing-land will keep you busy enough.
Quick Tips
1. Many dirt racers don't run the rubber boots on their ball joints as they trap dirt during racing and hold water from the cleaning process.
2. Grease is your friend in racing. Make sure ball joints and bushings work freely by keeping them liberally greased.
3. Use castle nuts and cotter pins on your ball joints. We've seen plenty of nuts come off ball joints, but that shouldn't happen. Use the right parts and you won't have to worry about it.
Using a worn-out ball joint...
Using a worn-out ball joint is a bad idea. Ball joints do eventually fail, which can quickly put you in the wall. To check yours, jack up the lower A-arm to unload the lower ball joint, then pull out on the top of the wheel while pushing in the lower part to feel for movement. If there is a lot of movement, your ball joints probably need to be replaced.
Worn-out A-arm bushings allow...
Worn-out A-arm bushings allow the entire front end geometry to change dramatically with every bump, turn, and brake. This can make a good car evil, so inspect your bushings often. If your rules allow, it probably isn't a bad idea to step up to a more solid bushing than the stock rubber bushing.
These solid A-arm bushings...
These solid A-arm bushings with inserts provide a precise fit but enough cushioning material for a racing application. Many suppliers offer steel bushings that are used predominantly in pavement racing. The shock of dirt racing usually requires the cushioning power of a rubber bushing.
A 'Cup chassis uses the A-arms...
A 'Cup chassis uses the A-arms and ball joints set-up just like your race car. The 'Cup chassis uses custom upper and lower A-arms but is required to use "production" ball joints. While many racers use off-the-shelf Moog or Perfect Circle ball joints, aftermarket companies like CV Products are offering low-friction, highly precise ball joints.
Many stock car chassis use...
Many stock car chassis use the old Chrysler ball joints that screw into the A-arms. Many suppliers sell sleeves that can be welded into the A-arm, like this one, so the screw-in ball joints can be used. The advantage here is different-length ball joints can be used to tune the camber gain from the upper A-arm movement.