If you race long enough and...
If you race long enough and hard enough, a crack in some of the welds holding your frame and rollcage together is inevitable. It is repairable, however, and any cracks discovered should be taken care of before the car takes to the track again.
Even if you haven't been in any wrecks, the suspension will show signs of abuse after a complete season. Just like the universal joints, Barham says you should pull the wheel bearings and seals and throw them out. No inspection is necessary here. It's also a good idea to pull the suspension completely down for a total inspection.
"I don't know many racers who have their control arms magnafluxed," Barham says, "but it isn't a bad idea if you can afford it. Even if you don't, look for hairline cracks in the welds and make sure none of the control arms are bent." Barham also says he replaces all the moving suspension components every year and puts the old pieces on his race trailer for use as spares.
If you are on a tight budget, virtually replacing the suspension every year can be difficult to swallow. If you are confident the control arms are still race-worthy, you can turn your attention to the attachment points. If you are racing a Street Stock-level car, you likely are forced to use bushings. They wear easily and should definitely be replaced after a complete season. Consider using polyurethane bushings if possible.
Rebuilding your brake calipers...
Rebuilding your brake calipers isn't difficult and should be done every offseason. It not only reduces the chances of experiencing a severe brake failure, but also helps reduce rolling friction.
If you are racing a purpose-built chassis, such as a Late Model, you probably have monoballs or Heim joints instead of rubber bushings. These eliminate flex but can still wear. A monoball is essentially a non-adjustable rod-end Heim joint. These don't necessarily have to be replaced after every season, but if you detect any slop or damage, trade them for new units. Barham says monoballs typically cost around $16 each.
Finally, go through the steering system as well. Tie rods and ball joints receive a lot of punishment and should be replaced. A broken component here won't just mean the end of your race, it will also result in a loss of control of the race car and probably a wreck.
If you race rebuildable shocks, it is definitely time to have them rebuilt. Even if you run nonrebuildables, consider having them dyno'd so you are certain they haven't suffered damage. If you race stock replacement shocks, paying for a dyno probably isn't worth the return on your investment. In this instance, you are probably better off purchasing a new set.
Springs, thankfully, can be used season after season if they aren't damaged. Barham says to have all your suspension springs checked to make sure they still rate out to your expectations. If they are good, clean them and put them back on the shelf. Don't allow your car to sit on the suspension springs all offseason, however, as this can cause performance problems.
Wheel bearings should automatically...
Wheel bearings should automatically be replaced every offseason.
Here's one area you should plan on overhauling every offseason: the brake system. Brake failure should be avoided at all costs. Begin by pulling the calipers and rotors-you've probably already done this to inspect the suspension. You should throw away the brake pads and flush the brake lines because both of those components will be worn after a season of racing. It's also a good idea to rebuild all four calipers. Rebuilding your calipers isn't a difficult task and mainly involves removing and cleaning the pistons and replacing the seals. Replacing the seals is important because they harden with heat cycles and eventually crack and leak fluid. Hard piston seals don't do a very good job of pulling the pistons back after the brakes have been applied, and this causes the brakes to drag.
Next, move on to the rotors. If you are forced to use stock rotors, this is a good time to have them turned and trued. If you are using racing rotors, this probably isn't an option. No matter what you are using, inspect the rotors for cracks. Small, spider-web-like cracks are OK as long as there aren't too many of them. If the rotors are obviously warped from excessive heat, it's time to have them replaced.
Over time, most foam used...
Over time, most foam used in fuel cells will break down. When this happens, the material will crumble and separate. This can clog your fuel filter and cause fuel pressure problems. Instead of just putting a fresh coat of paint on the outside of the can, pull the cell apart and inspect the bladder and foam every winter.
You should also check the wheel hubs and the wheels themselves for cracking. Barham says the hubs, especially wide-five hubs, are most prone to cracking around the stud ears (where the wheels bolt to) and the rotor stands. Wheels crack around the lug holes. Wheels and hubs are also prone to damage from light contact on the racetrack. Scrubbing the wall or touching wheels with another car can collapse the bead on a rim or crack a hub. Stay on the lookout for these signs of damage.
Finally, when the car is stripped down as far as you plan to go, take some time to thoroughly clean the chassis and everything that's attached to it. This is a good way to spot other potential problems.
As you clean the chassis, inspect every weld on the frame and the rollcage. Look for cracks in the welds. Almost all welds eventually fatigue and crack if they are stressed enough, so this is something you should always check. The highest stress areas on a race car are usually where the front and rear clips attach to the centersection and anywhere a suspension component attaches to the frame. If you spot a crack in the weld, it must be repaired before the car takes to the track again. If you are confident in your welding skills, you can make the repair yourself. Grind the weld to make it smooth, and grind a small groove between the two pieces of metal that had been originally joined. This provides more surface area for the new weld. Then reweld the joint thoroughly. Don't forget to touch up the raw metal with primer and paint after everything has cooled down to keep rust from attacking the metal.