Let's face it. Parts break, parts wear our, and we can easily overlook minute issues that can turn into big problems down the road--especially in the harsh environment of a racetrack. What started as a near-perfect race car, suspension component(s), or chassis setup can quickly become just the opposite as wheel-to-wheel racing can wreak havoc on our cars. On the other hand, what started as good race car can slowly change over the course of a drama-free race season, and with so many parts working together dynamically, diagnosing a problem can become frustrating and time consuming.
The halfway point of the race season is a great time to give the chassis and suspension of your race car a good onceover. We know the majority of racers are in tune with their race cars and have their hands on the major components on a regular basis. But a solid inspection and some preventative maintenance can go a long way--especially in the second half of a season when you're chasing a championship.
Preventative maintenance is extremely important for a number of reasons. Catching issues early can help you avoid problems on track, and in many cases can be much less expensive and time consuming to fix before it turns into big problems. Another benefit is a more thorough knowledge of your race car. The more familiar you are with your chassis and suspension, the easier it will be to locate and identify problems that might have otherwise gone overlooked.
Over the next few pages, we are going to cover 10 of the most important parts of the chassis and suspension to inspect and service around the mid-season point. Much of what we are going to talk about works together, and can be the difference between a properly and ill handling race car.
Shocks are an extremely important component to any race car. They control the distribution of loads as the chassis adjusts to load transfer. Over the course of one short feature, shocks perform an incredible amount of work--especially if you consider how much most race cars weigh. As a shock cycles, it also creates heat, which can shorten the life of seals and oil's viscosity, effectively changing the shock rate.
After a thorough cleaning, inspect all four shocks for leaks, bent shafts, and internal damage. Cycle the shocks to ensure operation is smooth and have them dyno'ed if possible. Setup changes over the course of the season can affect not only what shock rates are needed, but could requre a different shock package.
To complete the inspection, check the shock mounts on the A-arm and the chassis for any bent tabs, and cracked welds. The shocks handle a lot of weight. Bent and cracked mounts are very common. Again, a good cleaning may expose a problem that was hidden by a little dirt build-up from being on track.
A thorough inspection of your race car and all of its major components is a great way to prepare for the second half of your race season
Roll Center or Moment Center is one of those unseen things that can negatively affect a race car, when everything else looks right. Checking to ensure roll center hasn't changed is extremely important, especially because changing ball joints, installing new length control arms, installing new spindles (they are not all the same height usually, even if they are stamped the same), and use of different tires with different circumferences (this changes all of the chassis mounting point heights) will all change the roll centers.
If adjustments need to be made at this point, go back and recheck your bumpsteer and toe settings after getting the roll center where it needs to be. Changes in control arm lengths and angles affect the arc on which the ball joint travels, and that affects the bumpsteer.
In reality, your alignment should be checked before every race. At the very minimum, you should be checking caster, camber, and toe weekly. As part of a mid-season refresh, or anytime you change any front or rear suspension components, the alignment needs to be verified.
Verify that the alignment is where is should be. This includes Ackermann, bumpsteer (could have changed with caster changes or spindle changes), rearend alignment and rear steer (trailing arm angles), and toe (front and rear). With so many moving parts in both the front and rear suspension, it isn't uncommon for tolerances to change, parts to move, and alignment specs to change. Slight alignment changes can make huge handling differences on track, and that could be the difference between winning and losing.
A-arms, like any other link connecting the chassis to the wheels, usually see large amounts of load. These links, especially ones that change dynamically during the course of a race, take a beating. The arms themselves, plus the mounting points, and the spindles are all susceptible to wear from normal use. Visual inspections will usually uncover any issues, but slight bends might not be noticeable to the naked eye. Make sure none of the arms are bent or damaged, and with them removed, check for cracks in the welds and ball joint straps, and check for rust. A build up of dirt can cause rust to weaken the material. Make sure the bushings are free and the arms move freely before reinstalling the arms.
Check the body of all shocks...
Check the body of all shocks for damage. Dents, cracks, and leaks can all be or lead to damage that will affect handling.
When using a coilover setup,...
When using a coilover setup, be sure to inspect the spring mount for wear. Be sure to also inspect where the spring contacts the cap.
The shock shaft seal is another...
The shock shaft seal is another important part to check. A leaky seal can lead to shock failure.
Moment center is extremely...
Moment center is extremely important, and needs to be checked whenever parts are changed. Changes of most major components will affect the roll center.
Wheel alignment is huge and...
Wheel alignment is huge and should be checked often. Caster, camber, toe, Ackerman, and bumpsteer all need to be set.
Specialized alignment tools...
Specialized alignment tools are available to make the job easier, like the laser level shown here.
All rod ends need to be checked...
All rod ends need to be checked for dirt and debris, as well as excessive wear. Any worn or cracked rod ends need to be replaced.
A-arms should be checked for...
A-arms should be checked for bends or cracks. Bent A-arms should not be used.
Rod ends can almost be looked at as wear items, like brakes or tires. Although brakes and tires wear out at a much quicker rate, rod ends directly transfer high loads, and take tons of abuse on a regular basis. Add a dirty, unfriendly environment to the mix, and the rate at which performance degrades increases. All of your rod ends should be cleaned and greased on a regular basis. While cleaning, you should check for smooth operation with no wear. Check for cracks in female ends and bent male ends, clearance and excessive wear, and cracks in aluminum ends (your not really using aluminum rod ends are you?)
Braking systems see a ton of torture to say the least. In short-track racing, brakes see the most heat and abuse of all the systems in most race cars. Besides brake pads, which wear over time, heat can damage piston seals causing leaks, and cooked fluid, which reduces performance. Inspecting for issues before they become serious problems is huge--the last thing anyone wants is to drive into a corner and find out they have no brakes. A thorough inspection includes checking seals, pads, fluid, and caliper alignment. Brake fluid should be replaced fairly often, as moisture build up is common, and excessive heat for long periods of time breaks fluid down. Rotors and calipers should be checked thoroughly also. Check rotors for deep cracks, excessive wear, and warping. Improper caliper alignment can cause damage to the caliper, and if damage is present, said caliper should be replaced.
Any time there are moving parts, wear can be an issue, and there are a lot of moving parts in a race car's steering system. It is very important to inspect these moving parts (steering box, tie rods, drag link, idler arm, spindles, or rack-and-pinion if your car runs this style of steering), as almost any damage can decrease steering ability. Check for slop. Loose steering can be a good sign that something in the system isn't right. Check the seals for leaks, idler arm bushings on drag link systems for wear, and look for bent drag link components. Once everything is checked and reassembled, run the steering through its entire range of motion. Look and feel for any tight or dead spots, and ensure the steering is smooth through its entire range of motion in both directions.
The driving force of your race car is something that needs to be taken care of. The rearend sees many different forces as a car goes around the track. Engine torque is transferred to the rear wheel through the rearend, loads are shifted to the chassis through the rearend, and the weight of the car sits (literally) on top of it. Many times in wheel to wheel racing, the rearend can be damaged, and it may be minor enough that there is no visible damage, but over time, small amounts of damage can turn into big issues. When you have the opportunity to inspect the rearend of your race car, check the seals for any leaks, replace the gear oil, and check the axle tube to ensure nothing is bent. The internals are just as important. Check the pinion for play, check and/or replace springs in locker-type rearends, check the ring gear and pinion gear for wear, and look for bent or worn axles. Once your inspection is complete, check for worn lug nuts and studs (especially if your series has pit stops).
Check your springs for any height change from the start of the season. Although the tensile strength of the spring's material won't change, the height of the spring can change due to the constant weight of the car resting on it. This height change can affect the setup, as roll centers, corner weights, and ride height will all be affected. Beyond the height, check for bent springs and signs of coil binding, rubbing on shocks for coilovers, and incorrect mounts that contact additional coils on big springs. Note: Springs don't lose rate, they can lose height and that might increase the rate. The reduction of height with the same number of coils brings the coils closer together, which can add to the advertised spring rate.
Tying It Together
Preventative maintenance is important. The more time you spend examining the car and its components, the more familiar you'll be with it and the easier it'll be to spot problem. In most cases, small problems can turn into larger, more expensive ones, and catching them early can save you time and money, and many times will result in less part failures on track. Clean and inspect your car often, it's an important step on your way to the winner's circle!
There's no denying your chassis has a rough life. This is why it's important to inspect it regularly. Hard racing, bumpy tracks, even being strapped down in the trailer can cause bends and stress cracks that might not be easy to find. This is why checking the welds at the pick up points is extremely important. Once you've inspected everything, string chassis and measure for any changes--especially if you've been involved in any wrecks. Do a complete chassis alignment with strings or lasers to ensure the front or rear clip has not moved. What may have seemed like a light hit can cause large amounts of damage.
Welds on the A-arms, as well...
Welds on the A-arms, as well as on the A-arm mounts should be checked for stress cracks. If the welds are cracked, they should be ground down and rewelded or junked and new ones purchased.
Brakes are very important,...
Brakes are very important, so they should be checked regularly. Measure the rotor thickness to ensure they are within manufacturer specifications.
Also check the rotors for...
Also check the rotors for cracks or warping. A cracked rotor can come apart causing a lot of damage in the process.
Check for proper caliper alignment....
Check for proper caliper alignment. A misaligned caliper can cause one pad to drag the rotor, which can cause brake issues and slow the car down.
Check the steering box for...
Check the steering box for leaks.
Check all of the links for...
Check all of the links for bends.
Check all joints for wear,...
Check all joints for wear, and make sure the system moves smoothly through its entire range of operation.
Inspect the cover, hardwear,...
Inspect the cover, hardwear, and gears. Quick gear changes can damage commonly used parts as they get thrown around in a rush.
Inspect all of the seals and...
Inspect all of the seals and bearings in the rearend. Leaks and worn bearings can cause bigger, more expensive problems.
Inspect the gears for excessive...
Inspect the gears for excessive wear. If the gears are worn, replace them.
Inspect your springs for wear....
Inspect your springs for wear. If you run a coilover setup, check for contact with the shock body or shaft. Ensure the springs sit correctly in the spring cup.
Measure the height of the...
Measure the height of the springs, as springs can lose height over time. Also, check the rate and adjust your setup accordingly.
Check the front and rear clip....
Check the front and rear clip. Clips can move as a result of even small wrecks. String the chassis to ensure all four wheels are pointed in the right direction.
String or a laser will give...
String or a laser will give as accurate, straight line to measure off of. For detailed information on how to string your car see the story by the same name in the April 2012 issue of Circle Track.