Home > Chassis Tech >

MAXIMIZING RELIABILITY
MAXIMIZING RELIABILITY


 

Product Code: 006
.

Description
 

 

 

MAXIMIZING RELIABILITY

Through Basic Preventative Steps

By Mike Unger

I was at my first trip to Daytona for the WKA Manufacturers Cup this past winter and as I was getting my son though the scales and past tech I heard someone say “I think someone should write an article about how to properly prepare a kart.” Being a technical writer I am always open for new article ideas, so here it is. I can’t remember who actually said it but thanks for the suggestion.

The first thing to remember about prepping a kart is that there is more to it than just getting through safety tech. Safety tech, while extremely important and required by all sanctioning bodies, is only half of the work that needs to be done. There are a number of things you need to do to your kart to not only be safe but also to be as competitive as possible. A kart that only passes safety tech won’t be ready for the big race. You need to consider everything from the brake fluid to the numbers on the side of the sidepods. Just for simplicity let’s start at the front of the kart and work backward. I will cover everything from safety tech to common sense as well as some tips I have picked up though the years.

So starting from the very front of the kart let’s considering the nose and bumper. For those of you using CIK style bodywork (WKA Manufactures’ Cup Style) you have six pieces to keep an eye on. The plastic nose piece, the lower bumper bar, the upper bumper bar, the red plastic part than connects the two, and the two clamps that pull it all together. Check the plastic nose piece for cracks and tears especially around where the nose piece and metal bumper bars attach. Often cracks or tears appear here from excessive use. Replace if necessary. Check the bolts that attach the bumper bars to the frame. Make sure they are tight. If the nylon nuts are easy to turn from being on and off often replace them. If applicable, check that plastic piece that connects the two bumper bars. It has two bolts in it as well. Make sure those are still tight. Finally check the clamps that pinch the plastic nose around the steel bumper bars. Make sure these are tight and apply enough tension to keep from popping off. WKA says these quick release clamps are optional and you can bolt on the bumper if you like. I suggest using the quick release type and simply use a plastic wire tie to keep the clamps from popping open. If you are not using a CIK style front bumper you still need to look at the attachment points and make sure they are all tight. Nylon locking nuts are a must for all of these points as well. Remember for most sanctioning bodies nowadays losing the front bumper will get you black-flagged.

Now let’s consider the accel and brake pedals. Where these pedals attach to the frame it is required that the bolts be safety wired or pinned with cotter keys or similar. Check these bolts to make sure they are not excessively worn as they do provide the pivot for the pedals. Replace if necessary. Also check the nuts and make sure they are tight but not tight enough that it causes the pedals to bind because this can result in a stuck throttle or hanging brake. Make sure to clean this area from time to time as dirt and sand can get in there and cause parts to wear excessively. Also check the attachment of the brake rod and brake cable to the pedal. Make sure these attachments are safety wired or safety clipped as your chassis manufacturer designed. On the accelerator side if you are attaching the throttle pedal to the cable with a simple loop I suggest some kind of protection to keep the thin cable from rubbing against the metal pedal. I use a piece of plastic brake line or fuel line to protect the cable. Inspect the cable regularly, every year I see 3 or 4 karts sitting on the side of the track with broken cables. If you are using a metal rod at the throttle pedal check that attachment point as well. I suggest safety wiring that bolt also. While it is not required for safety tech it is a good idea.

Moving farther rearward now let’s consider the steering. First where it attaches to the frame at its front most point. Likely the steering shaft goes through a bracket in the frame, through a bushing and secured with a nylon bolt. An E type clip or safety wire on the end of the shaft is required by safety tech. Check to make sure that clip is still there and is tight. I have seen these vibrate loose and come off. Also check that bearing or bushing the steering shaft sits in. This bearing is attached to the frame with an internal C clip (snap-ring). Check for excessive wear on this bearing. An excessively worn bearing will effect wheel alignment and steering, replace if necessary. Moving up the steering shaft, look at the pivot that the steering shaft passes through and connects to the frame uprights. This is usually a plastic bushing block with a through bolt in it. Check that the plastic is not cracked or worn excessively. There should be very little movement between the shaft and the plastic bushing. If there is replace it as it can effect alignment and steering feeling. The bolt that attaches the plastic bushing to the frame uprights need be safety wired or clipped for safety tech as well.

Now let’s talk about the steering wheel. It may sound simple enough and is easy to overlook but a couple things need to be considered here. First is it worn and slippery to your driver? Often over time the leather or suede material gets matted down and too slippery to get a good grip on. Also inspect the spokes. Over time they can develop cracks and eventually break. Replace as needed. Next look at where the steering wheel attaches to the steering shaft. This is usually an aluminum hub. You need to make sure all of these bolts are tight and at least 3 of them are safety wired or clipped. Also inspect the bolt that attaches the steering hub to the steering shaft. This one for some reason always seems to vibrate loose. I recommend replacing that nut and bolt often. Also make sure that bolt is safety wired as well; double nut if possible to further reduce the chances of it loosening. Look at your gauge attachment to the steering wheel. Is it tight? Is the wiring frayed or is rubbing on an edge of a bracket that can eventually cause a problem? If so reroute and replace as needed.

Let’s move to the middle of the steering shaft and the tie rods and tie rod ends. The ties rod ends need to be connected to the steeringshaft with a bolt, nylon lock nut and safety wired or clipped. Inspect the tie rods and tie rod ends. Sometimes in the heat of battle you might not notice a bent tie rod or end. If you use a throttle cable all the way to the pedal, look where the tie rod and the throttle cable cross. Sometimes the throttle cable will rub on the tie rod and cause excessive wear. You also might consider rerouting the throttle cable to avoid that in the future. There are a number of kits available to relocate the cable and generally cheaper that a tie rod plus you buy piece of mind. Moving outboard to the spindles look at where the outermost tire rod end connects to the spindle arm. These bolts need to be tight and safety wired as well. Also inspect the spindles for bearing wear. Bearings that need replaced will allow the spindle to move slightly relative to the frame. The kingpins (the long bolt that connects the spindle to the frame) can use inspection as well. They tend to wear a little over time and in the event of hard contact can even bend. A bent kingpin can affect caster, camber and toe. Look these over closely and especially after an incident.

The fuel tank while a seemingly simple part can be a problem should it leak or come loose. Inspect the fuel lines for places where they could rub and eventually leak. Also pull the inlet line out of the tank from time to time and check the line. Over time it gets stiff, can crack, and will stop moving around in the tank. This will lead to fuel starvation in the corners and could damage your engine. 

Also put zip ties on all fuel line connections as they are required for safety tech. Also here is a good tip I picked up looking at karts on the grid. If you are using one of the quick removal type fuel tanks with the big plastic three spoked wing nut attach a zip tie to the frame and zip tie in a way that won’t allow that nut to loosen. Trying to keep the fuel tank in the kart with your knees while trying to race isn’t too fun or easy.

 

Moving to the sidepods now, these parts play an important role in protecting you from a side impact. They also will get you black flagged should they fall off. So for that reason check the connections often for tightness and replace the nylon locking nuts too. Since we remove the sidepods often to get better access to the engine and frame those nuts tend to wear out. I replace the 6mm Allen bolts with a simple pin and clip unit you can buy at any hardware store. It makes for easy removal of the sidepods yet provides a good strong attachment method. Just be sure to get a good thick clip and inspect those often as well.

Sticking with the frame part of the equation for now let’s consider the seat. Of course everyone knows it’s important it is neglected more often than any other part on a kart. The stiffness of the seat has a big influence on how the kart handles. If your seat is cracked, bottom blown out of it, or in general in very bad state of repair it is affecting the performance of your kart as well as a concern for your safety. Replace your seat if it has cracks or seems flimsy from too many years of racing. Also check each and every attachment point to make sure the seat bolts and seat struts have not loosened up over time. As frame flexes, the seat does too.

If you are like most karters you attach your lead ballast to the seat. Be sure to use 5/16in bolts for every 5 lbs of weight, and if the weight weighs more than 5 lbs two 5/16in bolts are required. Double nuts or safety wiring is required of all ballast and in the case of the WKA all ballast of required to be painted white.

Let’s talk about brakes now. Brakes are one of the things that you simply cannot neglect on your kart. You need to inspect them often and replace and repair as needed. You should only be able to push your brake pedal ½ way through its total stroke before it stops because the pads engage the disk. At that point the pedal feeling should be very stiff and not spongy or mushy. If the pedal stroke is too long it’s time to replace the brake pads. Follow your manufactures’ recommendations on how to replace and what pads to use. Often your manufacturer has a number of compounds of brake pads to suit your driving style. So while you are replacing them, get your kart dealer on the phone and see if there is something out there that can help you brake better. Look over the brake lines as well. Finally, look for signs of abrasion, leaks, and loose fittings. Do not take chances here. Replace anything that is questionable with a new part.

If the brake pedal doesn’t get firm after the pads contact the brake rotor the system needs to be bled. Again you need to contact your manufacturer and find out what kind of brake fluid is used in the system. There are a number of types of fluid, (DOT3, DOT4, DOT5 and so on) but they are not compatible with each other. Putting the wrong kind in your system can render it useless and dangerous. After you have identified what fluid to use you will need a brake bleeder and a couple wrenches.

There are a couple ways to bleed the brakes; I use the traditional kart gravity method. You will need a brake bleeder. It is simply a jig that screws into the master cylinder with an upright that elevates the brake fluid so it is the highest part of the system. Once the bleeder is screwed into place, loosen the cap on top of the reservoir and turn the valve open on the bleeder. Now your system is ready to be bled. Find the bleeder screws on the brake calipers. These usually come in 2 types. One is simply a small allen bolt that you remove and let the brake fluid flow out of. The other is a valve like automobiles use. The allen bolt usually makes a mess but it’s effective. The automotive type is an actual valve with a hole in it. To avoid the mess you can put fuel line over the end of the valve and drain the excess fluid into a container. Allow the caliper to bleed until the fluid is clean and doesn’t contain any air bubbles.

After you are satisfied the old fluid has been replaced and no air bubbles are present replace the Allen bolt or tighten the automotive style valve. Now close the valve on the brake bleeder, remove, and replace the bolt or cap on the master cylinder. Repeat for the other side of the caliper and other brake systems as needed. I recommend bleeding your brakes 2-3 times per year whether the brakes need it or not. Brake fluid tends to absorb water and keeping fresh fluid in the system is a good thing. Also brake fluid is very corrosive on paint and is not good for you to come in contact with it either. Use rubber gloves and clean your kart and your hands thoroughly after you are done.

Now we move on to the rear of the kart. Here is where you will find all of the dirt, grease and oil from the engine, chain, exhaust and the track. It’s important to keep your bearings and chain lubed but all of that lube also attracts dirt. That dirt gets into bearings and chains and in general will increase the rolling resistance and slow you down. Not to mention it will cause bearings and chains to wear out more quickly causing you to spend more money in the end. The only way around this it to keep the rear of the kart meticulously clean. One of the new pieces I have found that make this mundane job easier is the new Tillet chain guard. This chain guard encloses the sprocket on three sides helping to contain all of the lube from the chain. Containing all of that mess helps keep it off of everything else and keeps it from picking up dirt and grime that will eventually grind into your bearings.

Once a year I recommend taking your rear axle completely out of your kart, removing the bearing cassettes and thoroughly cleaning them. Check your bearings for excessive play, if they do replace them with new. If they do not have excessive play simply clean them, and re-lube them. Many racers pop the bearing shields off and flush the bearings with solvent to get them cleaned but in many cases that can cause problems as well. Often getting the shields to go back in place is a challenging task. Putting a bearing in the rear axles without a bearing shield will certainly cause you to replace that bearing sooner than later. So I recommend wiping the bearing off with the shield in place, carefully paying attention to the grime around the shield and then re-lubing with a quality lube. If the bearings still sound like a coffee grinder after this go ahead and try to flush the bearing out by popping the shields off. Clean, re-lube and re-install as before just pay attention to that bearing shield throughout the season as it is likely to pop off.

The bearing cassettes and bearing interaction is something that should not be overlooked as well. The bearing should fit snuggly inside the cassette yet should rotate relative to the cassettes without much effort. If it does not it needs to be cleaned out and polished up until it does. When you put the bearing back in the cassette I recommend using a small amount of anti-seize grease to keep things free. Before you put everything back together this would be a great time to replace those bolts that are stripped out or looking kind of bad with new ones. Also don’t forget to use blue Loctite on every bolt. You can’t afford to have a bolt come loose in a race.

That pretty much is it for the chassis stuff. Engine stuff is largely dependent on what kind of engine you have but things to inspect and rebuild are fairly standard. Clutches need to be inspected and rebuilt as needed. Broken exhaust springs need replaced and exhaust pipes need to be properly secured. Carburetor diaphragms should be replaced once per month at least, and the chain and sprockets need inspected and replaced as needed. When in doubt replace it. It is no fun to lose a race because you tried to get one more race out of that consumable part.

So there you have it from the front to the back, go over the whole kart and be 100% ready on raceday. If you take care of those maintenance items now you will get though safety tech quickly, and instead of fixing your kart between heats you can work on making it faster.


Share your knowledge of this product. Be the first to write a review »