October - Weekly Chassis Maintenance
Lets first talk about the tires. No matter what your current prep program is, tire prep should always begin with proper cleaning of the tire itself. For this, I recommend taking the wheels and tires off of the chassis, and seperately scrubbing them with a soapy solution of Simple Green or Orange Blast and water with a natural bristle scrub brush. This same solution works great for cleaning your air filters and pre-filters (see additional article concerning proper cleaning of your air filters >> HERE <<.) Clean the wheels at the same time, and take time to inspect the wheel and tire assembly. Check of dings or bends in the bead of the wheel, any tears or cuts in the tire, sidewall damage, etc. Scrub everything thoroughly, then towel dry.
While the wheels and tires are off of the kart, let's turn our attention to the rest of the chassis. I prefer to "bag" the engine and gauge rather than remove them from the kart. This is up to you and your time constraints. It is important not to get any moisture around your valuable gauge (tach/temp). Water and fine electronics don't play well together and should be avoided at all expense! Take the time to remove your gauge in it's entirety if time permits. That's the way we do on our sprint car. It's that important! On a kart though, I simply put a tight fitting ziplok bag over the gauge. You can also wrap duct tape or electrical tape around the open end of the baggie to seal out moisture as best as you can. For the engine, I use a large heavy duty trash bag and go over the entire engine, pipe, and clutch. A bungy cord or electrical tape will suffice to close off the bottom as best as we can. Finally, on to the cleaning. I use a power washer for most of my cleaning at the shop, but a good pressure garden hose will work also. Be careful, if you use a pressure washer, or visit the local car wash, not to spray water directly at the bearings on the chassis. Keep away from front wheel hub bearings, rear axle bearings, and anywhere else, that water may get into a bearing and hurt it. Around bearings, you will be fine by simply sponging clean any excess dirt and oil that has slung out.We'll take the bag off of the engine and sponge clean the sheetmetal and remove any loose dirt. We'll have the clutch off later for clutch maintenance, so we're not so concerned with that right now. Once the kart and engine is clean, take time to dry everything thoroughly. NEVER let the chassis air dry. Use a shammy or clean white cloth to go over the entire kart (not just the easy to get to shiny bodywork.) Also, be sure to drill a small 3/16" hole in the bottom of your seat to help drain excess water from it. This will save you time and not hurt the integrity of the seat itself. As you dry, take time to visually inspect the entire chassis. Take close consideration to welds, hardware, bearings, and other items that could have been damaged from the previous race. This cleaning should have taken you roughly an hour or more. If you were done any quicker, you probably didn't do the job well enough, or you've been racing on pavement, NOT on dirt! Next, I take a few minutes to blast off all of the bearing surfaces, heim joints, etc, with brake clean and wipe dry with a lint free paper towel. This would be a good time to re-lube these areas as well. The last thing we want is the chance for rust to attack the clean bearing surfaces. Im a big believer in Marvel Mystery oil and used it on most everything. You are welcome to use any oil you choose. The foaming aerosol oils work great at getting into bearings and heim joints, and work nicely as well. Lets look further into lubrication of your chassis. One of the most important items during weekly maintenance of your kart is that of proper lubrication. By that, I mean, primarily bearing and chain maintenance here. These parts have a limited lifespan and should be replaced on regular intervals. For most karters, that will mean once a year. If you are running less than twenty races per season, thats understandable. If, however, you are racing more seriously, and venturing out more than once a week to the track; consider replacing these items more often. Of course, at the first sign of wear or failure, the parts should be replaced, regardless of time of use. Thats a given. When it comes time to replace items such as bearings and chain, consider that you generally are going to get what you pay for. There are many different levels of bearings and chains available for kart racers to choose from currently. First, well take a look at rear axle bearings. Most kart shops push a bearing called free-spinning or oil-filled. There are also lesser quality bearings available at a much lesser price. Keep in mind, the quality will be considerably less as well. You want the free-spinning variety. Be careful what some vendors call free-spinning or oil-filled. What is commonly referred to as free-spinning is simply bearings with no seal contact. A seal is DIFFERENT than a shield. A seal is typically a rubber or synthetic plastic seal that contacts the bearing itself. It does a great job at sealing out the environments, but the extra contact with the bearing causes drag and robs valuable horsepower from your engine. You need a non-contact shielded bearing. Most kart shops dont even know what that means, unfortunately. As far as oil filled versus grease filled, don't be too concerned how the bearing has been packaged. We will be replacing any grease filled in the bearing from the factory with a lightweight oil anyways. Here, at CRE, we do not even offer the cheaper bearing to our customers. We only stock what we would run on our own karts. NTN offers a premium quality bearing, but there are now ceramic bearings that are even freer yet. Ceramic carries a HUGE price tag and our experience with them shows that they have to be replaced more often on dirt. That equals two negatives. Deciding on if they are worth the difference in dough, depends on where and at what level you are racing at. RBI is a huge manufacturer of bearings available to karters. RBI offers several levels of bearing quality as well. I would suggest just their best quality free-spin bearings. They should retail anywhere from 16 to 21 dollars or so, each. Most kart chassis OEMs use their mid-quality bearing, which is okay for beginners, but serious racers will replace them at the first sign of wear. Now that you've decided what bearings to run, let's talk about proper maintenance of them. Afterall, that is the meat of this article. Part of properly cleaning and lubricating your rear axle bearings, should include removing the rear axle every week if you do not have replaceable bearing shields. Some guys simply drill out the existing metal shields on the bearing itself and use that to clean the bearings between races. Some simply pry on the shields with a small screwdriver to slide them out on the inner race to access the ball bearings and ultimately clean them right on the kart. Honestly, the replaceable shields are the way to go -- not that I'm just trying to sell you something, but that way you won't have to rescale each time you take the rear axle out of the kart. IF nothing changed height-wise, realistically, you shouldn't have to rescale each time, but it's almost impossible to get the chassis back together exactly as it came apart. Close, sure, rarely exactly. Height differences make HUGE weight changes on the scales. This is much more critical than moving 5 or 10 pound weights around on the kart. If you do not have replaceable bearing shields on your chassis, you might consider purchasing them. Removing the axle is the old school way of cleaning the bearings and I still prefer that, (when I have the time.) Pulling the rear axle out is generally a half hour job including the time to clean the bearings and cassettes. That's not so time consuming, but I generally will find myself getting into chain maintenance at the same time, and then the hours start adding up. Again, I suppose it depends how seriously you take winning and at what level are you competing. The removeable shields completely replace the original bearing shield or seal, but do allow a little more dirt in the bearings. They really do an ok job overall. The ease of access to maintain them is worth the slight trade-off in most competitors' opinions. Your bearings will still last you a season if maintained properly. Some guys down south run NO shields OR seals....Keep in mind, their tracks rarely get dusty as do ours here in the midwest. They also run with an air filter that has the paper removed from it and no foam pre-filter...a much different environment for sure. How often should you clean and re-lube the bearings? Clean them out as often as you like -- I don't understand the term "over-maintenanced" or "over-prepared". You can't hurt anything by cleaning and lubing them more often. Use brake clean to clean thoroughly. I prefer Marvel mystery oil as my choice of bearing lube. Whatever you choose, be sure that it it very lightweight. Some guys use different lubricants -- nothing good or bad to say about any others. Beware that some seem to attract dust for what that's worth. In my opinion, definitely stay away from silicone based oils such as WD-40...By the way, WD-40 makes a terrible tire prep in my opinion as well. We'll discuss why is a tire prep article another month. ALSO, be sure to wipe the inside of the bearing cassette clean and wipe it with some light lithium grease or EP grease to allow the bearing to move freely in the cassette and allow the chassis to flex properly. Check very closely for any binding that may change how your kart chassis works. This is VERY important. Cassettes wear out too -- any excess "slop" will change how the kart scales and reacts on the track. Some guys will go to the effort of scotchbrighting all the hard anodized coating off of the contact surface of the cassette to bearing area. You could even go to the extent of having them teflon coated. That would be overkill at the local level. That will simply cause the cassette to wear faster and need replaced sooner. When you start running up front at Nationals, call on us to help you do that.
For chains, my proper maintenance procedure would be to cook the chain in a vat of oil to 400* for 30 minutes, then let cool. Replace with clean oil of you choice, and heat to 400* for 1/2 hour. You're set to go. That's my recipe, and I'm sticking to it. For most weekly racers, though, that's a huge bother. Most guys simply spray oil on the chain while it's on the chassis. Which, is ok for all practical purposes. Remember, chains are good for a season, then make good spares, the same as your bearings. Again, when it comes time for Nationals, we'll take my preceeding recipe approach. Make sure you get a "proper" chain lube. Again, we only sell what we use....VHT/PJ-1, in my opinion, makes the best chain oil. I do stock and sell a few cans each year of chain "wax". Some guys like this because it's not as messy and is easier to clean up. Personally, I could care less about getting messy, I want the lube to penetrate the chain pins and links....VHT does the best at this. Any foaming chain oil will penetrate the chain links better than a standard spray lube which will simply be slung off the first time you hit the gas. You can also use a "drip on" chain lube which doesn't penetrate the chain as well, but does an ok job. Again, the majority of this gets slung off of the chain before you ever hit the track surface. I stock and sell Lucas chain lube for this application. This also makes a good lube to "cook" into the chain as it has an excellent high pressure quality.
Hopefully that covered the basics of weekly kart chassis bearing and chain maintenance. Keep in mind that the more prepared you are before your next race, the faster you'll be on the track.