STORY TITLE TRACK TEST By Bobby Markiewicz TRACK TUNING THE

STORY TITLE TRACK TEST By Bobby Markiewicz TRACK TUNING THE CHASSIS Learning: Knowledge or skill acquired by instruction or study. (Merriam-Webster, 2003) Karting is a never ending journey of learning. If you go to the track and don t learn something then you are not paying attention. In both life and racing there is always something to be learned! The more I kart the more I discover that there is so much more for me to learn from both racing and the adventures that it brings. Shawn Zannon (of Briggs and Stratton Motorsports) was at the track on our test session and helped get the Animal engine fired up to get Regan Verhring (4-Cycle Central) out on the track to establish the baseline handling of our Coyote kart. It was obvious that it needed some fine tuning after the first couple of runs. For our setup day of our new Coyote chassis, 4-Cycle Central came out to help us at Badger Raceway in Wisconsin. Throughout the day of testing I started to realize something, my chassis, and engine were both junk. After spending the day tuning and tweaking the chassis to get the feel and performance we were looking for, my lap times where still consistently a second off of the best lap time for the track in the Animal Senior class. My lap times were very consistent. Different lines or approaches only seemed to slow me down, so it was obvious the chassis and/or engine were failing me. It had to be, right? Wrong! Regan Vehring the owner of 4-Cycle Central graciously spent the day with me tuning the Coyote chassis. We would both test out each configuration and then combine our thoughts so Regan could suggest a chassis adjustment to correct the issues. Well, Regan s lap times were consistently one full second faster than mine! By the end Having technical references at the track can be priceless when in a bind. Keep your favorite articles, forum discussions, and books close to help out. of the session he had the combination below the track record for the year. It was obvious to me that I was what needed the tweaking once the chassis was figured out. I was happy for this example in that it could so clearly shows what every chassis and engine builder have to deal with on a regular basis. Many times, outside of clear issues, the driver has a lot to do with being off the pace and no chassis or engine can correct for this, only practice and talent. If there was a karting hall of fame, Regan Vehring would probably be in it. He is a 7-time track champion at Badger and has been racing there for over 20 years but also has National wins in almost every type of kart racing. This gave me confidence, and some of 44 NATIONAL KART NEWS 800-942-0033 WWW.NKN.COM SEPTEMBER 2008

my pride back, knowing that I was being compared to the best. It is always better to learn and progress a skill by hanging around with people more capable than you (another one of those life skills learned in racing). Although everyone s pride tries to tell them differently! Accepting the fact that I could be faster and had lap time improvements to gain was the biggest step to helping my racing. Enough rambling, let s get to making the chassis faster, we will worry about the driving later. Last issue we looked at the initial assembly and set up of the Coyote Wide Track LE chassis. Because the chassis was so dominant at the track, I was confident that the equipment and my setup would give me the combination needed to be competitive. This being a new chassis, the first step was to Expert Advice by Jim Lipari of Coyote Motorsports The kart has an understeer (push) at corner entry. Correction? The kart is oversteering before the corner center. Correction? The kart is oversteering on center off. Correction? The kart is understeering (pushing) from center off. Correction? The kart has a hop in the corner. Correction? The kart seems stable in low speed corners but unstable and unpredictable in high-speed corners. Correction? The sprint track has more left turns than right turns (or visa versa), how do we set the kart up to best handle the dominant turns. Moving the front tires out has what affect? Moving them in? Moving the rear tires out has what affect? Moving them in? What point in the corner does camber have the most effect? In what situation would you adjust ackerman from the standard setting? What point in the corner does caster have the most effect? What are the effects of increasing or decreasing it? Overall the kart needs more traction and is loose front and rear. Correction? The baseline run proved the kart was not balanced in the left and right hand corners (tight in one loose in the other). Number one priority was to fix this balance so it was put on the scales. The cross was found to be out by almost 5%. This fixed the balance issue on the track. ADD CASTOR NARROW FRONT END NARROW REAR END INCREASE FRONT TRACK WIDEN FRONT AND REAR TRACK ADD CASTOR / DECREASE ACKERMAN COYOTE SETS UP ALL KARTS AT 50/50 SIDE TO SIDE INCREASES OR DECREASES WEIGHT JACKING, RESPECTIFULLY INCREASE (in) OR DECREASE (out) REAR GRIP MIDDLE WHEN THE RACE TRACK HAS LOW GRIP WHEN THERE IS A CORNER ENTRY ISSUE NARROW FRONT AND REAR TRACK COYOTE TRACK TEST give it one final look over and then get it out onto the track. Next step was to make 5 or so slow shake down laps while paying attention to any weird characteristics or noises that might be of concern. The kart was then brought into the pits, put on the stand, and had everything looked over. Especially important is making sure that things like hubs and axles haven t shifted and that everything in the brakes and steering are still secure. Now with confidence, we can go set some baseline laps to compare our changes to. In any kind of testing, you need to have a baseline number (or reference lap times) to compare your incremental changes to. Establish the baseline and then make one change at a time and record the results and effects. At first it is easy to feel lost, making it hard to know where to start. Remember though, any testing is good testing when done right! Step one is to establish the baseline lap times. Step two is to quantify the handling you are seeing on the track. At that point you will have a lap time to go with your observations. Then in Event Liability Programs available for: karts motards outlaw karts legends baby grands pocketbikes dwarf cars mini-sprints micro-midgets &more! An association of Independent Promoters & Clubs Since 1985! Joe Janowski - 317.774.7021 P.O. Box 2166, Noblesville, IN 46061 Insuring n Your Racing Success! c s Event Liability Programs Consulting Services Risk Management FOR Karting Events Charity Events & Special Events CallTODAY or visit us online: www.nkaonline.com SEPTEMBER 2008 800-942-0033 WWW.NKN.COM NATIONAL KART NEWS 45

COYOTE TRACK TEST step 3 you can implement incremental chassis changes from there on out and look for improvements. Having a driver that can communicate what the chassis is doing is so important to optimizing the kart s handling. This is especially true if you are the crew chief and never get out on the track to experience it for yourself. If you are the crew chief, make sure you are on the same page with your driver and explain to them the feedback that you are looking for. I have been in many different karts and can tell if a kart is understeering or oversteering and give general insight to what I think it is doing. Regan can take it to the next level and divide the corner up Tire pressure was set at 25psi for the day s track conditions. Tire pressure would normally be a big part of tuning the chassis at the track. But, Regan s experience in this department could get us close enough to take it out of the equation and work on the chassis. into sections to isolate the chassis component responsible for a given handling characteristic. Something that after this test session I also learned to start doing. The baseline laps showed that my average lap time was 44.75 seconds; Regan s time was 43.8 seconds. To me the chassis was unpredictable; it would shoot out mid corner without warning and lose a lot of speed from scrubbing the tires. The kart also proved to be much tighter in the right-handers than the left-handers. This track has a dominate amount of left-handers, so this is definitely a major issue. Regan s observations were the same as mine, but he also noticed that at the apex on the righthanders the kart was very violently losing traction from what he felt was a binding kart coming unbound at that stage in the corner. The goal now was to address the kart balance issue so we could then work on the fine-tuning. 4-Cycle Central uses a custom-made laser alignment system. The alignment is done right on the scales. The advantage of this system is that it sets the kart up with the wheels on and the driver in the seat. This affects the settings of the kart compared to just being on the stand because of the chassis flexing from the weight of the driver. The front wheels are also aligned to the back axle making the kart perfectly square. When the chassis is set, you now know the exact weight percentages and alignment just as it is sitting on the track. The kart was originally set with 1.5 degrees of negative camber, the caster straight up at 12 degrees and the toe at 1/16 out. Regan suggested that the camber be reduced to -.5 degrees because the hard tires don t allow The widest range of styles and configurations of Rod Ends and Spherical Bearings in the industry, from economy to aerospace approved, available for immediate delivery. Stock sizes 1/8 to 2, 3 to 30mm. The Motion - Transfer Specialists Aurora Bearing Cad drawings, 3D models and full catalog, available online at: www.aurorabearing.com QUALITY SYSTEM REGISTERED TO ISO 9001:2000 (WITH AS9100) 46 Aurora Bearing Company 901 Aucutt Road Montgomery IL. 60538 Ph: 630-859-2030 Fax: 630-859-0971 NATIONAL KART NEWS 800-942-0033 WWW.NKN.COM SEPTEMBER 2008

COYOTE TRACK TEST ABOVE: Tires can tell you a lot about your kart s handling. Not knowing where to start, the camber was set at 1.5deg, obviously too much for this combination. It can easily be seen here that only about 75% of the front tires were being utilized. LEFT: We kept the caster in the straight up position. According to Jim Lapari at Coyote Chassis, if we were loose on entry we would want to increase the caster to increase the pre-center bite. was twitchy in the rear on the high speed corners, meaning it would break traction unpredictably. Regan s feel said that the kart was still releasing a bind at the center off in the right-handers and was very unpredictably losing traction. He also felt that the kart was acting twitchy and hard to drive in the high speed corners. He stated that that the kart wasn t biting the track well enough, or was overall low on traction. Lap times were reduced to 42.7 and 43.82 for Regan and I, respectfully. Regan felt the best correction to the binding chassis was to loosen it up by loosening the front bumper and floor pan, which were currently tight. With the hard club tires the front needs to be free to work because the force put into the chassis is greatly reduced from that of a national level sticky tire. Track test number three. Sure enough, the binding issue was greatly reduced and the kart would stay planted without releasing at the center out. This made it much more predictable to drive in the low speed right hand corners. Lap times stayed similar but the kart was now more driveable. We were both still concerned with the high speed traction of the kart and the fact that it wanted to lose the back end so easily. I suggested adding caster to increase the mechanical weight jacking and give the rear more bite. Regan suggested was that he would rather do that as a last resort and use the dynamic cornering forces of the chassis to correct the problem. Adding caster does increase the weight jacking effects of the chassis, but it can cause the kart to get tight or not be as free rolling in the corner. the chassis or tire to flex into the corner much. The goal is to utilize as much of the tire as possible, maximizing the contact patch on the track. The wear pattern on the tire definitely proved this theory; only about 75% of the front inner tire was used. The tires can tell you a lot about a set up so pay attention to them after every set up change. The toe was reduced to zero because the chassis was new and the steering components were still tight. If the front end components were a little loose, Regan then suggested going out to the 1/16 setting to keep the kart from wondering. With the new front alignment the corner weights were then rechecked. As suspected, the cross was considerably off and probably contributed to the differences in the right to left cornering characteristics. The current cross was now 55%! It is normal for a new chassis to take a set after it is out on the track. It makes sense that things like spindles, chassis stress, floor pans and bumpers all will free up and fall in position when twisted on the track the first couple times. Also, the changes to the front geometry could have affected this some. Track test number two. On the track the kart felt much more balanced. The right and left turns felt predictable. My observations for this round were that the kart felt tight in the right-handers and ABOVE: Knowing and recording your lap times is essential to critiquing your on-track performance. A bystander and a stop watch will do just fine, but nothing is easier and more accurate than today s electronics. The Mychron 4 does a great job of displaying your lap times right on the display. Giving you the opportunity to instantly know where you are for that test session. These numbers can then be just written down or downloaded into their analysis software. The rear cassettes on this chassis were adjustable; to balance the cross it was just a matter of adjusting the height of the left rear while on the scales with the driver in the seat. Throughout our testing the kart was a little loose in the back and low on traction. To aid in weight transfer the rear tires were moved in.5. This proved to tighten the kart up and give it a more predictable feel for the driver. SEPTEMBER 2008 800-942-0033 WWW.NKN.COM NATIONAL KART NEWS 47

To tighten the chassis up we moved the rear tires in to get better weight transfer to the rear tires. I was always told to look at a chassis as triangle when looking at it from the rear, with the head of the driver being the top point and the rear tires being the lower corners. Moving the rear tires in allows the triangle to more easily tip to the outside of the corner adding traction to that wheel and tightening the kart. Moving the driver up would also have the same affect because it is increasing the height of the upper point. Lowering the driver or moving the tires out would have the opposite affect. For this session we moved the rear tires in about.5 inches on each side. Obviously, as the rear tires are moved in the kart becomes more prone to tipping so make adjustments in moderation. We had an exhaust mounting failure in our testing session. In my previous article I stated that if something goes wrong you have to learn from it to improve your racing. This was an obvious case of an insufficient bracket (I knew better). But, if you don t fix the issue, i.e. come up with a better bracket, it is just going to happen again! You have now recognized that the failure was a weak point and a corrective action must be taken. Track test number four. The kart responded accordingly to the tires being moved in. It seemed to help the overall traction of the kart and definitely helped with the high speed stability issue. Now the kart was more planted to the track and could really stick the corners. Overall, it was really coming around and both of us were feeling more comfortable with it. Ultimately, the kart was still a little low on track bite though. Granted, the Bridgestone YDS club tires are very hard, Regan s years of experience with these tires lead him to believe we could still do a little better. To help the transfer of weight we added the rear torsion bar to the kart. COYOTE TRACK TEST This has the affect of stiffening up the rear of the chassis and transferring more of the weight jacking effects through the kart. Track test number 5. At this point we were still moving in the right direction. The kart tightened up some, but that was what we were looking for. The bite to the track increased with the rear bar in the chassis and now allowed us to flat foot turn one without fear of losing traction on the center off. With this setting Regan laid down a 42.49 second lap which is well below the current track record! My best time for the day was a 43.7 second lap which was a second below what we started with. Looking further than just laps times though the kart was much more predictable which when in traffic is everything. Now with confidence, I knew what it was going to do when racing and would have options with my passing lines. Unfortunately, Mother Nature got the better of our testing session and a wet track cancelled any further testing. Nonetheless, the day was a success, we came to the track with a kart that definitely needed improvements and left with it running under the current track record for the season. Now that we drove it, we also got some ideas for some updates that we can do to finish the kart off. For the first time at the track we couldn t have ask for much more. It must be taken into consideration that Regan s help greatly increased SEPTEMBER 2008 800-942-0033 WWW.NKN.COM NATIONAL KART NEWS 49

STORY COYOTE TITLE TRACK TEST Mother Nature called our testing session short. Rain late in the day made us pack it up. But, not before Regan ran a couple laps under the track record for the year. My times still had some to be desired, but the chassis and motor were in tune. Next up is driving lessons! our ability to get from point A to point B with our set-up because of his vast knowledge not only with the Coyote chassis, but also the tires and track. The point to get from this though is the procedure for working towards the proper set-up. Track test the kart, form a specific opinion on the handling of the chassis, look at the logical chassis adjustment to help correct the condition (see side bar), and only make one change at a time. Then record your results and lap times for each track session and then move onto the next change. Before long you will have a log of the effects that each change presented along with a feel for the resultant change of each. Then in the future when track and chassis conditions change you have a good idea of what to go after. One other suggestion is to keep information available to you at the track. Print off set-up information from the manufacturer and your favorite forums and have them to reference if needed. If your favorite karting magazine has articles that are relevant to what you are doing post mark the pages and keep the magazines with you. For instance a couple months ago NKN did an article on tires, and how they should look and respond on the track. This is a great example of something you could easily reference at the track. Don t try to reinvent the wheel, do your best to learn from what others have in the sport. This is the fastest way to, well, getting fast. Next issue we will look at some of the updates we can do to our sprint chassis to not only make us more competitive, but also make it look better. Stay tuned! 50 NATIONAL KART NEWS 800-942-0033 WWW.NKN.COM SEPTEMBER 2008