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No Goats Racing - Tuning – Page 1

• Adjust left front and right rear to get - 1/4” increments you in to the corner. Move left front out • Adjust right front and left rear to get Move right rear wheel out 1/4” at a you out. time • Adjust stagger for the middle. Move left rear wheel in • Push (tight) means too much rear Move rear track to right bite. Increase left side weight • Loose means too much front bite. Decrease cross weight • If you’re pushing, move the seat Decrease rear weight percentage forward. Increase front weight in .25% • If you’re loose, move the seat increments backward. Move seat forward • If you have right front camber of -2.5 Check out and go to -3.0 what is the affect? If the kart was tight, the kart will now Tight in center of corner be freer. If the kart was right, it will Increase air in the left front now be loose. 1/2 lb. at a time Move left front out 1/8” - 1/4” at a Track Conditions time Cool, wet, soft tracks normally like Reduce air pressure in the right front lower left side weights as 1/2 lb. at a time well as lower cross weights. Increase air pressure in the left rear Harder fast track conditions and right rear 1/2 lb. at a time normally yield higher corner Try the same compound on a force, which requires more left narrower wheel. side, and / or more cross. On flat track: Pushes leaving corner Less rear percentage Decrease right front camber More left side percentage Increase left front caster On banked track: Increase nose weight More rear percentage Decrease cross weight 1/2%-1% Less left side percentage increments Harder left rear compound Pushes entering corner Harder right rear compound Understeer - Too much rear end grip Decrease front stagger Increase left front camber (more Move left rear wheel out 1/4”-1/2” positive) increments Increase right front caster Move right rear wheel out Decrease front track Move rear track to right Decrease right front stagger Increase rear stagger Softer right front compound Increase right rear air pressure Harder right rear compound Widen the front wheel width Wider right rear wheel Stiffen rear of chassis Decrease right front air pressure Increase air in left front Increase right rear air pressure Increase air in right rear Increase right rear stagger in 1/8” Decrease air in right front No Goats Racing - Chassis Tuning – Page 2

Decrease air In left rear Move right rear in as close as The change that’s making the possible difference is a reduction in cross weight. These changes Loose leaving corner either decrease left rear - right Too much front end bite front loading, or increase left Increase right front camber (more front - right rear loading, all positive) resulting in lower cross. Decrease left front camber Decrease right front caster Loose entering corner Softer left rear compound Oversteer - Too much front end grip Move left rear wheel in 1/4”-1/2” Rear is loose increments Decrease nose weight in 1/2% - Move right rear wheel in 1% increments Move rear track to left Increase rear weight Increase cross weight 1/2%-1% Increase cross weight increments Decrease left side weight Increase rear weight percentage Decrease left front camber (more Decrease right rear tire pressure negative) Increase front stagger Less right front camber (more Decrease rear stagger positive) Raise center of gravity Decrease left front caster Raise rear of kart Increase right front stagger Decrease rear stagger in 1/8” - 1/4” Very loose or four wheel drift increments Decrease left side percentage Move right front wheel out Increase cross weight Move left front wheel in Raise seat for more Move right rear wheel in Softer compound for more Move left rear wheel out Softer right rear tire compound Move rear track to left If softer compound unavailable use Move seat back new uncut over cut tires Raise center of gravity Decrease right front tire pressure Harder right front tire compound Decrease right rear tire pressure Decrease right rear tire pressure Decrease right rear stagger Softer right rear compound Reduce air pressure all the way Narrower right rear wheel around (same amount each Stiffen front of chassis tire) Check toe out Move front and rear in If you start out with this condition Loose in center of corner and are 10” wheels, go to 9.5” Decrease air pressure in left front Increase castor on both right front (1/4 - 1/2 lb. at a time) and left front in equal Move left front in (1/8” - 1/4” at a increments time) Increase air pressure in left rear and right rear (1/2 lb. at a time) No Goats Racing - Chassis Tuning – Page 3 No grip in corners Wider rear tires Other karts are faster in corners Softer compound in rear Too little grip/speed too fast Higher air pressure in front Too much slide Lower air pressure in rear Loss of time in corner Move weight to rear Raise seat Decrease stagger Move front track out Loosen rear Move rear track in Increase frame flex Adjust tire Pushing (understeer) Bogs down in corners Narrower front track Unstable, hops and loss of time Wider front tires Too much grip Softer compound in front Right rear tire overloaded Wider rear track Move front wheels out Narrower rear tires Move right rear wheel out Harder compound in rear Move rear track to right Lower air pressure in front Increase front and rear stagger Higher air pressure in rear Increase left side weight Move weight to front Lower cross weight Increase stagger Increase rear weight Tighten rear bumper Lower seat Decrease frame flex Increase right side air pressure Harder tire compound Bite: Front, left, cross weight To increase bite: Much slower in the straights Increase nose weight Gear ratio too short Decrease left side weight Wrong driving line in previous corner Decrease cross Take off a few teeth To decrease bite: Evaluate driving line Decrease nose Check carb settings Increase left side weight Increase cross No short distance acceleration Tight kart has more rear grip Gear ratio too tall than front Wrong line in previous corners Loose kart has less rear grip Evaluate driving line in corner than front Add a few teeth Stiff chassis is tight Check carb settings Stiff chassis transfers more Check kart setup weight Flexible chassis is loose Loose in the rear (oversteer) Flexible chassis transfers less Wider front track weight Narrower front tires Harder compound in front Narrower rear tires No Goats Racing - Chassis Tuning – Page 4 Tires If your tires are gaining .7 to .8 Sidewall: through a run and level off in Stiff sidewall for hard track the last 5 laps, your compound Soft sidewall for soft track is right but your chemical is Screwdriver test: not aggressive enough Blade all the in track = 22 Blade in 1/2” = 33 If your tires are still picking up at the Blade in 1/4” = 44 end of the run, you have too Hardness: much compound Hard tire for track Soft tire for not abrasive track If your tires feather but don’t fall off Air pressure: on the clock, you have the Less available grip = less air right compound but to much More available grip = more air chemical Rear stagger: Pushes rear of kart in corner If your tires feather and fade on the Tighter , more clock, your compound is too stagger soft Wider turning radius, less stagger When the kart is locked down to the Front Stagger: track or your tires are showing Controls weight transfer across signs of wear, they are too soft front of kart Less stagger = quicker transfer If you time other classes when you’re More stagger = slower transfer not racing and the track is Increase or decrease weight getting quicker, it is time to go percentages with tire pressure to a harder tire Very little changes required in tire pressure and stagger as small If the track is getting slower, as 1/4 lb. to 1/8” stagger to it’s time to go to a softer tire notice performance change Let air out of mounted tires after Durometer readings from Burris racing. When air is left in The durometer readings below are mounted tires they will grow taken with a lab grade larger in diameter especially in durometer at 70 F with 20 psi warm and/or sunny locations. in the tire SS-55 = 62 - 64 A properly treated tire SS-44 = 54 - 56 compound will show SS-33 / DXA = 50 - 52 grain but no feathering/ SS-22 / DXB = 42 - 44 shredding. It will pick SS-11 / DXC = 32 - 34 up .3 to .4 in 5 to 7 laps and maybe another Air pressure .1 through the run Higher air pressure loosens chassis: Less bite (looser) Same effect as harder No Goats Racing - Chassis Tuning – Page 5

compound is increased. Tire wears in center Front stagger: 1 1/4” to 2” Lower air pressure tightens chassis: Rear stagger: 1/4” to 1” More bite (tighter) Starting point: Reduce loose condition Front: 1 1/2” Same effect as softer Rear: 3/4” compound Rear stagger helps kart turn Tire wears on outside edges Increase rear stagger for tighter The bigger the split, the freer your turns kart. Decrease rear stagger for wider, more Left: 4-10 lbs. sweeping turns. Right: 5-12 lbs. Too much stagger can create too high inside tire temperatures Higher air pressure Too much rear stagger causes a Left front: scrubbing effect and increases Helps kart turn in center of corner Front stagger is commonly Right front: increased or decreased to Less turn at the center of change cross weight corner Increases in front stagger will create Left rear: more negative camber in both Loosens from center of corner wheels out Right rear: Balancing tires Less bite at center of corner Mount tire on the balancer and let it and exit roll to a stop. Mark a spot on the tire 180 degrees Lower air pressure from the heavy spot. Left front: Estimate how much weight it will Less turn at center of corner require to balance. Right front: Tape weights in place using duct Turn better at center of corner tape. Left rear: Rotate tire until the weight is at Tightens from the center of three (or nine) o’clock and corner out observe which direction Right rear: it wants to rotate. More bite at the center of If the weight wants to rotate back to corner and exit 12 o’clock. add more weight. Stagger If it wants to rotate to 6 o’clock, take Rear stagger is used to make the some off. left and right rear tires Do this until you can rotate the tire correspond with each other so to three or nine o’clock and let the castor doesn’t have to it go and there is little or no completely lift the left rear. movement. The kart will want to turn left Peel off the adhesive strip and at a greater degree as stagger permanently attach the No Goats Racing - Chassis Tuning – Page 6

weights to the wheel. front bite more (push less) Place duct tape over the weights for Wide rear track is loose safety. Wide track transfers less weight Stretching tires Narrow rear track is tight To stretch start with more air, first Narrow track transfers more 30 to 40 psi for an hour and weight if that doesn’t work about 60 psi for longer (up to days). Take Left front (Timing) it slow, try not to overshoot. Increase air pressure: After you get them sized, check Frees chassis at apex them every few days to make Increase camber: sure they haven’t moved. If Starts rotation sooner they do, work on them some Increase caster or move wheel out on more. You need to check them spindle: each week. Speeds reloaded chassis center off Front track Raise spindle & reset cross: If kart is not turning into the corner Slows weight transfer across properly: the kart Widen the front on each side to Tire choice: reduce the front end slide Determined by track (understeer) causing the conditions to be more direct. Controls amount of left front use Narrowing the front track will make the steering less responsive. Left rear (Timing) Wider front track is tight Increase air pressure: Wider front track steers harder Reduces and Wider front track transfers less slightly decreases stagger weight Move out on : Wider front track makes rear Slows rate of transfer bite more Frees kart coming out Narrow front track is loose Tire choice: (more bite) Determined by track Narrow front track steers conditions easier Controls amount of left rear use Narrow front track transfers more weight Right front (In charge of turning) Narrow front track makes rear Increase air pressure: bite less Decreases front grip on entry Rear track Increase camber: Move rear wheels in for more grip Controls contact patch across Moving rear wheels in will make front the tire bite less (push more) Increase caster: Move rear wheels out for less bite Controls amount of weight Moving rear wheels out will make transfer to right front No Goats Racing - Chassis Tuning – Page 7 Pull out on spindle: Small wheel circumference Reduces amount of weight Left front: transfer to right front Smaller will increase the cross Raise spindle & reset cross: weight which effects kart Increases rate of weight ability to turn in and exit transfer across front of Right front: kart Less turn into the corner Tire choice: Helps keep kart behind you Determined by track Keeps kart from becoming conditions loose in rear Left rear: Right rear (In charge of rotation) Turns better into corner Increase air pressure: Helps from getting push in Decreases contact patch middle of corner. May change stagger Right rear: Move out on rear axle: Tightens kart entering into Decreases weight transfer to corner right rear Tire choice: Large wheel circumference Determined by track Left front: conditions Will decrease cross weight Right front: Wheel placement Tightens kart, increase cross Moving wheel out from frame: weight Left front: Left rear: Helps turning in center of Less turn into corner corner Rear tight Right front: Too much could cause push Increase in cross weight speeds steering. Bearings Left rear: Worn bearings at the spindles or Less bite hubs in the front end can Frees it up off corner affect castor / camber and the Right rear: overall handling of the chassis, Less bite in center of corner it can mask a problem that no Moving wheel into frame: changes will cure. Left front: Neglected rear axle bearings can rob Tightens from center out the engine of horsepower that Right front: could be sent to the rear Slows steering reaction wheels instead. Left rear: Tightens from center of corner Toe in / toe out out Vital to the driveability and speed Right rear: on the straightaways More bite in center of corner A scrubbing front track will make the tires heat up faster No Goats Racing - Chassis Tuning – Page 8

and diminish speed weight off of that corner and when driving straight. the left rear corner. Toe settings from 1/16 to 1/8 of an inch out seem to be adequate Ballpark left rear weight and help the kart turn in To come up with a ballpark left quicker. rear weight, multiply right weight x left side%. This is how Cross much your left rear should Moving rear axle down toward track weight. Adjust cross to get raises chassis up = raises there. cross Move rear axle up to decrease cross Camber 1 turn of rear screw = 1 percent After finding your setup numbers, change in cross paint the top flat of the Lower right front spindle to increase camber nut for reference when cross making changes. One flat = Raise right front spindle to lower approximately .1. cross Changing camber on RF Lower left front spindle to decrease Yellow on top flat = -2.5 cross Turn outer nut toward back for Raise left front spindle to increase more negative camber. cross Turn outer nut toward front for Increase front stagger to increase more positive camber. cross Changing camber on LF Check toe and camber after Yellow on top = + 1.2 changing washers Turn outer nut toward back for more positive camber. Low cross low stagger setups work Turn outer nut toward front for good for long hairpin tracks more negative camber. - tracks where you can make Caster up more time on the straights More caster (both sides) will make than you can in the corners. the front end jack more weight and thus, make it grip harder. Say 50% is neutral. If you put the left front down = more weight Less caster (both sides) will make on it, that will lower cross. the front end jack (transfer) That puts less weight on the less weight and therefore, right front. That would be the make it grip less (tend to same as raising the right front. push).

If you raise the right front you will More caster split (more in right front take pressure off of the left than left front) will make the rear. kart want to turn into the corner on its own. If there is Raising the right front will take too much caster split in the No Goats Racing - Chassis Tuning – Page 9

center, the kart may want Cross weight 53 - 54 % 59 - 65% to push because the left front Front 44 - 45 % 44 - 46% isn’t de-wedging the kart enough with respect to the Nothing can work correctly without proper right front to free up the left percentages, settings and a well-balanced rear. chassis. Your first successful race starts on the scales, the information you obtain Less caster split will make the kart on the scales is directly related to your more responsive to driver success on the track. Notes should be input getting in and in the taken at this time using different air center but may either A) make pressures and how it will change the cross the kart too twitchy or B) weight. Front to rear and left to right make the kart bind up weight has to be changed by moving the because its not wanting to seat or moving added weight. travel the corner radius as much on its own. Although driver comfort is first, close attention to the VCG (vertical center of A good rule of thumb for caster split gravity) is important. The VCG is changed is 2 degrees. Some by the seat height and can effect the manufacturers run dynamic weight transfer while cornering. more but, with the high cross A higher VCG will require a higher left side weights being run these days, percentage most of the time to control side the right front is so much more bite of the right side tires. A lower VCG pre-loaded than the left front has the opposite effect. that more caster split isn’t generally needed to get the Gearing Info front end to turn left on its Gear ratio is rear sprocket divided by own. driver. It multiplies the engine’s by the ratio and divides Too much caster split is worse than the axle speed by the ratio. not enough as it will tend to make the kart want to be The higher the number in the ratio, pushy lazy getting in and the more torque (acceleration). through the center of the A 5.00:1 ratio has more torque corner. than a 3.00:1 ratio

Rule of thumb: 2* split. Never The smaller the number, the higher run less than 8* on the right the potential top speed. A front (high biting track) or 3.00:1 ratio will go faster than more than 13* on the right a 5.00:1 ratio at the same front (low biting, slow track). engine rpm.

Starting point percentages The bigger the driver with the same Low cross kart High cross kart gear ratio, the more inertia the Left side 55 - 56 % 54 - 55% kart will have. It will resist No Goats Racing - Chassis Tuning – Page 10

acceleration more than should end up with more top the smaller driver but will also end resist deceleration. Lead weight positioning 1 tooth on the driver = 3-5 teeth on Fit lower down for bigger driver and the rear sprocket, depending higher up for small driver on where you are on the ratio Heavier driver should secure weight chart. to sides of the seat to keep the kart balanced Larger driver = higher top speed, but Mount weights more toward front harder to get up to speed for better front end grip, and to back for better rear end grip Smaller driver = more pull off corner, In the wet have the weight as high as but less high speed possible to achieve better grip all around Smaller driver = more RPM Jetting Larger rear gear = more RPM The main jet affects the carb at all RPM’s. After selecting the Larger rear gear = more pull off correct jet (48-50) adjust corner performance with EGT. If not available use CHT to adjust 1 front gear = 3 rear gears with mixture screw. General rule of thumb: Add 1 driver gear to drop RPM Rich-out on mixture screw helps bottom end pulling Each rear gear = 100 RPM power Lean-in on screw helps top end 1 driver gear = 400-500 RPM max RPM’s. If track gets faster - drier - more Lean = higher CHT grip, drop teeth in rear and go Rich = lower CHT. up in air Shoot for 385-410 degrees If your engine cuts out at the end of If track gets slower - less grip, add the longest straight or appears gear in rear and drop air sluggish in the mid range, decrease the jet size. Larger track use a larger driver When the air contains more moisture (humidity), there is less oxygen Change rear gear to keep gear ratio to burn. Thus you need less 13 driver to rear = 4 to 1 fuel = smaller jet. 15 driver to rear = 4 to 1 adjustment If you are flat footing it, keep taking tension, lever weight and air some gear off the rear until gap affect the stall speed your lap times slow down. You or clutch . No Goats Racing - Chassis Tuning – Page 11

You need to know what RPM your Soak all of the remaining parts in engine produces its maximum acetone for 5 to 10 min. torque. This is the RPM at Blow the disks dry with clean air. which you want your clutch to Repeat the above a couple of times. engage. Remove all the contaminates Stiffer springs achieve higher stall possible. speeds (more clutch slippage). When reinstalling the clutch, put no Change the spring height by turning lubricant on the thrust bearing the bolt clockwise, which will and only enough grease on the increase the tension on the sprocket bearing to prevent it spring and raise the stall from locking up. speed. Use petroleum jelly. Don't use a hi- The more weight on a lever, the faster temp lubricant. The smallest it will engage the clutch. amount can get on the disks. The levers are controlled by the On the grid, put your foot on the springs. The more weight you and flat foot the put on the lever, the faster the for 5 - 10 seconds. Wait 1/2 a lever can overcome the rate of minute and repeat. Do this the spring and achieve lockup. 5 or 6 times, or until you start Fine tune the clutch by adjusting the to feel the clutch "hit" harder. springs or the lever weights. This process burns out the Air gap, measured with a feeler contaminates. gauge, is the distance between Repeating the process several times the clutch discs. brings heat slowly into the Air gap affects stall speed. The parts which prevents greater the air gap, the further distortion. Some smoke the pressure plate must travel coming off of the clutch during to compress the discs and is evidence of contaminates engage the clutch. burning off. Air gap has the least affect on the stall speed. What does a fast kart feel like? If the air gap becomes too great, the Bite clutch cannot fully lock-up and To get everything working you can chatter. have to get a good entry. Front must snap, almost to the Minimum air gap would be .030. point of being loose if the Maximum air gap .060. driver “yips” at the wheel Air gap .040" to .050" is ideal. to initiate weight transfer Use floater discs in various Weight must transfer pushing thicknesses to keep the desired the driver into the right air gap at a constant amount. side of the seat, loading the right side tires and Clutch cleaning unloading the left Remove clutch basket and sprocket Kart must not slide at the apex from the clutch. The may feel No Goats Racing - Chassis Tuning – Page 12

heavy How far is that? Flex and Pivot How is your kart compared to (some The driver should feel… specific kart)? The seat pushing hard Where is he faster than you? into your side Where do you think you are catching The left side unloading him? and moving up How does your motor feel? The right side loading Is it still getting faster when you’re and moving down into the corner or does it level The kart rotating at the off on the straightaway? apex Does it feel fast coming off the After rotation the steer corner? effort should go If you could be better at one point on down and the kart the track, where would it be? should begin to If you could change one thing about accelerate (the how it is driving what would it earlier after the be? apex the better Can you keep up coming out of the Center Off corner? Once the kart has navigated Could you drive under someone the apex at maximum getting off the corner if there speed and pivoted, you was a chance? have to get the best run possible off the corner. Some advice Randy Major and some The front end should still from Todd Godwin: remain positive www.dynamicsofspeed.com The left rear will begin to - Always start with a good baseline reload and the kart and don’t veer too far from it; you’ll should feel “alive” (as in always be faster in the end not flat or dead) - Never run a 2 lb split with tire The kart shouldn’t feel dead pressures (LR overworking) or - Don’t overanalyze things. Karting boggy (RR overworking) is very complex and most of the “conventional wisdom” answers are Questions to answer to make the wrong. A theory may seem logical but kart faster often the more logical solutions that How does the kart feel? people come up with are incorrect (I’ve Can you still drive it if it is freed up had about 3 tons of my own theories a little more, or does it feel like proven wrong because I simply didn’t the kart is ? have a good enough understanding); Does the kart feel faster at the if you truly want to understand beginning or the end? you’ll have to do lots of reading Did it get tighter or looser the longer (which isn’t too difficult) and you’ll you ran? need to work with one or two of the Do you have to turn the steering most experienced, best drivers in the wheel a lot or just a little bit? business (this is far more critical than No Goats Racing - Chassis Tuning – Page 13 all the reading) - Keep it simple, use as few adjustments as possible. With every adjustment there is just as great of likelihood that you’ll go the wrong way as the right

Please Note: I’ve accumulated this information from many different sources, many of them from Bob’s 4-cycle and other places on the Internet. I thank everyone who supplied this information for the use of us beginners in karting. Since the information came from many different sources, some of it may or may not be correct or may conflict with something else on the list. If something you change doesn’t work, try something different. Good luck!