Chassis Tuning – Page 1

No Goats Racing - Chassis Tuning – Page 1 • Adjust left front and right rear to get - 1/4” increments you in to the corner. Move left front wheel 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 toe 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 pressure 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 tire 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 weight transfer Move right rear wheel in Softer compound for more traction 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 tires 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 wheels 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 bumper Move rear track in Increase frame flex Adjust tire pressures 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 abrasive 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 turning radius, 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 rolling resistance 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.

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