Tech Tips/Software: Click Here for some Sample Software.
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| Scuffing tires. Never over inflate, Inflate to 25-PSI max. Inflate to running pressure. Run just fast enough to stay in groove. NEVER run new tires out of groove. Run at 85% speed for 2 laps, then slow down to warm up pace for 1 lap then return to pits. Quickly check temp, size and pressure. Log all data on your chart. If properly inflated and sized correctly when purchased, tires will come to size by this procedure. |
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| Changing wheel offsets can greatly affect a racecar. By changing wheel offsets, you can change the left-side weight bias in the car, add or subtract side bite and change track width of the car. The relationship of the right-side wheels to each other effects how a car drives off the corner. If the right rear is inside the right front, the car tightens; if the right rear is outside the right front, the car loosens. If you need more side bite, you can move the right rear in, which causes the weight to transfer more quickly to the tire. Moving the left-rear out will cause the rear end to drive toward the infield, thereby tightening the car. Keep in mind, however, that when changing wheel offsets, you also change wheel weights, so you must compensate by readjusting your corner adjustments. | ||||||
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| The Logical progression of trouble shooting should be as follows: Start at the corner entry, then the Apex (midturn), corner exit, and then finally the shoot (straight away). | ||||||
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| 50 to 100 LB in the front, 25 to 50 LB in the rear, MAXIMUMS USUALLY STIFFER ON the RIGHT. If the car is Tight on the exit , go heavier on the left front. |
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| Proportioning Valve: Install so the right front brake can be reduced. Car will tend to turn into corner when braking. Break Bias: PUSH (more rear) LOOSE (more front) Unlocked Rear: A push or loose condition under braking can result (PROPORTIONING VALVE OR DIFFERENT SIZE CALIPER ON ONE SIDE TO CORRECT PROBLEM). |
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| High rear weight % can cause entry and exit PUSHES and LOOSE in middle of turn. Excessive left rear bite can cause entry looseness (due to left rear getting more traction under braking, causing the car to turn). This may also cause looseness on exit. If so, Try reducing rear cross weight. If significant change in rear bite is necessary SPRING/SHOCK changes may be first. |
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| Raising the front makes tighter corner entry. 90/10-type mounted with more than 10 degrees down in front, can cause a loose cond. |
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| Torque arm length depends on rear weight percentage plus wheelbase length. If the torque arm is too short and the rear weight percentage is too small, the rear of the car will lift when the driver stands on the gas. The correct approach is to have a torque arm length that falls about 7 to 8 inches behind the horizontal center of gravity. This horizontal C.G. can be computed by multiplying the wheelbase by the front weight percent. The rule of thumb is the larger the rears weight percent the shorter the torque arm, because the horizontal C.G. is located further behind the front wheels. For example, 53 to 50 percent rear (42 inch arm), 58 to 54 percent (36 to 38 inch arm), a Short track with traffic use (32"TO 38"), a long track with sweeping turns use (38"to 44"). Generally moving the panhard bar from the right to the left of the chassis will cause tighter corner entry, as will running the panhard at a downward angle to the right. Weight transfer, balance, spring rates and percentages are the key. (the process is to make both rear tires pull evenly and at there max determine forward bite.) |
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| It takes little camber to place a racecar's rear tires flat on the track, even with large amounts of stagger. The formula for bias-ply tires is: STAGGER DIVIDED BY THE CONSTANT 6. THEN DIVIDE THAT NUMBER BY THE PRODUCT (multiply the two numbers) OF THE CONSTANT, .017, AND THE DISTANCE BETWEEN THE POINT OF SPINDLE CAMBER ON EACH SIDE OF THE CAR, AND YOU WILL GET THE NUMBER OF DEGREES OF SPINDLE INCLINATION NEEDED TO PLACE THOSE TIRES FLAT ON THE GROUND. FOR A TYPICAL REAR END WITH SIX INCHES OF STAGGER AND 48'' BETWEEN THE CAMBERED POINTS OF THE AXLE, 1.2 DEGREES OF CAMBER IS NEEDED ON EACH SIDE. HALF OF THAT IS ALL | ||||||