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SportTrac Discussion
General Sport Trac Discussion
Vehicle Speed Sensor Location ('01, Job 1, 4WD)
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<blockquote data-quote="Dan Long" data-source="post: 752533" data-attributes="member: 65387"><p>I don't think you understand the concept of this, no offense.</p><p></p><p></p><p></p><p>If you change your tire diameter or rear end ratio you will change the RPM's required to attain any given speed. Using a 4.10 gear, your driveshaft will spin 4.10 times for every 1 time your tire spins. Using a 3.73 gear, your driveshaft will spin 3.73 times for every 1 time your tire spins. Therefore, the 4.10 gears means your motor must turn faster to go the same speed.</p><p></p><p></p><p></p><p>If you change your tire size to a larger size, one revolution of the tire will cause your truck to roll farther, effectively lowering the rear end ratio, and lowering the engine RPM at any given speed. The opposite goes for changing to a smaller tire size.</p><p></p><p></p><p></p><p>The sensors are simply measuring either how fast the output shaft (drive shaft) is turning, or how fast the axle shafts are turning. If measured at the output shaft, the computer must know what gear ratio is in the rear end and what the tire diameter is to calculate how far one revolution of the driveshaft will move the truck. If measured at the axle shaft, the computer only needs to know how big the tire is to calculate distance moved for each revolution because the gear set has already multiplied the driveshaft rotation.</p><p></p><p></p><p></p><p>The VSS sensor is only telling your truck how fast the speedo should read. The RPM's are measured at the engine. Unless your speedo is accurate though, you don't know exactly how much difference you have in RPM at any given speed. The VSS also contributes to when your tranny shifts based on speed and throttle, so you want to have it reading correctly.</p></blockquote><p></p>
[QUOTE="Dan Long, post: 752533, member: 65387"] I don't think you understand the concept of this, no offense. If you change your tire diameter or rear end ratio you will change the RPM's required to attain any given speed. Using a 4.10 gear, your driveshaft will spin 4.10 times for every 1 time your tire spins. Using a 3.73 gear, your driveshaft will spin 3.73 times for every 1 time your tire spins. Therefore, the 4.10 gears means your motor must turn faster to go the same speed. If you change your tire size to a larger size, one revolution of the tire will cause your truck to roll farther, effectively lowering the rear end ratio, and lowering the engine RPM at any given speed. The opposite goes for changing to a smaller tire size. The sensors are simply measuring either how fast the output shaft (drive shaft) is turning, or how fast the axle shafts are turning. If measured at the output shaft, the computer must know what gear ratio is in the rear end and what the tire diameter is to calculate how far one revolution of the driveshaft will move the truck. If measured at the axle shaft, the computer only needs to know how big the tire is to calculate distance moved for each revolution because the gear set has already multiplied the driveshaft rotation. The VSS sensor is only telling your truck how fast the speedo should read. The RPM's are measured at the engine. Unless your speedo is accurate though, you don't know exactly how much difference you have in RPM at any given speed. The VSS also contributes to when your tranny shifts based on speed and throttle, so you want to have it reading correctly. [/QUOTE]
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SportTrac Discussion
General Sport Trac Discussion
Vehicle Speed Sensor Location ('01, Job 1, 4WD)
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