{"id":3231,"date":"2014-02-06T14:56:56","date_gmt":"2014-02-06T22:56:56","guid":{"rendered":"http:\/\/www.racingjunk.com\/news\/?p=3231"},"modified":"2016-11-30T12:04:40","modified_gmt":"2016-11-30T20:04:40","slug":"loose-as-a-goose-part-ii-why-arbs-are-necessary-in-most-drag-cars","status":"publish","type":"post","link":"https:\/\/www.racingjunk.com\/news\/loose-as-a-goose-part-ii-why-arbs-are-necessary-in-most-drag-cars\/","title":{"rendered":"Loose as a Goose, Part II: Why ARBs Are Necessary in Most Drag Cars"},"content":{"rendered":"

\"ARB<\/a><\/p>\n

In the opening segment of our \u201cLoose As A Goose\u201d series, we looked at the math, which shows how much torque you could be dealing with at the starting line.\u00a0 And in some cars (actually, most race cars), it\u2019s truly massive.\u00a0 We also looked at something else that\u2019s critical — Engine Torque Reaction which is the culprit for rolling the car out of shape on the launch.<\/p>\n

But that\u2019s not all that is happening when you (a) side step the clutch (b) foot brake it and (c) slide your finger off the transbrake button.\u00a0 There are other forces at play here too.\u00a0 Some might surprise you.<\/p>\n

Inertia and Torque<\/strong><\/p>\n

Inertia is a big player in the launch game. Inertia is the resistance of any physical object to any change in its state of motion.\u00a0 Tough to grasp for our situation?\u00a0 Consider a drag car equipped with a manual gearbox:\u00a0 The crankshaft, flywheel and clutch can be spinning in excess of 6,000 RPM prior to launch (in some cases, well in excess of 6,000 RPM).\u00a0 Combined these pieces can weigh more than 150 pounds and they can store a big chunk of inertial energy.\u00a0 When the driver sidesteps the clutch, this stored energy is added to that of the engine to accelerate the car and create chassis roll.<\/p>\n

Obviously, if the spinning mass energy of the crankshaft-flywheel-clutch assembly is delivered too quickly to the drive train, the resulting torque can (and often will) break the tires loose.\u00a0 The result is [obviously] a poor ET. Or worse. That\u2019s why Pro Stock and Comp and other class racers regularly setup the clutch to slip for several hundredths of a second off the starting line.\u00a0 This allows the inertial energy to be fed more gradually.\u00a0 What about automatics?\u00a0 The torque converter is a fluid coupling device that basically multiplies torque at the launch (refer to the simple calculations we did in the beginning of this series).\u00a0 In a nutshell, a foot brake automatic can have more starting line torque (at least for a wee bit of time while it\u2019s still \u201con\u201d the converter) than a Pro Stock car. An automatic car leaving off the transbrake can have both high initial torque and some of the inertia hit of a stick shift car.<\/p>\n

So now you\u2019re fighting a couple of issues.\u00a0 In the photos that follow, we\u2019ll continue to examine the solution \u2013 a drag race ARB.\u00a0 And in the next segment, we\u2019ll take a close look at one more piece of the puzzle \u2013 rear end torque rotation.\u00a0 It\u2019s getting interesting!<\/p>\n