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gearing for THR


Mark Pinson

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I'm going to be running with the pro sedans at THR. I have a full tube chassis car with a tire roll out of around 72. I was wondering what final gear most of the guys are running. I would like to limit my rpm's to 7800 or so

Best guess for overall if the motor combo is in the ballpark, 6.5 - 6.8. The Hoosiers run 68.5-71 for the short and 70.5 - 72.5 for the tall so figure your average rollout closer to 71 with the correct stagger and air.

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I'm going to be running with the pro sedans at THR. I have a full tube chassis car with a tire roll out of around 72. I was wondering what final gear most of the guys are running. I would like to limit my rpm's to 7800 or so

Best guess for overall if the motor combo is in the ballpark, 6.5 - 6.8. The Hoosiers run 68.5-71 for the short and 70.5 - 72.5 for the tall so figure your average rollout closer to 71 with the correct stagger and air.

when you say 6.5 -6.8 what are you saying. I use to run at redriverspeedway and it's a 1/4 mile track. I ran a final gear of 6:42 and i ran around 7800 to 8000 rpm's

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From the cars I have worked with and the gear they each run, I figure a top speed on the rear straight at ~80 MPH. Using that as a guideline, that would be something like running a 2.14 second gear with a 3.08 rear (6.59 overall) and turning 7843 on a 71 inch tire.. Now a 6.42 would put you at closer to 82 MPH and that would be one damn fast 1/4 mile track... We normally run a gear around 7.53 for a 1/4 turning 8200.

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From the cars I have worked with and the gear they each run, I figure a top speed on the rear straight at ~80 MPH. Using that as a guideline, that would be something like running a 2.14 second gear with a 3.08 rear (6.59 overall) and turning 7843 on a 71 inch tire.. Now a 6.42 would put you at closer to 82 MPH and that would be one damn fast 1/4 mile track... We normally run a gear around 7.53 for a 1/4 turning 8200.

cc speedway . mustang 214 .343 pinto 198 .355 .7600 . 8000 .. 1991 pops ran 214 .308 at cc .track to short for that gear but he won the championship with it .aboult 7200 to 7400 .lap times got down to 1630s.. tire 71 to 73 .goodyear text tires .

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Redriverspeedway is a 1/4 track with 11 to 12 degree banking in the corners. The lap times vary according to rules which is part of there problems. At 2000 pounds are lap times were around 14.6 according to the lap timers. When they made us weigh 2300 pounds are lap times went to 15.1. Now this was the tube chassis car's with 2300cc engines. The framed cars(pintos, mustangs, and so on) ran 15.6 to 16.0 according to the stop watch which is not that accurate. When i ran a pinto i ran a 6:67 final gear at 7200 rpms with a lap time of 16.0. My tube chassis car at 2300 pounds with a 6:42 final gear at 7800 - 8000 rpms ran a 15.00 to 15.10. The tires on both cars were the Hoosier's with 71 inch roll out. I'm guessing my final gear at THR will be around 5:50 to 5:80. What do you guy's think? By the way i appreciate the help. And can't wait to run with you guy's. I ran one race at thunder hill a couple years ago and had a blast.

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