rpm versus speed.
Thread Starter
Drifting
Joined: Apr 2007
Posts: 1,339
Likes: 2
From: port charlotte fl
rpm versus speed.
According to my build data I have a 2.95 rear which seems strange as the car was set up for drag when I bought it.I am getting 31mph per 1000rpm. Does this compute?? 700R4 tranny.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
That would be a 2.59:1 gear ratio. 31 MPH per 1000 RPMs is 62 MPH at 2000 RPMs. In what gear? 2000 RPMs gets me 70 MPH in overdrive with 3.07 gears. You should be going faster, still, with 2.59 gears. The best way to know the ratio, for sure, without tearing it a part, is to jack it up and turn BOTH rear wheels EXACTLY one turn while you count the driveshaft revolutions. Pay close attention the fraction of a turn. The driveshaft turns equals the ratio. Three and a little under a half turns is 3.45:1. Three and a little over a half turn, is 3.54:1. It doesn't cost anything do repeat the procedure several times to be sure you got it right.
RACE ON!!!
RACE ON!!!
Thread Starter
Drifting
Joined: Apr 2007
Posts: 1,339
Likes: 2
From: port charlotte fl
That would be a 2.59:1 gear ratio. 31 MPH per 1000 RPMs is 62 MPH at 2000 RPMs. In what gear? 2000 RPMs gets me 70 MPH in overdrive with 3.07 gears. You should be going faster, still, with 2.59 gears. The best way to know the ratio, for sure, without tearing it a part, is to jack it up and turn BOTH rear wheels EXACTLY one turn while you count the driveshaft revolutions. Pay close attention the fraction of a turn. The driveshaft turns equals the ratio. Three and a little under a half turns is 3.45:1. Three and a little over a half turn, is 3.54:1. It doesn't cost anything do repeat the procedure several times to be sure you got it right.
RACE ON!!!
RACE ON!!!
Drifting
Joined: Sep 2005
Posts: 1,867
Likes: 3
From: Pasadena Maryland
http://www.nightrider.com/biketech/c...mulas_page.htm
Formulas for MPH RPM gears & tires
mph = (rpm x tire diameter) / (gear ratio x 336)
rpm = (mph x gear ratio x 336) / tire daimeter
gear ratio = (rpm x tire diameter) / (mph x 336)
tire diameter = (mph x gear ratio x 336) / rpm
Just thought maybe these might help?
Formulas for MPH RPM gears & tires
mph = (rpm x tire diameter) / (gear ratio x 336)
rpm = (mph x gear ratio x 336) / tire daimeter
gear ratio = (rpm x tire diameter) / (mph x 336)
tire diameter = (mph x gear ratio x 336) / rpm
Just thought maybe these might help?
