Ford Power Stroke Nation banner

1 - 4 of 4 Posts

·
Registered
Joined
·
100 Posts
Discussion Starter #1
Just bought a 2000 Dually with 215/85/16 tires and at 70 mph it turns around 2100 RPM. The guy I bought it from says it is a 3.73 rear, does this sound right?
 

·
Registered
Joined
·
100 Posts
Discussion Starter #3
Thanks for the confirmation.
 

·
Yeah, it's like that
Joined
·
2,419 Posts
You would have a 4R100 tranny with a final drive ratio of .71:1. 215/85/16 have a Dia. of 30.39" with a circumference of 95.425" which tells you that your tire has to rotate 663.98 times so at 60 MPH your engine rpm would be 1758 with 3.73 (663.98 x 3.73 x .71) or 1932 with 4.10 (663.98 x 4.10 x .71) Now we need to figure at 70. We have a known at 60 which is 85.7% of 70. So with 3.73 you would be at 2051 (1758/.857) or 4.10 would be 2254 (1932/.857)

You have 3.73 gears which is kinda odd for a dually at least every one that I have owned.
 
1 - 4 of 4 Posts
Top