Haven't had the chance to get to the track yet. I wondered if someone could give me an idea if the would be much change in in RPM'S from going from a 39' to a 3.55 gears. I have two tire choices that I will use. One being a street tire and another a Hoosier quick time tire. Check the diameter, the street tire is a 26 and the Hoosier is a 27. I've tried to use the RPM charts on different sites but they all require some additional info, which this time it's not possible to put the info in to get an idea. Mainly looking at street RPM'S at say 65 mph and quarter mile trap RPM'S. Car is a dart sport, stock 360 with 727. Thanks.
3.91 to 3.55
- Thread starter 75ddart
- Start date
-
Leadfoot
Jane Goodall of the N&P Forum
Real simple. Do everything as a percent as opposed to an actual number. (always) A 3.55 divided into 3.91 says it's 1.101 less than a 3.91 Therefore at a 1:1 final drive out the transmission there will be a 10% reduction in RPM at the same speed. Tires? Do the same thing with the diameter. There's a 3 percent variation between the two. So a 26" tire will add 3% to the RPM over a 27" tire. A 27" tire will reduce the RPM 3% compared to a 26" tire.
Woods74
Broke Senior
Poisendart74, I checked out that link, was pretty cool. I ran the different gears ect and not much of a difference at the different speeds enough to change out the center sections. Thanks that link was cool.
A simple formula is to take the mph X gear ratio / (tire diameter X 3). For example, 65mph X 3.55 /(26 X3) 78= 2484 rpm. 65 X 3.91 / 81 = 3137 rpm.
Woods74
Broke Senior
Keep in mind tire height, center hub to ground measurement, say if you have a 26" tire, after it's on the car it's closer to 25".
younggun2.0
Well-Known Member
Great post.....
-
