Best Gear Ratio For...

<HR style="BACKGROUND-COLOR: #d1d1e1; COLOR: #d1d1e1" SIZE=1 itxtvisited="1"> <!-- / icon and title --><!-- message -->
<!-- BEGIN TEMPLATE: ad_showthread_firstpost_start --><!-- END TEMPLATE: ad_showthread_firstpost_start -->Ok , this is the set-up; flathead 175-200 HP, mated to 4 speed tranny with the following gears; 4.02, 2.41, 1.41, and 1.0. So the question is anyone have similar gearing, if so what's your rearend gear ratio? What's your RPM at 60 MPH? Share your experience, what do you think would be the best gear ratio, Thanks.

This is all going in my 51 f-1.

 

How talls your rear tire? Say its around 28" tall, and you stick a 3.00:1 gear in the rear, slightly over 2000RPM will put you at 60mph...

 

A simple formula for you to consider -
MPH,times trans ratio,times rear axle ratio,times 336 =
divided by tire hight = rpm

So for my car it would look like:
75mph, times .68 overdrive ratio, times 3.23 rear axle gear, times 336 =55349.28
divided by 26.6 tire hight = 2080 rpm at that speed
that's the best formula i've found for rear gear ratio calculation, and it's pretty damn accurate. Just figure out a comfortable rpm at cruise speed for you and plug in gear ratios until you find what you want.

 

or if you are too lazy for a calculator or Google,
http://www.richmondgear.com/101032.html

 

I've got a calculator, anyone with real world experience with this gear combo. Tires are 28.9.

 

Since you have the calculator, what's the question? What R.P.M. do you WANT to be running at 60 m.p.h. (or 65 or 70?). Your Flathead will be happiest running somewhere near it's torque peak-like 2200-2500 R.P.M. so gear it accordingly. Mine's happy with a 3.78 gear and 29 " tires

 

2500 rpm @ 65 mph w/28.9" tires = 3.31 gears sounds good to me.

 

my 264 inch nailhead pulls a T-5 and a 300 gear with a 26 inch tall tire . Benton Tennessee is a speed trap on hwy 411 and I can pull 5th at 35mph going through there. And it'll run 80 too

 

If you have a 4.02 1st gear you should be happy with a 3.0 or so rear set, I run a 3.0 rear with a blown 8ba, C4,and a 36 PU with 30" Rear wheels and am really happy with it. Used to run a 36 sedan with a Sag 4sp with 3.11 1st gear and was never really happy with 1st always wanted a T56 with 3.36 or T10 with a 3.44 or anything anything taller than the 3.11, it was not very happy off the line. Espically with the heavier sedan.
The PU cruises at 65 to 70 at around 2200 and goes way up from there

 

I thank you all for your comments.