Alot Of Gearing Questions Lately. 3:16

Y

YAMMIEGOD3:16

Active member
Joined
May 30, 2004
Messages
6,343
Location
webster n.y.
SOME GEAR SPEED NUMBERS FOR YOU GUYS. NOW REMEMBER THIS IS ON PAPER.
19-40 - 84
20-40 - 89
22-40 - 98
23-41 - 102
23-38 - 110 ( 00-02 srx stock )
21-40 - 93
21-39 - 96
23-37 - 117
THESE FIGURES WERE USED OFF A FORMULA FOR MILES PER HOUR FROM MICRO BELMOT ENG I HAVE USED FOR THIRTY YEARS. ANYBODY NEED A RATIO FIGURED I CAN DO IT FOR YA.
3:16 (yammie tony)
 
Last edited:
TONY! When did you pick up a '93 SX, I want it!

Also, just to clarify,.. Were those numbers only run on your SRX...What would the numbers be for a Vmax4?
 
Last edited:
MOPAR1RULES , 105 mph.
CHRIS, SAME ON VMAX 4,s AND MARK AND I FOUND A 93 EXCITER SX ON HARRIS RD. LESS THAN 2 MINUTES FROM MY HOUSE. MARK OWNS IT NOW BUT I HAVE DIBS ON IT. HOPE ALL IS WELL. 3:16 (yammie tony)
 
You also must consider the rpm you are clutched for, the drivers you have, and the pitch of the track. Also most clutches shift out past 1:1 so you should consider that as well.

It really is simple math, nothing complicated to it. For a given rpm, pitch, and drivers you can figure out a Factor (one time) that you can simply apply to the gear ratio to get a theoretical mph.

P = track pitch in inches (2.52 is common)
T = number of teeth on drivers (8, 9 or 10 is common)
R = rpm at shift out (hopefully same all across shift range)

Factor = P * T / 12 (change inches to feet) * 60 (change minutes to hours) / 5280 (change feet to miles) * R

-or simply-

Factor = P * T * .00095 * R - - - (simple factor to change fpm to mph)

Figure the Factor for your sled once, and then simply multiply that factor by the top gear and divide by the bottom gear for theoretical 1:1 mph.

For Example:

Say you have a 2.52 pitch track, with 9 tooth drivers, on a sled that is clutched for 8300 rpm . . .

2.52 * 9 * .00095 * 8300 = 178.8318 this is your factor to use for all future gear calculations.

Then if you want to try 20/40 gears . . .

178.8318 * 20 / 40 = 89.4159 mph

or 22/38 gears . . .

178.8318 * 22 / 38 = 103.5342 mph

Notes: be sure to recalculate the factor when any of the three inputs change. The easiest way to do this is with a simple Excel spreadsheet. I suppose I could post one of my mine.

Now once you actually change gearing, you might have to change clutching to match. And the vicious cycle continues . . .

Seems like we posted this a few years back, wonder if it ever got into the Tech Pages . . .
 
Ryan B said:
I've got an Excel spreadsheet that figures it for me. Just fill in the blanks:) Works great.
Click to expand...
If yours is all prettied up maybe we can add it to the Tech Pages. I never take the time to make my own spreadsheets pretty, so mine are simple with no color, automatic entry control, or instructions for use.
 
what i use ex-22 40 gearing divide 22 by 40 multiply by .0192 then multiply by engine rpm then multiply 1.12 this should bring you close
 
spreadsheet

Ding said:
If yours is all prettied up maybe we can add it to the Tech Pages. I never take the time to make my own spreadsheets pretty, so mine are simple with no color, automatic entry control, or instructions for use.
Click to expand...

It's pretty pretty. Send me your email and I'll shoot a copy over to you to see what you think.
 
You must log in or register to reply here.


Back
Top