I just take the number of RPMS divide by the gear box ratio (4th gear is
1.0 so the number stays the same as RPMS in 4th)...then divide that by the
rear diff...then I go to my TIRE REFERENCE web page and look up my Tire's
RPMS per mile and then divide the previous value by the Tire RPM
value...that gives me the distance my treads have rotated in a minute then
you multiply that by 60 (number of minutes in an hour)...
ENGINE RPMS divide by GEARBOX RATIO divide by DIFF RATIO divided by TIRE
ROTATIONS x 60 = MILES (traveled) PER HOUR
My current '76 Spitfire should be (1000 rpms in 4th gear with my 185/70r13's):
1000 / 1.0 / 3.89 / 886 x 60 = 17.4 mph
Terry L. Thompson
'76 Spit 1500
Maryland
At 05:57 PM 3/18/00 -0500, you wrote:
>
>I have a list of Triumph Gearbox Ratios that list the following, with out
>overdrive:
>411:1..... 15.7 mph/1000 rpm top gear
>3.89:1...... 16.7 mph / 1000 rpm top gear
>3.63:1.....18.0 mph /1000 rpm top gear Hope this helps with your interest
>in top speed.
>Mark Hornick
>66-mk-2
>
>
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