4 speed conversion
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
You should be fine then, it will just take a bit more throttle to get everything going. I have towed 4,000lbs before without trailer brakes, and I would say the max safe towing limit on these f100s is around 6,000 with trailer brakes.
Also, beware of your speedometer. Depending on what drive gear on your speedo cable, you may not be able to correct it for the higher gears.
Also, beware of your speedometer. Depending on what drive gear on your speedo cable, you may not be able to correct it for the higher gears.
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
The way to figure it is relatively easy with a calculator.
MPH X 5,280 gives you feet per hour
Feet per hour X 12 is inches per hour
Inches per hour / 60 is inches per minute
Inches per minute / circumference of your tire size. (In your case 94"). This gives you your wheel RPM.
Wheel RPM x gear ratio= drive shaft RPM
Driveshaft rpm is engine rpm in your case, because you have a manual trans with a 1:1 gear ratio.
Understand?
You can figure other trans gears by multiplying for lower gears, and dividing for higher gears. If you had an auto, TC slippage would also come into play.
MPH X 5,280 gives you feet per hour
Feet per hour X 12 is inches per hour
Inches per hour / 60 is inches per minute
Inches per minute / circumference of your tire size. (In your case 94"). This gives you your wheel RPM.
Wheel RPM x gear ratio= drive shaft RPM
Driveshaft rpm is engine rpm in your case, because you have a manual trans with a 1:1 gear ratio.
Understand?
You can figure other trans gears by multiplying for lower gears, and dividing for higher gears. If you had an auto, TC slippage would also come into play.
Thread Starter
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New User
Joined: Sep 2014
Posts: 19
Likes: 0
Well I drive it quite a bit not much over 70 and I like the bottom end I have so unless I find a nice 5 speed I guess I'll let the 3 speed stay
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