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tire height, rpm, and gear ratio calculator for direct drive calculations

3521 Views 2 Replies 2 Participants Last post by  michaeljayclark

ive been plugging in information to the sites calculators and not 1 to 1 ratio but putting the motor to the rear end it looks like 6 to 1 ration is the best to have the motor turning at close to 5000 rpm at 65 mph with the tire size that is on my 1994 gmc jimmy.

235/75/15 tires, 6/1 gear ratio rpm of motor at 65 mph is 4519

the calculators say the motor is turning 70 rpm at 1 mph.

can a netgain 9 inch motor handle having 500+ amps pulsing through it moving a 5000 pounds vehicle at 70 rpm and not melt?
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A warp 9 for direct drive on a 5000lbs vehicle is a bit small.

If you want direct drive on a full sized Jimmy, you are at least in warp 11 territory, and maybe warp 13. You are going to need a soliton or Z2K controller as well to get any torque.

The 6:1 ratio is probably about right though.

One thing in your favor, I see you are located in florida. No hills.

Since you already know your gear ratio and tire size, you can use that and the torque constant of your motor and the maximum amps your controller can deliver to figure foot pounds of torque at the wheels. Knowing that and the weight of the truck, you can get to theoretical acceleration.

Good Luck.
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budget doesnt allow for an 11 inch and soliton, im guessing well stick with the transmission
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