Topic: how to calculate torque specs in 4-lo/ double lo etc

[weakyota91]

a stock 3.0 for example is 150 hp at 3000 rpm and 180 ft lb of tourqe. how would i figure out what the tourqe is say in 4-lo with a transfer case having 2.57 gear ratio, or even better dual cases with 4.7s in the rear case. i know how to calculate crawl ratio but was curious if its possible to do the same with tourque?? Thanks

[1980yota]

I am fairly certain that information on the gears themselves would need to be known in order to calculate the output torque.  Diameter of the gear comes to mind as something you need to know. The number of teeth wouldnt be necessary nor the angular velocities since the gear ratio is known.

[emsvitil]

Gears multiply torque by the gear ratio.........

So 180 * 4 (1st) * 2.57 (low) * 4.7 (crawl) * 4.1 (diff) = 35657


Change for what ever your gear ratios are.

Every gear is only about 98% (except 4th which is 100%) so you need a correction of .98 *.98 *.98 * .98 =.92

or .92 * 35657 = 32804ftlb at WOT 3000 rpm engine.

less throttle would be less torque.

[weakyota91 [OP]]

so i dont know if im understanding this correctly, i dont think i am,  motor - 180 x trannys 1st gear 3.93 -single case 4lo - 2.57 x rear diff 4.88 = 8646 f-lb of tourque at 3k rpm in a 3vz-e