What is the calculation for torque multiplication?

steel1212

Active Member
Jun 24, 2004
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Frankfort, Ky
What is the calculation to figure out how much torque will be put on an axel? Moser's axels are rated to 5200 and I'm thinking thats not engine torque. I would like to see how much my car is making so I can do some figuring.

Its the one with tranny 1st gear, rear gear and engine torque.
 
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steel1212 said:
hope they fit? You measured right lol. What spline did you get?


I hope so to. I bought a 9in and pulled the axles and they measured at 26 1/8 and 30 3/8. So thats what I ordered. They are 31 spline to go w/ my detroit locker.
 
IIRC all non-spooled diffs are interchanable as far as axles lengths are concerned.

By the way, what "torque multiplication" effect are you going to get via axles? That term is usually applied to torque converters.
 
kmterrill said:
Shouldn't it be...

Torque (Axle) = Torque (Engine) x First Gear Ratio x Rear End Ratio

Of course that assumes no losses in the drivetrain.

Yep that's the theory.


Example -

350ft-lb x 2.27 (no units, it's a ratio) x 4.11 (no units, it's a ratio) = 3265.395ft-lb going into the axle.

It goes into it at a rate of engine rpm / gearbox gear ratio / diff gear ratio

So if that torque is at 4000rpm -

4000rpm / 2.27 / 4.11 = 428.738rpm at the axle. Which means in a manual transmission you need to have the axles spinning that fast to have all that torque going to it, otherwise it is going to be lost in clutch slipping. Which, with a 26" tyre is 33.15mph. Autos have the torque converter to allow the engine to spin to speed higher than the gear it's in, supplying more torque at lower rpm - allowing more torque at takeoff.