Torque wrench + multiplier + crows foot

[PKdebo]

I've got a torque wrench attached to a multiplier that is attached to a crows foot, and I'm trying to spec the input torque (at the wrench head) that will give us a corresponding output torque (at the crows foot).

I am aware of the calculations that need to be made when a crows foot (alone) is being used, but am struggling with the introduction of the multiplier.

This is what I came up with:

Given:
- Length of torque wrench is X
- Length of crows foot is Y
- Applied force is F

The equation for the moment about the crows foot reduces to: F*(4X + Y)
(please take a look at the attached pdf if you're interested in how I came up with this equation)

Am I on the right track?

 

[LightHero]

Is there a better way to calculate the input torque when a multiplier is used? Thanks in advance for your help!