The RevoKnuckle will likely be on the upcoming Focus RS, if they decide to produce it and if it comes to the US. It's one of the ways to help set the RS off above the ST aside form simply more power.
The Revoknuckle really doesn't function the same as an LSD. It's made to address a different issue.
- A LSD will help you put power down coming out of a turn. Getting power to the correct wheel.
- Revoknuckle changes the geometry of the front suspension as it attaches to the wheel knuckle to counteract torque steer.
Both would work together beautifully, but they are completely independent of one another. So yes you could put revoknuckles in a car without an LSD. Obviously having both would compliment each other better.
I would suspect to even try putting a RevoKnuckle on an ST you would have to order spare parts from Europe. Assuming you could get the Revoknuckles ordered, here's a first blush guess at what you'd have to confirm before trying it.
Compare everything that attaches to the wheel knuckle:
- Axle length
- wheel bearings
- Tie rods & ends, length fittings
- Brake caliper mounting points
- Macpherson strut mount point
- Ball joint mount
Most of that should be similar of compatible. For instance I can't imagine they moved the steering rack between the RS and the ST, so presuming tie rods would be fine, would obviously need to be adjusted. I doubt they changed the geometry of the brake caliper mounting points.
But the whole point of the Revoknucle is to change the geometry of the front suspension and where the steer points attach in relation to the axles. So you'd need to confirm that this change in geometry would be compatible with the Focus ST suspension, steering, and axles.
Assuming all that, the Revoknuckle would now compensate for torque steer. But the Focus ESC automatically uses small brake applications to counter the "feel" of torque steer. So now this system would be over compensating for the forces involved in torque steer.
So without retuning that, you'd still be using up brake pads, and not really fully taking advantage of having the Revoknuckles.
Cool idea, I'd love to see it done. Best of luck if you get serious about investigating the feasibility!