The front differential shown below is from an 800cc ATV. It is a torque sensing differential with full-lockup capability and 3.6:1 ratio.

The quad weighs over 800Lbs and can carry 2 adult passengers, two racks full of gear and tow 1,500Lbs of trailer (don't know the tongue weight) ...

I wonder how much power these units can handle? Suitability for Street use with a 3.6 ratio? Other quad differentials that might be more suitable? I don't know much about these units.



Notice the bevel gearing is not hypoid, making it suitable (I believe) for running reverse rotation shaft drive engines.
I don't know why I am always thinking about this silly shaft drive /reverse rotation issue! But I am, so humor me with some gentle banter!

No experience personally but I think Formula SAE teams sometimes use ATV diffs for their 600cc bike engines. Have a rummage around the forums:
http://fsae.com/groupee?cdra=Y&s=763607348

I work on ATVs quite a bit & cant recall a front diff failure that wasnt the result of neglect or abuse (not that I dont see any failing, it's just that they get neglected & abused a fair bit )
But the loads on the front diff aint all that high, 90% of the time it isnt working all that hard at all. The other thing is it's not common for them to clock massive milages, I cant recall seeing one with much over 30k & most do far less than that so how one will stand up to the load of hauling 5-600kg constantly I'm not sure but mabye worth a look.
Dont consider a Polaris one though, they have a hilliard roller system so that it only drives when the rear wheels turn faster than the fronts.

It looks like a cool option that might be well worth while pursuing if readily available at a reasonable price as it must surely cut quiet a lot of weight out of a BEC - although you might be pushing the torque limit safety factor a bit.

I wonder how the Bussa torque level compares to a 800cc ATV - I should think fairly closely becaus the ATV motor is most probably a low reving high torque motor.

One would also have to check torque multiplication in the lower gears.

That FSAE link was a good one. Lots of good data there. This thread in particular was good for me.

http://fsae.com/eve/forums/a/tpc/f/125607348/m/35510440821/p/1

G.

yes, but in FSAE we're typically only running 70hp/50ft-lb at the wheels due to our 19 or 20 mm restrictor in a sub 500lb car, so you may be running at the absolute limit of what an ATV diff is capable of. We erred on the safe side with our FSAE project a few years ago and went with a Civic-based Quaife, which we promptly disassembled and machined a 7075-Alu casing to drop the weight by half.

why not just use a diff from a small light 4wd? The drive ratio will be reasonable and it will be a lot tougher. Suzuki Jimny etc