Quaife ATB differential

The axle ratios have to be the same because in 4 wheel drive the output shafts to both axles rotate at the same speed. Gear ratios are a matter of interest for engine performance and vehicle weight only.
I emailed Eaton to discuss certain points and they confirmed that the Trutrac can be fitted in a front axle because it isn't a fully locked diff.
Back in the sixties it was usual to fit a disc style LSD in the diff. of a Mini for serious Rally driving. Some went as far as to increase the pressure loading on the plates but this increased the steering effort and was for strong men only!

Roger

So some casual googling over weeks tells me that axle ratios can change from one model to the next. If the Axle ratio the ATB LSD is made for is different will it mean the unit is incompatible with my car? For ex: for 3.73:1 vs 3.14:1 vs 4.11:1 diff's? This would mean different count of teeth in the gears - would it still work?

The axle ratio is a feature of the crown wheel and pinion. The crownwheel bolts onto the differential, so the ratio of the differential is determined by whatever crownwheel is bolted to it. In the case of the Quaife and any other aftermarket differential, they come as a diff only. You bolt your existing crownwheel to it, thus keeeping whatever gear ratio you already have.

To that extent, the issue of differential ratio is irrelevant to your situation. All you need to know is if the differential unit is the same in your axle as in the Jimny. The rear differential unit Suzuki use in the 2018 Jimny has been unchanged for decades. They are all the same from the SJ413 (possibly also the 410?) to the current model. They are 26 spline, 10 bolt.
At the bottom of this page is a list of all vehicles that use this same type of diff. The list is for an ARB air locker, but the quaife unit will be compatible with all the same vehicles. www.devon4x4.com/airlocker-suzuki-26-spl-10-bo.html

To answer your other questions, yes the driveshafts are strong enough. Fitting a second LSD in the front axle will only have an affect on driving when you are in 4wd. In my experience, the handling in 4wd is already biased towards understeer and I'd guess a front LSD wouldn't change that much.

Busta wrote: The axle ratio is a feature of the crown wheel and pinion. The crownwheel bolts onto the differential, so the ratio of the differential is determined by whatever crownwheel is bolted to it. In the case of the Quaife and any other aftermarket differential, they come as a diff only. You bolt your existing crownwheel to it, thus keeeping whatever gear ratio you already have.

To that extent, the issue of differential ratio is irrelevant to your situation. All you need to know is if the differential unit is the same in your axle as in the Jimny. The rear differential unit Suzuki use has been unchanged for decades. I they are all the same from the SJ413 (possibly also the 410?) to the current model. However there are some differences in the front differentials.

Thank you for responding. So as long as my axle is 26 splines 6.9" gear its all good? Or is the Axle shaft diameter also important? For example corresponding to this diagram does my Axle shaft diameter have to match D4? ATB LSD Spec Diagram

Overall the specs have remained the same to similar across the years but I am apprehensive some some minor spec change in parts might make it incompatible, hence I am double-triple-checking things before I import the unit at great cost.

I've edited my post above with more information that should answer your questions.

I understand now. The Diff attaches to the Crown which is driven by the Pinion and it does not matter what the ratio is. I think I am fairly confident now. I will post pictures of the installation a few weeks later once It arrives.

I was struggling with a beginners confusion - being a non-engineer, on this topic - but some things seem to fall in place now. Thank you for the patient replies.

Cheers