Clutch LSD on a 7" was an option on the S4 FC RX7, it was never offered on the Miata (Miatas all got helical or viscous). That said, of all the available options that clutch LSD would be my second choice after a TF. Rebuild parts are still available, they handle shock loading well and they're overall pretty tough. The only problem I have is that they're going for upwards of $400 for a worn unit in need of a rebuild, and they're nearly impossible to find in a junkyard.

I'm not sure why you're saying a helical LSD takes shock loading better than a clutch type. In a clutch LSD the clutches are there to limit relative motion between the side gears, that's all they do. When a shock load occurs the only thing that happens to the clutches is they stop rubbing against each other, all the load is taken by the side gears and spiders (which have their own limits, and are basically the most likely thing to fail in this situation in any diff that is not helical/torsen or Detroit/Ratchet-style like the TF) and transferred to the carrier. It's the one wheel spinning that the clutches don't like since they're being forced to rub against each other at high speed under the preload of the springs (and really, if it's set up tight enough that shouldn't happen in the first place but I digress).

Compare this to a helical where the outer worm gears simultaneously provide the differential action, control that action with their friction as they rub against the end of their bores in the carrier and handle all of the torque that is being fed from the carrier to the axle shaft- in this case you're still heating those little worm gears doing your one wheel peel and then when the shock load comes down they take it the same way the spiders and side gears would in an open or clutch diff.
The factory Miata torsens are famous for handling shock load very poorly indeed. It's not uncommon for a stock BP Miata to grenade its diff just coming off an icy patch onto dry asphalt under moderate to heavy throttle. Also why do you think the Torsen wasn't an option on the 7" diff in an RX7?
I'm not trying to badmouth the Torsen here either. It's an awesome design. For a road car application that doesn't see near-zero traction situations or shock loads often it's perfect. I am putting a Torsen in the transaxle I'm building for my DD. But it's not ideally a design I want to run in a rig that I'm going to be snot-bagging in the middle of nowhere.

Bazinga: front diffs were the same on all Sportages regardless of year, trans, or any other factor. There were a few different rear diffs, based on whether it was early 26spl or late 28spl, LSD or open, ABS or non-ABS.

Last edited by Tommychu; 02/17/14 06:39 AM.