No Humping. Straight Porking. 3

Drivetrain mods are for max winning IMO. Nothing you can do to your car is more under rated in it’s impact on performance and drivability… particularly differential set up. AE86 was a very simple lesson in this. A stock [Canadian] AE86 with an open diff is basically no fun at all. Tall and soft, it teases you often by playing like it’s going to take a fun set, but when it comes to actually holding a line, the inside tire explodes, the outside takes a nap and you decide you’d rather be a hockey player than a driving hero. Alternatively, you might spend your months wages on a trick new KAAZ LSD that all the hachiroku gods have told you that you need, and then go out there and feel like no matter what you do the car just understeers.

I’ve played with number of limited slip differentials, and from my experience, NOTHING compares to well set up clutch type diff. Yes they wear out, yes they chunk and chatter, and yes they are typically more expensive than helical type diffs, but they are not active/reactive in their torque transfer, and they do the same thing… over and over again, and if you don’t like what they are doing, just adjust them. Viscous humping is cool for pre-pubescent school kids. Helical diffs are fickle women who change their minds every half second. Yes carburetors are deprecated pieces of crap, but like the small block Chev, the salisbury type diff is still king.

What you are looking at, are the pressure rings and 1.5way cam opening for a KAAZ differential. Those hachiroku gods were not wrong to sway me towards buying a KAAZ unit as my first LSD 16 years ago. KAAZ offers great customer support, very good pricing and excellent adjustability in initial torque and total lock up with the purchase of different plates and shims. From my limited experience however, CUSCO units seem to be the bling piece, packing more clutch plates, and center sections with not only adjustable preload, but optional cam profiles as well. I imagine that a CUSCO unit will end up on my ZN6 at some point. This particular unit is for another car…

… a dedicated autox car. Although autox is probably the most common place for a an LSD like this to be used, stock settings are typically geared much more towards the higher speeds and larger radius of a road course, with stronger lock up and initial torque settings. While that can make a car feel stable at 150km/h, at 50km/h it tends to make a car feel quite invariable in attitude, unwilling to rotate… especially if there is a lot of weight over the drive wheels. This is the both the greatest strength and weakness of the clutch type diff versus a helical diff. Cars with a helical diffs tend to be a lot easier to rotate, but much harder to manage mid corner. A clutch type diff on the other hand, provides a lot of stability and predictability mid corner, at the cost of some nimbleness.

As I said though, clutch type diffs, tend to be easily adjustable. This KAAZ unit comes with 6 clutch plates on either side of the center section. These clutch plates alternate splining to either the casing (X) or center section (O). With six plates there are five friction surfaces that are activated under torque. X-(1)-O-(2)-X-(3)-O-(4)-X-(5)-O.

Without purchasing additional parts from KAAZ, these plates can be re-arranged to “soften” up the diff. Arrangement XXOXOO gives X-X-(1)-O-(2)-X-(3)-O-O three friction surfaces for a 60% (3 out of 5) setting. Other arrangements are possible. XXXOOO would be a 20% setting. Or we can transfer plates from side to side to get other settings. Instead of 3 X’s and 3 O’s on one side, we might have two X’s and four O’s on one side, four X’s and two O’s on the other. That would allow for XOXOXX on one side, and OOXOXO on the other for an 80% setting.

Note that this is a simple large scale adjustment, that will affect initial torque and over all lock up. For autox, and in general this is probably a fair solution, but other scenarios might call for a lower initial torque relative to braking and accelerating torque or visa-versa. In that case, KAAZ offers different cone springs, or additional clutch plates. Parts are quite affordable, and the entire units are also easy to disassemble. Think and play.