[Kevin M]

Originally Posted by Dean

See, it didn't even take Gary...

I'll go out on a limb again and claim that most if not all the 4WDs are either open, or "locker" fronts, not LSD.

Now the STI, and EVO RS have Helical Limited Slip Differential fronts, and Mechanical rears. The normal EVO has an open front by the way.

I need to do more research to understand the Helical LSD. I am more familiar with the straight mechanicals, and torsionals on the Audis... My guess is that on the Helicals, there needs to be significant wheel spin prior to power transfer.

I stick with my earlier assertion... Front LSDs are a huge challenge due to there impact on steering. There are very few situations where you want to compromise front steering in favor of front power...

Going back to your original "it depends" answer, an aggressively locking front diff would severly increase understeer. However, I htink a more moderate locking diff, just enough to prevent inside wheelspin, could really help. After driving an STi somewhat spiritedly for the first time, I could definitely feel the difference under power with high steering angles. The STi is much less inclined to wash out. It really tries to hold the line. I think that if the diff isn't locking, just "encouraging" the outside tire to try to keep up, it would work great.

The other issue is that you definitely have to make sure all 3 diffs work together well, or you'll have problems. Nate was going to just run the Cusco RS tarmac center diff in his coupe, but learned that Cusco strongly discourages that because it doesn't work well, especially with viscous LSDs like stock. Because of that, I think that even just adding a front SureTrac out of an STi to the WRX wouldn't make it as good as the full STi setup. I suppose if you got a DCCD 5MT and used the R180 mechanical LSD from an STi/22b (are they helical or clutch type? I'm not sure actually) it would work well. But, that would probably cost more than just getting a DCCD 6MT and rear diff.