What is the true difference between the evo lsd and the STi lsd? I haven't worked with AWD cars a lot so I'm not used to the advantages or disadvantages which each would offer. I know almost everyone on this site would say the evo's is the best but what are the true good parts and bad parts of each? How do they work?
What's the difference between helical and mechanical lsd's? Is the wrx or the STi lsd better?

 

which lsd? there are 3 differentials in each drivetrain :P

 

there is the one in the center for front to back .. one in the rear for left to right and one in the front for left to right.

 

May be you meant the active center differential?

 

he's talking about the limited slip differential.

There are 2 in evo with ACD (active center differential) in MR and 05 models, 2 in sti with Active electronic center differential in STI.

They work the same, but the ACD in STI, (called DCCD ) could shift the power more to the rear then the EVo MR could. I think MR could shift upto 50% and STI could shift upto 70% to the RWD.

Now, Active yaw control in the Evo is something different. If your'e a honda head, it's sorta like what Prelude 5th gen SH (super handling) model had as well as BMW 330 from last gen model had. What it does is it actively shifts all the torque from wheel that's most active and has most contact while cornering.

I believe in drag situation, STI has a bit of a advantage because of their 2.5 liter engine and DCCC (driver controlled center differential) could shift the power back to the rear like a RWD, since they have the boxer engine they could just like the skyline (built on RWD engine to AWD conversion).

However, even with the lack of AYC in EVo's STI's Suspension characteristic of understeering a whole lot even with DCCD and not cornering sharp enough (said to due to 2.5 engine and not JDM 2.0 liter enigine) I think EVo's got the edge on handling (MR) vs the STi, and even with bit tweaked EVO GSR vs STI.

There is no difference between their 2 LSD's, since all LSD functions the same. It's just how they work together with AYC and DCCD or ACD that makes it a bit more controlling and active than without having them like regular evo 8.