Anybody know which models, if any, of the 3IS come with a mechanical LSD? I'm not talking about the pre-torque, semi-LSD but like what the IS-F has had for a while now. I don't have my manual handy and lexus.com doesn't seem to list it either way.

What I'm really getting at is, when I completely disable traction control, what if any safeguards do I have? Am I still running an open differential like my old SC 400?

 

From what I remember I don't think any of the 3IS have a mechanical limited slip right now.

 

they have open diffs

 

Thanks, I thought that might be the case.

 

The 3IS utilizes a brake-based eLSD as part of the VDIM system like the 2IS and 08-09 IS-F models. In regards to your question on what safeguards are availabe when VSC is disabled, I know that for the 2IS, the eLSD function is disabled when VSC is turned off. On the 08-09 IS-F, the eLSD remains active and can only be fully disabled via the pedal dance.

I am curious to know if the eLSD on the 3IS remains active when VSC is turned off like the 08-09 IS-Fs or if that functionality is also disabled like on the 2IS. The way to determine this is to take a sharp turn while VSC is off, apply a moderate amount of throttle, and sense if the the rear brakes are activating on the inner rear wheel which would be an attempt to reduce inner wheel spin. Then you'll know for sure if you do have some safeguards available with VSC off.

 

the ISF LSD bolts on to the 2IS350, not sure about the 3IS350.