Replacing a LSD, what needs to be considered between 1, 1.5, 2 way?

Question

I need to replace the LSD on a 1995 (NA series) MX-5. The original diff was a viscous LSD, and over time has deteriorated as I hear they do. It is now essentially an open diff, if I lift one wheel off the ground it seems to apply torque only to the lifted wheel, and I would like to replace it.

I have seen that there are a few different types of diffs available, and of these they come in 1, 1.5 and 2 way varieties. The 2 way diffs seems to be more expensive in general, and I would like to know in what instances will having a 2 way over a 1.5 way be an advantage? 2 way to 1 way? In what applications would having a 2 way be a disadvantage?

Answer 1

First, as a fellow NA MX5 owner I would simply replace the diff with a Torsen LSD out of an NA 1.8 MX5 and be done with it. It's the most cost effective swap I'm aware of if you actually do need an LSD. Plus it's a fairly strong LSD anyway so unless you're planning to put silly power through it, it should last.

That said, the difference between the LSD types you list are as follows:

• 1 way locks only on acceleration
• 1.5 way lock on acceleration and partially on deceleration
• 2 way locks fully on both acceleration and deceleration

For a track only car I'd consider a 1.5 way LSD, or a 1.5 way/2 way for a drift car. But keep in mind that most of these are clutch type LSDs so they do need maintenance like clutch adjustments that the OEM torsen doesn't need. They also need setting up by someone who knows what they're doing before you can make good use of them.