Alright, im trying to figure out what i need to replace my N/A S4 open diff with an LSD unit. Will an S4 clutch type drop right in to my housing? What about an S5 viscous unit? Please give me any info u guys can, and please dont tell me to search, any of the keywords just bring up hundreds of useless threads. TIA.

 

Should drop in just fine, although you don't want the S5 viscous unit, the fluid breaks down over time, so they're mostly all open by now, or at very least are much less effective than they were before. If you're getting an S4, I'd reccomend at least taking it apart and checking all the thicknesses and such to be sure that it's still functional. Another option is a Miata Torsen, they're good units and don't wear out. For most uses the Torsen is the way to go.

 

This is the second or third time I've seen a similar thread this week.

I wrote a walk through on doing it. Check old threads started by me. It should come up.

James

IMO I'd go with an S4 unit. Clutch type.

 

If you can, find a miata torsen diff. Similarly drops right in and is superior to old worn out clutch types and superior to a new clutch type for anything but drag strip.

No matter what you have to set the pinion depth and backlash so a clutch type unit is no better. Although they are about 1/3 to 1/2 the cost for a used one.