FC3S Timmy

iTrader: (2)

which OEM LSD is best? its going on my autox car i dont wanna get an aftermarket either its too expensive

classicauto

iTrader: (3)

Best:

Price?
Durability?
Lock up capability?

NZConvertible

Torsen LSD from either a Miata (NA) or FD (Turbo). They're cheap and drop straight into the FC diff housing.

NeCr0mStR

iTrader: (3)

So I shouldn't rebuild the LSD in the 87 rearend I have sitting around? I should just get a miata (NA) and replace the internals in the 87 rearend? Or is the 87 still gonna be alright and should just rebuild that?

ProjectR13B

iTrader: (1)

for stock FC I've alway hear the S4 lsd is better than the S5, but I havnt had a chance to try out my 90 gxl to see if the lsd is any diffferent really.

JWteknix

iTrader: (2)

i have also herd s4 is the strongest of the diffs

Omixeo

iTrader: (1)

Is that from any miata? Or certain years?

NZConvertible

You could, but it'll be a lot cheaper to buy a used Miata LSD than to rebuild a clutch-type LSD, and you get a better diff (for a road car) in the process.

That's what I'd do. In fact I did (FD diff into Turbo).

True, but it's irrelevant unless you're drag racing a high-powered car.

RotaryEvolution

iTrader: (30)

it is all personal preference, many people will say they prefer one over the other but overall i would put them in these categories

S6/miata torsens do not wear like S4 clutch type LSDs do, yes they can break though but usually the case will break before the carrier or internals will. i suggest the torsen for drift or if you autocross alot, in retrospect i recommend the S4 clutch type LSD for drag racing where the clutches will not be wearing much and you will be getting full traction off the line when you need it.

Omixeo

iTrader: (1)

What about viscous types?

RE_GTUs

I would take the lsd I had on my 86 gxl, over the one I have on my 90 gtus,
I belive s5 switched from clutch type, to viscous

Omixeo

iTrader: (1)

It did switch. Thats what I have now im my GTUs, thats why im curious if a torsen is better.

Sideways7

iTrader: (7)

Yes, s4's had clutch type and s5's had viscous. The viscous diffs need basically no maintenance and no rebuilding, but are slower to react. Clutche types react faster but need rebuilding. The torsen more or less has the best of both worlds. There are certain models of Miata's that have the torsen diffs but I can't remember off the top of my head. There is a great writeup on how to do the swap in the archives, it also says which models have the diff.

13b4me

You can have a Torsen and keep the 4.3 ratio of the GTUs... Just source an Infini IV LSD...

Sideways7

iTrader: (7)

When you do the torsen swap, you keep your old ring gear because the miata's is the wrong size. That means you keep your old final drive ratio.

13b4me

Yea but I didn't say anything about a Miata LSD did I?

The Infini IV has a 4.33 Torsen LSD in a TII housing already...

Syncro

iTrader: (1)

Be nice guys...

I dont suppose my clutch LSD stood up to a quarter of a million miles - d'oh! Time for a rebuild kit!

Edit: Which Torsen Miata LSD's will bolt into a '86 NA ?

90FC

what kind of horsepower can a Miata or FD torsen LSD handle? Are they as strong as the turbo II LSD?

Roen

iTrader: (2)

Just curious, is it a 4.33 or a 4.30? It always says 4.30 in the stickies at the top.

13b4me

It's actually a 4.33 but they round it off...

Sideways7

iTrader: (7)

I just mentioned that because his is an NA so he can't use the Infini diff.

13b4me

Yes he can... He just has to use the appropriate extras to make it work!

Syncro

iTrader: (1)

Found my answer.
https://www.rx7club.com/2nd-gen-archive-72/how-swapping-miata-torsen-lsd-into-n-fc-diff-housing-229115/

Omixeo

iTrader: (1)

Well im thinking about finding a torsen from a miata like the write-up in the archives, that way I can keep the 4.3 ratio and have a torsen.

If I get the infini IV diff then ill need to get a TII driveshaft as well, not sure about the TII tranny.

Are you sure its 4.33? I always thought it was, but the specs in the FAQ say 4.300, so I just assumed that was correct.

NZConvertible

I think you need to admit this is a silly idea and more on. Not only is an Infini diff extremely rare, it'd take a lot more money and effort to fit than simply swapping in a Miata centre.