I have a 89 Rx7 coupe im not sure what model rx7 it is, it has a sunroof, back stock spoiler, the mirrors with the opening in them, and it has 4 piston breaks, power windows.

so im trying to find out if it has a limited slip diff in it but not sure how to tell.
the car isnt running at the moment.

is the any sign or marks on it to tell?

 

in 1989 the only 2 models to get a limited slip were the GTUS and the turbo.

the GTUS has no sunroof, and manual windows.

so unless someone put the LSD in yours, you have an open.

the simplest way to tell is just to jack up one wheel and turn it, a non torsen LSD will take effort to turn, open just free spins

 

typically if you jack up the rear of the car and spinning one tire spins the opposite tire the opposite direction, it is an open diff

 

Most of the time limited slips have a metal tag on the fill hole, but sometimes it gets lost.

 

Or an LSD that needs a rebuild.

The breakaway torque test is the most definitive as you will still feel some resistance even if the clutch packs are toasted or the viscous coupling is burnt.

 

S5 turbo here, no lsd.

What i've heard is that is was option?

If you are able to disconect the drive shafts, pull out the output shafts, u can see what you have by looking true. If you see a bar, u have got an open diff.

 

OP you do not have LSD. The only direct drop in LSD would be from a 86-88 GXL. If you plan on doing a turbo engine swap in the future then shoot for a 86-88 turbo rear end.

 

it was standard on the US market turbos. i guess its an option elsewhere?

 

ok...ok. good info. i picked up the rear of the car and turned one wheel, but the other one just stays in the same spot.

So i take it that it is a non limited slip?

 

If LSD, it should spin with the other (same direction), but with a open diff it should spin opposite, after what I've seen from my car and others.

But staying put? Might be a stuck handbrake tho

 

Turbos should be Limited Slip. They are viscous type though, so they will act open until the fluid inside heats up. You will not be able to cause enough friction inside with a wrench.

Again, there are diffs that will act open if the rear of the car is in the air. The only sure fire way to tell is by taking it apart and looking inside the differential.

 

car should be in gear when you do that or it may just be spinning the driveshaft

and yeah, a worn out LSD is not exactly a LSD anymore

 

I'd rather have a worn out clutch type LSD than an open... I can at least rebuild the unit at that point.

 

or get the open diff welded

 

You must not like having a daily driver that can take sharp turns or keep a set of tires on it for longer than a year.

 

Welded diffs suck

 

Miata torsen style LSDs are basically a drop in.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/how-swapping-miata-torsen-lsd-into-n-fc-diff-housing-203671/

 

i didnt have it in gear.

 

yeah so i jacked up my 7 and slapped it in gear and spun one wheel around and it spun both but one went the opposite direction of the wheel i was spinning.

I take it i have a open diff....right?
so does a open diff spend both tires or just one?
I dont want a 1 wheel burn out. LOL!

 

An open diff will spin one wheel if that wheel doesn't have traction.
So will a worn out limited slip...
A worn out limited slip and an open diff will act totally the same...

The difference is you can rebuild a worn out limited slip for a couple hundred bucks in parts and it will work just like new.
You can not just add clutches to an open diff.


You still might have a limited slip.

 

EDIT: and yes, you have a open diff aka Not a LSD


here's a better one for understanding imo

 

I know this is a resurrected old thread but my viscous will spin both wheels in the same direction when you spin one wheel, when the rear of the car is off the ground. I have always wanted to put the torsen unit from a Miata in but never have.