Early Miata Option Package Question

This morning, I looked at a ratty but completely original 91 Miata as a parts donor. It's got alloys, but manual windows and a non power antenna.

There's no way that this car would have been equipped with a viscous LSD rear, correct?

It could... I found a LSD in one of my track cars at work (92) that we all thought was stock. Only thing that makes sense was it was stock.

Reference for this and future:
http://www.miata.net/faq/miatachanges.html
http://www.miata.net/faq/america/index.html

The viscous LSD was a stand-alone option. You can't tell if it's in the car by looking at other things. But you can spot one visually - look at the stub shafts coming off the diff. If they're different on each side, it's a VLSD.

Keith wrote: The viscous LSD was a stand-alone option. You can't tell if it's in the car by looking at other things. But you can spot one visually - look at the stub shafts coming off the diff. If they're different on each side, it's a VLSD.

You can also call mazda directly and they can use the VIN to check if it was on the car originally, but this doesn't confirm if it is STILL on the car.

But Keith's way is the simplest... of course it doesn't tell you if the vlsd is still working... but it'll confirm what it is.

To confirm if it's working - and that diff was designed with only about a 40% torque split in the first place, so I think more of them work than people assume - do the standard LSD test. Wheels on surfaces with different traction levels, nail the gas. Works on all LSDs, is quick and easy to perform on a test drive without the need to marque-specific minutae.

I was going to answer but Keith pwnz.

Though I will point one thing out... Even the stubs don't tell the whole story. There are different stubs and axles specified for LSD and non-LSD applications. However, when I installed a VLSD into my 91 Miata, I reused the original axles and stubs. So if you look at my car, it'll appear to have an open diff - until you mash the gas on corner exit. They're not awesome LSDs, but they're a lot better than open. And legal in stock class, which is why I got one instead of a later Torsen.

You managed to use open stubs in a VLSD? From what I recall, the VLSD ones are different lengths.

Justin, we definitely did not use the open diff stub axles in your vlsd. You car wouldn't move under it's own power if we had.

hehe I just got a good lesson in the stub shafts. I was told (incorrectly) that the ones that had ears were vlsd, and the rather sqaure ones with no ears what so ever were open. a customer wanted a set of open stubs, and I went thru 20 diffs to find a pair. When I took them out they sure looked like ls to me, but didnt think to question, and sent them out. Of course my customer said these were wrong. doh, egg on my face ;) I did more research and found that the "ears" on a viscous are not symetrical, and the opens have symetrical ears. I then took another set out and compared them. I sent out the corrected shafts of course free of charge, and didnt ask the guy to send my mistake back. just having gone thru this with them sitting on the desk next to each other, there is no way in hell that the open stubs will work in a vsld diff, no way. LOL I just seen Josh responded and corrected the story WINK