The bearing journal diamater and the distance between journals would be a good start if I run across a '94+ Miata open diff to compare to. I don't think I will run across a Miata Torsen that is not inside an axle near by, but if the open diffs. are the same, the Torsen will fit.

I might even know a Miata owner that put in a Torsen that may still have his open diff. lying around.

Thanks

if you'll notice above, Dennis has compared part numbers to the ring and pinions between the Sportage and Miata and they are the same. if the Ring and pinion are the same, the carrier has to be the same- or at least have the exact same dimensions- so it doesn't really matter much if the casting is different. the only differences after having this information would be the outer diameter of the carrier bearings, possibly the inner diameter of the carrier bearings and the inner and outer diameter of the pinion bearing, but being that we don't need that pinion bearing measurement to swap the carrier, forget it. i have the front diff still. i didn't plan on taking it apart, but i'll see if i can get around to it sometime soon.

Hi Dave,

Even if the R&P are interchangable (that has been proven with Sporty ring and pinions put in Miata cars) it doesn't mean the carriers are interchangable. The carrier only has to be the same where the ring gear bolts on. It's quite possable that the bearings on the carrier and their relative positions on the third member casting are different.

I would have to be sure before spending the money on a Torsen.

By the way, Torsens are the best LSDs that I have ever used. I have one on the rear of my GMC Safari 4WD van. The only thing that I would prefer would be an Electrac but that isn't made to fit my axle.

distance between carrier and ring gear also have to match exactly, this pretty much means the carrier has to have the exact same dimensions or the gear teeth would have to be cut differently and therefore, would not likely have the same part numbers.

Hi Dave,

I posted a request over on one of the Miata forums for someone who swapped in a Torsen that still has his old carrier. If someone responds, we can compare measurements with either yours or Rob's and see if things will swap. So far the only Miata diff that I can get my hands on locally is '93 or older which is much smaller.

Just curious, What gear ratios are avail for the Miata?

I will open mine up & measure it for ya.

all the ratios available for the Miata are higher ratios, that's why those guys did the research to begin with- to find lower gears for themselves and that's how they found the front Sportage diff and now they use our gears.

ok, as some of you may know Ron Shroeder and i have been talking about t-cases and front diff traction devices. well, Ron found a Miata Torsen diff carrier on E-bay, sold by a guy that lives here in San Antonio. Ron paid, i picked it up and took my front diff apart (that has been lying on the garage floor for 5 months) and here's what i got:







and here are some other interesting shots:

notice the oil passages in the stock front 3rd member housing casting:



this was just a clever way i found i could loosen and tighten the bearing retainer rings (that's a 4-1/2" grinder spanner wrench):



this is the Miata diff as i received it from Gordon, a 50-ish year-old guy, in a house piled with parts, boxes and fabrication tools, like drill presses and metal lathes. he also had a project in the garage- a Supra engine and tranny- with a turbo AND a blower on it! expected HP- 700! he's going to use the stock Toy 8" differential with it, too. anyway:



Ron, let me know what, when, where, how, etc.

**edited for personal info and to add this:

Ron, also, let me know about using one of the t-cases to find out about getting the lower gears made. i know you want to do a dual case and that's a good i dea, but i am also hoping we can do the lower gears, that way peopl have a choice- AND the 2-door guys can get low too.

Dave,

Please check here while you are measuring . Email Daniel direct with the dimensions in metric and as accurate as possible (shows interest by more than one person...). Many thanks .

Hi Dave,

Thanks for picking the diff up for me.

Were the first few pictures my Miata diff in your Sportage front third member?

If it was, does bearing spacing and ring gear offset seem OK?

How is the slop of the half shafts into the Miata diff compared to in the Sportage diff?

I think there are snap ring grooves where the axles go into the diff carrier. Do they seem to be the same size and distance into the carrier as the sportage and are the grooves on both sides of both carriers?