Help Me Identify This Miata Differential

Picked up this Miata rear end earlier today. It's out of a '95. I was assuming it would be open and I'd be swapping in some RX-7 parts for the clutch LSD. However, when I pulled out the axle and looked inside after getting it home, I noticed that there's a plate instead of the spider gear axle. Is this a torsen?

Thanks guys!

Did it come out of a manual transmission car, or not? Automatics are all open diffs.

See if this page helps.....
http://www.miata.net/garage/diffguide/index.html

Came from a car with the manual trans and most options (power windows, A/C, cruise, etc). Yeah, I looked through the miata.net page, and the NB torsens look like this one internally, which is why I'm wondering.

If it's a 95 and a manual and had options (ie, not a base model), that's a torsen.

^ Ok, cool. From looking at that plate where the spider gear shaft should be I was pretty sure it was a torsen, but that confirms it.

Awesome. Best $70.93 I've spent in a while. Thanks Pull-A-Part!

Doesn't matter what it came out of, that's what a Torsen looks like. Nice score.

$70.93 - did they sell that for a dollar a pound?

Jelly. That is a screaming deal.

DeadSkunk wrote: See if this page helps..... http://www.miata.net/garage/diffguide/index.html

Jiminy crispness... That was a noble attempt to aggregate info, but I'm still pretty confused on a central point...

Am I correct in thinking that if I look at a '94-'02 Miata, and that if I jack it up and try to turn a rear wheel, and that if in that case the other wheel tries to go the same direction, that it is a torsen? Double-checking, if the car is in first, to provide max engine braking, I would expect either that the rear wheels would then go opposite directions, but with noticeable drag from the torsen preload, or that it might even keep turning both wheels the same direction and turn the engine over if you provide enough force at the wheel?

This is based on the assumptions, formulated from that page, that:
'90-'93 cars had open diffs or viscous LSDs
'94-'95 cars had open diffs or type I torsens
'96-'02 cars had open diffs or type II torsens
'03-on cars had open diffs or cone-clutch LSDs

It's tough that most of the spotters guides make it easy to identify a diff that's out of the car, but don't help much with IDing a diff which is still installed. If and when I do another Miata, it seems like an LSD is worth having from the get-go rather than having to source one later, unless the car is a really screaming deal...

In reply to ransom:

Apparently the best thing is just to call up Mazda with the VIN and ask what the car was equipped with from the factory.

Torsens will act just like an open diff if you try the "turn a wheel" test. There's very little preload. The later Tochihi-Fuji (sp) ones have a bit, but I don't know if it'll be enough to make the wheels go the same way.

If you have access to the running car, there's one test that will always identify an LSD of any type: mixed surface acceleration. Wildly mixed surfaces (like ice and dry pavement) may not provide enough traction, but a dirt shoulder will.

If you're looking at a Miata in the junkyard, you can play the "spot the model" game or you can just yank the fill plug and peer in with a flashlight. Look for worm gears.

Keith Tanner wrote: $70.93 - did they sell that for a dollar a pound?

Pretty much. The Pull-A-Part yards down here have some unbelievable pricing. Problem is they get picked over really quickly. When I got to this Miata it had only been in the yard for a couple hours and it was already missing some parts (and I took most of what was left).

Check out their pricing though: http://www.pullapart.com/parts/pricing.aspx?letter=&loc=3&#pricelist

This is how we get Lexus 1UZ and 2JZ engines for the Wreck Racing team on a $2000 budget.

JohnyHachi6 wrote:

Keith Tanner wrote: $70.93 - did they sell that for a dollar a pound?

Pretty much. The Pull-A-Part yards down here have some unbelievable pricing. Problem is they get picked over really quickly. When I got to this Miata it had only been in the yard for a couple hours and it was already missing some parts (and I took most of what was left). Check out their pricing though: http://www.pullapart.com/parts/pricing.aspx?letter=&loc=3&#pricelist This is how we get Lexus 1UZ and 2JZ engines for the Wreck Racing team on a $2000 budget.

Hahahaha.... PullAPart has fueled pretty much all of my builds in a big way. I probably pull about $5k of parts out of there a year.

Keith Tanner wrote: Torsens will act just like an open diff if you try the "turn a wheel" test. There's very little preload. The later Tochihi-Fuji (sp) ones have a bit, but I don't know if it'll be enough to make the wheels go the same way. If you have access to the running car, there's one test that will always identify an LSD of any type: mixed surface acceleration. Wildly mixed surfaces (like ice and dry pavement) may not provide enough traction, but a dirt shoulder will. If you're looking at a Miata in the junkyard, you can play the "spot the model" game or you can just yank the fill plug and peer in with a flashlight. Look for worm gears.

shhh.. just don't tell my local junkyard this. I've had them pull a few torsens for me because they think they’re all open diffs.

Easiest check for me has been the fill plug flashlight check especially when the car has been striped.

In reply to JohnyHachi6:

DAMN! Nice find. Was it the '95 that came in on the 11th?

I need to figure out how to setup an alert for when Miatas come in. We have way too many customers with open-diff Exocet donors.