Are all 3.9 lsd differentials the Torsen type?

cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 4:30 pm

As above just wondering from the knowledgeable

Thanks guys

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smy0003 · Postby **smy0003** » Mon Jun 27, 2016 4:48 pm

From the factory, yes.
But not all 3.9 diffs are lsd diffs.

cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 4:56 pm

That's cool, found one, the guy says it could be from Japan.. I considered the 4.3 he had but going from a 3.63 nb8b 6 speed standard to this one I thought I might be going a bit too short in the gearing.

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cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 4:57 pm

This one is an lsd and I think the 3.6 up to 3.9 with the 6 speed box should be a good place to be at

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hks_kansei · Postby **hks_kansei** » Mon Jun 27, 2016 5:10 pm

IF it is unmodified and is a factory LSD it will be a Torsen 2

However, it's fairly common for MX5 diffs to be chopped and changed, so if it's been opened up it could be anything from a Torsen, to a Clutch pack, to a spool or a weldy.

Spools and welded are usually advertised as such, since it's pretty obvious what they are.

Torsen or Clutch pack you'd need to ask them. (unless you can inspect in person, which is unlikely here)

cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 5:41 pm

This one is from all maz in clayton
Anyone got any experience with these guys?

In fairness he did sound a bit shady when I asked him about it.. He said it was an lad but would not specifically say Torsen

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hks_kansei · Postby **hks_kansei** » Mon Jun 27, 2016 6:14 pm

Allmaz are good guys, I've dealt with them heaps.

The reason they may not be 100% on the diff type is that they don't normally disassemble parts before sale (since if a part is in working order you wouldn't normally pull it apart unless you're rebuilding it)

If they say it's an LSD, i'd be confident it is.

It's most likely that it's a Torsen, since they were super common on MX5s (as far as LSDs go)
Torsen 1 or 2 is impossible to tell without pulling the diff open.

greenMachine · Postby **greenMachine** » Mon Jun 27, 2016 6:22 pm

cherrymx5 wrote:That's cool, found one, the guy says it could be from Japan.. I considered the 4.3 he had but going from a 3.63 nb8b 6 speed standard to this one I thought I might be going a bit too short in the gearing.

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Are you sure that is a 3.6 in your NB8B?

:mrgreen:

cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 6:29 pm

My nb8b is a 2001 1.8 vvti 6 speed..

I have learned that these were all 3.6 diffs

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cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 6:30 pm

What else can be in an nb8b?

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noobee · Postby **noobee** » Mon Jun 27, 2016 6:40 pm

cherrymx5 wrote:What else can be in an nb8b?

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anything that a previous owner has put in!
Mick

cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 6:45 pm

Oh right, I don't think it would have been changed, it does have an exhaust but that's about all mod wise..
Oh lowered springs and shocks which will be for sale soon

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cherrymx5 · Postby **cherrymx5** » Mon Jun 27, 2016 7:35 pm

Oh right, I don't think it would have been changed, it does have an exhaust but that's about all mod wise..
Oh lowered springs and shocks which will be for sale soon

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smy0003 · Postby **smy0003** » Mon Jun 27, 2016 9:49 pm

Easy way to check is to just find some points where your speed and rpm line up nicely. For example, off the top of my head fourth at 60kmhr is exactly 2500rpm in a stock nb8b.
Then use the flying miata gear calculator to check if that is in line with the 3.63 diff.

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