View Full Version : Help with differential identification

08-14-2015, 04:13 PM
http://gearheadsmiataclub.n et/vB/attachment.php?attac hmentid=1210&stc=1
http://gearheadsmiataclub.n et/vB/attachment.php?attac hmentid=1209&stc=1
http://gearheadsmiataclub.n et/vB/attachment.php?attac hmentid=1211&stc=1
All I know is what I was told. '99 sport package, thinking it can only be a 3.9 type 2 torsen.

Any info you guys can help out with would be great. Sorry for the pics my phone never can get the right direction when I post.

08-14-2015, 05:46 PM
Start here:

http://miata.net/faq/production.html#What %20are%20the%20featu res%20and%20options% 20available%20for%20 the%20'99%20model?

What you need you should find here:


Some other things I have read:

If the car had a 5-Speed, it has a 4.3 Torsen if it came with a Torsen. If it had a 6 speed which only the 10th Anniversary in 1999, it had a 3.9.

08-14-2015, 10:04 PM
Don't know why the rest of my post didn't show up. I thought I wrote it could only be one o the two, but I think it's a 4.3. Was hoping for the 3.9 but I'm prob going to flip this to someone who wants the 4.3 and try to pick up a 4.1 or a3.9. If I were going to stay na I'd be fine but from what I here boosted miata's need the lower gear ratio for 1st gear to be useful.

08-15-2015, 05:26 AM
You're welcome.

08-16-2015, 05:11 AM
depending on your price and location I might be interested in that possible flip

08-16-2015, 10:41 AM
Have you played around with Flyin' Miata's gear calculator? https://www.flyinmiata.com/tech/gearing.php

With a 5 speed and the 4.30 rearend each respective gear is a good bit longer than a 6 speed with a 3.90 rearend that I run. If you plan to run a 6 speed the 4.30 is going to be really tight, but with a 5 speed I don't think it'll be unreasonable at all.

08-16-2015, 12:19 PM
Very interesting!

09-06-2015, 05:16 PM
I'm so bad at following my posts. Was looking for the 3.9 after I put some boost down in my 1.6. From what I've researched the 4.3 is not unreasonable at all but with a 180-200 hp goal your shifting pattern becomes a little short. I'm so close to putting everything together, but time restraints and I do need some guidance on some of the holes I have in knowledge.

09-06-2015, 05:56 PM
You need to be more specific.

09-07-2015, 12:01 AM
it depends but probably yeah may be better off with a 3.9 or a 4.10 , But what kind or racing do you plan to do? first gear isnt really that important everything above it is , and you'd want a bit longer gearing if you were going to do autocross. but for drag racing , or track I think the 4.3 would work ok you will top out at 140 . But you will have nice short gearing .

09-10-2015, 09:22 PM
im setting the car up for just street fun. This was my intention from the begining i just dont have the time right noow in my life which is why the turbo is sitting on a shelf along with other parts. i may just throw the 4.3 in so i dont get stuck with the old rear on the side of the road.

11-02-2015, 08:37 AM
Sell me the 4.3.
I just done blowed up my 4.1

11-02-2015, 01:25 PM
Sell me the 4.3.
I just done blowed up my 4.1

You mean you now have an ultra rare, super lightweight air cooled 4.1 for sale.

11-02-2015, 01:30 PM
I do indeed.
Also have the less rare but still rare one side mount 4.1 but I'll keep that one. It's in the smurf

11-03-2015, 06:58 AM
Is the smurf still on life support?