What rear end do I want?
 

Hi all. I have a 90 miata with a vvt swap (i/h/e and standalone) and 6 speed. It is basically a track only car and at the moment it has a 4.1 diff but I also have a 3.9 just sitting here. It kinda feels a bit busy but I have next to zero track experience so I dont know how my opinion will change over time. What rear end would you put in?

Leave it alone. Go get seat time.

I agree, stick with the 4.10. At your power level I would think the 4.10s are probably quicker anyway. Get out on the track and see how you like it before you mess with anything.

I know that Savington likes the 6-speed + 4.3 combo. I want to swap it into my car eventually.

track time is definitely the priority and im working on that. ive only had this miata for a couple months though. i just figured i would ask since i own both and would rather have what is more suitable be in the car instead of in storage.

If you are going to stay NA, they it makes no sense to go to the 3.9. Keep the 4.1 in there and go drive.

i plan to stay na until im faster than the car which wont be for a while. the car is setup for forced induction though (forged internals, injectors, oil cooler etc) so its always a little tempting. ill keep the 4.1 in. i think the issue is that i havent had more than one track day at any particular track yet so getting a feel for the new tracks and the new car is a little bit much to be taking in at this point.

Work on your driving, but keep the 3.9, you'll want it once you go forced induction. Throw it in if you want, but it's a waste of time currently.

You'll just end up using 3-4-5 instead of 4-5-6. Shifting isn't the place to shave lots of time. Especially once you start running more power.

good to know. im not too worried about dropping lap times. i just got the feeling from my track days that i was kind of between gears for a lot of the corners and its hard to focus on other things when that happens. i guess that just means i need to go faster and avoid the lower of the gears all together.

as you get faster, which gear and where you are in gear changes. the 3.9 may work better now, but it may not as you get better.

I second sticking with the 4.1 also.