I have a boosted 10AE miata with the 6-speed and the 3.9 rear end(correct me if I am wrong about the rear end). I wanted to know if the 5-speed is better for boosted cars with that rear end because it feels like I am always shifting. Gary from TDR was saying he likes the 5-speed with the 3.9 rear end. What is your take on this and what are you running on your boosted miata?

i've got a spare 5 spd I'll trade ya for your 6 speed

no thanks i have a 5-speed and a spare 1999 motor

I run a 5speed with a 3.9 rear in one of my miatas and it feels so much better than the other I have with 5 speed and 4.1. The taller gearing is definitely a plus but the 6 speed is stronger. That being said I just broke a gear on my weaker 94 with 268k miles 233hp/235tq. My other 94 has 300+hp/260tq and no broken trans yet... Both run 94 5 speeds.

The comparison below keeps me from swapping to a 6 speed.

A common 15" tire size 205/50/15. Both cars with a 3.9 rear. 1st car with a 5 speed, 2nd with a 6. Gearings found on Randy's site (Hometown Has Been Shutdown - People Connection Blog: AIM Community Network) which I have saved if anyone wants. The image is a screen shot from http://fatboyraceworks.com/gears/

Attached Thumbnails

 

__________________

wow thats really helpful. thanks

I'm considering using this guy in OKC who claims he can "rim polish" gears and make the 5-speed substantially stronger. Unfortunately none of this information has hit the road/track yet. I have a spare trans, so I'd like to get it knocked out.

After destroying my 5speed and putting in a 6speed I still have the 4.10 gears but I have a new 3.63gearset and Torsen diff sitting in my garage just waiting for my ACPT carbon fiber driveshaft to show up and I can put them all in together. The 3.63 should be much nicer on the freeway, although 80-130mph is quite a Hoot right now! Ask Bryce.

I am so ******* jealous

I like low gear ratios. But I haven't had the opertunity to track mine yet either. But for the dragstrip, they are nice. I still have the 4.30 and the stock 5 speed.

The 6 speed with the 3.90's seems almost the same as my 5-speed with the 4.30's. Except a nice overdrive. My car tops around the 120's. I ran it up to 120 and I was pretty much out of rpms.

From that scale, it looks like the 6-speed with 4.10's. YOu would just have a granny low for first, Only good to help pull track trailor. 2-6th is all you would use.LOL

__________________
1993 Custom T3, External Wastegate,Haltech ECU, detachable wheel, hard dog, flyin Miata dual center exhaust, 15in bing blings, Eibach springs, kybs, pyrometer, & AEM WBO2.

It's pretty funny, 1st gear is only good for 20mph. Bryce was driving her out to Fredricksburg for the Texas Miata Roundup and we were cruising along at 80mph and I told him to punch it and run it out, well right at 130mph we started Banging off the rev limiter. We werte cracking up. After the engine build is done the Torsen, 3.63 and ACPT driveshaft are going in. I can hardly wait!

I bet it is a thrill to drive! Have you taken it to the dragstrip yet?
If you have any times I would love to see them. And then compare them to the 3.63 gears.

I have a 96 rearend in my storage. I think it should be 4.10. I might like the 6speed combo'd with the 4.10's.
But I did notice my first and second gear just vapor out. I am bearly in them and usually pulling away from the other guy. But in third where it has pull, it screams.

Do these cars with turbo pull better strip times with the taller gears?

__________________
1993 Custom T3, External Wastegate,Haltech ECU, detachable wheel, hard dog, flyin Miata dual center exhaust, 15in bing blings, Eibach springs, kybs, pyrometer, & AEM WBO2.

You don't have 4.10s then. My first gear is good for 30mph+ and the rev limiter with a 23" tire is at 142mph.

I would love a video........ Whe need to experience the Powa!

I've got a 96 5 speed with a 3.63 gear ratio and love it. I wouldn't trade it for a 6 speed (granted the 6 speed is sturdier but, it's too many gear shifts for an old fellow like me )

The best solution in my book would be a stronger 5 speed with 3.63 (or maybe 3.30!) gear ratios.

BTW, I've got a Torsen right now but will be changing to an LSD type diff very soon

Rafa, don't. The Torsen is superior to the clutch type, unless you are getting an OS Giken or a Kaaz unit. I am seriously considering switching back.

If you do I'm interested in the clutch type. But why go back? Is this because of the track events you do?

The Torsen is a better track/autocross diff IMO.

I am about to install a 6-speed and the 3.636 gears that Ben posted pictures of (and keep the Cusco diff I have). The only way I'd consider keeping the 5-speed is if it was stronger, it's done well of handling the power so far and has had no issues at all, but the peace of mind that comes with a stronger transmission is important, considering a mildly built motor and larger turbo.
I considered the Quaife gearset for a while, but could not justify the cost for a daily driver. Got a good deal on the 6-speed anyway.

__________________

Savington; I've faced a small issue ever since my shop installed the 3.63 gears in my car. I bought a diff from an RX-8 and I'm going to try to make it work. We'll see.

I know I stated before it was from an RX-7 but it's not. It's in fact from an RX-8.