2006 up Miata Transmission questions

[socorob]

Anyone on here know anything about these ? If so, are the 5 and 6 speeds the same length? Know where I can find some size measurements on the lxwxh of the tranny and is it electronically controlled in any way? It would be nice to have a 6 speed in the alpine.

[Moderator]

Keith Tanner will certainly know or at least have the measurements close at hand. If he doesn't chime in here presently, you can send him a private message. Here's a link to his profile page: http://forum.britishv8.org/profile.php?2,2444   Either way, please let us know what you find out, for future reference.

[mgb260]

Robbie, The Duratec with Miata trans would be a killer combo!

[socorob]

I think so too, right now I'm trying to get all the info I can to see how hard it can be. There's miata guys with the 2.5 with 2.0 head and cosworth parts getting 250 + whp NA. That's 70+ more than you can get out of an NA cologne and the engine seems to be 100 pounds lighter with bills stock 2.3 getting 30-35 mpg. Sounds like a lot of wins. I'm mostly concerned with height and oil pan ground clearance. I'm trying to see of the miata oil Pam is shallower and will bolt to the duratec. Cosworth makes a dry sump but it costs cosworth $$$. an ebay seller was nice enough to measure one for me and from front of bell to middle of shifter the miata 6 speed is about 28.5".

[mgb260]

Robbie, I looked at pictures of the 5 and 6 speed on EBay. The 5 speed looks skinny while the 6 speed was fatter. Shifter looked about the same distance back.

[socorob]

I think you could get a 5 or 6 speed at o e point so that makes sense. I still would like to find the other measurements and If it's computer controlled in any way and if there's a normal hookup for an electronic speedometer like the t5 uses.  Can't remember what it's called. I heard some newer cars get speed from the abs sensors instead of the trans? That would be an issue if that's the case.

[socorob]

It also appears the engine without accessories weighs a out 180 pounds. Very ligjtweight

[Keith]

Color me a bit skeptical on those power numbers, but you get what you pay for on internet power claims Cosworth has a 260 hp 2.3 that they used in the Caterham. The biggest problem is the greater displacement engines mostly have longer stroke, and they're rougher than is ideal for a sports car.

Anyhow...

I know more about the 6-speed than the 5. The trans does have the capability for an electronic speedo. However, ABS cars use the wheel sensors instead. There's still a spot to insert the sensor pickup in the trans, but there's a little pin that acts as a trigger on one of the shafts. It's left out of the transmission internals on ABS cars. Since all US 2006+ Miatas have ABS, this is a hassle. You can probably buy the pin and insert it yourself. We discovered this when trying to hook up a rally computer to a 2006.

There's no electronic control of either the 5- or 6- speed manuals.

The shifter is in the same location on the 5- and 6- speeds. I'm not 100% sure if the length of the trans is the same, but ask your local dealer for the part number for the Power Plant Frame for each. For extra credit, get the driveshaft part number. If they're the same, the trans has the same length. Both of the transmissions are related to the versions used in the 1990-05 cars, and in those applications they were the same length. The 6-speed is indeed wider.

We might have a 6-speed box sitting around at work. I'll check on Monday and get you dimensions.

[MGBV8]

Okay, Robbie, why?  I have yet to see a real need for a 6 speed in a car, including my dad's Miata.

[socorob]

Well, I do t know if it's needed or not. Right now I have 4.10 gears in my rear and I turn about 2850 at 70 in 5th. I think it would be. Ice to spin a little less cruisi g if  it doesn't bog the engine down.

[302GT]

Most 6 speeds have the same top ratio as a 5 speed, the difference is that there is a smaller gap between the top gear (6th) and the next lower gear. Check the specifications, do not assume anything. Note that many T 5s come with a 0.63 5th, and aftermarket 0.5 gears are available.

[socorob]

Actually, at least with the T-56, you get 2 overdrive gears. The 6th is around a .50 ratio, and 5th is about what the T-5 has. I'm not sure what ratios the Mazda uses.

[Keith]

I've got a number of cars with 6-speeds - including my MG. If they're well chosen, it's nice to have the extra ratios. The top gear in a T56 is a monster, but it's nice on a highway cruise if you have the engine to back it up.

It's usually pretty easy to find gear ratios. Just check the manufacturer brochures.

6 speed for a 2010 Miata:
3.82
2.26
1.64
1.18
1.00
0.79

The 5 speed is:
3.14
1.89
1.33
1.00
0.81

[socorob]

Thanks, we're you ever able to get any measurements from the transmission?

[mgb260]

Robbie, With those ratios I don't see any advantage with the 6 speed. You might also want to trade the 4.10 for a 3.55 also.

[Keith]

I don't have any loose ones to measure for dimensions right now, sorry. They're about halfway between a T5 and a T56.