new transmission

[Steampunk]

can't help you with pricing, but I can say that (once again unless I am grossly mistaken) no Australian delivered NA8's came in auto.
So unless you dont mind buying a JDM, stick with manual NA8.

[broady]

Honestly I wouldn't bother unless you were going to do the swap yourself...

Just wait for the right car to come up -- is the best advice I can give.

[StanTheMan]

chap on here was going to do it....he's not posting much on here anymore.

I figure the change over would be around $5k. The gearbox itself would be the cheap part. You could then also try to sell the automatic gearbox to try to recoup some money.
MX5HVN did have someone lined up to do the conversion.....I don't recall a figure. he may have kept that for himself. ..... but this $5 k figure is an estimate for labour , fittings, gearbox, diff ratio & so on.

you just have to hang around. A car for your needs will come up eventually. But then you have to be ready to just snap it up.

[Jeo]

My NA6 started out life as an auto and as the other have said; if you're not doing it yourself, don't bother; if you haven't bought the car yet, don't bother. Far easier to wait for the right car to come up rather than trying to bodgy something else to fit.

[bruce]

Give me your Auto 5 and $5K, and I will turn it into a manual 5. It may be a different car though...

[93_Clubman]

And wasn't the engine in one or more of the autos detuned slightly? Low comp pistons or similar?

[GP]

I think that's a myth, No evidence found as yet

[Matty]

I think that's a myth, No evidence found as yet

NA6 auto was apparently detuned, different cams.

[93_Clubman]

I think that's a myth, No evidence found as yet

Googled: miata automatic detuned engine - the 2nd link was from page 45 paragraph 1 of Brian Long's book, Mazda MX-5 Miata:
http://books.google.com.au/books?id=qCP ... q=&f=false

Alternatively, Randy Stocker's old Solo Miata engine page says:
"The automatic transmission version of the 1.6 DOHC engine has lower compression pistons to 9.0:1 and the camshafts have less duration. These changes were done for the automatic version to gain torque at a lower rpm and minimize detonation from the torque eating trans."
http://www.solomiata.com/Mx5Engine.html