Name an iconic sports car with a slick-shifting, bulletproof manual transmission. The answer is always Miata, right? Well, except for the latest generation.
A key ingredient to Mazda’s recipe for classic roadster performance has been lightness. And after the NC generation bulked up a bit, th…
<starts taking notes>
The Global Cup Cars, before moving to the sequential transmission, had an intermediate step with EMCO gears and stronger studs to replace the case bolts. We did that to our ND1 transmission (the original V1, I think, although I may be wrong) years ago and it's been handling high torque turbo power ever since. I don't know if the EMCO gears are still available but the trans shifts like stock. The case bolts can be swapped without removing the transmission. We also run a transmission cooler which I think is critical to the longevity of the transmission under hard track use - fluid temps will easily get to 300F and stay there without one.
My theory as to why the ND transmission had problems has to do with the late addition of the 2.0 to the lineup. The car was originally intended to use the 1.5, but for the US market they decided late to jam the bigger, torquier engine in there. There's a reason there were no early press drives of that engine. There were some packaging compromises involved and it obviously took the transmission beyond design limits.
In reply to Keith Tanner :
Keith thanks for that explanation; I was wondering how they got it so wrong.
It's actually an interesting transmission. To minimize losses on the highway, 6th is a direct drive 1:1 gear - it has no overdrive ratios. The only other 6 speed transmission like that which comes to mind is the Caterham one.
It's not all THAT light according to our scales: 95 lbs for the V1, including fluid. The original Miata 5-speed is about 75, the NB 6-speed is 88 (those two are probably dry, so add 4 lbs), a T56 is 145 (wet).
Keith Tanner said:It's actually an interesting transmission. To minimize losses on the highway, 6th is a direct drive 1:1 gear - it has no overdrive ratios. The only other 6 speed transmission like that which comes to mind is the Caterham one.
It's not all THAT light according to our scales: 95 lbs for the V1, including fluid. The original Miata 5-speed is about 75, the NB 6-speed is 88 (those two are probably dry, so add 4 lbs), a T56 is 145 (wet).
Interesting about 6th gear.
As for the weights that had me laughing about the Datsun; I put the heavy duty gearbox from a 210 in the 1200. The "big" box weighs 54lbs while the standard 1200 box weighs 38lbs. The both hold 1.2 quarts, so add maybe 1-2lbs?
Seems strange that the ND transmission is heavier than the NA/NB, but less robust. The Aisin AZ6 NB 6-speed is in the BRZ too (fairly torquey 2.4l) and I believe the AZ6 is rated for up to 250ftlbs.
Keith Tanner said:It's actually an interesting transmission. To minimize losses on the highway, 6th is a direct drive 1:1 gear - it has no overdrive ratios. The only other 6 speed transmission like that which comes to mind is the Caterham one.
Way back that used to be common with a lot of European cars (albeit with fewer gears) and efficiency was the usual reason given as well.
Nissan's CD series comes close. Most domestic OD equipped transmissions the last two gears are your typical overdrive gear, but the 5th in Nissan is 1:1 with 6th being the only OD.
In reply to Mr_Asa :
That's why I specified "6-speed" :)
In reply to Snrub :
The ND transmission may be less tolerant of overheated fluid. The fact that NA-NC Spec cars have never run a trans cooler and the ND Global Cup cars have done so from day 1 says something.
Three hours for the swap! Wow, that's fast work. Took me more than 20 hours to do mine but it was my first time pulling a transmission.
Andy, did your original transmission have the upgraded Mazda studs or was it completely stock?
So far, I haven't had issues with either my ND1 or 2 trans, I had an ND1 with a V3 or 4 trans (can't remember which) that I ran for 2 TT seasons plus a bunch of track days. My '22 ND2 has 1 1/2 TT seasons and a bunch of track days and so far, so good (11k miles).
I had the Mazdaspeed studs in both and have GWR trans cooling scoop on the new car. I change the oil a lot (every 10 track hours). Since I'm at 5k feet of elevation in Colorado, the 20ish percent power reduction probably helps my cause. I also shift with a lot of mechanical empathy; I learned to drive manuals on Triumph transmissions that were well past their use-by dates in the 1980s...I think those things were made of cheese.
If mine ever does crap out, the Walter one is probably the better long term choice although the Mazda Motorsports pricing is relatively painless.
In reply to Keith Tanner :
Hi Keith, I followed the forums closely when I owned an ND1, from memory there were reports of 1.5's also breaking gearboxes. With my limited knowledge I would summise that with a 1 to 1 6th gear and a tall ratio diff, more of the torque load is transferred to the gearbox rather than the diff. I personally know of 6 ND1 gearbox failures (all at the track) and have a friend who avoided the issue altogether using the BBR GTI adaptor place, NC gearbox and the FIAT diff. Being in Australia makes access to Mazda Motorsort and the likes of Walter Motorsport more difficult.
FarmerTed said:Andy, did your original transmission have the upgraded Mazda studs or was it completely stock?
Both my ND1, which stripped 4th gear completely and turned into a box of rocks (replaced under warranty) and my ND2 (broken thrust washer) were totally stock.
Everything in my ND2 transmission looked quite good when it was pulled apart, save for that spacer and the oil guide mounting tab. That pic in the story of the magnetic drain plug shows very little build-up of ferrous material.
Pvandien1 said:Three hours for the swap! Wow, that's fast work.
Darrin is really good. Fast but careful. They really worked the angles to get the new one stabbed w/o boogering anything and w/o lowering the back of the engine with a support as the service manual suggests.
In reply to Keith Tanner :
Still less than 100 lbs isn't bad...I wondered why that picture is only two guys lifting it overhead to install. Never could do that with my 1969 GM M-22 rock crusher 4 speed.
You'll need to log in to post.
