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Also, wanted to update everyone, a person has officially ordered the 2.0L supercharger kit to be mounted with manual transmission.
Will update once he gets it installed.
I inquired if that would fit non sky 2.0L and they let me know it does not fit .. only Sky platform
 
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Discussion Starter · #202 ·
Dan, did the individual get some definitive and believable answer re the torque rating on the Skyactiv-MT 'box?
No, not necessarily, I guess VT-Racing said they have never seen transmission issues with any of their Skyactiv kits (2.0 and 2.5), but your observations suggest that the MT will likely be sensitive to mis-shift/buzzing-the-teeth once you add the power of the supercharger. The nice thing about this kit is how gentle/progressive the boost is, seems like it's about as gentle as FI can be to a motor IMO.

I hope its better than the Skyactiv 6MT used in the ND. Seems they don't last long once you get upwards of 250whp, and the ND1 transmissions have experienced a pretty high failure rate with stock motors.....
The Miata transmission is not the same as the normal Skyactiv transmission, AFIAK, it is even lighter/smaller than what is in the Mazda 3/6/etc. with the 2.5L (though it's possible the transmission used with the 2.0L is closer to what is in the Miata, but that supercharger will only put out ~225whp from the 2.0L)
 

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Skyactiv drivelines, transmissions included, are built for efficiency, not power transmission. There is no reason to think that just because the MX-5 transmission looks different from the outside that its different on the inside. They are all built with the same design considerations. The Mazda 3 gearboxes don't fail like the MX-5 transmissions do, but the root cause of those failures has yet to be determined. Its quite possible that once you start throwing more power at them they will start to fail. Hopefully everything that Mazda has done to improve the longevity of the MX-5 gearbox in the past few years since the failures began will be also used in the Mazda 3.
This is a shot somebody posted of whats been happening to the MX-5 gear boxes, usually 2nd gear along with 3rd gear go away.....

 

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Discussion Starter · #204 ·
Skyactiv drivelines, transmissions included, are built for efficiency, not power transmission. There is no reason to think that just because the MX-5 transmission looks different from the outside that its different on the inside. They are all built with the same design considerations. The Mazda 3 gearboxes don't fail like the MX-5 transmissions do, but the root cause of those failures has yet to be determined. Its quite possible that once you start throwing more power at them they will start to fail. Hopefully everything that Mazda has done to improve the longevity of the MX-5 gearbox in the past few years since the failures began will be also used in the Mazda 3.
This is a shot somebody posted of whats been happening to the MX-5 gear boxes, usually 2nd gear along with 3rd gear go away.....

Holy crap!!!
This makes me even more concerned/curious about the reality of a CS turbo, since turbos surge which is very hard on drivetrains...

I agree with you, it is very logical to assume they are using similar design between Miata and Mazda 3, especially for the 2.0L, though I will point out that you mentioned 250whp which a 2.0L Mz3 supercharged will not get to (and with maybe 200tq to the wheels, it is torque that generally breaks stuff), so it seems likely that it will be ok in the case of the supercharger.
 
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This is also one possibility why you can't get a 6MT with a Mazda 3 turbo....Those pics by the way were from a mildly tuned stock ND1 motor....maybe 175 at the crank. Thats second gear that is totally stripped. 250 whp is seemingly the limit where you can absolutely expect a failure at some point, but many have failed with a totally stock 155hp motor too. This has been a problem since the ND with the SA-G power train was introduced.
 

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No, not necessarily, I guess VT-Racing said they have never seen transmission issues with any of their Skyactiv kits (2.0 and 2.5), but your observations suggest that the MT will likely be sensitive to mis-shift/buzzing-the-teeth once you add the power of the supercharger. The nice thing about this kit is how gentle/progressive the boost is, seems like it's about as gentle as FI can be to a motor IMO.



The Miata transmission is not the same as the normal Skyactiv transmission, AFIAK, it is even lighter/smaller than what is in the Mazda 3/6/etc. with the 2.5L (though it's possible the transmission used with the 2.0L is closer to what is in the Miata, but that supercharger will only put out ~225whp from the 2.0L)
I wasn't suggesting so much that when you mis-shift there would necessarily be a problem (though certainly there could be if you are really deep into the throttle), but by reason of the high frequency "buzz" sound on a muffed shift that I can hear... I can tell that a particularly "small-module" (puny) synchro teeth set up is used... and that as a result of i) puny dog-teeth and ii) non-generous synchro sleeve axial engagement - it doesn't sound like it's a robust 'box. The other comments in the Mazda blurb also suggest "light duty". Now a transmission or transaxle will have an instantaneous torque limit and a min-acceptable-service-life-based torque limit. If you apply high torque to a shaft that meshes with another - flexure in the mainshaft/layshaft combination can force the meshing gears apart. In doing this the proper gear-flank to gear-flank mesh is lost, and all of the metallurgical properties in the world won't give you an acceptable service life (duration). I think that's what is at play in Arathol's photo of a failed Miata transmission... and it is what I fear is one of the things that can happen with the C66M-R transaxle.

Incidentally, I could be wrong here, but I believe there is only one (1) Skyactiv-MT box out there, i.e. the C66M-R... for 2.0 litre and 2.5 litre 3's, 6's, CX-3's and CX-5's. Only differences being different final drive gear sets.
 

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Just to give a sense of how robust /coarse the dog-teeth are on a purpose-built performance set of gears (albeit straight-cut, non synchro ones... but nonetheless still having dog-teeth) note the attachment. This is NOT small-module (as applied to the dog teeth).
 

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This is also one possibility why you can't get a 6MT with a Mazda 3 turbo....Those pics by the way were from a mildly tuned stock ND1 motor....maybe 175 at the crank. Thats second gear that is totally stripped. 250 whp is seemingly the limit where you can absolutely expect a failure at some point, but many have failed with a totally stock 155hp motor too. This has been a problem since the ND with the SA-G power train was introduced.
Interesting ..
Im wondering if the pre sky MT5 on the 2.0L are less fragile .

Also , are those fails happening with OEM flywheels only or with also lighter flywheels or with stage 1 and higher clutchs ?
If the fail happening due to previous mishift/grinding or metal fatigue only because of higher contact pressure of extra HP?
 

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Interesting ..
Im wondering if the pre sky MT5 on the 2.0L are less fragile .

Also , are those fails happening with OEM flywheels only or with also lighter flywheels or with stage 1 and higher clutchs ?
If the fail happening due to previous mishift/grinding or metal fatigue only because of higher contact pressure of extra HP?
Yes, of course the transmissions used with the MZR motors are stronger.
Flywheels and clutches are not the issue, and neither is engine power. There seems to more than one contributing factor. PPF / driveline with excessive torsional flex, gearbox housing that has excessive flex, and most importantly the gears themselves are just.......weak. The Global Cup cars had regular failures until they found a vendor that could supply the teams with stronger gears that didn't strip out after one or two events.
You need to realize that Skyactiv drivelines are designed for maximum efficiency, and to get there much has been left out or built to a minimum standard to make everything as light as possible. You'd think that a car like the MX-5 that is advertised and sold as a sports car using its racing heritage as a selling point would be a bit more durable.
 

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Yes, of course the transmissions used with the MZR motors are stronger.
Flywheels and clutches are not the issue, and neither is engine power. There seems to more than one contributing factor. PPF / driveline with excessive torsional flex, gearbox housing that has excessive flex, and most importantly the gears themselves are just.......weak. The Global Cup cars had regular failures until they found a vendor that could supply the teams with stronger gears that didn't strip out after one or two events.
You need to realize that Skyactiv drivelines are designed for maximum efficiency, and to get there much has been left out or built to a minimum standard to make everything as light as possible. You'd think that a car like the MX-5 that is advertised and sold as a sports car using its racing heritage as a selling point would be a bit more durable.
Agree with all; just wanna know what "PPF" is (other than paint protective film)...?
 

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Hey everybody, I'm the guy that's getting the 2.0L supercharger on the 6mt. It's a 2014 3 iSport hatchback. I read through your replies and it seems like as long as I'm careful with my shifts, it should be fine. My feeling was that if the diesel 3's have the same 6mt tranny, the supercharger should be no issue. I'm happy to answer any questions and am even happier to get advice!
 

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If the diesel DOES have the same transaxle (and I thought it was different) then it lends credence to the suggestion it can take the torque. BTW it's not the care in shifting that is the central strength question; rather it is the ability to take the torque while in gear.
 

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Yes, of course the transmissions used with the MZR motors are stronger.
Flywheels and clutches are not the issue, and neither is engine power. There seems to more than one contributing factor. PPF / driveline with excessive torsional flex, gearbox housing that has excessive flex, and most importantly the gears themselves are just.......weak. The Global Cup cars had regular failures until they found a vendor that could supply the teams with stronger gears that didn't strip out after one or two events.
You need to realize that Skyactiv drivelines are designed for maximum efficiency, and to get there much has been left out or built to a minimum standard to make everything as light as possible. You'd think that a car like the MX-5 that is advertised and sold as a sports car using its racing heritage as a selling point would be a bit more durable.
Thanks !!
I figured the older model MT would be in a better position with wear n tear.
I am also thinking ..like you said with MX5 cup cars running into isssues of MT fail on the sky version ...
I would think that Japanese MX5 Tuners would have a solution...an upgraded MT that would fit or gearing.
OS Giken has for certain mazdas .... surely others may have ... but perhaps not for the sky versions
 

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Hmmm ... i think i found a solution for those who want a reliable heavy duty go crazy kinds MT transmission.
Kinda found it on the Mazda Motorsport parts website The Xtrac transmission .
Suitable for use in the TCR Xtrac - P1046T FWD TOURING CAR GEARBOX
But might be a bit overkill .

Would the MZR MT5 or Speed 3 MT6 be able to be mated to the Sky engine?
 

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If the diesel DOES have the same transaxle (and I thought it was different) then it lends credence to the suggestion it can take the torque. BTW it's not the care in shifting that is the central strength question; rather it is the ability to take the torque while in gear.
I thought the synchros were the main issue, and by not correctly shifting that was the problem. Glad to know it's not as important! I'm not sure if the diesel is the same, I guess I was just assuming that Mazda wouldn't develop a whole new system for the diesel engine.
 

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Discussion Starter · #217 ·
I'm curious, I understand there is fear of the unknown, but has anyone heard of a Mazda 3 with a failed manual transmission?

I understand that because things are lighter may mean they are weaker, but we are making some logical leaps. A great example is Corksport supposedly pushing 10+psi through this motor and claiming the engine could take more (even though lot's of people assumed because the engine components are lighter they are weaker which is not always the case).

I pinged VT-Racing, specifically their tuner I worked with, who said they have had no issues with their superchargers on the Skyactiv M/T. Obviously he is not an independent third-party, and I don't know what the sample size is, but at this point I think everyone is underestimating what these drive-trains can take (Mazda 3/6)...
 

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I'm curious, I understand there is fear of the unknown, but has anyone heard of a Mazda 3 with a failed manual transmission?

I understand that because things are lighter may mean they are weaker, but we are making some logical leaps. A great example is Corksport supposedly pushing 10+psi through this motor and claiming the engine could take more (even though lot's of people assumed because the engine components are lighter they are weaker which is not always the case).

I pinged VT-Racing, specifically their tuner I worked with, who said they have had no issues with their superchargers on the Skyactiv M/T. Obviously he is not an independent third-party, and I don't know what the sample size is, but at this point I think everyone is underestimating what these drive-trains can take (Mazda 3/6)...
My thoughts on this is if you are tracking your car like a MX5 Cup racer i would have a concern .
Otherwise ...enjoy the car , accelerate and shift smoothly.

As far as CS pushing 10+ psi through a OEM Sky engine... the concern i would have like other turbo'ed / speed 3 i know of pushing high psi
mainly on the track/ autoX / time events would be - heat issues - blowing a cylinder ring - head Gasket leak - Connecting rods & rod bearings.
Eventually the high psi and wear n tear / mileage will case one of these to fail and hopefully the sky is better built than the 2.3L
 

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I probably would be ok with the Supercharger set up with my manual in my '17 Mazda6. I have a numerically higher final drive gear, and if I pushed it - it'd generally be in the lower or mid-gears. I think the taller a final drive gear ratio is, and the higher the gear you're in when you push the car, the harder on the transmission it is. The stickier the tires are, also the harder on the 'box it is. You might say why would you spend all that $ and not extract all you can? Well, if the car needs, say, just a bit of a performance boost, well, then be temperate with what you ask of it with your right foot. Things in life often are such that you pay ever increasing $ for incrementally smaller benefits.

If you like the car and intend to keep it a decent period of time, an expenditure like this Supercharger kit can work for you.

These cars are good, they're fun, but it's my personal sense that trying to turn them into Corvettes or Ferrari's is a fool's errand. Don't let a Honda Civic Type R (FWD) owner hear this, but ultimately they are a FWD car you know!
 
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