Alex on Autos CX-90 review

i'll have to look at it later. he goes into more detail about the drivetrains than a lot of reviewers do. i think he's better known for showing how much extra space he has in different seating positions, especially the headroom.:LOL:
 
Read through a bunch of that. Was looking ok till he described the driving experience and engine being like a dual clutch at slow speeds..which I hate. Stopped reading there.
 
Brennor said:
Read through a bunch of that. Was looking ok till he described the driving experience and engine being like a dual clutch at slow speeds..which I hate. Stopped reading there.
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as long as it's a conventional automatic or close to it (not an actual DCT gearbox), they should be able to tune out the rough shifts. may be at the expense of fuel economy of course. it's also hard to tell what a car is actually like from a review, even a video review by someone thorough like alex, and he may have felt the need to compare the transmission to a DCT to give an idea of what it's like or his impressions of it.
 
potownrob said:
as long as it's a conventional automatic or close to it (not an actual DCT gearbox), they should be able to tune out the rough shifts. may be at the expense of fuel economy of course. it's also hard to tell what a car is actually like from a review, even a video review by someone thorough like alex, and he may have felt the need to compare the transmission to a DCT to give an idea of what it's like or his impressions of it.
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I’m reading a lot of info online regarding the DCT transmission on how it works and how to drive one. They drive and operate differently than a traditional transmission that has a torque converter. The CX90 I have with the Turbo S package does hit the gears rather quickly and gets you up to the speed when you want.
 
RhodiumRay said:
I’m reading a lot of info online regarding the DCT transmission on how it works and how to drive one. They drive and operate differently than a traditional transmission that has a torque converter. The CX90 I have with the Turbo S package does hit the gears rather quickly and gets you up to the speed when you want.
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is it an actual dual clutch transmission (DCT) though, or is it like the 6 speed auto in the other mazdas that is more-or-less a conventional automatic but doesn't use the torque converter?
 
potownrob said:
is it an actual dual clutch transmission (DCT) though, or is it like the 6 speed auto in the other mazdas that is more-or-less a conventional automatic but doesn't use the torque converter?
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The turbo-6 model features a new clean-sheet 3.3-liter turbocharged inline-6 with a single-scroll single turbo, paired with an electric motor mounted in the 8-speed automatic transmission. Total system output is rated at 340 hp and 369 lb-ft of torque.

Mitsuru Wakiie, the executive in charge of the CX-90 program, told Motor Authority the two powertrains' torque figures being the same isn't a coincidence (Turbo S and PHEV). The output is nearing the new 8-speed automatic’s power limit. The 8-speed automatic transmission is a clean-sheet in-house design featuring two wet clutches and no torque converter, the latter replaced by the electric motor. Behind the engine but inside the transmission casing sits the electric motor, then a wet clutch followed by the 8-speed automatic transmission, then another wet clutch, which hooks it all to the driveshaft.
 
RhodiumRay said:
From what I read they are designed after similar units that are in Mercedes, Porsche and the Mustang Shelby GT All high performance cars and also adds to fuel economy.
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Maybe I am reading your quote wrong, but designing a transmission to handle a certain torque load and building a new car that is near that max torque load seems bad. I highly doubt that those other car companies you mentioned would have done that.
 
dougal said:
Maybe I am reading your quote wrong, but designing a transmission to handle a certain torque load and building a new car that is near that max torque load seems bad. I highly doubt that those other car companies you mentioned would have done that.
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That was just a few words copied and pasted from a longer interview from the Mazda engineer. motorauthoritycom, January 31st interview. The brands I mentioned were just what I have read online separate from Mazda, nothing to do with torque but transmission designs.
 
RhodiumRay said:
That was just a few words copied and pasted from a longer interview from the Mazda engineer. motorauthoritycom, January 31st interview. The brands I mentioned were just what I have read online separate from Mazda, nothing to do with torque but transmission designs.
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Thanks. I ended up looking up the article and it says exactly what you stated:

"Mitsuru Wakiie, the executive in charge of the CX-90 program, told Motor Authority the two powertrains' torque figures being the same isn't a coincidence. The output is nearing the new 8-speed automatic’s power limit."

If that is really true, that is me tell me two things. 1) you will not see a Mazda engine with more than 369 lb/torque. So no inline 6 PHEV. Explains the PHEV, the inline 6 and the diesel engines. 2) I don't understand why they would create a whole new transmission design that was so limited in design. 3) the long term reliability of this transmission when at the max would worry me.

Anybody know if this is normal? I mean, I see the zf 8 speeds used in everything from a 200 hp car to a 600 hp BMW M class.
 
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It could be that the torque figure is nearing the optimal "reliability" limit.

I have typically seen transmissions have a 30-60% threshold between the mechanical power limits and the factory tuned torque. With transmissions, RPM is a factor when dealing with torque limits, so it could be that because of the low max TQ rpm of the hybrid combo, 370 TQ at 2k RPMs is nearing the reliability limits of the transmission. When you look at other performance turbo platforms, peak torque usually isn't seen before 2.5-3.5k RPMs. Only diesels have it this low.

So if/when this platform starts getting aftermarket support, I wouldn't be surprised to see tuners pushing out the torque band a bit in the event there really is un-tapped capacity in the new design.
 
ccspeedsix said:
It could be that the torque figure is nearing the optimal "reliability" limit.

I have typically seen transmissions have a 30-60% threshold between the mechanical power limits and the factory tuned torque. With transmissions, RPM is a factor when dealing with torque limits, so it could be that because of the low max TQ rpm of the hybrid combo, 370 TQ at 2k RPMs is nearing the reliability limits of the transmission. When you look at other performance turbo platforms, peak torque usually isn't seen before 2.5-3.5k RPMs. Only diesels have it this low.

So if/when this platform starts getting aftermarket support, I wouldn't be surprised to see tuners pushing out the torque band a bit in the event there really is un-tapped capacity in the new design.
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Maybe, but the maximum torque value of three version of their cars, all of which are very different engine designs, the PHEV, the Turbo S and the HO Diesel engines all cap out at 369 lb/ft of max torque. All generate it at different RPM values. It really sounds to me that they have developed a transmission that can't handle - maybe reliably - more than 369 lb/ft!

It would also suggest that don't ever expect Mazda to make a more powerful car with this transmission. Makes me also wonder if the reason why they have the electronic motor getting the car off the line is because of the transmission design...
 
I don’t see any issues with the transmission being designed for that limit.

I agree with the comments that this is likely the reliability limit. In other words, the limit were the transmission is likely to last for the life of the vehicle.

If you design a transmission to be more capable than it needs to be, then you are wasting weight and material, and it only makes sense if you are planning to use it somewhere where it will be used at that limit. If you are ZF and will have customer using it and another customer wants to pay the price to put that heavy duty transmission in its economy 4 cylinder car then sure why not. But if you designed it in house, then it doesn’t make a lot of business sense.

With the world transitionning to transmission less EV, and countries mandating forced EV transition, it might also be a bad strategic direction to bullet proof a transmission with the intent to sell it over 20 years in over increasingly more powerful powerplant.
 
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You have to take into account what "reliably" means. 100k miles? 150k miles? 200k miles?

Understanding that the mechanical limits of the transmission will likely be a good bit higher then what can be done reliably. If I had to guess there is probably about 5-10% of wiggle room to the theoretical reliable power rating of the transmission (~385-400 lb/ft torque).

The mechanical limits are probably dictated by the wet-clutches first, then the planetary gear clutches, then the planetary gears themselves. I wouldn't be surprised to find the transmission unable to hold/transmit more than 25-30% torque then designed (~460-480), sure there are plenty of examples where this number is much higher, but then its just a matter of how long will it last.

But at the end of the day, even if the transmission could only hold up to 400 tq reliably, if you were making 400 tq to redline, that is almost 500 hp. (HP = (TQ * RPM)/5252). The stock 370 ft/lbs, if it were held as a flat torque curve, is 460 HP. I dont know about you, but if it were achievable and reliable on the stock turbo and engine block/heads, another 80-120 hp is plenty for this platform.
 
dougal said:
Maybe I am reading your quote wrong, but designing a transmission to handle a certain torque load and building a new car that is near that max torque load seems bad. I highly doubt that those other car companies you mentioned would have done that.
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It wouldn’t be the first time… The first ND MX-5 Miata (2016) had a manual transmission operating right on the edge of the torque limit. The result was many failed units, especially for people taking it on the track (a legitimate Miata use case).

A key reason was the novel design approach of having a very low ratio rear end with direct drive in 6th gear instead of using overdrive ratios. The result was significantly higher torque on the output side, causing case and shaft flexing. Wasn’t a problem on the carry over automatics which used overdrive ratios and a taller rear end.

By 2018 they had gone through 6 manual transmission revisions, each time improving reliability, which really means torque capacity.
 
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