Detailed explanation of how the CX-90 AWD works?

[bulwnkl]

Has anyone seen, and would you please point me to, a detailed explanation of the drivetrain layout and function in the 6-cylinder CX-90?

I'm interested especially in details of how the AWD system works mechanically.
Thanks.

P.S. If one were to say something like, "It's very similar to the CX-xxx," that would be completely useless to me, as I am totally unfamiliar with any Mazda AWD or 4WD system since the late 1980s-era pickups.

***EDITED TO ADD:
I would like to know where power flows 'first,' how the front and rear axles are tied together (e.g. via a viscous coupler to the rear (or to the front)), whether the differentials are mechanical differentials or if they use clutch packs to 'engage' each half-shaft (a-la Honda's pickup and Pilot, in the rear), and so forth.

Thanks.

 

[sinistriel@]

Its a typical FR layout of AWD. Power leaves the transmission, goes through the transfer case out to a driveshaft and then to the rear differential. To bring power to the front differential there is an electronically controlled multiplate clutch that splines to the center shaft inside the transfer case. Pressure applied to the clutch set dictates the amount of torque sent to the front wheels. There is a gear ratio mismatch between the front and rear differentials of around 1%. This allows for a constant preload to always be applied to the ring and pinion in the front to speed up torque transfer and keep any drivetrain shock from occurring, it also enables more power to be sent to the front wheels if the clutches were fully engaged in the event the rears have no traction available. The coupling is supplied by JTEKT, this is an overview of how it looks.

Differentials are conventional spider gear with no clutches.

 

[youri]

Also, differentials are not locking differentials. The off-road mode use the brake to brake the freely spinning wheel and transfer power to the other side. It is not like Honda in a sense that it is not capable of torque vectoring. The uniqueness of the Mazda systems is that it tries to be predictive by using different data sensors on the vehicle to engage the AWD. (For example, if you try to start on an incline in winter, the awd will be pre-engaged instead of waiting for a wheel to slip).

 

[bulwnkl]

Its a typical FR layout of AWD. Power leaves the transmission, goes through the transfer case out to a driveshaft and then to the rear differential. To bring power to the front differential there is an electronically controlled multiplate clutch that splines to the center shaft inside the transfer case. Pressure applied to the clutch set dictates the amount of torque sent to the front wheels. There is a gear ratio mismatch between the front and rear differentials of around 1%. This allows for a constant preload to always be applied to the ring and pinion in the front to speed up torque transfer and keep any drivetrain shock from occurring, it also enables more power to be sent to the front wheels if the clutches were fully engaged in the event the rears have no traction available. The coupling is supplied by JTEKT, this is an overview of how it looks.

Differentials are conventional spider gear with no clutches. View attachment 323739

Thank you very much! That's exactly what I was looking for!

 

[bulwnkl]

Also, differentials are not locking differentials. The off-road mode use the brake to brake the freely spinning wheel and transfer power to the other side. It is not like Honda in a sense that it is not capable of torque vectoring. The uniqueness of the Mazda systems is that it tries to be predictive by using different data sensors on the vehicle to engage the AWD. (For example, if you try to start on an incline in winter, the awd will be pre-engaged instead of waiting for a wheel to slip).

Thank you. I may not understand quite what Honda means by 'torque vectoring,' because I thought that more or less meant using the brakes in connection with the traction control, but I think you're saying that's not what they mean(?).

 

[sinistriel@]

Thank you. I may not understand quite what Honda means by 'torque vectoring,' because I thought that more or less meant using the brakes in connection with the traction control, but I think you're saying that's not what they mean(?).

Torque vectoring by its base definition is the ability to transfer a varied amount of torque fore or aft and/or left to right. Technically any AWD vehicle torque vectors just by varying the amount of front to rear distribution. When an OEM throws the torque vectoring tagline out they generally mean left to right distribution for marketing purposes. You are also correct in saying that brake based systems can vary left to right which all of Mazdas systems have done for some time, they just stay away from the tagline. Some OEMs will use a clutch based system inside the diffs to send torque one way or the other. Others like Mazda will lightly touch one sides brake caliper which causes torque to flow in the opposite direction. A clutch based system for outright performance is superior but for most applications brake based works just fine.

 

[youri]

sorry i wasn’t very clear. I meant torque vectoring through the distribution of power to the left or right of the vehicle, through a clutch system like the honda sh-awd system

Sinistriel is correct that torque vectoring can also be done by applying the brakes, so my statement wasn’t entirely correct. Sinistriel explained it well, and brake torque vectoring is when you apply the brake on the inner side of the turn to help the car turn in that direction, but it is not a function of the AWD system, you could do this with a fwd or rwd car.

Mazda does use the brake to help with body motion in turns, but they are pretty adamant about it not being torque vectoring. By their claim they don’t use it to help turning, only to reduce unwanted body motion while turning.

All that to say mazda awd doesn’t have the ability to control the power sent left to right.

 

[sinistriel@]

sorry i wasn’t very clear. I meant torque vectoring through the distribution of power to the left or right of the vehicle, through a clutch system like the honda sh-awd system

Sinistriel is correct that torque vectoring can also be done by applying the brakes, so my statement wasn’t entirely correct. Sinistriel explained it well, and brake torque vectoring is when you apply the brake on the inner side of the turn to help the car turn in that direction, but it is not a function of the AWD system, you could do this with a fwd or rwd car.

Mazda does use the brake to help with body motion in turns, but they are pretty adamant about it not being torque vectoring. By their claim they don’t use it to help turning, only to reduce unwanted body motion while turning.

All that to say mazda awd doesn’t have the ability to control the power sent left to right.

This is where Mazda gets a little tricky, there is what Mazda says and what Mazda does. This is an internal training slide and I'm gathering data to put together a video. On my 3 Turbo you can monitor with the correct equipment under power watching throttle cuts as well as pulsing/applying rear brake calipers while turning, they use the TPMS to monitor tire temp with that as well as calculating rear brake temperatures. They don't market it that way but there is definitely some side to side transfer happening at least on that car.
The language in the slide is ambiguous enough to not say what they consider a traction event.

 

[youri]

I believe all these would be caused by Mazda’s “G-vectoring control plus”. In 2016, mazda introduced g- vectoring control. Even though the name is confusing it wasn’t really torque vectoring, instead it used the throttle to control the body motion during turns (slight throttle drop makes the front dip for example) all in the hope of reducing unwanted body motion throughout the turn.

More recently, G-vectoring control plus was introduced, which added small brake applications to the system. The goal here is to make the transition more natural during turning, but not to make the car turn more. That is why mazda says it is not torque vectoring. If you google it there is a lot of online info about the system.

 

[sinistriel@]

I believe all these would be caused by Mazda’s “G-vectoring control plus”. In 2016, mazda introduced g- vectoring control. Even though the name is confusing it wasn’t really torque vectoring, instead it used the throttle to control the body motion during turns (slight throttle drop makes the front dip for example) all in the hope of reducing unwanted body motion throughout the turn.

More recently, G-vectoring control plus was introduced, which added small brake applications to the system. The goal here is to make the transition more natural during turning, but not to make the car turn more. That is why mazda says it is not torque vectoring. If you google it there is a lot of online info about the system.

This is why I'm putting together a video of what is actually going on. I have the relevant internal engineering documents relating to G-vectoring. The torque transfer ability is separate from G-vectoring.

 

[youri]

I see. Well the slides refers to DSC (dynamic stability control). That is the system that helps prevents loss of control when the car start spinning. I can feel it and hear it apply the brake when i try to power drift in the snow with CX-9.

That being said i have seen reviews of the Mazda 3 turbo that suggests it’s all wheel drive as been tuned differently and more towards performance driving than the CX-9. It is possible that the brakes may be used to help with power delivery in corner. Maybe more similar to what Mazda calls kinetic control on the MX-5?

 

[sinistriel@]

I see. Well the slides refers to DSC (dynamic stability control). That is the system that helps prevents loss of control when the car start spinning. I can feel it and hear it apply the brake when i try to power drift in the snow with CX-9.

That being said i have seen reviews of the Mazda 3 turbo that suggests it’s all wheel drive as been tuned differently and more towards performance driving than the CX-9. It is possible that the brakes may be used to help with power delivery in corner. Maybe more similar to what Mazda calls kinetic control on the MX-5?

Yes the 3, CX-30 and CX-50 use an updated version called Evolved i-ACTIV. It uses a gear ratio difference to overdrive the rear wheels and functions mechanically the same as the GR Yaris and Corolla. The 3 has the most aggressive tuning of the three of them and the 3 turbo is even more so. Turning on sport uses a different G-vectoring map for the turbo car, you can get the rear to step out and will power oversteer in the wet. It's a good amount of fun when you learn how it operates.

 

[dunhillmc]

This is why I'm putting together a video of what is actually going on. I have the relevant internal engineering documents relating to G-vectoring. The torque transfer ability is separate from G-vectoring.

Are you sure? Mazda has always described GVC as using engine torque and GVC Plus as using engine torque plus adding brakes

Mazda talks | i-Activ All-Wheel Drive

The Mazda i-Activ all-wheel drive technology helps deliver a safe, fun, and fuel-efficient driving experience in any road conditions. With 27 sensors placed ...

youtu.be

On the CX90 Mazda stopped using the G-vectoring verbiage and instead uses Kinematic Posture Control (like the Miata) because they say it's geared towards rear wheel biased systems

 

[bulwnkl]

Thanks to you both. Perhaps some of my confusion comes from being too strict with "torque" and "power." We tend, I think, to interchange those words rather more freely than is appropriate (I do it regularly), but when I'm thinking of something like "torque vectoring" I tend to be strict in my interpretation.

To give a practical example, a standard open differential (spider gear type like most of us in N.A. think of when one says 'open differential') always splits torque 50/50. Mechanically, it cannot do anything else. However, it may split power anywhere from 100/0 to 0/100. That is because there is no power without movement (rate of work accomplishment), so if one wheel is off the ground and the other is stuck solid, power flows 100/0 to the wheel that's off the ground.

Sorry for being obtuse on occasion.
(-:

I really look forward to the video presentation!

P.S. If either of you have similar diagrams or descriptions available for the other CX models, I'd love to see how they work, too. PM is fine if they're not already in those models' sub-forums (I didn't find them with a brief search).

 

[sinistriel@]

Thanks to you both. Perhaps some of my confusion comes from being too strict with "torque" and "power." We tend, I think, to interchange those words rather more freely than is appropriate (I do it regularly), but when I'm thinking of something like "torque vectoring" I tend to be strict in my interpretation.

To give a practical example, a standard open differential (spider gear type like most of us in N.A. think of when one says 'open differential') always splits torque 50/50. Mechanically, it cannot do anything else. However, it may split power anywhere from 100/0 to 0/100. That is because there is no power without movement (rate of work accomplishment), so if one wheel is off the ground and the other is stuck solid, power flows 100/0 to the wheel that's off the ground.

Sorry for being obtuse on occasion.
(-:

I really look forward to the video presentation!

P.S. If either of you have similar diagrams or descriptions available for the other CX models, I'd love to see how they work, too. PM is fine if they're not already in those models' sub-forums (I didn't find them with a brief search).

I tend to stay out of internet discussions on torque split because its a wildly volatile subject that often ends in arguments lol. OEMs make it worse by talking about 60/40, 50/50 /30/70 etc because its never a set amount in real life. I put this video together quickly awhile a go to discuss how the Evolved version used in the 3, CX-30 and CX-50 work. Mazda evolved i-ACTIV AWD real world examples.

 

[heywardjr]

Thanks to you all contributors here. I learned an awful lot here. Much appreciated.