Awd

[joevac10]

I am currently a happy CX-7 owner (I've had if for about a month now). I have a gt AWD and I have a question about the AWD. How do you know when the AWD kicks in? Is it full time AWD?

 

[UpNorth]

It's my understanding that it is not fulltime AWD, just when needed. But I too have wondered how I would know if I was in AWD. According to the manual, the 4WD light will flash when you first start the car, but otherwise it looks like it is not a good sign (or normal) to have that 4wd symbol light up.

So I'm really not sure how you can tell if you can't otherwise feel it. I've certainly felt real solid while driving in wintry conditions and deep snow.

 

[vbbuilt01]

I confess I don't know either, but I'll speculate that the designers engineered the CX-7 so well, that you don't have to know or need to know when power shifts to the rear. Totally seemless. Total integration with traction control and stability control.

With the ice storm we had yesterday, here in northern VA, I have to say I'm totally impressed with the handling and performance of the CX-7. My CX-7 handled the ice and snow with ease. If I lost traction, I couldn't really tell. Only way to know if there was a problem, was to watch the vehicles around me, slippin' and sliding.

Vince.

 

[Alpha Wolf]

The car runs on just the front two tires normally.

When it detects slippage on them it will start transferring up to 50 percent of the power to the rear.

This is done to improve mileage and efficiency as pushing all tires takes more power than just pushing the front two.

I am not sure how to tell when it is engaged. Hopefully it will be transparent to you when driving. You will just keep going with traction.

 

[erhayes]

The Mazda line does not make a true AWD vehicle like Subaru or Audi or ?

 

[singlemalt_18]

The car runs on just the front two tires normally.

When it detects slippage on them it will start transferring up to 50 percent of the power to the rear.

This is done to improve mileage and efficiency as pushing all tires takes more power than just pushing the front two.

I am not sure how to tell when it is engaged. Hopefully it will be transparent to you when driving. You will just keep going with traction.

All Wrong!

I don't know where everyone comes up with this stuff...

Go to post #12 here and read it all if you really want to know what you are driving:

http://www.msprotege.com/forum/showthread.php?t=123660829

THE AWD IS CONTINUOUSLY VARIABLE AND FULL TIME!!!!

 

[erhayes]

Alpha Wolf has it correct according to CX7 literature.

 

[Alpha Wolf]

I have done a bunch of research on the internet as well as all the documentation on their AWD.

I have heard various definitions of full time all wheel drive.

If it is on all the time and you do not have to manually do anything, it is considered full time all wheel drive.

Another adds the requirement for all the tires to be driven all the time. I am unsure if the Subaru or Audi constantly provide 50 percent power to their rear wheels. They may as both were originally developed for Rally Racing not street driving. Thus they may operate differently. I will look into it a my wife drives a Subaru Turbo.

I have checked and they use a viscous coupling: which means they contantly try to provide equal power to all four wheels. When any one wheel slips power is shifted to the other slower wheels. It appears they have open differentials so it is possible to get one tire spinning like crazy and your car stuck in mud with no movement. Does anyone have the tech specs on the CX 7 systems?

" The viscous coupling is found in most Subaru all-wheel-drive vehicles. It is used to link the back wheels to the front wheels so that when one set of wheels starts to slip, torque will be transferred to the other set, for example front set to the rear set.

The viscous coupling has two sets of plates inside a sealed housing that is filled with a thick fluid. One set of plates is connected to each output shaft. Under normal conditions, both sets of plates and the viscous fluid spin at the same speed. When one set of wheels tries to spin faster, perhaps because it is slipping, the set of plates corresponding to those wheels spins faster than the other. The viscous fluid, stuck between the plates, tries to catch up with the faster disks, dragging the slower disks along. This transfers more torque to the slower moving wheels -- the wheels that are not slipping. The plates are not directly connected, the "friction" of the thick fluid between the plates is responsible for the transfer of torque and therefore, one does not directly drive the other."

If it is usually off and you must manually engage all wheel drive then it is 4 wheel drive (like Mitsubishi does as do most Pickup Trucks)

I have talked to a number of Mazda techs both in person and on line on how this system works and in every case they say it only drives the front tires unless the system detects slippage.

The car drives the front wheels ONLY unless they slip. When slippage of the front tires is detected the system will automatically shift power from 0 percent up to 50 percent of the engines power to the rear wheels. The system will constantly change this as required by slippage it detects or does not detect.

The CX 7does not drive all 4 tires all the time. This was done to increase mileage and possibly a reduction in production costs and maintenance issues.

The system is active all the time, it just does not transfer power to the rear until the front start to slip. Thus while it is a full time all wheel drive system, it does not power the rear wheels all the time.

Please if you have factual MAZDA information to the contrary please feel free to provide it. I.E. specifics on the actual coupling hardware found on our cars and how these interact to provide AWD. Similar to what is available on most Subaru sites...

Continuously variable is Marketing speak meaning it constantly checks for slippage on the front tires and if detected will transfer various amounts of power to the rear tires up to 50 percent from 0 percent and any in between which stop the front tires from slipping.

Your link does nothing to prove otherwise. Some feel that it may transfer something all the time but there is no factual proof, just their feeling of how it works and even these stated that there are times when NONE would be sent to the rear tires. IE FRONT WHEEL DRIVE ONLY.

Even tiny slippage will cause the system to transfer power to the rear.

 

[vbbuilt01]

The Duel

In one corner, we have Singlemalt and in the other corner, there stands Alpha Wolf. Both contenders for the 4WD/AWD Crown. Listen carefully, you can hear them converse with their managers. In a few seconds, the bell will be rung and they'll come out swinging.....

(enguard)

Vince

 

[Alpha Wolf]

In one corner, we have Singlemalt and in the other corner, there stands Alpha Wolf. Both contenders for the 4WD/AWD Crown. Listen carefully, you can hear them converse with their managers. In a few seconds, the bell will be rung and they'll come out swinging.....

(enguard)

Vince

(lol)

(rlaugh)

 

[meanstreak]

I'm so confused... so if I drive backwards does my CX7 become rear wheel drive?
(bang) (help) (gtfo)

 

[singlemalt_18]

I have talked to a number of Mazda techs both in person and on line on how this system works and in every case they say it only drives the front tires unless the system detects slippage.

The car drives the front wheels ONLY unless they slip. When slippage of the front tires is detected the system will automatically shift power from 0 percent up to 50 percent of the engines power to the rear wheels. The system will constantly change this as required by slippage it detects or does not detect.

The CX 7does not drive all 4 tires all the time. This was done to increase mileage and possibly a reduction in production costs and maintenance issues.

The system is active all the time, it just does not transfer power to the rear until the front start to slip. Thus while it is a full time all wheel drive system, it does not power the rear wheels all the time.

Ding-Ding!

I'm ready to just say UNCLE....

I do not have any Mazda specific information - I don't care. AWD is what it is. These multi-wheel drive systems NEED RESISTANCE to work properly; just like the old posi-traction. Without resistance the systems become brain-dead.

The light on the dashboard is for the TCS. TCS is the system that is designed to detect slippage through monitoring relative wheel rotation. TCS has NOTHING to do with AWD. AWD in the air , or on ice, is useless. That is why there is TCS.

The "marketing speak" is in all stuff everybody is reading. Just because Mazda may have tweaked the logic in the system, DOES NOT MEAN THEY HAVE REINVENTED THE WHEEL !!! Certainly not for $26k to $31k. A bias to the front under low resistance, is not the same as FWD.

I would submit that a AWD system that spends 99% of its time dragging around a couple of un-used appendages IS NOT DESIGNED TO BE EFFICIENT! It just doesn't make sense.

I can tell you for a fact, that when I am at a stop light, and I nail it from the green light... my back wheels are driving, and the front are NOT slipping.

Cars are meant to driven, just drive...

Zoom-Zoom!

 

[Alpha Wolf]

I do not have any Mazda specific information - I don't care. AWD is what it is. These multi-wheel drive systems NEED RESISTANCE to work properly; just like the old posi-traction. Without resistance the systems become brain-dead.

Actually it depends on the unit and the design. The old Posi units in my 57 Pontiac Rear End in my 64 GTO Super Street Eliminator car used clutches that basically locked both axles together unless one tried to speed up or slow down when turning they were locked together even when the 16" wide slicks were being spun up in a bleach box full of water ie no resistance. The same was true in the 12 bolt in my Nova. Though the 10 bolts in old GTOs used springs and cones to lock the rear end up. Resistance allowed these to unlock so the outsided tire in a turn would not drag in a turn. These had no brains as they were simple mechanical devices. No electrontic were needed. But they tended to be all or nothing. Fully locked or fully released.

I am hoping to find more specifics on both the TCS and the AWD units used in our cars because I perfer to know how something works for sure than just go on hype and rumors. Yes they are different systems but that does not mean there are no connections between them. I don't think Mazda would double up on sensors on a price sensitive car to isolate them when it would not be necessary.

The light on the dashboard is for the TCS. TCS is the system that is designed to detect slippage through monitoring relative wheel rotation. TCS has NOTHING to do with AWD. AWD in the air , or on ice, is useless. That is why there is TCS.

Actually you are forgetting there is an AWD light which is what some others were refering to. I think it is used just to test the system on start up, others were hoping it would light up to tell them the AWD was doing something.

While that may be so, as I do know know how the AWD, which is stated to be electronically controlled works, it is also possible the two are linked in some way where by the TCS system feeds info to the AWD system. Possibly how it detects slippage on each wheel etc... Again. I would like to see some tech info on both systems to see how both work and whether they are independant or somehow linked.

Slippage on some open differential AWD can leave only 1 tire per axle turning because one will spin up and the other will not move. The Posi action can be an critical part in how your AWD works. It could mean have 4 wheels driving on slippery roads vs only 2.

The "marketing speak" is in all stuff everybody is reading. Just because Mazda may have tweaked the logic in the system, DOES NOT MEAN THEY HAVE REINVENTED THE WHEEL !!! Certainly not for $26k to $31k. A bias to the front under low resistance, is not the same as FWD.

I am sure you are correct. I assume it is not an entirely new system. The Mazda 6 AWD seems to be labled the same. They may have lifted some or all of it from that car to save money. And yes a front end bias is not to say it is a FWD car. Again until it would be best to find documentation from Mazda or a tuner who knows the system outlining how it works. Then we could positively understand when it would be running on just the front wheels and when it would start distributing the power to the rear. But you are correct, the AWD system is always on.

I would submit that a AWD system that spends 99% of its time dragging around a couple of un-used appendages IS NOT DESIGNED TO BE EFFICIENT! It just doesn't make sense.

First off define efficient. From a manufactures prospective, it must not only provide the benefits of additional traction when needed but also reduce the power and mileage loses when possible. Free wheeling the rear wheels is more efficient from a mileage and horsepower prospective as the FWD cars are lighter and since they do not have to drive the mass of the drive shaft axles and wheels of the rear tires they get better mileage than our AWD cars. Hence efficiency. Thus it is obvious that to keep the power only driving the front wheels causes less power loss than driving all four plus a long drive system. Thus, this system only powers the rear when front wheel traction is insufficient is logical from a power and mileage efficiency stand point. I would agree that it may not be optimal for maximum traction by not dividing power all the time. But a car design is all about compromises. It would be good if we can obtain the specifics the system uses so owners know when and how their system will work. Remember cars have been around for a long time without AWD and some like Formula 1 cars, Top Fuelers etc are quite efficient for only driving 2 wheels.

I can tell you for a fact, that when I am at a stop light, and I nail it from the green light... my back wheels are driving, and the front are NOT slipping.

That may or may not be true that there was no slippage. Small amounts of tire slippage cannot be detected by the seat of the pants and will not leave black marks on the pavement. The system may be sensitive enough to start activation on an amount of slippage that we cannot detect but the wheel sensors can. Thus, if detected and power was transfered the result would be that all four tires are driving when you did that. But yes, my car will not lay rubber like my old mucle cars would and thus the slippage is not obvious without 30 ft of black marks.(drive2)

Until more information becomes available I for one would not put an AWD car on a dyno as most wheel dynos I have used slip even with sticky racing slicks and so it would be a bad thing to have the rear sitting on solid ground suddenly get 50% hit of 244 hp at the wrong time...

(hi)

 

[singlemalt_18]

- These had no brains as they were simple mechanical devices. No electrontic were needed.


- just go on hype and rumors.


- Yes they are different systems but that does not mean there are no connections between them.


- And yes a front end bias is not to say it is a FWD car.


- But you are correct, the AWD system is always on.


- Free wheeling the rear wheels is more efficient


- it is obvious that to keep the power only driving the front wheels


- this system only powers the rear when front wheel traction is insufficient

My brain dead comment was not meant to imply that these systems are anything but mechanical. Even the viscous couplings you describe, which are the heart of these AWD set-ups, are a mechanical device. They are both constant and dynamic by nature. Its not rumor or hype, or marketing. The mechanical operation just doesn't work without the resistance.

I also agree that they have probably developed some means of "communication" with the TCS; I would think it is more of a way to get more critical info to the TCS.

I believe alot of the misunderstanding about this FWD bias is the result of it being looked at in reverse. Instead of it being FW only, and "waiting" to engage the rear, it is AWD that, as drive loads and road resitance "equalize", seeks to "float" the rear... until drive loads begin to become more uneven. Many want to think it starts at zero and can go to 50%, I think it starts at 50% and flows to the zero.

I DO NOT BELIEVE Mazda would be watering down the handling and traction of a modern AWD system, simply for fuel efficiency - not with the numbers FWD owners seem to be getting. (I average 17.5 to 18 mpg without fail.) Nor would they be doing it for more horsepower when there is the DISI turbo. Nor would they do it when there is a FWD model already available - what would be the point of adding a 400 lb AWD system to a vehicle, that spends most of its time not in use? That, would not be efficient.

The ONLY alternative is that it is both full-time, and continuously variable.

Maybe for 2008 Mazda will offer a version with locking rear hubs for those who absolutely, positively, need to know!

 

[Alpha Wolf]

My brain dead comment was not meant to imply that these systems are anything but mechanical. Even the viscous couplings you describe, which are the heart of these AWD set-ups, are a mechanical device. They are both constant and dynamic by nature. Its not rumor or hype, or marketing. The mechanical operation just doesn't work without the resistance.

Are most AWD now viscous couplings these days and not clutch type systems? I have yet to find anything on what Mazda uses on our cars. It states electronically controlled, but not the actual mechanical mechanizim used to accomplish this. I suspect it is some time, and yes I thought you were speaking of external resistance vs internal and yes you are quite correct regarding viscous coupling system.

I also agree that they have probably developed some means of "communication" with the TCS; I would think it is more of a way to get more critical info to the TCS.

Does anyone know how the TCS works? Is their some form of locking hubs or posi units or does it use some sort of brake activation or what? Or is it like the Subaru stock system which is an open differential. I don't think it really matters who is talking to whom. But it would seem to be redundant for dual systems duplicating the funtionality.

I believe alot of the misunderstanding about this FWD bias is the result of it being looked at in reverse. Instead of it being FW only, and "waiting" to engage the rear, it is AWD that, as drive loads and road resitance "equalize", seeks to "float" the rear... until drive loads begin to become more uneven. Many want to think it starts at zero and can go to 50%, I think it starts at 50% and flows to the zero.

That may be the case however, most look at it in the opposite because that is how Mazda describes its functioning. They may be just simplifying the description for non-motorheads or they may be accurately describing how it does function. Until they release more technical info on these systems we will not be sure.

I DO NOT BELIEVE Mazda would be watering down the handling and traction of a modern AWD system, simply for fuel efficiency - not with the numbers FWD owners seem to be getting. (I average 17.5 to 18 mpg without fail.) Nor would they be doing it for more horsepower when there is the DISI turbo. Nor would they do it when there is a FWD model already available - what would be the point of adding a 400 lb AWD system to a vehicle, that spends most of its time not in use? That, would not be efficient.

I did not take your comments as brain dead.

It is hard to say. But it is an engineering fact that you incure power loses when power passes through a power train. Viscous coupling by its nature does not lock up and therefore has internal power losses due to both slippage and the power required to move the parts. The more and heavier the parts the more power is lost driving the power train instead of the wheels.

I would disagree that Mazda would not be aware of how mileage sensative CX customers are, you only have to browse any forum to hear all the bitching as it is so I think that trying to keep the EPA ratings up to that of the competitions cars does matter. But I would agree that the losses due to weight and power losses only appears to make a minor difference in mileage between AWD and FWD cars. My AWD averages 21 mpg.

As to the power, this car's engine is not superpowerful. Considering most of the competition is using V6 or V8s of up to 300-500+ hp (Porsche) for their cars I do think Mazda would do what they could to maximize the power of this car while using their existing I4 turbo engine to keep costs down. This car is not super fast as my 1970 Beetle with a 1.9 liter non-turbo motor will run away from my CX7. Granted it is far from a stock VW (Weber carbs, big cam etc) but the point is, it does not have an over abundance of power from my prospective. But my perspective is not the norm. I have raced an 8 sec 600hp Roadster, 10 sec 500 hp GTO, 11 sec Street legal Nova Drag cars and ride an 10 sec liter sport bike which does 0-60 in under 3 seconds. So a high 14 sec Cross over is not an overly fast ride for me. While I think the 2.3 turbo was used as a compromise for production costs (existing engine) and in an attempt to maximize mileage and lower costs with a 4 vs a 6. This is one area I feel was a bit of a failure as the mileage is at or below what some SUVs with V6s or even V8s get. Just reading all the bitching about mileage would support that others also feel this way. While I am getting far better than most who are complainng I was hoping it would do 24 mpg on the freeway and only extreme babying and low cruising speeds on flat terrain can get you near this number. Not normal driving.

The ONLY alternative is that it is both full-time, and continuously variable.

Maybe for 2008 Mazda will offer a version with locking rear hubs for those who absolutely, positively, need to know!

While I would agree it is full time and continously variable, I still need more info to be sure exactly how it functions. Until then I will assume what I have been told is true as it makes more sense to have it start at 0 and go to 50% since most normal driving conditions do not require the rear wheels to be powered. At least to me. Why default a system to the state that is least used? That does not make sense to me from an engineering standpoint.

Let me know if you find any documentation regarding how it actually functions so all the owners will know for sure how it works. I will keep looking myself.

(drive2)

 

[singlemalt_18]

- I did not take your comments as brain dead.


- I would agree it is full time and continously variable, I still need more info...


- Let me know if you find any documentation regarding how it actually functions so all the owners will know for sure how it works. I will keep looking myself.

LOL! I never thought you meant MY comments were brain dead! I was referring to mechanical functions being rendered useless... (not very Alpha-like... your sensitive side is showing!)

Not to disappoint the crowd that's gathered for this match-up, but I think we may agree on many points. I still go with my gut on some of the details because I just don't think there is any holy grail in this. The CX-7 is an exciting new model from Mazda that is making many more members to the Mazda family; its not some new species or element on the periodic chart - in my opinion.

The TCS is primarily a braking function, but some have said that is can also reduce engine power too - if so cool, but I would need proof on that one! The 4WD indicator is a warning light for oil temp, and apparently disparate front to rear wheel speeds. If that light goes on, there is a problem.

Go for it... if you can actually find any hard tech info, as a recovering analytic, I would be very interested.

Joe

 

[Alpha Wolf]

LOL! I never thought you meant MY comments were brain dead! I was referring to mechanical functions being rendered useless... (not very Alpha-like... your sensitive side is showing!)

Don't tell my Wolf/Dogs they may get ideas.....(evil)

I have run into individuals who take a discussion with differing opinions and turn it into a war room battle. People that immature should not be on forums if they cannot keep discussions on an intellectual level. Nice to meet someone who doesn't even if you like typing in Caps to highlight your points.... (wiggle)

Not to disappoint the crowd that's gathered for this match-up, but I think we may agree on many points. I still go with my gut on some of the details because I just don't think there is any holy grail in this. The CX-7 is an exciting new model from Mazda that is making many more members to the Mazda family; its not some new species or element on the periodic chart - in my opinion.

I think the only point we are not in line with is how it actually works which requires some tech docs to clearify it one way or the other for sure.

The TCS is primarily a braking function, but some have said that is can also reduce engine power too - if so cool, but I would need proof on that one! The 4WD indicator is a warning light for oil temp, and apparently disparate front to rear wheel speeds. If that light goes on, there is a problem.

That is what I heard as well but I cannot find anything to support the later yet. I think most were hoping it would light up to tell them it is engaged. I feel you are correct that it is just a trouble light and that the actual operation is transparent to the driver which is as it should be in my opinion. If you need lights and to know it is on, get a 4WD that you have to manually engage.

Go for it... if you can actually find any hard tech info, as a recovering analytic, I would be very interested.

Joe

Hopefully there will be more tech info on our car released soon...

Hang Loose
Darryl

(hi)

 

[Otto]

Regarding TCS... it is my understanding that TCS as such only uses the ABS to function. It is the DSC (dynamic stability control) that adds some sensors and can also modulate throttle

 

[CX7_Scott]

You're all wrong - Mazda vehicles are all-wheel-drive. Inside each tire is a traction troll that lives there (the tire-pressure monitoring system makes sure they can breathe - which is why you should NOT use nitrogen, it will kill your AWD). But the tire trolls decide when to give the wheel traction or not. The idea of viscous couplings and so on is just marketing mumbo-jumbo and there is no such real thing.

They can scurry through the hollow drive train like a HabiTrail system and all-four can put power to one wheel if they want. It's quite simple, really.

Now... go drive and have fun!

 

[joevac10]

This was a simple question and I was looking for a simple answer. You guys are just typing all this information that has no relevance to the question I asked. You are not impressing me with your (lack of) knowledge on this topic. Just admit you don't know th answer to my question.....