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Discussion Starter #1
My 2003 A6 2.7T is getting long in the tooth and I am looking to purchase a replacement in 1.5 years or so.

Does anyone have details on what kind of AWD the new CTS uses? Also, is there a chance that Cadillac will give us AWD with a manual tranny in the future?
 

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I tried to investigate this topic because like you I have a "quattro background" and I know how much fun and power it gives, especially taking into account I live in a place where at least 6 months out of 12 each year there is much snow, ice and mud on the roads.

There are really very few sources and they seem to be contradicting.

The system in CTS is supposed to be borrowed from the SRX and STS. I initially thought it is an open differential in the center with the ESP (Stabilitrack) vectoring torque by way of braking individual wheels and cutting power. Which is not exactly a strong system, since it relies altogether on electronics and merely forces the car to slow rather than redistribute power to make it steadily and predictably glide, like a torsen based quattro. Similar simple systems were used by Mercedes and BMW, but they abandoned them in favour of more complex, more mechanical systems.

However one of the magazines (don't remember which one exactly) recently reviewed the 2008 CTS and reported that in normal conditions the AWD sends 75% power to the rear and up to 100% to either axle, which precludes the simple open center diff strategy. In fact, GM refers to this system as having some kind of advanced "transaxle", but I have yet to find any further detail to that.

Also, reportedly Stabilitrack can be switched off for a bit of fun even with AWD, though I'm not sure.

And besides, you can order a limited slip differential as part of a performance package together with AWD. I believe this combination could make the car a very handsome handler on slippery surfaces.

One final thing, AWD requires that you also order advanced brakes on the 2008 CTS, hence I conclude this system still DOES heavily rely on brakes, at least when Stabilitrack is operational.

These are all pieces of info and assumptions I have ;)
 

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Are you sure that you have to order the J55 high performance brakes with awd?

Its only 395 dollars so its not a big deal but I am not seeing that option of high performance brakes on the invoices of the AWD vehicles available locally.

I do not believe the J55 option is necessary for the FE2 AWD equipped vehicles.

As far as how effective the AWD setup will be? I would suggest it will be more than capable of most street driven situations.

If its not? The best move in my opinion would be to equip the vehicle with "SNOW TIRES"

With that I'd say the vehicle can easily handle snow situations as long as the snow is not too deep because of its sedan like ground clearance. (just like the AWD sedans such as BMW/Audi/Mercedes etc)
 

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Okay, here is a piece of info that seems to shed the light on the AWD system.

http://www.duemotori.com/news/auto_news/15886_All-Wheel_Drive_System_to_Debut_in_All-New_2008_Cadillac_CTS.php

This reports that the system is BorgWarner ITM-tc (Interactive Torque Management Transfer Case) with Vehicle Dynamics Control (VDC) software.

"We are proud to launch another all-wheel drive application with Cadillac and General Motors," said Cindy Niekamp, President and General Manager, BorgWarner TorqTransfer Systems.

This is weird since I thought BorgWarner only develops AWD for front wheel drive based configurations, including the ITM susbsystem. BorgWarner website seems to concur with that - I found only FWD-oriented systems there. Also, Stabilitrack seems to be a genuine GM software not related to Borgwarner's VDC.

What puzzles me even more is that BorgWarner unit can be coupled with the standard RWD GM's rear wheel limited slip diff. While I salute GM for building such a complex and surefooted system, it seems the amount of effort to integrate these parts into a whole smoothly working system must have been colossal and it is strange that GM just didn't ditch LSD for AWD to save development costs since I guess this combination will only have a slim effect for 99% of buyers.

I don't think I understand it all well yet, but information about the Borgwarner unit seems to be sound.

JBsZ06:

I looked again at the ordering guide and figured out the J55 is only applicable for AWD if the Y42 performance pack is installed. Moreover, J55 MUST be ordered with this combination, and the only case it is available otherwise is RWD with the Y43 performance pack. Go figure why it is these exact combinations when performance brakes can and must be ordered...

"I do not believe the J55 option is necessary for the FE2 AWD equipped vehicles."

Yes, this is exactly the case. The combination Y42(inc.FE2)+MX7(awd auto), both engines, REQUIRES J55, and for an additional charge, to that. Other than that, Y43(inc.FE3)+MX0(rwd auto) REQUIRES J55, but for no additional charge. As I said, go figure...

And now regarding you handling inquiry.

BorgWarner is a very sound company. They developed the ingenious DSG for Volkswagen. AFAIK, they are also developing torque vectoring AWD systems similar to Honda's SH-AWD which seems to be a very nice system which controls oversteer/undesteer by actually OVERRIDING as opposed to just braking individual rear wheels like most systems, although it is still not genuinely proactive and pre-emptive like the quattro.

So I think the borgwarner based AWD CTS, especially with the LSD, must be a very nice ice handler, with a bit of fun RWD bias. It is most definitely neither a torque vectoring setup nor a genuinely proactive system, but it should be very surefooted. But surely this is only an assumption. I hope the 2008 comes to Russia before winter ends, so I'll be able to give it a try in snow.

"If its not? The best move in my opinion would be to equip the vehicle with "SNOW TIRES" "

Snow tires help a lot, but a genuinely good handler makes a trip not just happen, but be fun as well.
 

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Discussion Starter #5
The system in CTS is supposed to be borrowed from the SRX and STS. I initially thought it is an open differential in the center with the ESP (Stabilitrack) vectoring torque by way of braking individual wheels and cutting power. Which is not exactly a strong system, since it relies altogether on electronics and merely forces the car to slow rather than redistribute power to make it steadily and predictably glide, like a torsen based quattro.
That's what I heard initially and to be honest, I wouldn't want this kind of AWD on a luxury performance sedan. If that's to be the case, I'd rather go with RWD and snow tires.

Too bad Borg-Warner press release does not give us enough details.
 

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"I do not believe the J55 option is necessary for the FE2 AWD equipped vehicles."

Yes, this is exactly the case. The combination Y42(inc.FE2)+MX7(awd auto), both engines, REQUIRES J55, and for an additional charge, to that. Other than that, Y43(inc.FE3)+MX0(rwd auto) REQUIRES J55, but for no additional charge. As I said, go figure...

Thanks and you are correct. AWD without the Y42 you don't need J55.

Order AWD and Y42 handling package and you do need to pay an additional 395 dollars for J55.

Not a big deal but kind of weird they just don't make it part of Y42.

Thanks for the clarity.

JB
 

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On the interrior shots of the 08 cts I did see what appears to be an autostick which offers auto and manual shifting.
It actually gives you three different shift modes.
  1. You have the normal automatic mode.
  2. If you move the shift knob over to the manual mode but do not up or down shift, it retains fully automatic shifting, but is in sport mode. Sport mode provides firmer shifts.
  3. Lastly, you can use the shift knob to manually upshift/downshift. Note however, that it will not let you downshift to a gear that would cause over-revving.
:cheers:
 

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I have it in my current car. It is useless, IMHO.
I agree, the manual mode on the automatic is a complete joke. It is extremly slow reacting to your inputs. The transmission will still shift when it wants to even if it means letting the engine hit the rev limiter.
 

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It actually gives you three different shift modes.
  1. You have the normal automatic mode.
  2. If you move the shift knob over to the manual mode but do not up or down shift, it retains fully automatic shifting, but is in sport mode. Sport mode provides firmer shifts.
  3. Lastly, you can use the shift knob to manually upshift/downshift. Note however, that it will not let you downshift to a gear that would cause over-revving.
:cheers:
That seems like a nice setup for a sports sedan.

I would have preferred a dual clutch sequential shift technology as it costs less to build, gives better emissions, fuel economy and most importantly performance.. but it will be three years before that transmission hits the domestics..

First Chrysler, then ford and eventually GM..

GM makes the best automatic transmissions with torque convertors in the world so I expect they will be the last of the big three that make the transition to Dual clutch sequential transmissions..

It will probably be emissions and fuel economy that eventually makes GM change over..

I've driven the CVT in the audi A4 and Nissan Altima...Thanks but no thanks..
The DSG in the Audi TT and VW GTI were cool but in the CTS I would be satisfied with the GM 6 speed toque convertor automatic.

Just shooting the breeze.

JB
 

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I am the AWD Development Engineer for the 2008 CTS AWD. If you would like details on system operation feel free to e-mail me.
 

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Avatards hopefully you're reading here because I'm new to the site and learned I cannot reply to PM's before posting 20 times?: hmm: Never heard of that one before. Anyway perhaps responding here will enlighten others on the on the CTS AWD system. The transfer case utiilized in the new CTS is what we at GM refer to as an Active system. Unlike an open center differential transfer case, an electronically controlled clutch is used to transfer torque to the front axle. This system requires far less brake intervention and is integrated with the stability control system for optimum performance. As one reader commented, this requires far more development than open center differential transfer cases but provides an advantage in traction and stability as compard to an open system. An explaination of the control algorithms would be way to lengthy to cover in detail here but in short, the system reacts to steering input, throttle input, wheel speeds, stability inputs, etc. For optimized handling the steady state torque split is approximately 25% front/75% rear. Almost all available torque can be sent to the front wheels in the event the rears are slipping. The controls are designed to be preemptive meaning torque is sent to the front wheels based on throttle inputs, etc. in order to reduce/eliminate slip before it occurs. The systems is as I previously stated integrated with stability control. For instance, when the brake system detects slip, engine power is adjusted accordingly to ensure smooth and controlled behavior. LSD (limited slip differential) is available on AWD models. While electronic stability and traction control can be disabled, the transfer case cannot. Hopefully this is informative and helps those considering AWD understand it's function.
 

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I agree, the manual mode on the automatic is a complete joke. It is extremly slow reacting to your inputs. The transmission will still shift when it wants to even if it means letting the engine hit the rev limiter.
Have you driven the 08 CTS yet? While still not as advanced as DSG, the DSC in the '08 CTS is quite an improvement over the previous Sigma cars. Where last year's CTS would downshift and "drag" the RPMs up (causing the car to lurch forward), the 2008s perform a nice rev match before downshifting, which gives you a smooth, quick downshift.

Also, the computer logic will NOT force an upshift at high RPM, which allows you to run through twisty corners at 6,000+ rpm and have better control over the power to rear wheels. This is a big deal for me, as Mercedes' "manumatic" will upshift halfway through the corner if it thinks the revs are too high.

As someone who loathes an automatic (I drive a 6MT), I was pretty impressed with the 6 speed Automatic DSC in the 2008.
 

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jjab4444:

Thanks a lot, this was very helpful and answered most of my inquiry. I applaud the fact that Cadillac abandoned the open differential strategy, this must have made the system much more flexible. It's good the system was designed to be preemptive, though I'll really have to test drive it against the next gen quattro to see how much sensitive and smooth it is.

Could you be more specific how turning off Stabilitrack would affect throttle control and individual wheel slippage braking? Would the basic (braking) traction control elements still be active?

Also could you please answer the question about AWD operation under braking (does the front axle get deactivated under braking)?

Thanks!
 

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I agree with Cadillac Tony about the manual activated up shifts in the CTS. I've driven a 2006 C6 with the paddle shifters and the CTS up shifts three times faster when you push the lever forward. The first time I tried it, I inadvertantly let up on the accelerator to shift, as if I were driving a manual. If I timed it right (before reaching redline), I could upshift without letting off the accelerator. The automatic rev matching on down shifts is so smooth, you hardly notice it happenning.
 

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jjab444
I read on a GM website that the AWD car is only 229 pounds heavier than the RWD car. Why does the AWD get bigger brakes than the RWD?
 

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Discussion Starter #18
OK, thank you for the explanation. Looks good. Now I am definitely buying this car in a year or so.

Is there any chance at all that AWD will be offered with the manual transmission ? I'll buy the auto, but manual would be nice to have.
 

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A few more answers to previous questions in no particular order........When the Stability/Traction Control system is operating normally (not intentionally disabled) and slip is encountered the engine torque is momentarily reduced to enhance traction. This is a common strategy not only among GM vehicles but industry wide as well. It reduces wheel speed flare and provides for smoother acceleration. If the vehicle needed to be "rocked" as when stuck in deep snow it may be more advantageous to disable traction control. Although I work closely with the stability/traction control folks I am not intimately familiar with all of their control algorithms and have to defer detailed brake questions to them. When braking a small amount of torque is still transferred to the front axle to enhance stability. The amount will vary depending on a number of inputs that are all part of the control algorithms. As far as vehicle weight a reader commented on an AWD car being 229 pounds heavier. That's pretty accurate with the addition of a front axle, t-case, etc. As to why the vehicle in question had bigger brakes, quite honestly I don't know since the AWD system in itself does not drive bigger brakes. I can only speculate that the AWD car had the FE2 suspension with bigger brakes as compared to a RWD FE1 car. To the question of an AWD with a manual transmission, there are no plans at the present time to offer this configuration.
 
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