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What's the story on the optional limited slip differential?

28K views 38 replies 13 participants last post by  jwq2 
#1 ·
My wife and I are considering replacing her ancient Saabaru with a new Stelvio base model. Given that the ability to go uphill (STEEPLY UPHILL) in snow is the primary reason for getting an AWD vehicle, the hints about some sort of optional LSD are very interesting. However, I can't find anything about said LSD on Alfa's site (which is frankly unhelpful) or any other promotional materials.



1) Is there actually a LSD that can be optioned onto the base model Stelvio?
2) What option pack is it part of or otherwise how would a dealer refer to it?
3) What are the technical details of the LSD?


Thanks guys.
 
#2 ·
Find it under the "TI Sport Performance Package". This package includes the LSD and active suspension. As for the LSD there may be others that can comment on its ability to climb steep hills in snow. My 2017 Giulia Sport Q4 with AWD does not have the LSD. I can easily drive up steep hills in snow.
 
#3 ·
OK, with that help, I managed to find it in the brochure. Bad news is that the Base can't get the Performance Pack. We hadn't planned on stepping up to a Ti due to the fact that there's nothing we want from it other than the heated stuff and ordering the Winter Package on the base is $1200 cheaper.



Is there a good reference anywhere for what the adaptive suspension in the Performance Pack actually does?
 
#6 ·
Yeah the "steep hill" is actually our driveway. This place was built before any sort of code or zoning enforcement in the area. Now, a builder wouldn't be allowed to build on this lot due to the steep hill against the road. Our driveway starts flat near the house but gets drastically steeper as it gets to the road. The last car-length of our driveway where it joins the road is a touch over 30 degrees (yes, degrees, not percent). Unfortunately, due to the shape of the land and the trees just off the side of our lot, you must stop right at the top of the driveway in order to see if there's cross traffic from the left. Effectively, every day we have to do a standing start out into 50mph traffic off of a 30 degree incline. In the winter, my wife's Saabaru will do it even if there's snow and slush on the driveway but my Connect (FWD only, sadly) actually won't pull itself to the top of the driveway, let alone get onto the road from a standing start, even on snow tires if there's anything but bare pavement. I have to go take the tractor out to plow the blacktop and then give the sun time to melt what's left before I can get my Connect out of the driveway. Once I'm on the road, yeah it's pretty damned flat around here so there's rarely a problem.


The entire point of keeping her in an AWD car is so that she can get out of our driveway reliably to go to work.
 
#10 ·
OK, now hang on a second.


There's a Ti Performance Package for the Ti (obviously) and a different listing for a Ti Sport Performance Package (for the Ti Sport, obviously). In one PDF I'm reading, it sounds like they both are supposed to have the LSD and the Active Damping. However, in the Alfa Romeo Brand Book PDF, the chart for features and options lists the LSD only under the Ti Sport Performance Package. Is that a copy/paste oversight or do you really have to start from the Ti Sport, not merely the Ti, in order to get the LSD?
 
#12 ·
Not at all trying to discourage you from asking questions here, but I also recommend going to a dealer and seeing if you can talk to a tech about it. There are some pretty major raging threads on this forum on how bad Alfa's documentation is versus what is reality with the builds.

Also, calling @ALFATECH who may be able to help you out.
 
#13 ·


different wheels on rollers test.

Ok, this is a quad with torque vectoring - but I'm of the opinion that the mode selected for slippery makes more of a difference than lsd or torque vectoring, as the nannies step in, and the performance stuff primarily delays that. so in your situation, you would likely be selecting A mode, early intervention .... they don't say which mode they were using for this.

I will say that on freezing/frozen rain ice, mild uphill, the difference in modes/tire spin/rear friskiness (nanny intervention) is very apparent, but it goes in all of them. my wife used A for the large skating rink at her office and was very pleased, and I ..... really like this car, fun when maybe you shouldn't be looking for it

there are other vids by these people with different vehicles for comparison.
hope this, and Allroads off road and Marzio's snow vids help.
 
#14 ·
WOw Cool Vid!

After watching this one You Tube pushed me similar vidoes on Lexus and Mercedes 4X4's.

Cool to see them fail where the Stevlio passed.

After "mudding" in my sports TI - I can honestly say it was the steadiest I have ever driven in the mud.

We have had 2 weeks with big 8 inch plus snows this month - The stelvio has gone through it like a champ.

This video helps me understand why. Great find.
 
#15 · (Edited)
The Q2 LSD is a torsen-type limited slip, it is not the torque vectoring unit on the Quad I am almost positive. Could be wrong though.

Lost is right though, in your situation the LSD is unnecessary.

The Q4 AWD uses the brakes to move power side-to-side so you won't get stuck when one or more wheel loses traction and the center differential is a hybrid limited slip/torque vectoring unit that will actively send power to the axle with traction while allowing up to 2.5% slippage between axles. Combined with "A" mode which limits slip enough to allow the vehicle to "walk" on top the snow instead of digging into it, you will most likely be surprised at how well the vehicle handles bad weather and traction. Might still want winter tires as once all the tires lose traction there is nothing any AWD system can do, but if there is any traction to be had the Stelvio tends to find it and keep going even without limited slip differentials.

Having the LSD will help handling as it responds faster than the electronic system, and it relieve work on the brakes so it will help them last longer too. Definitely benefits to having it, same thing with the active suspension. Still nice to know that you don't have to pile on options to get a functional AWD system, that is standard (on AWD models).

Here is the video I did that goes more in depth as to how the brakes work with the AWD and how the front axle uses a trick lower ratio to make the system more capable than people think....





On a side note, anyone knows where I can get some roller like that let me know....I cannot find them anywhere. Truth is it is not a real world test...in most situations with bad traction ALL the wheels will be slipping to some degree not just one or two, or even three, and getting out of the situation has more to do with the system's ability to put enough power to the wheels to get them turning and the car moving, without putting so much power down that wheels start slipping which stops movement. That is what low range excels at in a traditional 4x4 and why that is the "get unstuck" mode off road, the Q4 system uses electronics, sensors, and multiple systems to do, effectively, the same thing. Which the roller tests do not demonstrate at all, but they look super cool and I have an idea I need them for....
 
#16 ·
Here is my first video on the Stelvio, at 17:30 I go up a loose hill, you'll notice at the bottom I go into a dip the lifts the front passenger side wheel, when this happen the car basically stops....this was not me, I was giving it gas. This was the predictive AWD system not knowing what to predict, so it stopped and took a millisecond to figure it out. Once it did, it felt like the car locked itself into a 4x4 mode and it just powered up that hill like it was going for a nice jog. Don't underestimate this system.


https://www.youtube.com/watch?time_continue=1052&v=LG9mbec93iE
 
#17 ·
Allroad, you are correct on the lsd on 4's vs tv on 6cyl, thought I was clear that they were different but ...

"hope this, and Allroads off road and Marzio's snow vids help." - you are making it too easy, but yours is the first that comes up on my general link.

hope all is well with you.
 
#19 ·
Hm, that article quotes the chief engineer as saying there is a slightly lower axle ratio at the rear,

...however the article Lost posted in another thread quoted an engineer as saying the front wheels rotated slower than the rear, which would put the lower ratio at the front...(lower ratio rotates slower than higher, 5th gear is faster than 1st, but 1st delivers more torque that's why it is better for accelerating from a standstill).

The other article also said the power split was 50/50, Alfa US officially says 60/40 (the 60 is the front split), now this Autocar writer quotes an engineer as saying more goes to the rear....which works accept if the lower ratio is at the rear, that would create understeer when power goes to the front..which is not what happens.

At least the information is consistently inconsistent.

Would like to point out there is alot of incomplete information in that article though..

The only part of the Q4 that involved Magna International is the center diff, which is an off-the-shelf unit used in BMW X-Drive, modified by Alfa to be lighter, faster and stronger. Also to allow overslip. The Magna unit has no mechanical slippage function, all this is why (per Alfa) the center diff in the Q4 is an Alfa patented unit and unique to Afa and probably Maserati..can't confirm that.

The chassis domain control is the brain of the system and that is Magneti Marelli (stamped on the cover).

I think alot of people would disagree with the brake pedal being firm and consistent too. I love the brakes but let's be honest firm the pedal is not. Consistent feeling is also arguable.

Then there is the line about the differential sending up to 885lb/ft of torque to the front axle. That would be almost 200% of the Quad's torque peak, so the split would be 200/0 front/rear? How does that mean more power goes to the rear? Is there some crazy torque multiplier going on?

Or maybe there were translation issues happening...

Really wish Alfa had thier Media/PR information as refined as the driving experiance.
 
#20 ·
Hm, that article quotes the chief engineer as saying there is a slightly lower axle ratio at the rear,

...however the article Lost posted in another thread quoted an engineer as saying the front wheels rotated slower than the rear, which would put the lower ratio at the front...(lower ratio rotates slower than higher, 5th gear is faster than 1st, but 1st delivers more torque that's why it is better for accelerating from a standstill).

The other article also said the power split was 50/50, Alfa US officially says 60/40 (the 60 is the front split), now this Autocar writer quotes an engineer as saying more goes to the rear....which works accept if the lower ratio is at the rear, that would create understeer when power goes to the front..which is not what happens.

At least the information is consistently inconsistent.

.......
apparently there is a difference between the giulia and the stelvio though, giulia is 60/40, stelvio 50/50
 
#21 ·
I think most of the magazine writers these days would be as qualified and happy writing about kittens or hotels or ...
they just aren't mechanical, so maybe they took some notes, forgot what was said etc.

the one article I posted seemed to correspond closely with actual things AR engineers have said in various youtube things - so I'll go with it. although I believe it was an Italian article translated by google, so still some interpretation is required.

but the biggy - when I drive it, those things makes sense with what I am feeling and the response of the vehicle, and that's the confirmation that counts to me. now those impressions include some wet snow donuts, some uphill glare ice corner experimentation etc
if I can't trust me, who can I trust? you, of course, may feel totally differently .... and I encourage everyone to draw their own conclusions, because you can't count on bad and conflicting articles.
 
#23 ·
I have the performance package on my TI sport. Would not even consider a car in Colorado without LSD. LSD work much better than traction control by braking and is even more effective on RWD. To me going up a slope is less of a problem than trying to stop on a down slope where most of the braking is on the front. For this, I use the paddle shifters to downshift instead of the brakes to slow down knowing the rear wheels will stay balanced.

I recall that the performance package is available on the sport (non Ti) trim. Also, be aware that they will automatically add the infotainment upgrade to the build price at a cost of about $900. FYI, the adaptive suspension only works in dynamic mode.
 
#24 ·
I have the performance package on my TI sport. Would not even consider a car in Colorado without LSD. LSD work much better than traction control by braking and is even more effective on RWD. To me going up a slope is less of a problem than trying to stop on a down slope where most of the braking is on the front. For this, I use the paddle shifters to downshift instead of the brakes to slow down knowing the rear wheels will stay balanced.

I recall that the performance package is available on the sport (non Ti) trim.
The current brochures only show a Ti Performance Pack and a Ti Sport Performance Pack. The base or base Sport aren't eligible for a Performance Pack.



FYI, the adaptive suspension only works in dynamic mode.
It depends on exactly what Alfa means by "active" suspension. There are a number of older systems where the mechanical valving inside the damper can be adjusted from outside the damper (I've had some our cars for almost 15 years) and, if you put an electromechanical control box on top of that, the car could just turn the overall damping rate up or down when you change modes on the DNA dial. Marketing people might call that active. However, the info I've been able to find online suggest that Alfa is using "active" to mean a continuously variable damper in which the instant-to-instant damping rate at each corner is varied by the computer in response to sensor inputs. This allows the system to do things like stiffen the car in roll during a corner but still have compliance to soak up bumps or to be soft enough to absorb high-frequency noise/vibration and sharp impacts but still maintain rigid primary chassis control. If that's what Alfa means by "active", then the system is constantly active even when it's running on the soft/normal programming in N and A modes. Going to D or Race (QF) would just switch programming to make the car feel stiffer.
 
#25 ·
"I use the paddle shifters to downshift instead of the brakes to slow down knowing the rear wheels will stay balanced."

with the Continental anti-lock system each wheel is modulated independently - it stays balanced while providing better control than relying on engine braking. I'm old, pre anti-lock of any type, but this braking system is exceptional, and will slow or stop you far better than dragging the rear wheels, while maintaining steering.

yes, I've tried hard braking on an icy downhill, as well as wet and dry.
 
#27 ·
I am not suggesting that the Stelvio does not have a very good AWD system as well as a good anti-lock system because by all reports it does, but for me trying to control the car while applying the brakes is not optimal. I have been driving on packed snow the last month and when I brake the front wheels alternate between rolling and skipping as the anti-lock system activates; this can not be conducive to good steering. I find it much more likely that the car will swap ends when the braking force on the front than by slowing the rear via gearing. But to each there own, good luck and stay safe.
 
#29 ·
Hey, that makes sense and I hope you are right. Maybe that's why my car handles so well while still being comfortable. All I know is what the dealer told me and that is consistent with the vehicle operation in which a button is pressed to turn on the active dynamics and a light comes on to show it is engaged and this can only be done in dynamic mode. But again you could be still be right that it is active all the time and the button just stiffens the suspension in dynamic mode. (and by active dynamics I mean dampening and stiffness adjusted and controlled by sensors as you described rather than by a mechanical system in the shock which I believe is what cars not equipped with the performance package have).
 
#30 ·
FWIW, if you want to learn more, the most common implementation of this idea are Magnetorheological dampers. Basically, they're filled with a goo that gets more viscous (thicker) when you expose it to a magnetic field. Wrap the damper in an electromagnet and, by varying the strength of the electromagnet, you vary how the damper responds. A shortlist of cars I know of with these systems are the Acura MDX, Audi TT and R8, Buick Lucerne, Cadillac ATS, CTS-V, DTS, XLR, SRX, STS, Chevrolet Corvette, Camaro ZL1, Ferrari 458 Italia, 599GTB, F12 Berlinetta, Shelby GT350, Holden HSV E-Series and Lamborghini Huracán. Delphi and BWI have marketed the system under the MagneRide name. Delphi has been a Mopar/FCA supplier in the past, haven't they?


The Volkswagen Audi Group has a similar tech they put on their fancier cars but I don't know what they call it.
 
#31 · (Edited)
Delphi has been a Mopar supplier, however pretty sure the supply chain on this vehicle is primarily Magneti Marelli and Magna International. Wouldn't be surprised if Delphi is in there somewhere (possibly even as an alternate supplier of some components) though.


According to the owners manual (at least the one available online) The Active suspension varies the dampening continually, however in "D" you can choose between a comfort or performance setting, that is why the button on the DNA selector only does anything in "D". In every other mode the suspension adjusts automatically only, in "D" if the light is on you're in performance mode, otherwise it is comfort...or vice versa...not sure didn't read that far.


What is interesting is Alfa does not describe the active suspension as magnetic, they say it is electronically controlled and that is it. Might be magnetic, might not.


Look up "Synaptic Dampening Control" from Magneti Marelli. It is an electro-mechanical system designed to be integrated with ABS, TC, power steering and other vehicle control systems for integrated predictive vehicle dynamic control. Here is their marketing speak...(typos on thiers…) IMO this is the system in Alfa Romeos.

"By controlling the shock absorbers, the Synaptic Damping Control reduces oscillations of the vehicle body under all driving conditions, thus ensuring the highest levels of safety, comfort and handling.
By means of special sensors, the system can identify the current driving scenario and roadway conditions, then chooses the most suitable control laws accordingly. One of these laws is the “Sky Hook”, which isolates the passenger compartment and makes it ideally stable in case of outside disturbances.
Thanks to an electronic control unit featuring high calculating power and to accurate solenoid valves capable of providing an immediate answer, controls are applied in real time, neutralising and solving any problems caused by rough road conditions as they arise.
Even in case of sports driving, the system can assist the driver by increasing manageability and manoeuvring accuracy, without being forced to give up high comfort standards."
 
#32 · (Edited)
for a description of the active damping, see :

http://home.planet.nl/~jwq/giulia/dampers.pdf

as said, the system does not use magnetic dampers, but electrically controlled dampers, together with 5 accelerometers and other inputs, controlled by a chassis domain control module.


From Macgeek, earlier:
The twin-tube shock absorbers are made by ZF-SACHS. They are controlled by the Magneti Marelli Chassis Domain Control Module (CDCM). There are five active damping sensors on the vehicle. There are two sensors located on each of the front steering knuckles, and there are two sensors located behind each headlight underneath the hood. There is one sensor located in the CDCM, which is located in the trunk of the vehicle. As such it can monitor longitudinal and lateral acceleration, pitch, roll and yaw rates.

Each shock absorber has an electronically controlled solenoid valve that is connected to the CDCM via electrical connector and associated wiring harness communicating via the high-speed 500 kb/s CAN-CH (CAN-C2) data network. The system monitors the solenoid valve temperature, current (out of range), short to ground or open circuit, signal plausibility, all the various accelerations, individual wheel speeds, brake pressure, throttle pedal position and rate, engine speed, steering angle, transmission state, eLSD activation, torque vectoring module activation, active aero activation, etc.
 
#35 ·
Regardless of the details, mechanically they hit a grandslam, hat trick hail mary on the mechanicals
 
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