Need a definitive answer regarding Limited Slip Differential

[HYTECH]

Hytech, thanks for your support I truly appreciate your assistance, but that leads to another problem. Only one local dealer has a V8 in stock (so far) and I already have a black on black, so I am looking for an "arrest me red" variant. I have been told that one might be available, but I would have to commit to delivery and once it is here, I own it regardless of the differential.

If you have to commit to delivery then you would have to sign paperwork on a perticular vehicle it Will have to have a vin on this paperwork. get the ball rolling enough to see this paperwork and find out the vin. Then we can go from there.

 

[HYTECH]

Now I'm looking in the shop manual and I don't see a thing about a LSD. it is possible the discontinued them. I'll see what I can dig up.

 

[Mark_888]

Now I'm looking in the shop manual and I don't see a thing about a LSD. it is possible the discontinued them. I'll see what I can dig up.

Here is the latest from the Hyundai Canada website. No mention of LSD that I see, but there is mention of TCS (not sure the difference):

GENESIS 3.8

Performance Features
3.8L V6 DOHC Engine with Dual CVVT
6-Speed Automatic Transmission with SHIFTRONIC™
4-Wheel Disc Brakes
17” Aluminum Alloy Wheels

Safety Features
Anti-lock Braking System (ABS) with Electronic Brake Force Distribution (EBD)
Electronic Stability Control (ESC) with Traction Control System (TCS)
Advanced Front Airbags, Front and Rear Seat-Mounted and Roof Mounted Curtain Airbags (8)
Front Electronic Active Headrests

GENESIS 4.6 w/ Technology Package

Performance Features
4.6L V8 DOHC Engine with Dual CVVT
6-Speed Automatic Transmission with SHIFTRONIC™
4-Wheel Disc Brakes
Electric Hydraulic Power Steering
18” Aluminum Alloy Wheels with Hyper Finish

Safety Features
Anti-lock Braking System (ABS) with Electronic Brake Force Distribution (EBD)
Electronic Stability Control (ESC) with Traction Control System (TCS)
Advanced Front Airbags, Front and Rear Seat-Mounted and Roof Mounted Curtain Airbags (8)
Front Electronic Active Headrests


The USA website also mentions TCS (apparently on both V6 and V8), which they define as follows:

"Traction Control keeps the rear wheels from spinning, eliminating fishtailing to help keep the car under control. Oddly enough, this slowing of tires actually helps you accelerate faster."

 

[mikec]

Many cars with a limited slip differential have a warning sticker on the driver door jam reminding owners to not run the engine with the transmission in gear and only one rear wheel jacked up... the LSD will route power to the on-ground wheel and you'll fall off the jack. I don't know if the Genesis has this or not; my car is at home now or else I'd check.

A true test for a LSD is to get the car on the service bay jacks, engine off, transmission in neutral (and the dash will nag you to put it in Park), parking brake off. Turn one rear wheel in the normal forward direction. A car with a working LSD will have the other rear wheel turning in the same direction; if it has a conventional differential the other wheel will rotate opposite.

mike c.

 

[dts2]

Hytech, As I mentioned, there is only one V8, with Tech, that is local to me and it is not my first choice in color, but I do have the VIN (KMHGC4DF5AU094264), so maybe that will help resolve the mystery. I suppose I could suck it up and take it if it had the LSD. I also know it was manufactured in January of 2010, so it is relatively new.

It is really unfortunate that Hyundai would delete an item like LSD, especially in what is touted to be a luxury/performance automobile. However, it appears to be the case and it is sad that the dealers (two so far) have no knowledge of the change and not a lot of interest in researching the answer. I can honestly say that I have yet to find a Hyundai dealer who do not have the stereotypical car salesman on staff, and that includes the sales managers. I did so want to stay with the Genesis, but it is fast becoming too painful an experience.

 

[Navion 49]

Have had mine about a month now. Build date January 10/2010 and I have LSD on mine. I am in Canada and also have a factory brochure that states LSD comes with the 4.6. Don't know if this helps you or not!

 

[Mark_888]

Still have not heard anyone explain the difference between Traction Control System (TCS) and LSD.

 

[dts2]

Mark 888:
Explanation: Traction Control System TCS is a electronic/mechanical system that senses when one of the rear wheels are spinning and applies the brakes to that wheel. In theory, the other wheel will then get traction and move the vehicle. When in full effect, this process can jump from wheel to wheel. In a perfect world it should work, but engine power is also factored in and in the case of the Genesis, the power is reduced (in my opinion to save the motor from over revving), and it just sits there doing nothing.

A limited Slip differential (LSD), sometimes called positraction , mechanically shifts the driving power inside the differential focusing on the wheel that has the most traction. That is why cars so equipped put down two strips of tire rubber when the gas pedal is mashed. In today's automobiles that are equipped with both, you can usually turn off the TSC and rely solely on the LSD, at least that is how the Cadillac CTS/STS works. It is, IMHO, a much better solution to ice and snow and even wet streets.

 

[dts2]

A follow up note to anyone who is interested. Last night I visited my fourth Hyundai dealer in quest of an answer (with the best treatment yet) and told that to the best of their knowledge some 2010 Genesis V8's still come equipped with LSD, but not all. They assured me that there is a way to identify those so equipped and are currently in the process of locating one. True or false, I guess we will all find out soon. At least this dealer did not lecture me on TCS and how it is just as good as LSD. It was a breath of fresh air and if there is such a Genesis available I will be leasing from them.

By the way, still no official response from Hyundai Customer Service. Oh, and we didn't talk final numbers, but it looks like their price is close to $100 less than the other three. Just goes to show how much money gets left on the table.

 

[QCTLG]

Still have not heard anyone explain the difference between Traction Control System (TCS) and LSD.

TCS (Traction Control System):

Using the wheel speeds determined by the ABS, a spinning rear wheel can be detected. The brake for that individual wheel can be applied (shifting the torque through the LSD to the other rear wheel) and the engine power can be reduced. Good systems will use the brakes first and then feather the throttle as necessary. Our Genny kills the throttle at the first sign of wheelspin, which is NOT good in corners.


LSD (Limited Slip Differential):

The differential ("diff" or pumpkin) takes driveshaft torque as input and divides it between the rear wheels, allowing different speeds for each rear wheel which is needed for turning. An open diff will send torque to the wheel that accepts the most (usually even, but if a wheel spins, it will accept more). An LSD will send torque to the wheel that resists the most (the one that has grip).

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[Mark_888]

TCS (Traction Control System):

Using the wheel speeds determined by the ABS, a spinning rear wheel can be detected. The brake for that individual wheel can be applied (shifting the torque through the LSD to the other rear wheel) and the engine power can be reduced. Good systems will use the brakes first and then feather the throttle as necessary. Our Genny kills the throttle at the first sign of wheelspin, which is NOT good in corners.


LSD (Limited Slip Differential):

The differential ("diff" or pumpkin) takes driveshaft torque as input and divides it between the rear wheels, allowing different speeds for each rear wheel which is needed for turning. An open diff will send torque to the wheel that accepts the most (usually even, but if a wheel spins, it will accept more). An LSD will send torque to the wheel that resists the most (the one that has grip).

Hyundai distinguishes Electronic Stability Control (ESC) from TCS (Traction Control System), so maybe I should have asked for a definition of all 3.

 

[dataguy]

Hyundai distinguishes Electronic Stability Control (ESC) from TCS (Traction Control System), so maybe I should have asked for a definition of all 3.

http://en.wikipedia.org/wiki/Electronic_stability_control

TCS reacts to wheel traction, while ESC reacts to steering issues (i.e. intervenes when the physics of the car exceeds the driver's assumed intent).

 

[Mark_888]

http://en.wikipedia.org/wiki/Electronic_stability_control

TCS reacts to wheel traction, while ESC reacts to steering issues (i.e. intervenes when the physics of the car exceeds the driver's assumed intent).

Doesn't LSD react to wheel traction. Does anyone really need LSD if they have TCS and ESC?

You LSD freaks (no pun intended) are worse than us suspension freaks.

 

[Water Boy]

Does anyone really need LSD if they have TCS and ESC?

I do
LSD = more traction
would you want a 1 wheel wonder in the snow or 2.

 

[Mark_888]

My suspicion is that a modern TCS (Traction Control Systems) and ESC (Electronic Stability Control) provides the same function as LSD. Here is a quote from Ask.cars.com:

"Limited-slip differentials may become less popular as ABS-based traction control now serves a similar purpose. The traction control computer monitors wheel rotation and applies the brake to the spinning wheel. This allows power to shift to the opposite wheel."​

Another person on a different car forum claims:

"...the car is much more stable in poor conditions with traction control.

The reason is simple. With a limited slip, if one wheel has no traction, it will simply spin at the same speed as the wheel with traction. However, that also limits its ability to provide lateral traction. With traction control, the brake is applied to the wheel without traction, preventing it from spinning and thereby maintaining some lateral grip. This means that the limited slip will make a car more "nervous" in poor conditions as the rear end will tend to jump around more.

It comes down to what the driver is accustomed to, but overall I think that traction control is superior in most on-road situations."​

Now, if one is racing, that may be a different story. But I have heard that the only newer BMW's that come with mechanical LSD are the M series.

"The 2009 BMW 7 Series has Electronic Differential Lock Control (simulated limited-slip differential through individual wheel braking)."
http://www.roadandtrack.com/tests/impressions/2009_bmw_7_series​

 

[dataguy]

I'd also argue that if your tires grip, then you don't have to rely solely upon systems that deal with slipping. If the intent is to forgo proper snow or all-season tires because a car has a LSD or any other TCS, I'm not sure that's the best move.

 

[mikec]

Electronic Traction Control System = computers modulate engine power and/or apply brakes to a spinning (slipping) wheel, to help get the car moving on poor traction surface. Basically TCS makes it so you can't "peel out" and instead controls power to whatever the tires & grip can tolerate to help you get moving. It's sort of like anti-lock brakes (ABS) in concept: ABS modulates the brakes to prevent a wheel+tire from locking up and skidding - so that you get as much braking effort as the tire grip will allow. (in theory... under some conditions ABS actually hurts but most of the time it helps.) ABS helps a "panicked" driver that is stomping way too hard on the brake pedal - ABS modulates the braking effort to just what the tire grip can actually use. TCS does the same for when you "mash the throttle" instead: limit engine power to whatever available tire grip/traction can tolerate.

ESC = Electronic Stability Control. This is "TCS Plus." ESC also looks at steering inputs, spinning out, etc. ESC systems modulate engine power, apply brakes to one or more wheels, etc. to help keep the car from spinning out and to keep it going in whatever direction the driver is commanding via the steering wheel.

Differentials: a mechanical gearbox that has one input shaft and two output shafts. Normally the output shaft RPMs are some exact fraction of the input shaft RPMs (the "final drive ratio" - typically about half to one fourth of the driveshaft RPMs on passenger cars). The two output shafts are not physically tied together though so they can rotate at different RPMs if needed - like when the vehicle is going around a corner/curve.

LSD = Limited Slip Differential. A conventional differential (also an "open differential") tries to split the driveshaft power 50-50 between the two drive (rear wheels on a Genesis) wheels. When going around a corner, the inside wheel is actually turning slower than the outer wheel. The differential allows the wheels to turn at different rates - but the "average" rate matches what the wheels would be turning if you were driving straight ahead. However... the plain/open differential's 50-50 torque split between the two wheels assumes both wheels have equal traction. If one is on pavement and one is on ice... the power ends up going to the wheel that's on ice - causing it to spin/slip a lot. In fact, it'll probably be spinning twice as fast since the other wheel is not turning at all... to keep the average. LSD differentials have a mechanical, and sometimes electrical/computer, mechanism that limits the difference in RPMs between the two wheels. When one starts spinning much faster than the other, this mechanism starts "locking" the differential so that the other wheel (the one presumably on pavement and not on ice or soft dirt) starts getting some engine power. Modified 4 wheel drive vehicles (not "all wheel drive" - I'm talking the true off-roader 4x4 types) often have a true "locking" differential: the driver can flip a switch/pull a lever/etc. and physically lock the two drive wheels together - forcing them to always turn at the same RPM. This makes the wheels skid a bit when going around a corner (since one can't speed up while the other slows down) but it's the ultimate in off-road/sloppy traction because you don't need to wait for one wheel to slip a bit BEFORE the differential reacts and sends power to the other wheel. Folks crawling over rocks, with one (or more) wheels lifted clean off the ground, love locking diffs because they don't have this reaction delay.

Traction control can do most of what a basic LSD does. It just relies on the computer to recognize speed differences between the two drive wheels... and it needs that difference to be large enough (so that it doesn't react to normal RPM differences when turning). Some traction control systems work by applying the brakes on the spinning wheel; this forces some engine power to the other wheel through the normal differential. Most also reduce engine power - including the Genesis system.

I have the V8 with LSD... last Christmas it saw it's first (and only) snow road while I was visiting my folks. On a clear road, I let it go to about 15 MPH and then stomped on the brakes. The ABS did their job - with the usual clunking sound of the ABS "modulator" mechanism. Then, from a stop, I mashed the gas. The ESC traction control function activated (with a vengeance as it typically does in a Genesis) and reduced engine power a lot... but I started rolling forwards. I didn't try "drifting" to see if the ESC would do anything to prevent a spinout. Riding shotgun, mom wouldn't have liked that.

mike c.

p.s. Just to be complete:
4WD - four wheel drive - uses a mechanical coupling between the front and rear axles to split engine torque. This "transfer case" is basically a stick-shift transmission on simple systems; an electronically controlled stick-shift tranny on fancier systems. Both the front and rear wheel axles have differentials to split the power; usually only the rear diff might be LSD while the front is a conventional "open" differential. A LSD on front (steering) wheels leads to funky feedback in the steering wheel. The transfer case doesn't have the ability to modulate RPMs like a differential... so a 4WD vehicle going around a tight turn on dry pavement often "binds" because each of the 4 wheels needs to turn at a different RPM and this transfer case prevents the front and rear axles from having different average RPMs. That's why most 4WD systems can't be used "full time" - they should only be used on poor traction conditions so a wheel can skid/slip slightly when it wants to be at a different RPM.

AWD - All Wheel Drive - uses something more like a "center differential" (compared to a transfer case gearbox) to allow "full time" operation. The center differential allows different average RPMs between the front and rear axles... though the "average of the two averages" will be constant. Because of this, AWD systems can be "full time." Subaru's system is like this. If the center differential is purely mechanical, 50% of the engine power goes to the front wheels, 50% to the rear wheels. Audi's "Torsen" (a name derived from "torque sensing") center differential and other electronic center differentials use clutches or other mechanisms to split the engine torque. Such systems can send 100% torque to either the front or rear axle if desired, or any split (e.g. 20% front/80% rear) under computer control based on the type of car, traction conditions, etc. Sports cars will generally be programmed to send torque to the rear wheels most of the time, engaging the front wheels only when the rear slips. Family sedans/minivans will generally be the opposite: they'll drive the front wheels the majority of the time, only feeding torque to the rear axle under hard acceleration or when the front wheels both spin/slip.

 

[dts2]

My final comment on the topic. Apparently no one truly knows for sure, although those who I have spoken to are reasonably confident that the LSD went the way of the Dodo in the 2010 model. In fact, the one dealer who thought they were still available was supposed to call me yesterday (Monday), to confirm and take my order. No call, so no order. Why the change, considering the value to some of us? I can only speculate that it might have been the cost factor, considering that additional features were added to the 2010 variant. Or, maybe there were too many warranty claims for a blown third-member, since there are a few of us who wanted to disable the TCS so that two wide strips of rubber could be laid down in the road. Whatever it is, I can share that the other manufacturers jumped on board and the LSDs of the past few years (with a few limited exceptions), are gone. Even the Cadillac CTS with the Performance Package has deleted that unless the summer tire package is added….not so good in the snow, to be sure. However, everyone states that TCS is so improved that the LSD isn't necessary. Having real life experience I disagree, but my opinion holds no water and since I have fewer options than I did when I started this thread, so be it.

The Genesis is a fine automobile. Every other non-Hyundai dealer agrees that down the road it will be major competition and in once case the sales rep followed me out to my car and drooled all over it. Awhile back, I promised myself that if I couldn't get a Genesis with LSD I would go with the Caddy CTS, but now that is also a moot point. I still have to visit BMW and Mercedes Benz, but except for the very high end I am sure I'll be told how great the TCS is and that LSD is no longer necessary.

So, it looks like there will be another Genesis in my future. I'll go through hell in snow, but I can't walk away from the features and price. I will be one happy camper until the snow falls and then I guess I'll take a vacation day and stay home.

 

[Mark_888]

...Or, maybe there were too many warranty claims for a blown third-member, since there are a few of us who wanted to disable the TCS so that two wide strips of rubber could be laid down in the road.

OK, so you really don't need it for the snow, you need it to burn rubber. I don't think Hyundai (or most other automakers) are going to consider that as a legitimate reason for LSD on a car of this type.

If you are looking at BMW, I believe that you will have to go with an M series to get LSD. However, there are quite a few after-market LSD's that are sold for BMW's that don't have it.

As you suggested (and it was mentioned previously in other posts) ESC and TCS have advanced to the point where LSD is no longer needed, even in bad weather (except if you want to burn rubber). But if you have really bad weather for any significant amount of drive time, then you should be looking at AWD anyway, or FWD at a minimum.

 

[BacktoHyundaibychoice]

As you suggested (and it was mentioned previously in other posts) ESC and TCS have advanced to the point where LSD is no longer needed, even in bad weather (except if you want to burn rubber). But if you have really bad weather for any significant amount of drive time, then you should be looking at AWD anyway, or FWD at a minimum.

Or negotiate a good deal and use the savings for winter tires, lease or no lease.
I've mentioned the same aversion to changing tires as the OP (as a lessor), and last winter I counted the actual number of days that better tires would've made a difference. Out of 4 months there were 5 that I hated the Dunlops and my 100 lbs of cat litter weren't enough. And we had double the average amount of snow for the second consecutive year.
Luck? Good plowing? Judicious use of 2nd gear in faux manual mode?
Whatever. A better tire is the only thing I REALLY want to see on the 2011 model when my lease is up this November.