FWD, Limited Slip Differential, and Snow

[metroplex]

Can anyone enlighten me on the effects of driving a FWD car equipped with a limited slip differential in the snow?

I was looking at the Honda Civic Si which comes with a helical limited slip differential (Torsen-style?). Assuming the tires are half-way decent in light snow, how does the LSD affect predictability/control in snow? I know from experience that a LSD in a RWD car (such as my Crown Vic) makes all the difference using all-season tires on light snow with an aggressive rear axle ratio.

I figure that a LSD in a FWD car should give it better versatility for taking-off in the snow since you can actually steer the powered wheels. I was thinking about getting either an AWD or FWD car for the winter, but it has to have a manual transmission and have decent acceleration (weight to power ratio of under 16:1). The Civic Si coupe seems to fit the bill just nicely, and even the Civic EX seems to meet most of my specifications.

 

[UncleRunkle]

I drove my ford contour with an automatic tourque biasing differential (similar to torsen but made by Quaife in the UK) with 18in wheels and pure summer tires. I drove it for two months in the heart of one Missouri's worst winter in years with no problems...ice, snow, snow packed on top of ice, melted snow frozen over top of powder snow..all of it and no real problems as long as you take it eazy.

 

[moribundman]

Quote:

---

Can anyone enlighten me on the effects of driving a FWD car equipped with a limited slip differential in the snow?

---

My VW Scirocco Mk II had an LSD. I drove with that car into the mountains to go skiing in the winter. I was driving through foot-deep snow on serpentine mountain roads. 'Nuff said.

 

[Warlord]

Might make you understeer a bit more but you'll probably be able to plow through deeper snow than a lot of SUVs. In a truck anyways, I would prefer an open diff in the winter.

 

[1sttruck]

"In a truck anyways, I would prefer an open diff in the winter."

Same here. I've noticed that my open diff 'fails gracefully', just spinning a tire, while the signature of a limited slip is breaking loose and kicking the rear end around. A limited slip seems to work fine on mixed traction surfaces, like a wheel on the road and the other in mud, but on uniformly slick surfaces guess what happens when one wheel starts spinning and the limited slip dumps a bunch of torque to the other wheel that is also on the verge of breaking loose ? It breaks loose, which is not a problem crawling thru a parking lot, but it can be entertaining at speed in a corner or on a crowned road.

I prefer an 4x4 open diff with a selectable locker, but they're not available for my axle so I use good tires and carry chains in the winter. I'll start carrying them year around as a friend got stuck in his 4x4 truck with a limited slip, as his A/T tires didn't have the traction on wet clay and he slid off of the road. Chains aren't fashionable though.

 

[metroplex]

When I drove my Vic in the snow with the stock open differential, it fails gracefully but it still failed. I couldn't go anywhere faster than 15 mph. Just tipping open the throttle would result in wheelspin and the rear end wiggling around while people behind me were beeping their horns.

I installed a Traction-Lok (clutch based LSD) and kept the stock Goodyear Eagle LS all-seasons. I went into an ice/snow/slush filled parking lot and was making slow turns, taking off, stopping, etc... without any problems. I'm a firm believer in the use of a limited slip diff at least in a RWD application.

It seems that the use of a LSD in a FWD application works just as well based on some of the feedback in this thread. I was concerned that it would make it even more dangerous, but I'm not one to apply excessive throttle in a turn/corner on snow/ice covered pavement regardless of RWD/FWD/AWD/4WD.

 

[Gary Allan]

LSD's aren't too bad in the pucker factor if you've got enough mass over the rear tires ..like your Crown Vic. OTOH, a pickup ..my jeep ..it can take a bit of getting used to. Like when you're on a not too slick a surfaced highway and the rear wheels want to track straight ahead while you're on a curve @ 50 mph

I have a OEM spicer TrakLoc on my 4 banger TJ. I really should have spent the extra money on a TruTrac. My clutch type is kinda static in its effect ..while the TruTrac would have allowed a little non-reactive state (turning, etc.). Hit a patch of ice in a power on situation with my TJ and that back end is swinging in the breeze.

...I don't know about FWD in a snow situation. I can see the problems with a power on turn with king pin inclination (other alignment alterations involved with turning) and see some adaptive techniques being developed. My TJ, with an open front diff, will tend to plow forward in a turn if I'm under too much power (in 4WD). If you're not in close quarters, a blip of the gas will kick the tail end out to correct it, ..but then you're kinda doing target practice. That is, the skill is up to you and not built into the vehicle.

 

[metroplex]

I had a TrueTrac in my Crown Vic... I blew out the side cap bolts because of a design defect. Trac Tech didn't offer any type of help (replacement/repair with a fee, etc...) and instead suggested I upgrade to a better designed TrueTrac. These units aren't cheap ($400+) so I decided to go with a take-off Mustang Traction-Lok which has worked much better in the snow since the torque biasing is much less lenient than the TrueTrac/Torsen which tends to act as an open differential.

The LSD in a FWD application has me wondering. The Civic Si is spec'd for a 60/40 weight distribution with the most weight up front. The LSD should offer very good take-off/traction on snow covered roads but what would really happen in a corner/curve or a turn? Assuming the driver is an average driver on the road, would it be as predictable/more predictable/less predictable than a RWD application with a LSD?

 

[H2GURU]

metroplex,
As an all-weather driver with many years under my belt I can say that technique and tires will have as much if not more impact than your vehicle. I see you're from an area that gets some snow although not as much as the U.P. In my area 4X4s were 5% of vehicles sold until the blizzard of "78 which crippled the Northeast for a week. Since then, playing off of "fear & consumption" (MARYLIN MANSON)the sales have almost reversed with 4-wheel drives dominating the market. If driving in the snow is a must for you (job or hobbies)then get a set of 2 spare rims at recycling yard and mount some STUDDED TIRES on them as these will get you thru most problems as long as you have clearance on underside of car. I gotta say though, for the cars you're considering I would lok hard at the CRX... good luck.

 

[bluemax1]

I'm in Southwest MI. Driven both FWD and AWD (my current daily driver = 400HP 3000GT VR4) in the snow.

The LSD helps. With a fwd, if you get a little too crazy with the go pedal in a turn, you would tend to understeer, however, with fwd's (and awd), you can turn the wheel and 'pull' the car where you want it to go. I wouldn't like driving a car without an LSD in the snow. There's only so much letting off the gas or using the brakes can do.

I've had to drive around stuff when I knew the car wouldn't stop in time and the added traction the LSD provides increases the ability to control the vehicle. Granted I've had some experience driving in low traction conditions from amateur rallying starting back in the late 80's. when I used to drive the fwd, I'd control the yaw angle of the car with the steering, throttle along and handbrake. With the VR4, the handbrake slows all 4 tires so it's more of the throttle and steering. I use Nokian Hakkapellitta RSi tires all-around for winter and the VR4 will out accelerate, corner and brake just about everything out there including 4x4's. BTW, the stock VR4 diffs are open front, viscous center and viscous rear. I now have a helical (Torsen-type) front and Kaaz clutch-type rear. Waiting on a small specialist company to produce the helical center diff. I road race (NOT streetrace) the car Spring-Fall.


Max

 

[1sttruck]

"I went into an ice/snow/slush filled parking lot and was making slow turns, taking off, stopping, etc... without any problems. I'm a firm believer in the use of a limited slip diff at least in a RWD application."

Ice/snow/slush is a mixed traction situation, where a limited slip works fine. A former coworked had a limited slip on his 5L Mustang, and on ice it was a long series of get moving, break loose, rear end kicks around, straighten, get moving, etc., until he got home. At speed reaction time becomes more challenging.

Selectable lockers offer even more ability than a limited slip, and they're obviously used when needed.

 

[metroplex]

Ice is a totally different story. There's enough salt on SE MI roads to make the ocean jealous, so I'm more concerned about the slush, unplowed roads, and light snow.

The point behind my comparison is that the same vehicle performed significantly better in the same conditions using a LSD versus an open differential.

 

[Bror Jace]

metroplex, in my experience it depends a lot on the unit. I had a 2003 Nissan Sentra SE-R SpecV with a limited slip front diff. Upon even moderate acceleration both tires would spin (studded Nokia Hakka 2s) and then the wheel hop would start and the front of the car would hop left and or right looking for traction. It felt as though you could easily end up in the next lane unless you were being very, very careful.

Take this for what you will.

 

[moribundman]

Quote:

---

It seems that the use of a LSD in a FWD application works just as well based on some of the feedback in this thread. I was concerned that it would make it even more dangerous, but I'm not one to apply excessive throttle in a turn/corner on snow/ice covered pavement regardless of RWD/FWD/AWD/4WD.

---

Any feature that will enable you to keep driving in adverse conditions is inherently dangerous because this feature may easily allow you (maybe even entice you) to exceed your driving skills.

My primary concern with driving under adverse conditions are about directional control and stopping power. Someone with a highly capable car can be very dangerous -- certainly more dangerous than the person who decides to not even get out on the road.

PS: My Scirocco was always equipped with true winter tires.

 

[JHZR2]

IMO, its more than just LSD. It is tires, of course, but also MT gearing, which translates to how easily and smoothly you can get power down when, say, starting on a steep incline.

The whole package has to be balanced, and judging by a co-worker's Si, which he ended up selling, it may be too high strung to efficiently and smoothly launch under the harder conditions, compared to a more benign FWD car, and at that point, the LSD might bea moot point.

JMH

 

[rjundi]

Put some decent winter biased tires on and the LSD will not be much of a concern. The biggest issue you will run into with it is the factory tire size is 215/45/17 on a relatively lightweight car. Not sure if downsizing is possible for winter treads. You may be able to overcome the tires with driver skill.

With regards to the Civic SI being high strung at take off is simply so far from the truth. The motor has very little torque 139 ft-lb @ 6100 RPM.

 

[1sttruck]

"The point behind my comparison is that the same vehicle performed significantly better in the same conditions using a LSD versus an open differential."

A limited slip is also prone to putting you in a ditch, or worse, as it doesn't know what type of road you're on. A brother talked to an Alaska state trooper who was doing a survey of winter accidents where vehicles left the road; SUVs often rolled and pickups were often bassackwards, both types of vehicles that often have limited slip axles in that part of the country. Cars were usually just off the road, especially heavier, slower vehicles like older Volvos. I guess a Crown Vic would fall in the same category, and would present fewer problems than a pickup or SUv or sporty car.

 

[Tosh]

Metroplex: Have you considered a 2003 Acura CL-S 6spd? It also has a LSD (and is much more car than a Civic). And I believe both it and the Civic Si have traction control as well, so you won't get much chance to spin the tires too much unless you turn it off.

Personally, if I drove in snow, I would like to have a SAABARU 9-2X. Since I never do, I don't want to pull around an AWD system. When I lived outside Cleveland I had an 85 SAAB 900 5spd. There was never any problem getting going in the snow; it was stopping and steering that were the challenge (as Mori and others have alluded to).

 

[metroplex]

Tosh: I'm mainly looking at getting a new car. Acura stopped making the RSX after the 2006 MY. The Civic Si seems like a cheap throw-away car that is sporty enough to make it a fun car as well.

 

[Tosh]

Quote:

---

The Civic Si seems like a cheap throw-away car that is sporty enough to make it a fun car as well.

---

Interesting that you would make this attitude public. When my friend half-jokingly said his TSX was 'disposable,' he lost all hope of getting any thoughtful car advice from me. Perhaps it's not too late to redeem yourself before your BITOG brethren?