limited slip FWD

[chuck b]

It's winter, and I'm bored. There aren't any exciting new small cars out there from my perspective (why, where are they???). Sometimes I wish I weren't a car nut so I wouldn't notice the weaknesses in every car. So I'll just ask questions until spring.
Why are limited slip devices so rare in front drive cars? I have a bunch of theories, but I think I'll wait for your replies.
My experience with LSD on FWD is from my SE-R where it is nice to have for autocross as well as a great help in the snow. One needs to be careful in the snow due to side to side loss of stability, but there's much better forward bite. I also drove Salah's type 'are' down there in Iohway, and came away very impressed as that sucker pulled hard.
Here's a list I've compiled of sporty, FWD cars with LSD and a manual is as follows- please make corrections/additions:
Sentra SE-R 91-94 viscous
NX2000 91-93 viscous
200SX SE-R 95-97 (lsd not available in ’98) viscous
Infiniti G20t 93-96 99-02 viscous
Integra Type R ’97-98, 00-01 Helical
MazdaSpeed Protégé 03, 03.5 Tochigi Fuji Sangyo Conical ring torque sensing thingamajig
Neon SRT-4 04-05 Quaife Automatic torque biasing?
Mini Cooper S 05 Quaife
Acura CL Type S 03 helical
Sentra SE-R Spec V 02-05 helical
Prelude Type SH 97-01 Torque sensing ATTS- active electronic torque transfer system

The rare CL Type S has me curious. Anyone test drive one of these?

[aansorge]

I've heard that those CL's are suprising. Still, its mostly a luxury car. Type's R's R great, but hard to find in stock condition and generally overpriced. The MazdaSpeeds and SER's will probably get bumped down to GS in '06 if the 05 Coopers don't get moved back up to DS (if autocross placement is important for you 'other' car). The Cooper S is going to be a PAX killer in 2005 but offers little room as a primary car. And by the way, why front wheel drive? Snow tires do exist! How about a used 330i!!

[DCM]

To quote Chuck; It's winter, and I'm bored.

Chuck, go to this web-site.
They need corner workers, and even $20 membership, which also gets you one race.
$30 more to have aN ANUUAL LICENSE.
WHERE ARE YOU GOING TO FIND A CHEAPER LICENSE?
Dwight



http://www.angelfire.com/mn/icerace/index.html

[StevenMosley]

Chuck, Are you thinking of selling me your car again?

[chuck b]

no way steve, i'm not selling, not after putting in new shocks and mostly fixing the leaky tranny and other stuff. the car feels so responsive in first and second gear (it peters out in 3rd-5th) but after 10 years of the same car, i'm still obsessed with the idea of a new everyday car. i test drove a mazdaspeed protege and it was sweet handling, but no cruise, not appreciably quicker, and flat seats (cripes, with such a sweet handler ya need tall side bolsters). maybe i can convince the fiancee to learn stick and keep the datsun in the garage. anyway, no changes anytime soon. i'm getting married next fall and last i checked, people want to be paid for wedding services.

But my main point is not my car ownership! It is simply, why are limited slips so rare in vehicles?

If four wheel drive/ quattro/ etc. is so popular, it seems like a much lighter, simpler system should be more common, especially when most people never need the 4WD. Perhaps people never need a limited slip either, but getting up my driveway in the winter, or a snowy hill can be done with a limited slip. All my friends sit and spin. If it weren't for my parents visiting and my lovely fiancee getting on my case to showel, I wouldn't bother! It takes pretty extreme situations to need 4WD.

So I'm opening up the discussion on theories on why limited slip is rare in FWD. I've got my own ideas, but I was hoping to hear from the fellow bored auto nuts.

[Blue03CivicSi]

Originally posted by chuck b
If four wheel drive/ quattro/ etc. is so popular, it seems like a much lighter, simpler system should be more common, especially when most people never need the 4WD. Perhaps people never need a limited slip either, but getting up my driveway in the winter, or a snowy hill can be done with a limited slip. All my friends sit and spin. If it weren't for my parents visiting and my lovely fiancee getting on my case to showel, I wouldn't bother! It takes pretty extreme situations to need 4WD.

So I'm opening up the discussion on theories on why limited slip is rare in FWD. I've got my own ideas, but I was hoping to hear from the fellow bored auto nuts.

I think it's because most people don't understand what a limited slip differential does, and that AWD/4WD is a much simpler concept for lay people to understand: all four wheels turning always means better grip and handling, right?

[shane86]

Originally posted by Blue03CivicSi I think it's because most people don't understand what a limited slip differential does, and that AWD/4WD is a much simpler concept for lay people to understand: all four wheels turning always means better grip and handling, right?

I also feel that it's because most FWD cars produced today are intended to be little more than point to point transporters.
and if there's a way to save a few bucks, that's all that most consumers care about.

it's a real pity people don't understand their own cars.

[aansorge]

Unfortunately, I see electronic limited slips as the limited slip of the future. With the advancements in electronics and the fact that ABS is already hooked to all the tires, it gets pretty hard to justify torsens etc.

[DCM]

My first car with a limited slip was a 1966
Volvo 122 wagon. Back in.................
On a very slippery road, it doesn't steer!
It understeers bad!
It will get you out of a pickle, but anyone who has it needs to be trained in it's usage. Just like ABS, or any number of other things. The average car is built to understeer.. Why? Inexperienced drivers.
Safety Fast [that's an MG thing]
Dwight

[fitz]

Originally posted by DCM


My first car with a limited slip was a 1966
Volvo 122 wagon. Back in.................
On a very slippery road, it doesn't steer!
It understeers bad!
It will get you out of a pickle, but anyone who has it needs to be trained in it's usage. Just like ABS, or any number of other things. The average car is built to understeer.. Why? Inexperienced drivers.
Safety Fast [that's an MG thing]
Dwight

You had a 122 Wagon? My first car was a 1968 122S sedan. We've got to stop using the same kinds of cars, people will begin to talk.

[ps13drifter]

don't some vw's come with limited slips????

[Blue03CivicSi]

Originally posted by ps13drifter


don't some vw's come with limited slips????

GTI's come with EDL (Electronic Differential Lock). It's not a real limited slip, it's just a system where the car uses the ABS to slow down a wheel that is spinning too quickly.

http://www.houseofthud.com/differentials.htm#EDL

[SalahK]

Originally posted by aansorge


Unfortunately, I see electronic limited slips as the limited slip of the future. With the advancements in electronics and the fact that ABS is already hooked to all the tires, it gets pretty hard to justify torsens etc.

Electronic diffs that use ABS as their mechanism to limit slip are REACTIVE and just dont provide the immediate response time. They also feel artificial especially when all the wheels want to spin say coming out of a corner under full throttle. The ABS wants to control all the wheels thus limiting how aggressively you can drive the car. SAFE but NOT FUN! The Haldex AWD system used in Ford, VW and most of their subsidiaries is a typical example of this type of system.

Electronic diffs that use a MECHANICAL device such as a clutch-type LSD to limit slip are ACTIVE and seem to work a lot better. Examples of this type of system are the STi's DCCD center diff and the Evo's ACD. In these systems the slip is controlled mechanically but the electronics tell the diff how much power should be distributed to either axle (DCCD) or how much wheelspin should be tolerated before the diff locks up (ACD).

[phile]

Originally posted by DCM

The average car is built to understeer.. Why? Inexperienced drivers.
Safety Fast [that's an MG thing]
Dwight

And no car was more built to understeer than the MGB. The angle of the rear leaf springs caused serious roll understeer. And people think rear-steer is a new concept. :-)
The front camber curve was a factor also.

The stock MGB is one of those cars that will understeer LESS after the addition of a husky front sway bar.

Of course, by the time BLMC built Dwight's car, the suspension was different, and not improved, from the original. The good news is that Dwight's suspension is no longer the way BLMC built it. :-)

Oddly enough, the spring angle on the semi-elliptic-spring Spridgets caused roll oversteer. A front bar tamed that, too.

LSD in FWD? The Quaife or TorSen is probably the best way to go. I'm not a fan of electronic control.

[pinhead]

I think that there are a couple reasons why you don't see so many FWD's with LSDs:

A) FWD's tend to be econo cars, and LSD's cost money.

B) the static front weight distribution bias of a FWD means that it doesn't need an LSD quite as bad as other drivetrain configurations. For example, consider a Camaro / Mustang. They have most of their weight on the front wheels, and make a millions ft*lbs of torque. Without an LSD, all they'll do when you get on the gas is make a single blackmark. At least with an LSD, you get two black marks :dancin:

But I think B) is the reason why the LSD-equiped MR2 didn't instantly dominate C-Stock : The rear biased weight distribution didn't benefit from an LSD as much as the more balanced Miata does.

That's how I see it, I could be all wrong, though.

[DCM]

Just wait'll I get the camber adjustments installed!
And the composite rear springs, with the traction bars. Intersting though, maybe not enough HP, but I don't have a problem with wheelspin like I did with my '65. It would lift the inside rear wheel in tight turns and spin.
I really don't need a 'locker'
Now unto a weight saving campaign, those heavy bumpers ya' know.
Safety Fast [it's a MG thing]
Dwight

[jungle]

lemme say this....when i put an LSD in my GTI i nearly soiled my pants....I had to re-learn how to drive the thing....especially when i over cooked an entrance ramp and when up it at 45 degree angle to the normal flow of direction.

Then I discovered QUATTRO! mmmmmm....Torsen Center Differential...OMG!!!!! Never again will i go back to a one wheel wonder!

[fitz]

Originally posted by DCM


Just wait'll I get the camber adjustments installed!
And the composite rear springs, with the traction bars. Intersting though, maybe not enough HP, but I don't have a problem with wheelspin like I did with my '65. It would lift the inside rear wheel in tight turns and spin.
I really don't need a 'locker'
Now unto a weight saving campaign, those heavy bumpers ya' know.
Safety Fast [it's a MG thing]
Dwight

I never had a problem with wheelspin (far less power than you have) but did have a real problem with axle hop. The tube shock conversion actually helped a bit in that regard.