Curious as to how much of a difference there would be daily driving on pavement with the occasional time attack occurrence in a RWD car. RWD is fine in the winter, but I'm wondering if the clutch type would "really" be an issue on icy highway roads or if that is BS. I also wonder how useless the torsen would be in the winter.
thinking of buying a new car, wonder if getting the factory torsen is worth it
Get it. I installed one in my Impala SS... pretty aggressive, too. The tech guy said that it will act much like 800# springs in a clutch posi, but much smoother.
I have been VERY impressed so far. Excellent torque bias, but almost no "pushing" around corners in a parking lot. I will never go back to a clutch-type. Definitely worth it.
I honestly haven't done much winter driving with it, but I would imagine it would be just as good as a clutch posi, especially when it comes to getting you moving/applying traction to both wheels.
If you're worried about slipping wheels with a torsen on ice/snow I can say that I've had it happen with the RX-8 (when starting on a frozen driveway for instance). If you get stuck or are spinning wheels like crazy you can get them to lock up by applying a little handbrake though - works pretty well.
By the nature of torque biasing differentials in a rwd, if you are spinning tires, its natural inclination is to rear-steer a little. I dont know how this plays out on ice/snow because ive barely seen or driven on either in South Texas.
I was always under the impression that torsen would go 'open' on slippery surfaces and that other (clutch) diffs were better for low traction situations. Is this not true?
BobOfTheFuture wrote: I was always under the impression that torsen would go 'open' on slippery surfaces and that other (clutch) diffs were better for low traction situations. Is this not true?
I thought the same thing, for extremely slippery situations like ice and greasy muck. Once a wheel is free-spinning the torsen becomes as useless as an open diff would be in that situation.
I have run the ZF 2 and 3 clutch LSDs in E30 and E36 race cars for a long time. The primary issue I have is that they drag on corner entry and cause a little understeer. You can have new ramp angles cut to change them to a 60/40, 80/20, etc but it is always a fixed value. The secondary issue I have is that it is a pain in the ass to replace the clutches and under race conditions I tear them up every season. I finished my last race weekend with the equivalent of an open diff.
I am changing to a Torsen type for this season for the "on paper" benefit of constant progressive change and low maintenance but I'm also completely changing the center section to a Winters QC as well as all the control arm geometry so I won't be able to really evaluate the LSD alone.
With all of that useless trivia said... get the factory torsen. It is only ungood when you hang a wheel in zero traction and you can drag the brakes to stop that from taking all the power from the other wheel if you have to.
I have a torsion diff in my Camaro (autox only car) and even in the rain with Hoosier slicks on it, I never had one tire free-spin. It will spin both wheels together in the rain, but the tires (and too much throttle) are the problem for the most part. As long as both wheels are in contact with the ground, it works quite well. It is when one wheel comes off the ground that it acts like an open diff. I like it better than the clutch type, action is smoother to me.
Had the factory torsen in my FMII turbo Miata. With snow tires, and the right type of snow, the car was capable of shooting 10' tall rooster tails of snow off both wheels. I never had ANY issue getting going in snowy or icy conditions.
Have no worries.
BobOfTheFuture wrote: I was always under the impression that torsen would go 'open' on slippery surfaces and that other (clutch) diffs were better for low traction situations. Is this not true?
I think this is true to some degree (the clutch packs need to have a preload spring to work well in this situation though, IIRC). That's why I added that bit about the handbrake. If you're spinning one wheel a lot with the torsen, you can apply a little handbrake and it will keep that one wheel from spinning with no load and it will start locking up the diff. Basically, you gently apply the handbrake and continue accelerating and it locks the diff up.
Apparently, the H1 hummers had torsens and came with instructions to do exactly this. Anyway, it works pretty well.
I have a Torsen in my supercharged Focus. Installed it the same time I put the supercharger on in 2005. I've driven it in snow, ice and the wet red clay at the Summit Point RallyCross courses and never had a problem.
Yup, the torsen in my s2000 is way easier in snow/ice than my old 240 with a nismo clutch LSD. Plus it's nearly zero maintenance.
One more vote for the torsen
While it's true that a tire with zero traction will make a torque biasing differential act similar to an open differential, that's all in how it's designed to work. But there's more to it than that. The differential can only bias the torque reaction from the tire with less traction. If that amount is zero, then zero torque can be biased. However even a small amount of torque reaction on low traction surfaces will be biased through the differential. So yes, if there is a very large disparity of traction between the two tires, it may still 'seem' that it's just acting like an open differential. But as the difference in traction between the two tires becomes more similar, so too the effectiveness of the differential seems to increase. Thus if both tires have similar traction, even on a slick surface, the differential should still generally work well enough. And if you do have further unequal traction problems, as has been mentioned, it's possible to create a little reactive force with the brakes to get biased to the other side. I believe on the HMMWV (Hummer) with having all three diffs as torque biasing units, you didn't so much use the hand brake so much as used a bit of brake pedal while giving it gas so that regardless of which 1 or more of the 4 wheels had traction, that's where the power would get biased. this would also probably how it would have to be done with FWD too, even though you'll also have extra brake drag on the rear tires too. But yes, on a RWD car a little hand brake would probably be more ideally functional.
As it pertains to buying a car...Get the Torsen. There really isn't a downside that I can think of for a driving enthusiast.
I installed a gear type in my street/strip car. I gotta say that the car is much easier to push in the staging lanes, i believe that would likely translate to better fuel mileage vs a clutch type.
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