limited slip dif.

[jayjack]

i heard that limited slip differentals could accually be a bad thing wile turning on slick roard. is that because the outside wheel turns alot faster than the inside one, so the inside tries to spin at the same speed and you could loose controal. is that at all correct?

[curtis73]

someone fed you a line. Limited slip differentials still allow full differentiation of the wheels, so in a turn the inside tire still turns slower just like on an open diff. The benefit is that both tires retain traction so grip is improved.

There are several types of limited slips, though. Most commonly, they use clutches that are held together with springs. I have that type and I notice that during hard turns the car wants to scuff the front tires a bit to the outside, but I never noticed it being a problem in snow or ice. Any drawbacks to it are more than outweighed by the traction benefits.

There is also an on-demand limited slip typically used in trucks that is commonly referred to as a gov-lock. It functions the same way as the above type with clutches, however they are normally disengaged resulting in an open differential. There is a little centrifugally operated mechanism that senses when one wheel is spinning faster than the other and it applies pressure to the clutches making it lock them together.

There are some now called Torsen (torque sensing) that use some configuration of helical gears and they provide the best of both; full differentiation with full torque split to both.

The only time a limited slip would be a problem on slick roads in a turn is if you're doing things like parking lot maneuvers or tight slow turns. In a normal turn like at an intersection or something the amount of resistance to turning is so neglegible that you'll never notice it regardless of how slick the roads are.

[Black Lotus]

My experience goes like this:
Accelerating in a turn without LSD, the inside (unloaded) tire tends to loose traction and spin harmlessly. However the car doesn't accelerate very well.
With LSD, the power to the wheels is more evenly distributed and the car accelerates better out of the corner. However, while cornering, the outside tire is seeing both lateral cornering forces and forward acceleration forces. Therefore it will tend to loose traction suddenly, and if it's a rear wheel drive car, the back end will tend to step out and could lead to a spin--if the driver is unskilled.
One caveat with non LSD cars on any road--if the inside tire is spinning under power exiting a corner, then for whatever reason gains traction (and this happens), the outside tire may suddenly break loose. Suddenly car control can become much more difficult than with LSD.
So, on the whole, IMO, LSD tends to smooth things out and makes car control much more predictable.

[jayjack]

would it be hard to swich from open dif to LSD. i mean could i fing a LSD that would fit where my existing difs are?

[curtis73]

Depends on the car, but most likely yes. What car is it?

[jayjack]

its a 96 gramd merc mostly stock. would LSDs really even help much in my car? i mean traction is almost never an issue with it.

[curtis73]

Nah. If you noticed poor winter traction or had enough torque that dry traction were an issue I'd spend the money, but its not a big deal.

I had an 82 Caprice that was poor in the winter, but instead of buying a $300 LSD plus the labor to install it, I bought a set of Blizzaks for $150.

Some really high performance cars actually handle better WITHOUT it. The Lotus Exige came without it because it was shown to have less grip in full-effort track racing (mostly due to the excellent weight transfer and the light car) but public outcry was huge for the LSD and they started offering it. Tiny car, short wheelbase, lots of power, and short sidewall tires made it a little more tricky in turns since the back liked to get ahead of the front, but that is a RARE exception.

[Moppie]

Originally Posted by curtis73

The Lotus Exige came without it because it was shown to have less grip in full-effort track racing (mostly due to the excellent weight transfer and the light car) but public outcry was huge for the LSD and they started offering it. Tiny car, short wheelbase, lots of power, and short sidewall tires made it a little more tricky in turns since the back liked to get ahead of the front, but that is a RARE exception.

I think you will find it came with out an LSD because no one made one for the original Rover K series motor/gearbox the Exige/Elise used.
Then they switched to a Toyota power plant, and of course an LSD became available with with the Celica Motor/Gearbox.