How does limited slip differential affect handling?

[Snoopyjh]

Hello, I just got my BRZ not too long ago, and it's the first car with LSD that I've ever owned. So what does that mean? I get the basics of it but does this mean that I can push and accelerate during mid-corner without spinning out? I'm still kinda scared to just push the car harder during cornering because I feel like i'll just kick the rear end out and end up spinning out.
I feel like im at the limit going about 45mph in highway ramps barely on throttle LOL

[CoolHandMoss]

You can definitely still spin out with an lsd. The biggest difference would be that you can put more power down on corner exit. The rear end will still get lose if you get too aggressive though.

[Spuds]

I'mma put this up here just in case you are asking from a technical perspective. The twins have a helical torsen differential. Step 1 is to understand the mechanics.

https://auto.howstuffworks.com/differential.htm


You'll notice the locking under a number of conditions. One is when making a sharp turn from a stop. You might hear some wheel slip even though you are driving mildly.

Another is when you have one wheel on a low friction surface (dirt, gravel, snow) and the other on a high friction surface. You'll be able to accelerate at what the wheel with higher friction can support.

If the back does break free, both wheels will continue to push the car in a predictable manner, since both wheels will start slipping at the same time.

I've also noticed that when accelerating around a mid/high speed corner (like an on ramp) the car tends to try to straighten out (well, until you get wheel slip). I've attributed that to the differential as well, but I'll defer to more experienced drivers on this one of there's a better explanation.

[dutchman1]

Originally Posted by Spuds

I've also noticed that when accelerating around a mid/high speed corner (like an on ramp) the car tends to try to straighten out (well, until you get wheel slip). I've attributed that to the differential as well, but I'll defer to more experienced drivers on this one of there's a better explanation.

You're right, some of that is the diff. But mostly it's just a result of weight transfer. More weight off the steering tires means less turning.

[CSG Mike]

Originally Posted by Snoopyjh

Hello, I just got my BRZ not too long ago, and it's the first car with LSD that I've ever owned. So what does that mean? I get the basics of it but does this mean that I can push and accelerate during mid-corner without spinning out? I'm still kinda scared to just push the car harder during cornering because I feel like i'll just kick the rear end out and end up spinning out.
I feel like im at the limit going about 45mph in highway ramps barely on throttle LOL

Specifically, you have a torsen LSD, which functions in a very specific, distinct way.

I you jack up your rear wheels, and turn one, you'll notice the other spins in the opposite direction.

This opposite spin is the force that assists your car in keeping traction on your inside rear wheel, under throttle, while cornering. Otherwise, torque flows to the path of least resistance, and when that inner rear tire spins, you get almost zero acceleration.

The LSD increases the power delivery limit of your car.

A clutch type LSD can completely lock the rears together, so you can spin either both, or neither, as well as stabilize (or destabilize intentionally) the car under braking.

[Racecomp Engineering]

Originally Posted by Snoopyjh

Hello, I just got my BRZ not too long ago, and it's the first car with LSD that I've ever owned. So what does that mean? I get the basics of it but does this mean that I can push and accelerate during mid-corner without spinning out? I'm still kinda scared to just push the car harder during cornering because I feel like i'll just kick the rear end out and end up spinning out.
I feel like im at the limit going about 45mph in highway ramps barely on throttle LOL

Where in MD are you? You should try giving auto-x a go. It's a relatively safe, easy, and cheap way to explore your cars limits. And you can get an instructor.

Check out Boxerfest coming up next weekend too.

- Andrew

[Tokay444]

Positively.

[Snoopyjh]

Originally Posted by Racecomp Engineering

Where in MD are you? You should try giving auto-x a go. It's a relatively safe, easy, and cheap way to explore your cars limits. And you can get an instructor.

Check out Boxerfest coming up next weekend too.

- Andrew

Man I'd love to! LOL Where do u get all the autocross and boxerfest infos!

[Spuds]

Originally Posted by CSG Mike

Specifically, you have a torsen LSD, which functions in a very specific, distinct way.

I you jack up your rear wheels, and turn one, you'll notice the other spins in the opposite direction.

This opposite spin is the force that assists your car in keeping traction on your inside rear wheel, under throttle, while cornering. Otherwise, torque flows to the path of least resistance, and when that inner rear tire spins, you get almost zero acceleration.

Last I checked, open differentials behave the same way.

One of the drawbacks of Torsens vs clutch LSDs is that Torsens need both wheels to have some amount of traction to lock. Torsens transfer torque as a multiplier, meaning if one wheel has no resistance the multiplier has a 0 torque to multiply. This results in 0 torque on the other wheel for the math challenged among us.

The opposite spin shows what happens when the torsen fails to lock/limit torque difference. It's easier to drive the other wheel than it is to drive the gearbox through the inverted reduction of the ring/pinion because it is not locking.

[CSG Mike]

Originally Posted by Spuds

Last I checked, open differentials behave the same way.

One of the drawbacks of Torsens vs clutch LSDs is that Torsens need both wheels to have some amount of traction to lock. Torsens transfer torque as a multiplier, meaning if one wheel has no resistance the multiplier has a 0 torque to multiply. This results in 0 torque on the other wheel for the math challenged among us.

The opposite spin shows what happens when the torsen fails to lock/limit torque difference. It's easier to drive the other wheel than it is to drive the gearbox through the inverted reduction of the ring/pinion because it is not locking.

You're absolutely correct; a torsen with a wheel (or both) in the air, is an open diff!

[Racecomp Engineering]

Originally Posted by Snoopyjh

Man I'd love to! LOL Where do u get all the autocross and boxerfest infos!

This is a local group for autox. It's not the national type SCCA competition but they're good people that can get you started if you reach out to them.
http://capitaldrivingclub.com

This is the Boxerfest event page. We'll be there. There's also an auto-x with instructors upon request. Good for newbies.
https://www.boxerfest.com

- Andrew

[Sleepless]

The LSD in the BRZ actually makes it trickier to apply power in a corner since it allows power to be applied to the ground much better than an open diff. This means the tires now have to corner and accelerate. You can also use power to loosen the rear to rotate the car mid corner.

So, yes, the LSD can make the car harder to drive fast. But, when mastered, an LSD car will be faster