Silly questions about Limited Slip Diff.

[scottmandue]

Yes, I have been around here enough to know better than to put "LSD" in the title of thread.

First question: If I remember correctly, if you jack up the rear of the car so both wheels are off the ground (ridiculously easy on my Miata) when you spin one wheel if the other wheel spins in the opposite direction you have an open diff. however if the other wheel spins in the same direction you have a LSD.
Correct?

Second question (this is the silly one): Is it always and advantage to have a LSD?
Growing up all the hot rods had a LSD, and when you buy a car you usually pay extra for a LSD, and as Archie Bunker said "That is how you know what is better in America... It cost more!"

[masraum]

From what I understand the jack the car up and spin the wheel test is not a good test on the miata because we have torsen rears (except for the first few years that had viscous LSD). I've found that in pretty much every miata that I've even driven that it's possible to tell if the car has lsd when pulling away from a stop and turning or pulling a u-turn. If you are kind of heavy on the gas and the car has lsd, you'll usually hear the inside tire chirping as it tries to spin and traction and LSD fight each other.

My first miata had an open rear, and the current one has LSD. I much prefer the LSD. LSD can make a car less stable. If you get on the gas while cornering a car with an open diff will spin one tire, but the other tire will probably keep your car from sliding or spinning. With LSD if you manage to overpower the available traction, you are going to go sideways because both rear tires have lost traction. LSD is good for acceleration in a straight line or in traction limited settings, but that also can adversely affect cornering stability. LSD will also normally make the car understeer more.

I haven't had a problem with the behavior of the car with the LSD, but I can tell a difference mid corner. When I'm not near the limit, too much gas will make the car push, and close to the limit, too much gas will make the rear end step out.

[scottmandue]

Originally Posted by masraum

From what I understand the jack the car up and spin the wheel test is not a good test on the miata because we have torsen rears (except for the first few years that had viscous LSD). I've found that in pretty much every miata that I've even driven that it's possible to tell if the car has lsd when pulling away from a stop and turning or pulling a u-turn. If you are kind of heavy on the gas and the car has lsd, you'll usually hear the inside tire chirping as it tries to spin and traction and LSD fight each other.

My first miata had an open rear, and the current one has LSD. I much prefer the LSD. LSD can make a car less stable. If you get on the gas while cornering a car with an open diff will spin one tire, but the other tire will probably keep your car from sliding or spinning. With LSD if you manage to overpower the available traction, you are going to go sideways because both rear tires have lost traction. LSD is good for acceleration in a straight line or in traction limited settings, but that also can adversely affect cornering stability. LSD will also normally make the car understeer more.

I haven't had a problem with the behavior of the car with the LSD, but I can tell a difference mid corner. When I'm not near the limit, too much gas will make the car push, and close to the limit, too much gas will make the rear end step out.

Hmmm... my car has the aluminum fined diff cover, does that indicate open or LSD?
Is there a decoder of the VIN or the door sticker that would tell if it is open or LSD? (Think I have a Miata book that may have the VIN codes in it)
Would the fact that the rear slid out on me when I went into a turn a little too hot after our first rain indicate anything?

My Miata is an auto, for some reason most people think the autos came with an open diff.

[Rusty Heap]

wow, in your Sig, you're bragging about a 944, a Miata, and a Hyundai.........


no wonder you're wondering about LSD.


simple.

Apply Right Foot steering device that is located in the right side of the foot well. Just peg it, brick or log or other leverage device + rep points

if you need to do so in wimpy wet grass, such is the life of a Miata.

2 tire spin = LSD, one tire burn out = you have your answer.

[Dantilla]

Originally Posted by masraum

LSD can make a car less stable. If you get on the gas while cornering a car with an open diff will spin one tire, but the other tire will probably keep your car from sliding or spinning. With LSD if you manage to overpower the available traction, you are going to go sideways because both rear tires have lost traction.

Which is what makes Limited Slip so much fun!

I have an early Miata with LSD. Great little car. The only vehicle I have with an open diff is an old Chevy truck I bought recently. It too will have either a limited slip or locker before long.

Limited slip is always an advantage.

[scottmandue]

Dan, tried to PM you, you box is full.

[scottmandue]

Originally Posted by Rusty Heap

wow, in your Sig, you're bragging about a 944, a Miata, and a Hyundai.........

No brag... just fact,

[masraum]

Originally Posted by Rusty Heap

2 tire spin = LSD, one tire burn out = you have your answer.

No, not really, under certain circumstances a car with an open rear can and will spin both tires and leave two marks on the ground.

But thanks for playing.