LSD Handling explanation

[Project S13]

Alright after reading through all 5 pages of results for the search query 'lsd' I have a question I'd like to ask. This pertains to the 2-way clutch lsd in a 240sx. My car is not a daily driver, though I like to retain some daily driveability (at least enough to drive to events that may be 2-3 hours away) My focus is drift events and autocross, I have heard about 2ways being very poor for AX but couldn't that be at least partially tamed with driving technique?

Mainly asking about handling characteristics.

From this month's SCC letter to the editor: (by the editor)"..[clutch type lsd's have some preload locking the wheels together even when no power is being applied.] This can make turn-in sluggish and unpredictable as the diff fights to keep the car going straight. The amount of locking also ramps up very suddenly when power is applied, causing a shift toward understeer on power and making it difficult to follow a smooth line if you feed power in and out in a long corner."

And yet people are saying the 2way is all about oversteer. Also I have read warnings from users about heel/toe downshifting a 2way in the rain...talking about spinouts and such. I don't drive like a maniac but the understeer/oversteer descriptions I have read seem somewhat incongruent. Can someone set this straight or give the info that links the two extremes of handling to the one unit?

I hope a few of our kind gurus will help give a more wholistic explanation of the 2way lsd behavior for me. Tech detail is encouraged as well. The descriptions of seemingly contradictory handling charcteristics make me want to seek a fuller answer. If there's a different/better forum to post this in please enlighten me. Thanks guys

[Project S13]

I typed this late at night...blarg. After rereading it I think it would be better to ask this:

I'm seeking a more full description of how 2way lsd's react to different forms of driver input.ie: what the car's reaction is when entering a turn under braking, maintenance throttle, and under mild and heavy power? Behavior during heel/toe downshifts?

[sr20power]

yeah i like your question better....but what? no input for the guy?

i'm by no means a expert or anything....but i autocross and drift. i have driven w/ a stock vlsd and now have a cusco rs 2-way i also daily drive my car...

for autocross events, i did think that it would be a disadvantage because that it would lock up too much for a tight course. its all about pedal control, i didn't have any problems understeering/oversteering on tight corners. but alot easier to break the rear end loose...

i have not drifted my car w/ the 2-way, but i have drifted my brother's car (s13) w/ the same 2-way ... and i have to say that it is more predictable to oversteer the car and you don't need to be stepping on the gas as much like the vlsd to have them stay locked. the kick-back isn't so sudden, more predictable/controllable...

for rainy days... i have no problems. just don't drive like an idiot, you'll be fine...

sorry no technical fact or anything, just my 2 cents...

[cdlong]

i think it's an either/or thing. either it's pushing, or it oversteers. either both rear wheels have traction and continue to push the car forward or they both break loose and slide.

[Nismo_Freak]

From this month's SCC letter to the editor: (by the editor)"..[clutch type lsd's have some preload locking the wheels together even when no power is being applied.] This can make turn-in sluggish and unpredictable as the diff fights to keep the car going straight. The amount of locking also ramps up very suddenly when power is applied, causing a shift toward understeer on power and making it difficult to follow a smooth line if you feed power in and out in a long corner."

He's right.

On throttle you will understeer if the tires can't break free, and off throttle you will understeer just the same. The problem then lies in inducing the car to become neutral, the diff is still locked and can cause sudden oversteer.

Basically you will fight the car alot more than you would with a 1-way, VLSD, open diff., etc. Especially in a tight corner, low speed, on/off throttle situation like auto-x.

I personally don't see the luster in a 2-way diff. I've driven cars with them and honestly the simple VLSD is tons easier to control because you can more readily predict the cars attitude. Just my opinion.

[KASilvia90]

I always thought 2-way LSD was the thing to do for good handling? After reading this, it would seem like open-diff. woujld actually offer the best handling because the tires dont both spin as easy? Am i right or wrong on that one.

[Project S13]

A helical or a 1.5 way would probably be your best bet for grip and versatility. They give good traction and allow you the option of turning the car with the throttle if you have a decent amount of hp, otherwise the helical especially won't really interfere with your driving too much because it's alot gentler and more prgrossive, from what I understand. 2-way differentials give more/high traction to the drive wheels. In a RWD that = understeer or good, powerful oversteer & oversteer control. A 2way would also be good for drag racing, as it improves acceleration and straight-line braking. But yeah, from what I understand cornering is made more difficult.

Aside from the added traction for drifting, why are these so popular for drifting? More importantly, what kinds of techniques/corner entries would let you drift into corners? Especially without using the ebrake, clutch slips, or under-rev matching on downshifts?

[nismofly]

drifting can also be done by feinting, which is where you steer right going into a left turn for example, then quickly turn the wheel left and use the weight transfer to start the drift...you can also use power over, which is basically just a power caused oversteer controlled into a drift

im not a drifter but thats how i understand it

as far as the LSD, for say winter driving circumstances where it would be used to aid driving, as well as the handling aspect, i think isnt it the 1.5 way thats better for like snow and rain and the HLSD just aids in handling?

[Project S13]

As I understand it 1.5 way lsd's are easier to control and easier to go fast with. This is because understeer during braking is minimal in comparison to a 2 way clutch type, so grip driving is easier. Helical differentials are great for grip driving but lack the extreme lockup preferred for maximum drifting performance. 1.5 ways can be versatile and decent for drift also.

[evildky]

I always thought 2-way LSD was the thing to do for good handling? After reading this, it would seem like open-diff. woujld actually offer the best handling because the tires dont both spin as easy? Am i right or wrong on that one.

a LSD does help handling, it aides in corner exit so your inside tire isn't spinning when you try to exit a turn, it also give more predictable oversteer so you can use your pedal modulation to turn the car in a tight corner and not overheat one tire and get sloppy and too much rotoation

[Project S13]

Hey what's up Evildky?

You're in louisville eh? Cool man maybe I'll see you at an AX or the lexistreets cookout the 22nd of this month, I'm in lexi

a LSD does help handling, it aides in corner exit so your inside tire isn't spinning when you try to exit a turn, it also give more predictable oversteer so you can use your pedal modulation to turn the car in a tight corner and not overheat one tire and get sloppy and too much rotoation

A 2 way lsd will give the rear alot more traction, so it will be more difficult to turn at first, but it's great for drifting and can be driven quite fast with developed driver skill. It doesn't instantly make grip driving any easier though, imho

[evildky]

Hey what's up Evildky?

You're in louisville eh? Cool man maybe I'll see you at an AX or the lexistreets cookout the 22nd of this month, I'm in lexi

A 2 way lsd will give the rear alot more traction, so it will be more difficult to turn at first, but it's great for drifting and can be driven quite fast with developed driver skill. It doesn't instantly make grip driving any easier though, imho

I'm at all the Autocrosses in Louisvile, and I am trying to make one or 2 in lex this year, already hit one in cinci (actually in KY but hosted by cinci)

[Project S13]

So you're going to the one up near louisville...this coming weekend. Someone told me ft. knox or something?? I've never been up there but I heard it was at a runway or something. Pretty nice track??

There's one in lex that same weekend I was planning on going to but if the entry fees are the same i may go to the better/bigger location b/c the one is lexi is usually a pretty short course ~40-45 seconds :/