Hey !

After searching through the threads, I didn(t find a post answering my question :
There are basically 3 types of Clutch Pack LSD :
- 1 way : open under coast (decelleration), full lock under power (accelleration)
- 1.5 ways : not full lock under coast, full lock under power
- 2 ways : full lock under both coast and power.

So my question is : which of the 1.5 or 2 ways is better (in an average track day car) ? I've heard a lot of racecars ran with a 2 way one, but doesn't it create unwanted understeer when entering ?
So isn't a 1.5 better for cornering (same exit power, but better entry speed?)

What you've described as a '1 way' is something along the lines of a Detroit Locker, used in lots of oval cars and other more simple circuit racing cars, including V8 Supercars, not really a desirable alternative to a LSD unless you need to put a huge amount of power down with rubbish tyres.

The '2 ways' sounds like a fully locked differential, useful for drag racing and the odd circuit application like some Group C cars where a lot of power has to be put down in a car that is easy to drive, expect understeer everywhere and increased risk of breaking driveshafts.

For a normal track car a limited slip diff (partial lock power and coast) is normally the better option.

In LFS we have I believe a 1.5 way LSD for some of the road cars (with coast half the amount of power locking, only power locking adjustable - IIRC) and something that doesn't quite fit the 2 way LSD description from above, namely one with fully adjustable coast and power locking percentages, which is obviously the "best" LSD since you can completely tune it to your needs.

The only place I've seen 1, 1.5 and 2-way diffs mentioned is Gran Turismo.

The manual for the first one had a good explanation in it, one is more suited to FWD and another more suited to RWD IIRC

Thanks for your answers, but as I wrote this OP in a hurry, I didn't have time to explain it properly

What I mean by the Locking is how locked the differential gets when a wheel (the inside one) starts to slip. Meaning how much torque is transfered from the inside wheel to the outside one

1 way : behaves as an open diff under deceleration, but locks up under acceleration.
1.5 way : partially locked under deceleration, locked underacceleration
2 way : locked under both acceleration and deceleration

All of these above, of course, happens when the inside wheel starts slipping.
If I would compare with LFS clutch pack settings :
- 1 way : 10% coast / 80% power
- 1.5 way : 50% coast / 80% power
- 2 way : 80% coast / 80% power

My question is because I will buy soon a new car for trackday amateur racing (Mx-5 miata) and i have the choice between a 1.5 or a 2 way. So I wanted to see if you guys thought that the 2 way was a good alternative (or is it just that I don't manage to cope with the Understeer when cornering )

Having no trackday experience at all, I'd opt for a 1.5 way one. Though don't confuse LFS' locking percentages with the locking you'll get from a real LSD. There it entirely depends on the ramp angles on how much of the engine input torque is used to press the clutch plates together. I think with such an LSD you'll get something equivalent to 40/20 or 50/25 locking (power/coast) in LFS.

for a miata, you won't have that much power going to the ground.

Its my understanding that you want the diff to be as open as possible for best handling. You don't want to bind up your nice handling miata with a super tight diff

Unless you're going with an aftermarket diff, the mx-5 will come with a tornsen. The torsen is actually going to send MORE power to the inside tire until it starts to slip, and then it'll transfer power back to the outside. If the speed of the inside tire is greater than the preset ratio in the diff, it'll lock the diff.

Quote from spanks :

for a miata, you won't have that much power going to the ground.

Its my understanding that you want the diff to be as open as possible for best handling. You don't want to bind up your nice handling miata with a super tight diff

Unless you're going with an aftermarket diff, the mx-5 will come with a tornsen. The torsen is actually going to send MORE power to the inside tire until it starts to slip, and then it'll transfer power back to the outside. If the speed of the inside tire is greater than the preset ratio in the diff, it'll lock the diff.

The power is a real "issue" on a Miata. I will have 115hp, so I need to get every single one of them down the pavement and not loosing them I guess I'll opt for a 1.5 way, so that the entires won't be that sacrificed compared to the 2 way one. Plus, as a Miata is ultra light, I guess that I can recover quite fast (not much inertia). What do you think ?

I've never really found inside wheel spin to be a problem, and the handling is a joy - I wouldn't want to muck around too much with adding a diff that will barely improve traction but ruin the handling... Unless you are a superb driver I reckon the tradeoff would cost you time, not gain it.

Quote from AndroidXP :

In LFS we have I believe a 1.5 way LSD for some of the road cars (with coast half the amount of power locking, only power locking adjustable - IIRC)

I thought it was the other way round, the basic road cars having 2-way diffs while the others have 1.5-way (although you can turn a 1.5 way into a 2-way in LFS).

Perhaps you're getting confused with dampers, where on those cars, the damping figure sets the rebound directly, while bump damping is set to 50% of that.

Could also be

Quote from tristancliffe :

I've never really found inside wheel spin to be a problem, and the handling is a joy - I wouldn't want to muck around too much with adding a diff that will barely improve traction but ruin the handling... Unless you are a superb driver I reckon the tradeoff would cost you time, not gain it.

thats what I was trying to say

even with the torsen that puts more power to the inside wheel (and can make you faster around corners), I've never had the thing spin the tires, or tire, out of a corner.

lol v8 supercars use detriot lockers now?
i thought they used to use Full Spools cause detriot lockers are extreamly savage with on/off power.

anyways drifters use 2 way cause like he said its pritty much constant locked diff.

so i guess the theroy is how would u want to setup the car?

Quote from MAD3.0LT :

lol v8 supercars use detriot lockers now?
i thought they used to use Full Spools cause detriot lockers are extreamly savage with on/off power.

anyways drifters use 2 way cause like he said its pritty much constant locked diff.

so i guess the theroy is how would u want to setup the car?

Mostly for racing in club tracks (very narrow angles, repeated left-right changes) or autox.
But just to precise, if the locking value is 50% it doesn't means that it behaves all the time liked a halfway locked diff : it just behaves like this WHEN the inside wheel lose traction

Tristan is quite right, so I guess a 1.5way(i guess the power/coast locking ratio are 50 and 25% for a Miata) will be just fine, as I usually do my best times with a setup that oversteers a bit in entries and have understeering in exits.

reviving an old dead thread!

my 95 miata has a torsen, and i wish it had a 1.5 way (mine is a type 1/ 1-way diff)

I've driven both open diff cars, and cars with LSDs. I can say that the lsd for SURE helps keep the power down. (until you lift a wheel with a my torsen anyways)

the only thing i have against the 1 way is that it locks HARD and quickly. It creates an oversteer situation when I want, but I have to keep the throttle mashed, otherwise i get snap oversteer even if i don't lift completely. I think this is due to the torsen unlocking, and also due to the tiny wheelbase.

I would opt for a clutch pack 1.5 way with custom lash and backlash settings if possible.

I went from an open diff to a Kaaz 1.5 way clutch pack LSD in my miata and wouldn't go back.
The factory torsen acts as an open diff as soon as one wheel loses traction, rendering it useless. The clutch pack will always have power on both wheels.
I did not notice any more understeer from the diff than I had before. When broken in properly, the LSD locks smooth and nicely. I shimmed it a little tighter (more preload) so I get some low speed, tight turn (basically only in parking lots) noise and inner tire skipping. Even on the streets, pulling out of a tight turn, it puts the power () down nice and smooth, with the rear-end coming around ever so slightly. You'll also get rid of funky 'one-tire-fire' when acting the boyracer in your local mall parking lot

Like I said, wouldn't go back to an open diff