Most of the production car uses 1 way LSD which are the torsens. 1way LSD only affect the wheel when the GAS PEDAL is pressed. if u let go of the gas pedal, the LSD wont do its job. for exmaple, u are going 45mph and wanna make a sharp right turn in front of u. u brake abit and turn in the corner hard, then slam on the gas and counter steer. the moment u turn into the corner, ur right rear wheel will start spining.This probably won't cause a big deal though because it is the outside rear which is doing all the work anyway and it will probably continue to do its job merrily. On a standing start drag race, this is advantageous as when you put your foot down it will not allow one wheel to spin wildly whilst the other just rolls along. Both wheels will be pulling / pushing the car forward.

Simply, 1way= only work under gas, 1.5way= work under gas, functioning half when not gas. 2way= functioning both on and off gas and willing to lock both of the spining wheels which jus recommend for drifting
hope this will help

 

thanks!

 

It all boils down to predictability and making the car easier to handle at the limits. Two locked wheels will always behave better than 2 wheels doing their own thing. Under deceleration, a locked pair of wheels will make the car lose traction in the rear more progressively. This is important when you dive into a hard corner while losing speed. Throttle-off oversteer...

This can happen with an open diff, but the difference is that with an open diff, your rear will go from totally planted to way out of wack, but with 2way, it'll progressively let out.

I drove with a Cusco 1.5way clutchtype LSD in my old AE86 and it made the car much easier to drive hard in any and all conditions. It gripped better and I could accelerate through corners earlier, yet it allowed me to put the tail out with the throttle. It made the car track straighter in snow/rain under throttle, and if the tail came out from me doing something stupid, it was easy to correct with good countersteering and a quick stab at the gas pedal.

 

[QUOTE=RED MX5,Nov 28 2007, 03:43 AM] I'm too lazy to try to explain it, when I can just steal this from the KAAZ Web site.

 

[QUOTE=S2KPUDDYDAD,Nov 28 2007, 08:37 AM] I have a Kaaz 1.5 LSD in my car. I found that using 2 oz of a 4 oz bottle of GM limited slip differential additive to my diff oil keeps the thing OEM quiet.
Before using the additive you would here it going around every corner now, I here nothing
I agree with you saying that it is

 

I have never driven a car with a KAAZ or any other kind of clutch diff.
All I can say is that I liked my S2000 on the 2 track day's I have been to.
Stock engine, 4.57's, S-02's & Koni Yellows.
The pro driving the S2k prototype on the Nurburgring liked it a lot too.
Maybe the S2000 suspension works best with all 4 wheels on the ground?
I guess more experienced and/or professional S2000 racers could think otherwise.

RED MX5 Posted on Nov 28 2007, 10:28 AM
The KAAZ doesn't have the Torsen side gears to assist in generating locking power.

From the Torsen website:
[QUOTE][I]By adding preload springs (this is design specific), the TORSEN T-2R will stay locked with low torque inputs.

 

Under hard braking the brakes totally override anything the differential is doing, so when threshold braking the LSD type and setup (normally) doesn't make a significant difference.

There seems to be some confusion about the way the action of the LSD affects the cars handling, no doubt because there is a lot going on. I want to try to clear some of it up, but to do so I think I have to go back to some of the basics.

When a car is turning, the outside wheels have to travel further than the inside wheels. In a FWD application, the rear wheels are just tagging along behind, so when turning, the inside rear wheel turns a little slower than the outside rear wheel, so that both wheels cover the different distances in the same amount of time. If you were to connect an axle between the two wheels in this configuratoin, so that it forced the two wheels to turn at the same speed, you would prevent the rear wheels from turning at different speeds while cornering, but the two tires still have to cover different distances in the same time period, so one or both of the tires are going to have to slip al little to make up for the fact that it's speed can no longer differ from the tire on the other side. In the FWD application this would have two obvious downsides. The back tires would wear out faster, and since one or both of the back tires are always slipping a little when turning, some of the tires available grip will be lost.

With RWD, we're stuck with axles at the back, so we have to decide what to do about the difference in wheel speeds during cornering. The simplest solution would be to drive only one wheel, and let the other wheel roll freely. While you'll never see this kind of setup on a modern automobile, it's still a collections of tradeoffs that are worth understanding. All the power would always go to one wheel, and it would always be the same wheel. Upsides would include zero scrubbing when cornering, and potentially longer tire life for the tire that never delivers any power to the road. Downsides would include things like poor traction during acceleration (because only one tire can push the car forward). Handling at the limit would depend on which way you were turning. When cornering, the inside rear tire is unloaded (more or less, depending on how hard you are cornering), and the outside rear tire is doing most of the work. With one wheel drive, if that outside tire also has to deliver the power to the ground, it will spin easily because it's doing all the work of both cornering and acceleration. Car will tend to oversteer. If on the other hand, the inside rear wheel is the one getting all the power, it too will spin easily, because it is unloaded and just doesn't have much grip, but when it spins, it will not have any effect on the outside tire that is doing most of the work of cornering, so the car will not be nearly as prone to oversteer when the throttle is applied.

Easy to see why modern cars don't use one wheel drive.

If we go to the other extreme, and lock the two rear wheels together, so that they always turn at the same speed, we have the same problems we had with the FWD configuration when we tied the rear wheels together, but we also have issues related to putting the power to the ground. Whenever we accelerate, both rear tires will be turning at the same speed, and this will naturally push the car straight ahead. If you have small front tires, and big back tires, a car with no differential can push the car streight ahead even with the steering at full lock. So, when the back tires have grip, a car with no differential will understeer more than it would if the wheels could turn at different speeds. As the limit of the rear tires grip is approached, this all changes, because the back tires are already scrubbing, and when the tires spin, they will both spin at the same time, and the back of the car has almost got to slide out if you're turning and both back tires are spinning. So putting it most simply, when there is no differential action, the car will have more understeer, up to the point where the back tires start to spin, and then it will have more oversteer.

Now it is important to keep in mind that things like understeer and oversteer in this context are all relative. A car that has massive understeer will underster more with a locked axle, and a car with massive oversteer will have even more, because the back tires already slide first, and tieing the two back wheels together only makes it worse.

BUT, with the two back tires locked together, we get good straight line grip because both tires share the power equally at all times.

A typical differential allows the two rear wheels to turn at different speeds, and when one wheel loses grip, all the power goes to the wheel that is spinning. That's why cars without an LSD often leave one long rubber strip instead of two. When cornering, this is a very safe setup, becasue if you jump on the gas too hard, the unloaded inside tire spins, but it's the other tire that is doing most of the work of cornering, so the unloaded spinning tire doesn't take away the critical grip you're using to keep the tail tucked in. This is in contrast to what happens if the axle is locked up, by an LSD or because it doesn't have differential action, because in those cases, when you get on the gas hard enough to spin a tire, both tires spin, and the car slides.

The LSD allows us to have some of the advantages of both an open diff and a locked diff, and every LSD type and variant offers a different combination of tradeoffs. Torsen dominates the OEM LSD market becaue of the particular tradeoffs they offer. They do a good job of sending the power to both wheels when needed, and allow differential action even under some acceleration conditions, so tire wear isn't impaced negatively by scrubbing. They will also send all the power to the wheel that spins, once it's lost all it's grip, so they leave the outside wheel free to deal with cornering forces, and offer a safety margin just like an open diff, once you push the tires too far. On top of that, the Torsens are virtually maintainence free, needing only occasional oil changes, and reliability is usually as good as it gets. The Torsen is the first choice for so many manufacturers becasue it makes all the right compromises for their purposes.

In point of fact, there is absolutely nothing wrong with a Torsen, and they are suitable for almost any application. A stock S2000 on OEM tires does not have enough grip to corner hard enough to unload the inside rear tire enough for the Torsen to let it spin, and the car's suspension has been tuned to achieve the desired results in conjunction with the action of the Torsen LSD. When R compound tires are put on the car, the extra grip is enough to unload the inside rear tire during hard cornering, but the unloading and resulting tire spin is NOT due to the way the Torsen works. The inside rear tire unloads because the rear roll stiffness is too high, and the right way to address the issue is to adjust the roll stiffness at one end of the car or the other (or both). Even if you have an LSD that won't let the inside rear tire spin when it unloads, it will still be unloading and delivering poor grip. A different LSD is NOT the way to fix the situation with R compound tires and wheel unloading. Anti-sway bars and springs are the way to address that problem.

So, I guess that brings us back to the original question, and the answer is still the same. Driving styles and venues differ, so we have a whole spectrum of LSD types and actions to choose from. An LSD like the KAAZ makes a car like the S2000 even more responsive. People already get into trouble with the S2000 becaue it responds so quickly to driver inputs, so this is the LAST mod most people should probably consider. On corner exit, the KAAZ is locked as soon as you're on the power, and it stays that way. Even the smallest change in throttle setting goes directly to *both* rear tires, and this instantly changes the slip angles at which they are operating. One way to look at this is to see it as making the car easier to steer with the throttle, and in fact, it does, but the car is still very hard to steer with the throttle, so I prefer to just say that it is more resonsive to throttle inputs. It's a perfect match to my aggressive driving style, and it makes it easier for me to drive the car in the ways I like to drive it (not on the street, but in those places where I can push the car as hard as I like). One of the reasons I bought the S2000 was because I knew that its quick reflexes would make me a better driver, and after I had learned to deal with the stock cars reflexes, it made sense to raise the ante by making a few mods. In expert hands the KAAZ might make the car faster, but in my hands I'm not at all sure that's the case. It's just like the car itself, something that will ultimately help make me a better driver.

Sorry for the long post guys. It's important to understand that the LSD and its action is a part of a much bigger package that involves many other things, including the suspension tuning, tire type, torque, power, gearing, and so on. In general though ...

Looking at the effect the diff has on how easy it is to spin the car with the application of throttle, from most forgiving to least forgiving, is ...

1) Exotic traction and stability control setups (many variations).

2) Open differential.

3) Torque sensing LSD.

4) Locker type LSD.

5) Agressive (fast acting) locker type LSD.

 

[QUOTE=RED MX5,Nov 28 2007, 01:33 PM]So, when the back tires have grip, a car with no differential will understeer more than it would if the wheels could turn at different speeds.

 

LOL, I don't mind answering questions (when I can), as long as you guys don't mind the long posts I make in my attempts.

I would actually say that the chief benefit of an LSD like the KAAZ is that it makes the car more responsive to throttle inputs. Certainly, in a straight line, having the two rear wheel in lock-sync is a good thing, but in a car like the S2000, the whole car is about responsiveness and handling in the twisties, so it's the effect that the LSD has in those situations that matter most. I think the real question is whether or not making the car more responsive to throttle inputs (when cornering) is a good thing or not, and that all depends on how you drive and what you're doing with the car. For me, making the car more responsive to throttle inputs means that I have to be more accurate with my throttle inputs, so I become a better driver (at least, that's the theory behind my choice ... it remains to be seen whether or not I'll actually become a better driver ). Really, I just like the challenge of the speedy resonses; That's one of the main reason I bought the car in the first place.

As for "ultimate rear grip," the effects of the LSD, if any, will depend on the particular circumstances. Most of the time we measure grip on a skid pad, and as one end of the car or the other approaches its limit, we increase our speed very slowly, to put off the breakaway for as long as possible, so we can get the highest possible numbers. I always call that the "steady state" cornering grip, because except for spikes you see when racing or autocrossing, the steady state numbers are the highest numbers you achieve laterally. As you approach the limit on the skid pad, throttle modulation is critical, and I think the resonsiveness of the KAAZ makes it harder to get the car to the maximum possible steady state cornering. There are really so many variables that it's impossible to say which type of LSD or which setup might produce the most grip in any general way. To maximize traction coming off turns, the ideal setup is probably the OEM Torsen combined with an RLTC, with the RLTC set up for something in the neighborhood of 5% slip.
(I'm talking out my butt to some extent here, because I have zero experience with the RLTC.)

I hope I didn't just confuse you more. In the case of the S2000, think of an aggressive LSD as a way to make the car more responsive to throttle inputs. Depending on how you drive, it might not make any difference at all, and for many, it could be a very bad thing. For those of us who aren't seriously racing the car, this kind of mod is basically just a toy. The stock car has great responses to all the drivers inputs, so like a supercharger, an aggressive LSD is something the car needs about as much as a submarine needs screen doors.

It is a hoot though.

 

Thanks, that does help. One thing I just remembered is something I read in "Racer Magazine" (given to me after a skip barber school) about the Ferrari and Porsche ALMS cars (I think that's what they were). In any case, someone commented that if you were driving one of the cars (can't remember which was which) on the edge of adhesion then you were driving on the ragged edge, but in the other car if you were driving on the edge of adhesion you would be driving calmly and comfortably. Both are just as fast, just different styles. I thought that was pretty interesting and it's similar to this discussion .