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I have this on my car but still i am yet to find out what it actually does. I take from the name that it has something to do wiht traction but this may be wrong. Can someone explain this to me. Thanx in advance
Sam
 

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The LSD in the IS300 is a Torsen LSD, it transfers power from the slipping wheel to the wheel with traction based on a built-in torque bias. I'm not sure what the bias ratio is for the IS, but it's probably something like 4:1 or so. You can read up on this and the several other types of differentials here:
http://www.howstuffworks.com/differential8.htm
 

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I'm sure this questions has been answered before, but here's an explanation.

The limited slip differential (LSD) ensures that power is provided to BOTH rear wheels under all circumstances.

Now, this statement may not make sense unless I give you an example, so here goes:
In a car without LSD, if one tire loses traction, it will get all the power and will spin (while the other tire with traction, will not spin at all). However, a car with LSD will provide power to both tires.


I believe that the Torsen LSD in the IS300s is 25% (or 1/4 as webguyIS mentioned). The percentage number denotes the percentage of torque applied to the slower turning wheel from the faster turning wheel. In a straight line, both drive wheels turn at the same speed, so no limited slip action is occurring. In a turn, or when one tire is spinning more than the other (such as on snow or ice), with LSD, 25% of the torque from the faster wheel is applied to the slower wheel, effectively 'limiting slip'.
LSD can cause increased tire wear on the inside tire during cornering -- the tire itself will have to slip slightly to counteract the limited slip's desire to have both tires turning at the same speed. It will also increase oversteer in wet or slippery conditions, but it will also increase understeer in tight corners under dry conditions. This is simply due to the fact that with a limited slip, the drive wheels tend to want to turn at the same speed, making the car tend to want to go in a straight line. When it is slippery, however, both drive tires will tend to lose traction at the same time, increasing oversteer.

The advantages of LSD are less inside wheelspin when accelerating out of a tight corner. This also translates into more horsepower to the pavement and faster autocross times -- provided that the suspension is tuned for the limited slip. The ability to accelerate out of corners without excess wheel spin can be a great advantage.

(most of the information presented here has been researched on the web… you can get almost any question answered there)
 

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Originally posted by soulstalker:
(most of the information presented here has been researched on the web… you can get almost any question answered there)
Ain't it the truth?! =)

Great explanation!
 

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So it sounds like the pluses/minuses are:
+ less wheelspin accelerating from corners
- more understeer (dry)
- more oversteer (wet)

Sounds like a tradeoff I could live without, actually.
 

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Originally posted by STKSKI:
I have this on my car but still i am yet to find out what it actually does. I take from the name that it has something to do wiht traction but this may be wrong. Can someone explain this to me. Thanx in advance
Sam
Do a search this topic has been beaten to death.

 

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LSD mostly comes down to this:
Do you get snow and ice?
If yes, then I would seriously consider getting LSD.
 

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Originally posted by ckolsen:
So it sounds like the pluses/minuses are:
+ less wheelspin accelerating from corners
- more understeer (dry)
- more oversteer (wet)

Sounds like a tradeoff I could live without, actually.
Honestly the less wheelspin + is a very LARGE + compared to the other two, which only occur during extreme cornering.
 

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Yes this topic has been covered many times on is300.net...

Also, since every is300 has electronic traction control the LSD is less needed on this car since the traction control can help get you out of situations (where one rear tire is stuck on mud, snow or ice) just about as well as the LSD would.

The LSD would be most useful if you have engine upgrades to the point where you can accelerate at the limits of the tire traction.
 

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Originally posted by TEG:
The LSD would be most useful if you have engine upgrades to the point where you can accelerate at the limits of the tire traction.
Which is precisely why it's great for cornering! Autox will never be the same. =)
 

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Originally posted by Papo-Salsa:
What about the traction control? I think you are paying for something you really don't need

Traction control limits the engine's power if slippage is detected. The LSD let's the engine put all the power down but redirects that power if one wheel is slipping more than the other. I imagine TRAC kicks in after the LSD does since Torsens are instantaneous, but I'm not sure how they act together. Personally I'd ditch TRAC for the LSD anyday if it was possible.
 

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Simply stated, Traction control (Trac) reduces wheel spinning by applying the brakes to the wheel (decreasing total HP to the wheels).

However, LSD reduces wheel spinning by redirecting the torque to the other wheel (preserving total HP to the wheels).

Ideally, you would wan LSD and have Trac off while racing, to preserve HP. But for everyday driving (and rain/snow driving) you would want LSD and Trac (and maybe Snow mode) for maximum traction.

[ April 25, 2001: Message edited by: soulstalker ]
 

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Originally posted by Papo-Salsa:
What about the traction control? I think you are paying for something you really don't need
I agree; it also adds an extra couple hundred pounds like on the prelude SH *which is not a true LSD*... compared to the S model (I belive), the SH has more hp but with the extra weight it is actually s l o w e r . . .


edit: I should have made myself clearer; I was refering to the 97-current Preludes. I don't know why they did away with the AWD, but anyway...

[ April 26, 2001: Message edited by: LawGirl ]
 

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Doesn't the Prelude SH have the 4 wheel steering or something like it? TRAC doesn't add any weight, it's all electronic, but LSD might add some, anyone know how much? I'd guess only 20-30 lbs, anyone know?

Originally posted by LawGirl:
Originally posted by Papo-Salsa:
[qb]What about the traction control? I think you are paying for something you really don't need
I agree; it also adds an extra couple hundred pounds like on the prelude SH *which is not a true LSD*... compared to the S model (I belive), the SH has more hp but with the extra weight it is actually s l o w e r . . .

[ April 25, 2001: Message edited by: LawGirl ][/QB]
 

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The older Prelude had 4WS, but not the Prelude SH. The SH has what Honda calls ATTS (active torque transfer system) or something like that. It's supposed to reduce understeer. Problem with the SH is that it's like 200 lbs heavier than the normal Prelude and it has uglier rims. Also, I've heard that the effect that ATTS produces is similar to what a Quaife differential can do. Anyone care to explain how ATTS and the Quaife differential work?
 

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scc's 8 great rides issue last year had a quote on atts on the prelude sh...something like "atts makes the prelude sh the only fwd car in the world capable of power on oversteer, which makes as much sense as making gasoline driving in reverse." or something like that...i could have mixed some stuff up but i know that those 2 points are made, maybe unconnected...
sorry...my memory is failing...
maybe i'll go dig up my issue...if i can find it...
 

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Originally posted by LawGirl:
I agree; it also adds an extra couple hundred pounds like on the prelude SH *which is not a true LSD*... compared to the S model (I belive), the SH has more hp but with the extra weight it is actually s l o w e r . . .
The S and SH have the exact same power specs, it's just that the SH is heavier so it's slower.

The ATTS system works by directing power to the OUTSIDE wheel during a turn. This reduces understeer and slippage on the inner wheel, which promotes oversteer since the front outter wheel is essentially pulling the car around a turn.

Like I've said before the SH is heavier (88lbs to be exact), but it can definitely corner well. That ATTS worked wonders when I was test driving it. Of course purists complain since it's neither a true LSD nor traction control system, and the fact that it's lacking the strength to handle any real power (i.e. more than +50 over the stock 200hp).

[ April 26, 2001: Message edited by: webguyIS ]
 

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Originally posted by webguyIS:
The S and SH have the exact same power specs, it's just that the SH is heavier so it's slower.

[ April 26, 2001: Message edited by: webguyIS ]
Then doesn't it make more since to NOT get the SH? I,personally, driving around Dallas don't do alot of cornering (unless I'm in my underground parking garage lol) . So, I guess it is personal preference, but it doesn't make a whole lot of since(notice: I did not say it doesn't make ANY)to spend extra $$ on something that is heavier, and something I wouldn't really use or benefit from.
 

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The Prelude SH's ATTS is quite different from the Quaife differential as the ATTS is ONLY used during corning and not during straight line launches or braking like the Quaife.

During autocrossing events, the ATTS in Preludes, 4-wheel-steering in 240SX, and other such gadgets tend to fail because of the extreme usuage. My question is or will the TRAC in the IS300 have the same malfunctions?
 
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