Quaife for the 01E transmission?

[maRS2]

For the rear we can may be try to fit one Cusco limited slip
like here:

http://www.cusco.co.jp/english/e_cont.html

[maRS2]

Some better explanation:

What is the purpose of a limited slip differential (LSD)?
Differentials are used to split torque from the engine across two axles while still allowing them to rotate independent of one another. Open differentials, however, can only provide as much torque as the wheel with the least amount of traction will allow. Limited slips are used to improve traction under various conditions. This can be either under acceleration or deceleration depending on the limited slip characteristics. Basically the limited slip works by transferring torque from one axle to the other (sometimes effectively locking the two axles together). The Subaru's AWD system uses 3 differentials (front, center, and rear) to distribute torque to all 4 wheels.


What effect will this LSD have on my car?
This rear LSD will allow the driver to put significant power to the ground and accelerate quickly. Weight transfer will naturally provide less traction for the front wheels than the rears but on slippery surfaces or with large power outputs rear traction can still be a problem. For rally use a 2-way type rear LSD is a necessity for optimum grip on gravel while helping to improve stability under braking by working to prevent rear wheel lockup.


How does this Cusco LSD work?
The Cusco RS type LSD is a plated style LSD. This uses a series of friction plates which engage to transfer torque as necessary. These clutch packs are applied by a set of pressure rings which are forced apart by the pinion cross shaft when acceleration or deceleration torque is applied to the diff (1-way types have no LSD action under decel). The greater the torque the greater the clamping force on the friction plates. Because half of the friction plates are splined to the differential case this slows the slipping wheel and transfers torque across the diff. case to the other wheel. In some circumstances their may be enough clutch plate friction to effectively lock the two axles together under high torque situations.


What does it mean when a LSD is described as 1-way, 2-way, etc.?
This describes the LSD action under deceleleration. 1-way types have no LSD action under decel while 2-way types have equal LSD action under both acceleration and deceleration. 1.5-way types have reduced LSD action under deceleration compared to acceleration. These features are achieved by changing the ramp angles on the pressure rings.


How is it that the Cusco LSD can be configured in two different ways?
The pressure rings on the Cusco LSDs have two sets of cams (or ramps). For example the Cusco rear LSDs we offer can be changed from a 1.5-way to a 2-way type simply by assembling the LSD with the pinion shaft on the 2-way cam.


What advantages does the Cusco type RS LSD have over other brands of plated LSDs?
The type RS LSD uses light coil springs between the pressure rings instead of conical springs on the end of the clutch packs. This provides an advantage for most applications by generating less initial torque. Reduced initial torque translates into smoother operation, less clutch wear, and excellent reaction to delicate throttle work. These LSD's also feature radial oil grooves on the clutch discs and a "oil through system" of oil circulation for maximum durability and efficiency. The case and internal components are forged from high strength chromoly steel. These units will handle considerable power with ease.


Does this LSD require special oil?
This type of LSD works best when used with gear oils containing friction modifiers. We offer Motul PA gear oil for racing and high performance applications (rear differential use only!).


Are these units rebuildable and are there any features that can be "tuned"?
Rebuild components are available from Cusco and we can provide them on a special order basis. The characteristics of the LSD can be tuned through several methods. First, the lockup percentage can be altered by changing the order of the friction plates. 100% locking is recommended for rally applications while 30 or 60% locking is recommended for street or autox applications. Second, pressure rings with alternate ramp angles are offered for some applications. And lastly the initial torque can be adjusted though the use of clutch discs of various thicknesses available in the rebuild kit.

[puppetman]

I emailed billzcat about fitting the center torsen diff in the rear. he told me that it would work. I still have the emails.

[maRS2]

some other intresting reading
1. The DCCD is actually composed of 3 different "components". The differential action is by way of a planetary gearset which has a 65% rear torque bias built in. The driver controlled portion is a result of an electronic clutch which is pulse-width modulated to provide partial or full lockup depending on the position of the rocker switch or the DCCD's automatic programming. This electronic clutch is attached to one part of the planetary gear in order to change the torque bias frontward or to fully lock up planetary gearset. I believe there is also a viscous portion to the differential which provides LSD action when one axle experiences wheelslip under unlocked or partially locked condition.

2. The standard center viscous diff. is a 4kgf unit. This rating is an indication of the viscous resistance force when there is a 100rpm difference in axle speeds. Heavy duty STi competition units are built with more plates and different oil to air ratios to provide more viscous action. Early (pre-1999) units were available in 12kgf and 20kgf ratings while later units are available only in the 20kgf rating. I believe the Subaru viscous center diffs are designed with hump phenomenon. The hump phenomenon occurrs when the viscous oil heats dramatically and expands to the point where the pressure inside the diff. causes the viscous plates to actually contact each other and lock solid. This attempts to prevent overheating of the viscous oil during high wheel slip conditions.

3. The rear viscous LSD used on the Subaru WRX and some RS and Legacy models is very small. Disassemble a differential with one in it and you will be hardpressed to even notice it. There are probably only a couple of plates inside of it.

4. Kaaz and Cusco LSD units are clutch types (sometimes referred to as Salisbury type LSDs...I think). Clutch type LSDs are often available in different configurations....known as 1-way, 2-way, or something in between (usually 1.5way). Basically this refers to the type of ramps used to force the clutch plates together under speed differentials. 1-way types have ramps that will only lock the differential under power. 2-way types have ramps that lock the diff. both on power and on decel. 1.5-way types provide 50% LSD action on decel. Generally 1-way types are best used in the front of an AWD car on tarmac and 1-way or 1.5-way for the rear. On gravel 2-way rear LSD is best for traction and 1.5-way can often be used acceptably in the front. Having LSD action occurring in the front during corner entry particularly on grippy surfaces, is going to cause significant understeer.

5. Quaife units have several disadvantages. One is that they are incapable of fully locking up like a clutch type. Which leads to disadvantage two in that they won't function if there is no torque going to one wheel (as in the case of the inside wheel lifting completely off the ground or on ice). On vehicles that routinely lift the inside wheel I have heard that they can sometimes self destruct when due to the sudden speed changes inside the diff. Not sure if that is true or not.

6. The Suretrack uses a funky arrangement of cams and ramps to provide LSD action. Like the Quaife units they are not too intrusive or noisy but I do believe they also have similar disadvantages as well. I have the Subaru new product tech info at home on it and will have to go re-read it. I had a hard time understanding exactly how it worked on first read.

One other thing....

Most clutch type LSD's can be "tuned" to provide different characteristics. By tightening up the clutch packs or increasing the preload on the pack its possible to speed up the locking action and make it more or less progressive. Also, changing the ramp angles can also allow the LSD to "spin up" faster.

The Kaaz units generally come with a good bit of preload so they are very noticeably and noisy as the LSD stick-slips under cornering. It can be very annoying on the street for daily driving. The use of special gear oils with slip modifiers along with careful break-in is important to minimize this as much as possible. On the other hand the STi factory clutch type rear LSDs are set up with minimal preload and lock up as progressively as possible. This makes it fairly transparent most of the time but at the same time slower to come on when wheel slip occurrs.

[maRS2]

May be one of those can be fit or modify to fit the rear of S2/RS2

[maRS2]

If you look on the quaif web site the one who fits to the S4 2.7T fit the 02J trans
And Kaaz make one 1.5 way LSD for 02L trans so it should fit the S4 2.7T and may be the S2/RS2 rear diff

[maRS2]

May be one of those can be fit or modify to fit the rear of S2/RS2

[maRS2]

The price for the Kaaz for 1.5 way Lsd for 02J trans is 880$ so about 600€

[Billman]

What kind of diff's are the stock S2 diffs?

Greetings

[Lee]

Quaife will modify the ATB differential to suit our cars. Pick up the phone and talk to them...this is their speciality, more than supplying standard bits. They may even give you one for small money if they percieve there is a market for them. I would fit 3 ATBs to my car if they were developed. Likely only a slight change to a few components anyway to make them fit so Quaife are probably up for this. If I had some standard S2 diffs lying around I would jump in the car and go to see them straight away!

[Lee]

ATBs are superior to a fixed ratio LSD and are very clever pieces of mechanical engineering.

[S2central.net]

Lee - Can you post a quick write up on this subject - tailored to the S2 application. Differentials have always hurt my head - especially the LSD variety. Things of sheer mechanical genius they are...

Love your idea of talking to Quaife with sample parts to play with... Maybe there are one or two spare gearboxes & diffs that can make their way to you via the garage meet ?


Paul

[maRS2]

Lee go to the Scooby and Evo forum and you will see that for the rear the fixe 1.5 way ratio with front ATB(quaif torsen or suretrac) gives much better handling.
Why would all the guy's change theire original scooby STI suretrac (same as Torsen or quaif) to a mechanical 1.5 way on the rear.
Those have many option to play on the after market LSD and they know and tested much more that we will ever. a 4 wheel drive is the same wether it's a Sub, audi, Mitsu or what ever.
Read all what i posted and you will shurely understand the intrest of the mechanical 1.5 way at rear that is locking at 50% on lift off throttle.
ATB are not locking when off the throttle.

[AnLe]

Quaife will modify the ATB differential to suit our cars. Pick up the phone and talk to them...this is their speciality, more than supplying standard bits. They may even give you one for small money if they percieve there is a market for them. I would fit 3 ATBs to my car if they were developed. Likely only a slight change to a few components anyway to make them fit so Quaife are probably up for this. If I had some standard S2 diffs lying around I would jump in the car and go to see them straight away!

Front diff is easy, just change to 01e gearbox, I dont think there is no need
to make crappy 012 s2 5 speed tranny any upgrades, waste of money

To get three lsd is just matter of the fact that somebody has to do it, but I have no resource to buy atb just see if it fits.

[Lee]

If I had some spare bits I would be straight to them to get some made.

Writeup on a Quaife ATB? Took me ages to get my head around it myself when I first saw a writeup on it years ago! I picked up their catalogue at Autosport International last week but didn't talk to anyone this time around although I have spoken to them some time ago about it. IIRC they have a good description there but most might not understand it. At what level of understanding would you need a writeup? It is easier for me to describe the ATB to an engineer than to a postman! It would be easy to summarise its function and benefits but another thing to describe how it does it internally. Animations help but they can confuse too.

Best way to understand a basic differential operating is to get a Lego Technics one! Lego rocks. If I can dig some out of the attic I will bring it to the garage meet and explain it to you. Once that is understood and the nomenclature in the audiences head describing the others types of LSD and ATB/Torsen gets a bit easier. Actually, never seen the inside of a Torsen but the name (TORque SENsing) suggests it is a type of ATB. Got any pictures on one inside so I can see how their solution differs from Quaife to get the same kind of function?