Hi all,

Does anyone know how much torque either of these units is capable of trasferring to the rear wheels?

I found one source that said the stock Viscous Coupling Unit LSD in the '03-'04 could transfer a maximum of ~500ft# of torque to the rear. What I haven't found is just how much slippage and loss there is in transfer compared to a spooled/welded center diff.

I have found no source with information on the Cusco center LSD. I assume that due to its design, a clutch pak style LSD, that it should be able to trasfer more torque to the rear with less slippage and loss, but I can't find any information to support that assumption. . .

Here is how I propose to test this:Of course I don't have the money or the time to do this myself. It would be great to see a racing team try this test. Or maybe some, somewhere in the world has already done a similar test?? Let me know what you think.

EVOlutionary

 

Do you have a link to the Cusco center diff ?

 

i would like to know this as well

 

What I can tell you is that there is a Evo 8 MR in the Philipines that runs 9 sec and it has more than 700whp with a Cusco diff.

Look on the fastest registri 1/4 mile and you will find it.

Carlos

 

i always thought that the power split for the Viscous Coupling in the Evo was somewhere around 60/40. you sure Cusco make a center diff for the Evo. i didn't think they could because of how the Evo center diff is design. the Visicous Coupling is not in the diff itself.

 

i'm pretty sure all evo 8's and 9's are 50/50.

 

50/50 is only for ACD when locked. viscous coupling are like torque converts, they always have some slip. the slip is determine by how thick the fluid is in the coupling.

 

the Limited slip device in any dif does not control the torque split of the diff. all lancer evo center diffs are 50/50, including the acd diff.

A differential has a special property in that the torque from the engine is divided between the front and rear in a fixed ratio, regardless of the rotational speeds of the front vs the rear. So, this basically means that 50% of the torque the engine is creating in an evo is being sent to the front, and 50% is being sent to the rear NO MATTER WHAT.

lets say the car makes 200 ft-lbs of torque and has a center LSD. lets also say the front wheels are on ice, and the rear wheels are on pavement. what this is going to do is put far less load on the engine (for example, half the total load), so it will produce less torque(half the torque). thus, far less torque is put down to the ground, because now the diff is splitting 100 ft-lbs, and 50 ft-lbs are going to spining the front wheels on ice. so, your only getting 50 ft-lbs to the ground to move the car with. now, if it were an open diff, the front wheels would just spin, putting near zero load on the engine and thus it would make miniscule amounts of torque, thus the car wouldnt move or barely move. this is INCREDIBLY simplified, but thats how it works in essence. bottom line is a diff is split in a fixed ratio.

 

Edited: Ok, I read to far into this and just realized which differential you meant.

 

www.cusco.co.jp

That is about the only place I could find anything. Z1 Performance used to have them listed about a year ago, but not any more.

From what I understand, when you use a Cusco LSD, you get rid of the VCU. Stock the "LSD" is made up of the gears in the tranny and the VCU in the TCase. The Cusco, because it is a clutch pack style LSD has everything built in and will be housed in the tranny.

For the center diff, Cusco makes a 50:50 unit and also a 35:65 unit. I am interested in the 50:50 unit. . .

EVOlutionary

 

thanks for the clarification, that's what i thought.

 

Uhh, wrong. Do you even know what’s the purpose of a diff is. It allows the speed difference between left to right or front to rear depending on where the diff is being used. When vehicle is turning, all the wheels travel at a different speed. If a diff is always 50/50 split, then it’s useless and not really a diff, it’s a spool or a welded diff. in an open diff, if one wheel is on ice and the other on tarmac, the wheel on ice is going to spin at twice the normal speed and the car doesn’t move. That means that the wheel on ice is getting 100% of torque and the wheel on gravel is getting 0% torque (hence the car doesn’t move). With a LSD unit, it does not allow one wheel to get 100% of torque but it does allow a little speed different from side to side to allow a car to turn properly, this little speed difference is why you have a power split of 60/40 ect. In an Evo with viscous coupling, when you launch your car in the rain, the front wheels will always brake loose before the rear wheels, hence the front wheels get more torque. ACD have two states, in lock mode or open mode. In lock mode, torque is split 50/50 (like a spool or welded diff), in open mode more torque goes to the front wheels (don’t know how much more but Evo are designed to be front wheel bias. Subaru are rear drive bias, so rear wheels will brake loose first). The different settings on the ACD just tell the diff how long to stay lock when the car is turning. So when the ACD is in open mode, you’re not getting 50/50 split.

 

We're talking about the center diff that splits load between the front and rear .. not side to side. I think what most people are saying is that the center diff is always splitting torque 50/50 (front/rear) and then the LSDs in the front and rear are taking care of the rest.

So, how I'm understanding this ...

There is 100% torque available. 50% in the front and 50% in the rear. No matter how you split it between the left and right, the torque on either the front or rear will always be 50% of the total.

So the 4 corners would effectively be:

25 - 25 (F)
25 - 25 (R)

or possibly when cornering ...

35 - 15 (F)
30 - 20 (R)

or maybe this with ice on the left and tarmac on the right ...

10 - 40 (F)
05 - 45 (R)

Either way, you still get 50% when you do the math.

 

Just found this. Bozz performance has a little info. http://www.bozzperformance.com/cusco_lsd.htm

 

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

Apparently, Cusco's site was built with Adobe GoLive ... they didn't even change the page title. sorry ...