V8 Torsen on rear

[Graham]

Any joy yet with the rear diff project, this is really interesting and as my diff has a slight hum, and if its possible to cheaply do an LSD conversion without buying mega expensive custom jobbies, i might do that in Oz.
Graham

[The Spanish]

I think they are working on it this week. Hope to have updates by the end of the week, but don't worry, soon enough it will be finished.

Cheers

[elijahallens2]

After this weekends track event I now know I need this mod. Traction is a big problem in these cars. I never really had this problem in the S4 but I guess weight probably held the weels to the ground a little better. Can't wait to hear how this works for you.

Elijah

[alg]

I will now sound like an idiot. But why would you want to do this ?

[The Spanish]

Ok, let me explain.

You are exiting a bend on full throttle.

The center torsen will distribute torque front and back. As you are accelerating you have 60/40 to the back for example. Front and back diffs are standard open diffs, so they will send more torque through the easyiest path, in this case the two inside wheels as they have less weight on them, so less suppose 70/30 to the inside wheels.
In this case you could have out of the 100% of the Torque available:
Inside Front: 28%
Outside Front: 12%
Inside Rear: 42%
Outside Rear: 18%

So the inside rear could start spinning, because of the nature of open diffs, if this was to happen, all available torque at the rear would go through the spinning wheel so no use of the back axel. Of course the center Torsen would divert power to the front, so the next weekest link would be the inside front and could spin, so all available torque at the front would go to the spinning whell ending in both inside wheels spinning, producing major understeering.

Now if you fit a Torsen to the back, the back diff will send more power to the wheel with more traction, in the case above Outside rear would have around 50% of available torque wich is great because is the wheel with more weight on it, because of corner and acceleration, helping the exit of the corner and even maybe providing some power oversteering.

Hope I explained well

[S2central.net]

Thats about right - we could argue numbers all day long - but I think you have explained it well.

[maRS2]

I found a V8 rear Diff torsen from 1991 and a spare rs2 diff.
So will follow you on my RS2
Spanish your my master
regrads,
<fabien

[The Spanish]

Your are more lucky, same crown and pinion on the RS2 and V8 so you could transplant also crown and pinion from v8 to RS2 as it is used to work with that one.

Everything else should be the same.

[alg]

Ok I now understand the theory. Has anyone show this is the way to go in practice ?

[Fat Audi 80]

I will now sound like an idiot. But why would you want to do this ?

Christ and there was me thinking I had missed something! I was going to ask the same question and was plucking up the courage!!!

I think basically the thread title is misleading ( I understand the language barrier so I understand why ).

We are talking about rebuilding the rear diff of an S2 with V8 internals to make it an LSD...

I think I will give this one a miss.

Cheers,

Steve.

[The Spanish]

Ok I now understand the theory. Has anyone show this is the way to go in practice ?

Well Mitsubishi with the EVO, most good Impreza's (Spec C, P1)

All rally cars, Porsche Turbo, Nissan Skyline ah! and all competition rear wheel drive cars, so I think is kind of important

[maRS2]

Ok I now understand the theory. Has anyone show this is the way to go in practice ?

All the rally team even the smallest and the mitsubishi evo and subaru wrx production car show this in practise
since year's.
The audi quattro system is a very poor 4 wheel drive sytem only one LSD (in fact a torsen) good for highway use(german style) but not optimum for rally style specialy in the mountain on those 180° turn where you loose all the power on the inside wheels spining like hell

[S2central.net]

Yep just about every race/rally car in existence has a limited slip differential (LSD) on the driving wheels.

In my days of Group N rallying, where an LSD was illegal unless factory homologated, it was a well known 'secret' modification that made an otherwise standard car very much quicker round the corners. We could never afford such an item at the time, plus some of the wiser RAC-MSA inspectors would occasionally do a quick but clever test of the differential at scrutineering which used to nobble some of the cheaters.

The basis of the test was both driven wheels in the air (engine off, car in gear) then they would turn one wheel clockwise. On an open differential, the other wheel of course turns the opposite direction... an LSD however would allow the other wheel to rotate in the same direction. Confused me at the time, but I understand it now !


Paul

[Henka]

Your are more lucky, same crown and pinion on the RS2 and V8 so you could transplant also crown and pinion from v8 to RS2 as it is used to work with that one.

Everything else should be the same.

Remember that transplanting the V8 ring and pinion WILL mean extensive work dialing it all in. When just switching the diff you just set the correct backlash.

[alg]

Thanks I was just curious. Now what we need is a consistent source other than old V8 rear diffs !