Torsen differential Q's

Is it correct that the 205's came factory with the torsen type rear differential? Or do they also come with a viscous unit like the 185?
 

CMS-GT4

Active member
Yes and no. RC/CS/GA came standard, some regular gtfour's also recieved them, but how to determine if an alltrac did is the hard part.
There is a number used to identify the gearbox, but it seems to only be related to CS models.
 
Okay, I figured not very many normal 185's would have got the torsen. The torsen and the VC have the same case design I'm assuming then?
 

CMS-GT4

Active member
92 All-Trac":3fr61mdv said:
Okay, I figured not very many normal 185's would have got the torsen. The torsen and the VC have the same case design I'm assuming then?

Externally they are both identical. Its almost like an insert that makes the difference. It would be open, not VC. There was only 1 diff. offered, and that was torsen. VC is in the center diff.
 

toayoztan

Moderator
There was a post on this a while back. I believe Gary actually had good figures on it. Was it mentioned that all (or most) 93's came with torsen?

Bryan
 

Rally Guy

New member
I have heard from several sources that all '93's came with a TORSEN rear dif. This is NOT confirmed by me - just rumour. I had the car up on the weekend and did the suggested tests...

The "spin one wheel and see if the other spins the same or opp direction" test revealed that the other wheel spun in the opposite direction. Suggesting either open or TORSEN. Inconclusive.

Then, with the car idling in gear and the hubs spinning - I tried to stop one rear hub - there was substantial resistance to this. I COULD do it - but it was fighting me something feirce.

Doing the same at the front (which we KNOW is an open dif in a stock config) yeilded VERY different results - I could easily stop the spinning hub with minimal effort. The other hub kept spinning happily.

This suggests to me that "something" special is happening in the rear dif. Hopefully a TORSEN!

Anecdotal, split-traction launches also sure suggest that it's an LSD.

Just my two cents.

RK
 
I think you have some good points. However my old powertrains teacher at UTI explained that if you spin a VC LSD the other wheel should spin the same direction, but if the clutch plates are wearing out it will spiin the opposite direction.

Wouldn't a torsen spin the same direction like a posi since it locks whenever ANY slippage is detected? It is purely mechanical and reacts to direct torque.

There's got to be some way to test them and find out which is different. When I spin one rear wheel the other spins the opposite direction. This would mean my clutch plates are wearing out, but my rear end definately transfers power 100% how it should. I can see the evidense when I launch.
 

coyoteboy

New member
This is one thats interested me - i have severe resistance on the rear spinning hub too, but mine is 99.9% certain an original '90 ATA diff.
Never spins only one rear wheel even on a beach.

Torsens, clutched, viscous all behave in odd ways and ive spent ages trying to find out how to work it out - id love to know.

J
 

st185-sainz

New member
AFAIK in Europe all ST185 have REAR Torsen. I have had some ST185 up to now and also opened the diffs cause I was interested in what I have and there was one everywhere!
The CS models have it for sure. They have the same diff than ST205.

Centre is everywhere Viscous. Every gearbox has the same lever to convert into FWD, open diff and viscous. (ST165/185/185CS/205)

The ST165 has got an open rear diff. The housing looks different to the Torsen one although the mounting is the same!
 

coyoteboy

New member
That might explain why - mine is a UK model. I'll have to take the back off and look some time but right now its not leaking and seems to be performing ok so I'll leave it lol :)
 

NA

New member
There has to be some sort of pattern.

you could start something like this up.

Model year Front Diff. Rear Diff.

Example:

ST165 1988 Open Open

if you dont know dont guess or you could mess up the results.
 

mototebok

New member
st185-sainz":3s6pun4x said:
The ST165 has got an open rear diff. The housing looks different to the Torsen one although the mounting is the same!


I was under the impression that the 165 had a torsen rear.
 

Rally Guy

New member
Man, the amount of differing information about these is comical. I can only add my anecdotal information...

My '88 ST165 sure seemed to have an OPEN rear dif - one of the reasons I sold it.

My '93 ST185 sure seems to have an LSD rear dif - one of the reasons I BOUGHT it.

Just adding a few data points. Does anyone know for SURE what years came with what?

In the Porsche world - there is an option code sticker you can check to see if your car has nifty things like an LSD (mine DOES NOT). Does the All Trac have ANY way of knowing what options came on a specific car??

RK
 

toayoztan

Moderator
NA":116dn6wq said:
There has to be some sort of pattern.

you could start something like this up.

Model year Front Diff. Rear Diff.

Example:

ST165 1988 Open Open

if you dont know dont guess or you could mess up the results.

I believe all the front diffs were open. It's the rear that is questionable (torsen or not). For the middle diff, i don't know if all came with VC or not.

Bryan
 

CMS-GT4

Active member
All front diffs are open. All center diffs are VCL, except for early 165's.

Rear is open on most. The only proven gt4s to have come standard with rear torsen are the 185RC/CS and the 205.

Some claim that there are some 185s that came with torsen, and some claim that only '93 model came w/ torsen standard.

On another note, there is a code on the door panel to determine the gearbox and rear diff. It seems the code only shows if you have a CS model gearbox w/ torsen or not.

The BGB lists 2 seperate diffs for the '92 year. Open, and torsen.
 

toayoztan

Moderator
Alright, i've got my spare rear diff from my 92 sitting in my garage. Sometime this weekend or so, i may as well open it up to see the mystery behind it. Does anyone have a picture of what i'm supposed to be looking at or for if i have a torsen or open? Thanks!

Bryan
 

CMS-GT4

Active member
Torsen looks like this.

It also comes apart with a different snap ring, I believe. I remeber the BGB telling a slightly different way to taking both apart.

67torsen.jpg
 
Top