Torsen differential Q's

Corey

Active member
I'm messing around with the EPC.

Could you please PM me your frame build number if you dont mind? I'd like to see what part number comes up for your rear diff.

I've found the canadian market did get some LSD's based on the part numbers - which are different than the JDM market.
 

casey_2005

New member
Mine says 824/E56 :shrug:

Oh wait, I have an all-trac camry... :doh:

Anyways I read all ten pages last night and hopefully I can shed a little bit of light on the subject. Wouldn't the best place to look to see if the LSD was even offered on the all-tracs be the original dealership brochures?

http://www.toyotareference.com/

So that's what I did and came to the conclusion that no US spec all-trac was offered with one from the factory. Must have been something that was installed at the dealership, I guess. For instance take a look at one of the Supra, SW20 MR2, or Corolla GTS brochures and you will find under the "mechanical" section each says Limited-slip Differential and they are either standard (S) or optional (O) depending on the car.

Now look at the Celica all-trac brochures and there is no row titled "Limited-slip Differential". There is a row referencing the "All-wheel drive with variable torgue split" or "All-wheel drive with viscous center differential" but none for an LSD.

Again this brings me to the assumption that no US all-trac came with one from the factory, so unless a dealer installed one and marked the car in some way the only way to distinguish whether or not you have a LSD would be to open up the rear end and take a look...enjoy. :D

BTW, this is my first post here so hi everyone, looking forward to being part of the community.
 
alltracman78":3it4r0u6 said:
I thought I would add this here too, in case anyone missed my edit a few posts up.
I have previously stated the RC rear diff has a different ratio.
I was wrong. It is the same as the regular 185 ratio.

Southern Viking,
I just checked my 92. It came with a TORSEN rear diff. Codes are below.
737/E150F

I also had a 93 that did NOT come with TORSEN rear. Luckily I am moving my storage this week, so if someone would be so good as to bump this thread to remind me, I can check the door code on it [I still have the dr door].
Also, I have a wrecked 91. I don't know which is in it at the moment, but I can at least check the door sticker, assuming it's intact. :p

Resurrecting an old thread, but maybe timely. My son has (2) ST185's, and the door jamb nameplate on both says:
- A/TM: -737/E150F

This would be the same as Alltracman78, and he says he has TORSEN. Do we have any new information telling us that, by chance, both my son's ST185's (MY 1990) also have TORSEN rear differentials? Or is the only way to be sure is to open them up to see what's inside? I hate to do this now, as both had fresh oil changes and I'd rather not pull the drain plug, or worse yet, physically remove them from the cars.

My son did get an ST205 rear differential the other day, looks really good, and we inspected it and verified it is a TORSEN unit.

Also called Toyota service to see if they could shed some light on the axle code -737, and they tried hard by calling around, but ended up not finding what they expected to. Trucks have a wealth of information on axle code decoding, but evidently, the ST185's were not very well documented.

I do believe the 4-digit axle code ties to:

- 1st digit: ring gear diameter
- 2nd & 3rd digits: gear ratio
- 4th digit: number of pinions and if lsd or not

The first digit on our ST185's is a "-", which isn't helpful.

If anyone on this forum has become more enlightened on this subject and would like to respond to this old thread, would like to see what this particular axle code really means!
 

CMS-GT4

Active member
No correlation with US codes were found to show rear LSD installed. AFAIK no US alltrac has been reported as to having a torsen rear from the factory. All that were checked in the related threads were found to have been open. This includes 93 models which were rumored to be fully loaded. TRD did list a rear clutch pack for the alltracs, so it is more likely that if any have a rear lsd from the dealer, it would be the trd unit sold as an option. This would also have no codes to indicate this. Only way to know is how the rest of us checked. Look inside.
 
In my reply above, alltracman78, if I interpret his old post properly, had a 92 All-Trac with that axle code that he confirmed was TORSEN. Did he later recant that input?

Also, in the attached PDF file I got from a Toyota rep who contacted someone higher up in Toyota North America, came this 1990 publication indicating TORSEN was an option.

I do agree that there seems to be no absolute evidence that TORSEN was ever either not provided at all in North America, may be been offered as an option (which doesn't seem to show up on specification sheets, so how could they have been requested when placing orders), or being intermixed with open differentials by chance on North American builds (which I highly doubt given the significant cost difference at the time between a conventional open differential and a TORSEN differential).

Does anyone know in what way, in real driving situations, one would benefit from a TORSEN rear differential vs. a conventional open differential? Seems like many are getting used ST205 differentials to swap out on their ST185's to get a TORSEN - just wondering what is different in the driving experience between the two.

Also, a related question to your reply, if TRD did provide a dealer installed LSD unit, was it a clutch-pack LSD, not TORSEN?
 

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CMS-GT4

Active member
AFAIK, he is not the original owner, so there is no way to know if that was factory installed. For some reason I thought one of his 185s was also an import, but I may be thinking of someone else. Others with that code (including mine) don't have LSD. So he would be an outlier either way.

In the other thread I found simply you had to look inside of the diff. I drained the fluid in mine and looked inside with a light to find my 92 did not have a rear torsen. I now have a rear 205 diff.

The torsen is a good lsd for moderate hp. The 205 guys were reporting breaking them in the 400hp range, and on US autox'er broke his with less, but he was really pushing it.

A torsen is going to distribute power smoothly, but only under load. So if you lift a wheel in a corner, its open. Its going to do the most on corner exit than anywhere. I find it an improvement over the open diff, but I autox. For a regular street car, it may not make much difference for some.
The clutch pack is a better option I think, but more expensive.

EDIT: The TRD unit was a clutch pack. Also this same PN for the TRD diff was later carried by TRD for the rav4 as they are a direct replacement.
 

underscore

Well-known member
93celicaconv":3js1i7aj said:
Also, in the attached PDF file I got from a Toyota rep who contacted someone higher up in Toyota North America, came this 1990 publication indicating TORSEN was an option.

They may have generated that document but then later retracted the option for a torsen rear diff.

93celicaconv":3js1i7aj said:
I do agree that there seems to be no absolute evidence that TORSEN was ever either not provided at all in North America, may be been offered as an option (which doesn't seem to show up on specification sheets, so how could they have been requested when placing orders), or being intermixed with open differentials by chance on North American builds (which I highly doubt given the significant cost difference at the time between a conventional open differential and a TORSEN differential).

I'd say there's no evidence that it ever was offered as an option in North America. Was it even an option elsewhere in the world? I can't say I've ever heard of anyone having any proof of a factory-installed LSD in any non-RC/CS/GrpA 185. They may have considered it and that's why it pops up here and there and all these rumours exist, but I'd say that's about as far as it went.
 

MWP

New member
underscore":ll56c1ci said:
I'd say there's no evidence that it ever was offered as an option in North America. Was it even an option elsewhere in the world? I can't say I've ever heard of anyone having any proof of a factory-installed LSD in any non-RC/CS/GrpA 185. They may have considered it and that's why it pops up here and there and all these rumours exist, but I'd say that's about as far as it went.

Every single ST185 delivered to Australia (both normal and GrpA) had a torsen rear diff. It was "standard equipment" here.
 
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