Oem torsen LSD test (Need volunteers)

eddie_gt4

New member
Cody Mamak":2jiby0ka said:
(...)Do I have a open or a TorSen??
:shrug:

yes, you have a Torsen and a stronger gearbox (that was used in ST185 CS too :D )

p.s. Conan, another one pre-02-1992 EDM ST185 that was equiped with a E151F gearbox :twisted:
 

coyoteboy

New member
I'm a 150F 767, UK original car, and I believe all UK cars came with LSD and CS box? Although it now has a 205 box in it.
 

lumbercis

Moderator
I don't think any USDM cars got a Torsen "on purpose" else the BGB would list information about them as it does for the open diffs. There may be a few cars that ended up with them by chance. Maybe they were originally destined for a different market, then a few orders from the U.S. came in, or maybe they ran out of open diffs, had a few extra torsens laying around, etc. Or maybe just a simple mistake since the exterior casings are pretty much identical. In any case, if you have a USDM car, I wouldn't get your hopes up about having a torsen, in all likelihood, the few that have them are flukes.

J.
 

CMS-GT4

Active member
It was a dealer option. So, I think they were open standard, and its random if the new owner opted for the lsd or not.
 

coyoteboy

New member
I dont remember seeing it as a "dealer" option, but bear in mind that Toyota have been capable for many years of ordering a "custom spec" vehicle from the factory based on your order in the dealer - which is what happens today with many manufacturers.

Many toyota 4x4s came with option packs too, but all have their vin plate "axle" specification correct for the type of diff spec'd?
 

SowndWave

New member
I am currently doing my whole rear suspension, diff, and subframe bushings. So i'll take a peek in through the plug holes and test out the diff on the bench. I have a feeling its an open diff unfortunately...

Though I really wish it was torsen...
 

SowndWave

New member
Time for some enligtenment.

First, If you do not know and understand fully how an open aka conventional diff works. Go here and learn it: http://auto.howstuffworks.com/differential2.htm

I tend to go into too much detail, so if you have A.D.D. you might want to skip ahead to the summary at the bottom.

Torsen AND Open Diff's:
--Spin both rear wheels in opposite directions with the input shaft(pinion) stationary.
--If you try "test 2" and have the pinion spinning (jack up off the ground all four wheels and let idle in first gear), hold one wheel still, the other spins double speed of the pinion.
--If you resist the 2X spinning wheel, the stationary wheel you are holding will begin to have torque transfered to it and will start moving.


Now, the difference is indistinguishable. They both perform the EXACT same way in standard operating conditions. The difference lies in this; Open diff's supply torque to the wheel with the least traction, whereas Torsen diff's transfer torque over to the wheel with the most traction. However there is an exception, if on the Torsen set up a wheel has 0 traction, it is rendered useless and becomes a completely open diff unable to transer torque to the wheel with traction.

Test #2 tells you, you have a differential, it doesnt help with determining Torsen or Open. While doing the test, what WOULD indicate this however would be if you could actually measure the torque on each rear wheel at any given time and compare them side to side where you would see the torque split occur and which wheel it goes to.

Open diff's transfer the torque evenly, always. Straight line on perfect dry pavement each side of the rear wheels has 25% of the total engine torque, remember we are AWD and 25% to each wheel = 100% at the engine. If one wheel is on dry pavement, the other on wet the coefficient of friction is different. Now the wet wheel might spin a bit here and there, leaving the diff with 10% torque on the DRY wheel, and the remaining 40% on the wet wheel, because open diffs transmit power to the wheel with least traction.

Torsen diff's transer the torque depending on its gear ratio torque bias. Once again straight line with perfect traction both rear wheels have 25% traction. If we have the same scenario with one wheel dry, one wheel wet, and the wet one having a small ammount of wheel spin, the torque to each wheel changes. Torsen transfers the torque away from the wet, spinning wheel to the dry, grippy wheel depending on its torque bias. If it was a 5:1 torque bias, the dry wheel now gains 40% torque, and the wet spinning wheel gets 10% of the torque.


NOW, if thats explained properly (god I hope so and I hope you all gain something from that and I didnt totally waste my time) then I will summarize my results:

SUMMARY
--Test # 2 gives you no indication whatsoever of what diff you have.
--Pulling the drain plug on the bottom of the diff and shining a pen light up inside and being able to see the worm gear/wheel sets gives you an indisbutable result.
--Without being able to test the torque acting on each wheel, visual inspection is the best way to determine if you have a Torsen or not.


That said, I found out I do have a Torsen, and I'm quite happy with that. Questions? Comments? Concerns? Complaints?
 

Gary ST165

New member
fact: my friends jdm feb 1991 st185 narrow body does not have a rear LSD. It has been inspected with a boroscope.

 

RedCelicaTRD

Moderator
If I remember right the stub portion that you can see will look the same. They are different where they enter the diff carrier itself, so you can't see it.
 

CMS-GT4

Active member
You would have to pull the stubs as said below. There might be a slight difference right at the base of the housing on the shafts but I can not remember and I no longer have my old open dif.
 

timmey

New member
Dammit!

I have a E150F - 734 tranny in my 1991 GT-Four A. :shrug:

I noticed that no one else has listed 734, any idea what that one is? Plain-old LSD :(?

From what SoundWave is saying the test is inconclusive, and my diff was just filled with Royal Purple and I don't want to drain and fill it again just to visually inspect. If I have to wait then I'll wait, but shouldn't it be as easy as looking up the tranny code, or did they do Torsen and non-torsen using the same tranny codes? Like is there a list that Toyota has that can tell you?

Cheers,

Timmey
 

timmey

New member
It turns out 734 is the JDM "Pre-facelift" tranny code seeing mine is a Pre-facelift, and I found this post. There is basically nothing else on the forum regarding that tranny code other than this post below and in Gary ST165's pic of his buddy's 91 engine tag:

eddie_gt4":3po2rbfe said:
SouthernViking, I guess that "E150F-734" is a tranny & diff code of some (all?) "pre-facelifted" JDM ST185's :oops:
but whether 734 = viscous LSC or Torsen, I don't know :shrug:

btw, other sources on i-net also mention such code...
jus go google with a "E150F-734"

Gary ST165":3po2rbfe said:
fact: my friends jdm feb 1991 st185 narrow body does not have a rear LSD. It has been inspected with a boroscope.


Gary ST185: Your buddy's 91 narrowbody...is it open or torsen? I thought both are considered LSDs.

Timmey
 

Razzo

New member
my 1990 narrow body jdm gt-four is open diff. Most gt-fours came with open diff, except a few rc models and 93+. i have a tranny code of e150
 
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