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Old 09-13-2016, 01:40 PM   #151
Crazyced
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Quote:
Originally Posted by mrsaturn7085 View Post
Depends on fluid, pre-load on the disc/plate stack, etc.
I'd say stock STI specs.

Quote:
Originally Posted by mrsaturn7085 View Post
If you remove the c. diff. you can measure mechanical initial torque using (custom-made) splined shafts that you can attach to torque wrenches. Since you are asking about the LOCK situation - you'd also need to energize the electromagnet. You can see how quickly this all becomes really fun to do...
I believe I've read someone post about them doing this as the only proper way to test viscous LSDs.
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Old 09-13-2016, 06:56 PM   #152
mrsaturn7085
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Quote:
Originally Posted by Crazyced View Post
I'd say stock STI specs.
I believe this is unpublished but following a rebuild, this could be tested. Viscous diffs are a little easier as the spec is well-known.

Torque transfer rate of the STI upgraded center viscous is 20kgf-m/100rpm and the OEM viscous that Subaru installed in... pretty much everything is 4kgf-m/100rpm.
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Old 06-05-2018, 05:04 PM   #153
BrandonDrums
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I've read this whole thread, done some research and realized there are some misnomers about Helical and Torsen. Yes, updating a thread from 2006 now in 2018...

So, TORSEN and Helical do behave very similarly as long as both tires are on the ground and experiencing SOME traction. Once one wheel is lifted off the ground entirely there are big differences.

I've read all the way through and people tend to miss that key point:

TORSEN diffs vector torque either direction variably depending on slip and lock up completely when one wheel is in the air. This means Torsen's are great for good steering response, maintaining maximum traction in all conditions but are less good for when you want the system to lock up with both wheels on the ground. Won't happen, torque split will always be variable until you've got one or both tires in the air.

Helical diffs vector torque either direction variably depending on slip but completely lose anti-slip capability with one wheel in the air without help from a clutch-pack. With a Clutch-pack, the variabile torque distribution starts to be lost and advantages diminish vs. traditional Viscous or Clutch LSD's where the whole axle starts to try to lock up whenever slip occurs.

The end.
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Old 07-05-2018, 01:51 PM   #154
mihael
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I was wondering if anybody knows if the 6MT Torsen diff would fit into a 5MT gearbox. Because there are plenty of 6MT used ones for sale but I can find none from a 5MT.
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Old 07-05-2018, 02:51 PM   #155
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Don't know for sure but I severely doubt it - especially given the speedometer gear and such.

That said... the ring gear bolts on the 5MT differentials are different but still work fine on 6MT front diffs. They actually have the advantage of being tall enough to install lock-wire, should you feel the need.

Quote:
Originally Posted by BrandonDrums View Post
I've read this whole thread, done some research and realized there are some misnomers about Helical and Torsen. Yes, updating a thread from 2006 now in 2018...

...

The end.
Frankly, this explanation is lacking, but not totally inaccurate.

Helical = extremely broad category of differential... key features include rack and pinion gears rather than plates (or pawls), non-open behavior, and passive control only. If you've got a planetary gear-set rather than a ~90 deg. rack and pinion... well that may or may not be called a helical, depending on who you ask.

Torsen is a brand name for a helical gear type limited slip diff produced by JTEKT corporation (company name has changed in the past). Even this statement is difficult to say 100% accurately, as JTEKT calls just about all their differentials 'Torsen'... though some of them branch into planetary gear designs and behave entirely different from one another.

Not all helicals behave the way Brandon mentioned, and not all Torsens behave the way he mentioned, either. In the same sense - not all helicals are Torsen, and not all Torsens are helical.

Since 2007, the STI uses a Torsen T-2 type LSD in the R180.

The front helical LSD (5MT/6MT) resembles GKN differentials and therefore would not be called a Torsen (unless JTEKT manufactured it and essentially copied GKN designs).

STI competition parts (plated front diffs. and rear rebuild kits) were made by GKN (presumably) until somewhere in 2008-2010 where STI changed suppliers to Cusco given the performance and tune-ability (there was an FIA addendum for this change-over but I don't have it in front of me for the exact date). Unfortunately, the supply chain for spares/rebuild kits suffered and these must be sourced directly from Cusco now (which is actually probably easier than getting the old STI competition stuff in the USA).

Reliance on GKN makes sense as the competition hollow driveshafts STI sold for rally were definitely made by GKN (they say so right on the box). They also run about $6-8k for a set of 4...

Last edited by mrsaturn7085; 07-05-2018 at 03:46 PM.
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Old 07-05-2018, 06:00 PM   #156
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Thank you very mich for your answer! I am looking everywhere for this information. I know of someone who put a OEM 6MT helical into a diesel Legacy 5MT. But I don't know if that works for a WRX (petrol) 5MT. I wrote to Quaife UK who manufacters a helical for Subaru front to ask them if that is for 5MT or 6MT and they said they that they don't have it listed for either one (!) and I should open my transmission and check if my dimmensions are the same with their diagram...
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Old 09-06-2018, 02:48 PM   #157
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I would like to add that since buying a 6MT with a suretrac front, I have done research on how it worked exactly other then 'some magic happens'.

Here's the document that put it all together for me:
http://www.lezo.hu/szerkezettan/hajt...fferencial.pdf

For anyone else that would like to understand how their suretrac LSD works.
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Old 11-28-2018, 03:39 PM   #158
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best options for a front LSD for a 04 wrx that drives on a lot of snow and ice half the year. If i get a clutch type front, will the rear vlsd need upgrading or have negative effects?
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Old 02-02-2019, 09:58 AM   #159
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Quote:
Originally Posted by mihael View Post
I was wondering if anybody knows if the 6MT Torsen diff would fit into a 5MT gearbox. Because there are plenty of 6MT used ones for sale but I can find none from a 5MT.
ADS makes a viscous center diff. Might be of interest to you. I think Flatirons sells it.
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Old 02-02-2019, 10:22 AM   #160
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Default Who here can tune clutch style racing diffs? Where to go?

I have OS Giken diffs. Over the course of weeks I have tried to find resources for educating myself in how to tune diffs. I've not found any books, articles or videos on the subject. How to learn and test?
Even if I could, where do I buy parts? One authorized service center for my OS Giken's said they would not sell me parts. OS Giken, CA wants me to send mine to California... That's shipping a heavy diff 2,500 miles each way and the time involved.
I've yet to find an authorized service center in New England or the East coast.
Any recommendations? Has anyone tuned their own diffs?
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Old 02-02-2019, 11:44 AM   #161
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Quote:
Originally Posted by Scargod View Post
I have OS Giken diffs. Over the course of weeks I have tried to find resources for educating myself in how to tune diffs. I've not found any books, articles or videos on the subject. How to learn and test?
Even if I could, where do I buy parts? One authorized service center for my OS Giken's said they would not sell me parts. OS Giken, CA wants me to send mine to California... That's shipping a heavy diff 2,500 miles each way and the time involved.
I've yet to find an authorized service center in New England or the East coast.
Any recommendations? Has anyone tuned their own diffs?
I dont know about authorized but places like Vermont Rally should be able to do it, or atleast recommend someone to you. They build the Subaru America rally cars.
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Old 02-02-2019, 01:53 PM   #162
jamal
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Cusco's lsd guide has some information about how spring pressure, plate configuration, and wedge angles and stuff change the characteristics of how their diffs work. Might be relevant?

If this google drive link doesn't work I can host it elsewhere:

https://drive.google.com/file/d/0B51...ew?usp=sharing
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Old 02-02-2019, 02:59 PM   #163
Scargod
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Thanks guys! I actually have a call into Lance @ Vermont Racecars right now.
And, that Cusco guide is very helpful!
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Old 02-15-2019, 10:49 AM   #164
jbama03wrx
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Default Center Diff 03

Is it true the new produced diff has an improved ring that will not come off and end up ruining the tail shaft gears?>
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