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#1 2020-02-24 11:14:49

92X'r
Member
Registered: 2020-02-23
User Number: 46817
Posts: 2

Front & rear differentials

Hello, I recently purchased a 92x and have found out the diffs are somewhat subpar. I searched through the forum and have found a little info about our diffs although I have not come across anyone who has bothered to swap the popular TorSen equipped differentials. They are pricey, about $850 minimum is what I've found. I am curious as how badly an open rear end effects traction especially as you begin to add some power, this will be my daily driver for a while so I prioritize reliability first although I plan on a tune, tmic, CAI, DP, custom exhaust some suspension components and maybe a few other go fast bits.. with a decent amount of parts how much more noticable would the TorSen diffs be.
Edit* I was thinking also, if my diff is open and only one wheel is spinning with I have any torque steer?????

Last edited by 92X'r (2020-02-24 11:17:01)

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#2 2020-02-24 11:26:21

snowphun
Member
From: Central CT
Registered: 2005-11-09
User Number: 890
Posts: 598

Re: Front & rear differentials

Playing with diffs is a lot of trial and error and expense, I would recommend getting into some other cars to feel the differences and see if it's worth it to you. I never experience significant torque steer in a Subaru, nothing like a fwd car with some power. Opening the rear diff to replace the stock lsd (which is pretty feeble) is easy enough, the front diff is not a job most people can do at home. You'd be better off swapping in an STI drivetrain which gives you a better rear LSD, DCCD center and LSD front.

Normal street driving you'd be hard pressed to notice any of this.

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#3 2020-02-24 12:11:54

krazykarguy
Worst ninja editor, ever.
Supporter
From: South of North Carolina
Registered: 2007-04-06
User Number: 1944
Posts: 8642

Re: Front & rear differentials

If you are planning on upgrading the intercooler, I assume you have an Aero.

As such, the rear differential is a LSD. The center diff is either a viscous coupling locking diff (MT cars) or a computer controlled clutch-type (AT cars). In the 5MT cars, the center is open until the coupling heats up, and then power would be rerouted once it locks. The front differential is open on all stock 9-2xs.

Like snowphun noted above, there is no tangible benefit outside of full 90mph rally drifts on dirt where a front LSD would help, as it would make day-to-day steering less accurate. You want to be able to spin up just one front wheel in most driving situations to assist with steering - as the understeer this generates generally makes the car safer. With the AWD, extra power via the rear wheels can overcome the understeer and neutralize the car.

As soon as the front axle begins experiencing lots of slip, that power will be rerouted to the rear. I never considered the drivetrain in my Aero to be 'subpar' - quite the opposite. In the snow it was very easy to point even when in a 4-wheel drift (in snow, of course). You can literally feel the diffs working under the car at all times. 

https://forums.nasioc.com/forums/showth … p=15812529

^^^ This should help.

Last edited by krazykarguy (2020-02-24 12:15:56)


2005 Aero 5MT
2014 Ford Mustang GT Premium 6MT - Sterling Gray Metallic

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#4 2020-02-24 17:33:38

deliverator
Member
From: Centennial, CO
Registered: 2006-04-26
User Number: 1114
Posts: 786

Re: Front & rear differentials

Iirc, there used to be gc8 torsen (front?) diff that was fairly readily available for around $450 and a straightforward swap into our cars.

Diff setup itself is either no big deal or a black art depending on how you talk to. I've seen one dealer's outsourced shop screw it up badly (for an mx-5) and after that I had the replacement rebuilt by a diff pro.

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#5 2020-02-24 22:45:48

slowautoxr
Member
From: Decatur, AL
Registered: 2019-07-26
User Number: 46537
Posts: 26
Website

Re: Front & rear differentials

I used to RallyCross an earlier Subaru ('95) with JDM WRX engine.  It had open differentials. Even in the muddiest conditions it performed well.  However, before the engine expired, I was planning on upgrading the differentials.  The first one being the front.  The thought being that the front would be able to pull the car through the corners better.  However, if both front wheels are spinning, this can also lead to a pushing condition.

These cars do not have torque steer.

For street use, I cannot see it proving to be a tangible improvement.  Only if you're looking to change the handling characteristics during racing type events do I see it useful.


Charles
2005 Aero

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