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Differential FAQ: Consolidated and made relevant for Legacy owners


whitetiger

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Anyone know a rebuilder of Cusco LSDs ? I've searched in vain here and Google....no one seems to advertise that they know how to do it.

Nothing like a race track to find the weak points in man and machine.

"Good Judgement comes from Experience. Experience comes from Bad Judgement"

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Try Rallispec in Berlin NJ http://www.rallispec.com/

Great, thanks. I see they have "Plated LSD rebuilding & tuning" on their website. And a price list too. $250 for an LSD rebuild/tune is a lot cheaper than a new one.

 

 

Thanks!

Nothing like a race track to find the weak points in man and machine.

"Good Judgement comes from Experience. Experience comes from Bad Judgement"

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  • 1 month later...

Thanks all for this very informative thread.

 

Question for the Suretrac gurus...

 

I just put a GRB 6MT into my EDM GH8 WRX. To keep the cost and weight down I elected to stick with an R160 rear diff. Like all the later 6MTs the front diff is a helical unit and DCCD, and being late and EDM it has the 1.1:1 transfer gears. We pulled my stock rear diff out and were a little surprised to find it was an open unit when the spec sheet says EDM models have VLSD. Thinking it wouldn't be great for handling to have a helical diff up front and open in back, we started looking around for a good VLSD unit but came up blank. My friend however had a Suretrac unit laying around so we tossed that in (with appropriate 3.545 gears).

Anyway, I have a bit of a noise at low speed, more noticeable when slowing through about 20kph to almost stopped, on level ground. It sounds a bit like the whump-whump of helicopter blades. Applying even the lightest bit of throttle shuts it up. Going down steep ramps into parking lots it's also quiet. Just wondering if any of the Suretrac initiates had had issues like this. I will probably swap another diff in to try and isolate the sound.

Edited by fahr_side
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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It sounds like the engagement of the ring and pinion of that diff need to be checked. If it was put together wrong it could make noise and could be only during deceleration or acceleration or even just cruise when you hear it.
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Turned out to be a bad input bearing in the (older) diff housing we put the Suretrac into. I really like this diff. Much more effective than the VLSD and no side-effects as on mechanical units.
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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  • 2 months later...

every time it snows I start thinking about diffs.. and while not necessarily lgt specific I thought this might add to the conversation with lots of pictures: http://thefactoryfiveforum.com/showthread.php?13240-A-spotters-guide-to-Subaru-differentials

 

I am still not clear on what people are doing to "improve " on a r160 diff.. can you re shim it or can I try to find a spec -b rear diff (since they are like unicorns anyway I doubt I would find one) or spend big $ and get a ppg one?

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the rear VLSD R160 is weak becuase the spiders gear are weak and the VC unit in there cant transfer alot of tq and is only reactive, not tq sensing. You can keep the r160 case but upgrade the unit itself for more strenght and better traction, or go to the spec b/07+ STI R180 assuming you can maintain the right drive ratio. If you have a 4.11 drive ratio, you have to find the unicorn nissan 4.11 R180 ring and pinion to make that work.(i had one, but sold it) There are a bunch of r160 unit upgrades out there to do. Many companies like Cusco make Clutch type diffs. Quaife makes a Helical ATB diff which is nice as well. you can also try to find the JDM STI AP Suretrac for the r160 used(i did this as well) but they are hard to find.
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  • 2 months later...
  • 1 year later...
what rear differential is in an '11 3.6r sedan? I have an r160 cusco from my wrx but

can't find any information as to what's in the 3.6. Thanks!

 

r-160.

Nothing like a race track to find the weak points in man and machine.

"Good Judgement comes from Experience. Experience comes from Bad Judgement"

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  • 2 months later...
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Can someone tell me if you can put a front LSD for a STI gearbox (TY856) into a 6MT TY756 gearbox without modification? Is this what is meant below?

 

Thanks

 

 

So what should I upgrade my car with?

 

RS/WRX/Legacy front 5mt/6mt: Torsen/Helical or Clutch type. There is a JDM helical unit that fits the 5mt front. 6mt people can put in any front LSD available for the STI 6MT.

 

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I have been told by two sources that there is machining involved if you use an STI LSD in a TY756. Have you done any measurements?

 

A WRX LSD will work, but it is 2x the cost...:eek:

 

Still trying to sort out the nomenclature for all the different models.

 

Yes you can, any 6MT front differential will work; I have an AP SureTrac front LSD from a JDM spec C and plan on installing it the next time the drivetrain is out.
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I have been told by two sources that there is machining involved if you use an STI LSD in a TY756. Have you done any measurements?

 

I misread the first question. Pretty sure you're talking about the 5th gen+ 6MT, and the WRX 6MT. The spec B 6MT is a completely different animal, altogether. The STI front diff should work just fine in a spec B box, but not in the new TY756.

 

A WRX LSD will work, but it is 2x the cost...:eek:

 

Do you mean an aftermarket WRX LSD will work? Thought the WRX has an open front diff.

Edited by LatentWagen
LW's spec. B / YT / IG
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Do you mean an aftermarket WRX LSD will work? Thought the WRX has an open front diff.

 

Thanks Latent.

 

The LSD I was referring to is an aftermarket Subaru type:

http://www.rallispec.com/dif_gls_rst1903.html

 

From what I was told, this unit will fit my TY756: RST-1903 "Ver.5/6 STI Type RA and S201"

 

While the other unit, would require machining: RST-1913 "standard factory front LSD on all MY06 and newer STI models"

 

I am new to Subarus, hence the confusion!

:spin:

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The information you got sounds correct.

 

The newer 6MT, aka TY756, is basically the same old 5MT, but with an extra gear. It makes sense that the old 5MT front differential would drop in.

 

The older 6MT, the ones found in the STi and the spec B, are structurally different than the 5MT or the newer TY756 6MT.

LW's spec. B / YT / IG
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  • 2 years later...

Hello everyone. I broke my rear diff 05 lgt 5eat. Yes i track it and it is my daily. The tranny is built and so is the center diff along with valve body and hexmod goodies. So the next weakst li k finaly went. From what i understand is im stuck with the r160 but can upgrade the internals? Can someone please help me understand?

 

 

 

Ok so im being told my rear diff is a type ra gear with sun dials with a gear ratio of 2.63. Everything i find says its a r160?

Edited by stikiller
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yes, you have a R160 with 3.92 gears. you should be able to get a R180 and rear axles from a Spec.B which should also be 3/92 ratio, swap over the R160 drive shaft yolk on to the R180 and put the diff and axles right in. Done and done.
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