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So I just picked up one of these....Subaru Front LSD


whitetiger

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I've been trying to find a good USDM STI Front LSD, but it seems that most people are just selling the entire transmission, and not parting out the front LSD. For those that have done the swap, are you buying the LSD new? If so, are you sourcing these from the dealer, or some other source?
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I've been trying to find a good USDM STI Front LSD, but it seems that most people are just selling the entire transmission, and not parting out the front LSD. For those that have done the swap, are you buying the LSD new? If so, are you sourcing these from the dealer, or some other source?

 

 

THE ONLY front LSD that people report NO/ZERO/ problems with is the factory helical front LSD currently sold only by Rallispec. It would be nice to get it on Fred Beans Parts and what not. YES I have that one, and it transforms the car. Whitetiger, FPerron also have it also like it very much. FPerron has a unique story in that he tried one other brand, M-Factory (i believe) and it was a pain in every body place.

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I have the MFactory helical unit. Only thing that needs to be done to make sure the axles stay in is to shave/cut a 2-3mm off each axle and it'll fit. After that the unit fit/works great and does what it needs to do. But for those squirmish on doing that, then go with the unit that Rallispec sells. Either way you'll be satisfied.

 

I believe FPerron had the Quaife unit which came with its own axles that just simply didn't fit and had a major debacle until he decided to return it and get the rallispec unit.

 

Anyways... front LSD rulez!

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The helical unit offered by Rallispec is only for a 5MT, however. For us 6MT folks, what is the comparable unit to purchase?

 

THE ONLY front LSD that people report NO/ZERO/ problems with is the factory helical front LSD currently sold only by Rallispec. It would be nice to get it on Fred Beans Parts and what not. YES I have that one, and it transforms the car. Whitetiger, FPerron also have it also like it very much. FPerron has a unique story in that he tried one other brand, M-Factory (i believe) and it was a pain in every body place.
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Damn. I've been following this thread and thinking this LSD is something I'd kind of like to do some day in the not-too-distant future, when I eventually need to get my clutch replaced.

 

Unfortunately, that future is not so distant: my clutch started acting up today, and I don't have the fundage to do this as well. :mad:

Seek first to understand, then to be understood.

 

In other words: SEARCH before you post!

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So far I have had good luck with an OBX helical front LSD in my '05 LGT 5 speed that I swapped into my GC WRX swap racecar.

I have a full season of autocross, rallycross, and wintercross(hybrid track day with chicanes to keep speeds below 120mph).

I am putting down about 330whp.

I had to use '02 wrx cv axles and axle seals assemblies.

 

It it a noisy little bugger but it transformed my car a inside wheel peeler to a point and shoot gravel throwing beast!

[ame=http://www.youtube.com/watch?v=l1hTI0P4fzk&feature=youtube_gdata]YouTube- sebaru, Swapped Imrepza '06 WRX[/ame]

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  • 2 weeks later...

Btw, I found some exploded assemblies of the 05 LGT axles and the 08+ WRX axles. Attaching pictures for comparison. My axle seals are starting to leak a little bit, so I am thinking about replacing them when I do a clutch and hopefully front LSD. I'd like to try running a Quaife unit if it will work properly, even if I have to run axles from a different car. I would assume the shorter inboard side of the WRX axle would properly fit in the aftermarket LSD. Will do more research before I decide to risk it. :lol: Maybe I'll just go with the JDM STI unit otherwise

 

WRX is the first one, LGT second

1012708819_2008wrxaxleassembly.png.1f98485f3de67e53a5f13de2e71f77c9.png

163694092_legacyaxleassembly.png.1e5fd59af31ee58cfc19969cb6614989.png

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I know that some differentials (rears in particular) use shims between the carrier bearing races and the housing, while others use shims between the carrier bearing and the carrier case - all of which help to ensure carrier bearing preload. Do our differentials (rear OR front) require shimming, or is it just a simple open the case, take out the stock diff and swap the ring gear to the new diff and replace? Seems too easy to me, so where's the hard spots - axle deinstall/reinstall notwithstanding?
- Pro amore Dei et patriam et populum -
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shimming is meant for clutch type diffs where load determines how fast and hard the diff locks up and how much preload they have. our stock viscous diffs are not preloaded by design as they are rated on tq/rpm of slip. helical/torsen diffs have a certian amount of preload inherant in their design and is usually very small to non-existant since they are tq sensing based on how the mechanics move in relation to each other, but they cannot be shimmed.

 

you can get a clutch type diffs for all subaru rear ends and for the 5/6mt fronts instead of a helical, but they gerally harsher and make noise when they engage and require friction modifiers and normal service including periodic rebuilds. Helicals need no special fluid and never have to be rebuils since there is not clutch material to wear out.

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lets talk about the rear vLSD for a moment.

look at this.... http://www.avojdm.com/product_info.php?cPath=21_22_23&products_id=47

 

does this mean that the rear vLSD is rebuildable? i was under the impression that it was a sealed unit.

 

 

and look at this. is this what comes in the car OEM?

 

http://www.avojdm.com/product_info.php?cPath=21_22_23&products_id=46

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shimming is meant for clutch type diffs where load determines how fast and hard the diff locks up and how much preload they have. our stock viscous diffs are not preloaded by design as they are rated on tq/rpm of slip. helical/torsen diffs have a certian amount of preload inherant in their design and is usually very small to non-existant since they are tq sensing based on how the mechanics move in relation to each other, but they cannot be shimmed.

 

you can get a clutch type diffs for all subaru rear ends and for the 5/6mt fronts instead of a helical, but they gerally harsher and make noise when they engage and require friction modifiers and normal service including periodic rebuilds. Helicals need no special fluid and never have to be rebuils since there is not clutch material to wear out.

 

I think Subitonic was referring to shims that set the position of the differential within the housing and shims that set the depth of engagement of the pinion on the ring. If that's the case some shimming is probably in order. On the cars I've worked on, it was always necessary to make the two adjustments so that the pinion teeth were engaging in the middle of the face of the ring gear teeth. It might be different for Subarus, but I doubt it. I just don't see how it would be economical to tolerance the shafts and casing so well that you wouldn't need to shim the carrier bearings.

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well yes, if you are talking about ring and pinion engagement, then shimming the correct engagement is mandatory. all diffs must have the pinion depth set right and carrier preload set right as pat of the installation, including subarus
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lets talk about the rear vLSD for a moment.

look at this.... http://www.avojdm.com/product_info.php?cPath=21_22_23&products_id=47

 

does this mean that the rear vLSD is rebuildable? i was under the impression that it was a sealed unit.

 

 

and look at this. is this what comes in the car OEM?

 

http://www.avojdm.com/product_info.php?cPath=21_22_23&products_id=46

 

No, But for almost $1600 I would do the STi R180 w/ 07&^ Spec.B rear axle shaft. If memory serves me right. It looks like a open dif. I believe the clutches are between the side gears & the carrier.

 

Mike

Mileage:331487 Retired/Sold

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well yes, if you are talking about ring and pinion engagement, then shimming the correct engagement is mandatory. all diffs must have the pinion depth set right and carrier preload set right as pat of the installation, including subarus

 

^^ and ^ was what I was referring to on a diff change-out.

- Pro amore Dei et patriam et populum -
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