Need a Spec B owners help!

[BAC5.2]

I had a question about the R180 in the back of a Spec-B.

 

Can anyone tell me the spline count on the differential? I imagine it'd be the same as any other R180, but I just want to be sure.

 

Also, it's true that the Spec-B has a helical type rear diff, right?

[Long Island Legacy]

SpecB has a Torsen rear diff. Do not know the spline count tho.

[BAC5.2]

Thanks, I thought so but wasn't sure.

 

Is it actually a Torsen, or is it a different-brand helical-type LSD?

[fishbone]

Different brand? TorSen is a type, not a brand.

[BAC5.2]

Torsen is a brand. They were owned by Bosch, but sold in 2003 and renamed Toyoda-Koki Automotive Torsen North America Inc.

 

http://www.torsen.com

 

Most helical differentials are "called" torsen because it's an abbreviation of "TORque SENsing". Torsen differentials operate very differently than your typical helical LSD. According to Torsen, the 2007 STi had one in the rear diff, but no other models. Still, that may not have been updated for the 2007+ model years, and it's possible the 07/08/09 Spec-B's got a real Torsen differential.

 

Torsen diffs and more generally known Helical diffs work in a similar way with similar outcomes, but by very different means.

[fishbone]

Most helical differentials are "called" torsen because it's an abbreviation of "TORque SENsing".

This is what I was referring to.

[BAC5.2]

Kind of like calling Giant Brand Facial Tissue "Kleenex" when, by "Kleenex" you really mean "Kleenex Style"?

 

Now that we've determined that Torsen is a brand, not a type, does the Spec B have an actual Torsen brand diff, or does it have another brand Helical Type differential?

[fishbone]

Torsen, TorSen, TORSEN (which is the brand).

TBH I am not sure. If you refer to TORSEN, spec.B is not listed. If you refer to the Subaru literature, it refers to Torsen with an ®. Searching Google and a couple threads here gave no conclusive results. Hopefully somebody will chime in.

[Darkness of Death]

according to my brochure, it's TORSEN with the ®.

[Long Island Legacy]

to the OP, are you doing a specb swap tranny swap?

[BAC5.2]

A 6-speed swap has crossed my mind, but I'd probably opt for a trans with DCCD and a front LSD. If I were going to settle for a Viscous center diff, I'd just put a PPG 1-4 helical set in my current trans and be done. I do like the idea of a helical-type rear LSD, and was curious about the splines on the diff.

 

Actually, I wouldn't mind doing a 6-speed with a mechanical center diff, so long as it wasn't Viscous. I wonder if Torsen would build a Subaru center differential. I'm SURE the proposition has come to them before, and they already package a very very similar unit in the Audi.

 

That would be a really cool setup. Torsen front and center with a clutch-type rear diff.

 

I HAVE driven the only WRX in the world with Helical differentials in all 3 locations (all PPG. The PPG front diff, the rare PPG rear diff, and the only PPG center diff in the world). It was like driving a Hummer. You could have 3 wheels on ice and one on pavement, drag the brakes, and drive like it's a regular Sunday morning. I don't know how that setup handles in aggressive driving though, I was mostly concerned with how it would behave in low-traction settings and during a launch. My initial thought would be that it wouldn't rotate very well (though it would be BOMBER in the dirt). That's where I think a clutch-type would come in handy.

[Darkness of Death]

the odd thing i am finding in the brochure is that it is saying that the 5 and 6mt is viscous-coupling LScentreD.

 

i thought only STi was front LSD? or am i understanding the terminology wrong?

[BAC5.2]

the odd thing i am finding in the brochure is that it is saying that the 5 and 6mt is viscous-coupling LScentreD.

 

i thought only STi was front LSD? or am i understanding the terminology wrong?

 

The Spec-B doesn't have DCCD, but a Viscous center diff exactly similar to the 5MT. That's the center diff, not the front diff.

 

The Spec-B, like the 5MT, has no front LSD, at least according to what I've heard.

[Darkness of Death]

so...there are 3 diffs..ok..

i thought it was only 2 (front and rear)

[BAC5.2]

Center too! That's how it's AWD!

 

The STi's have DCCD, which is more like a manually controlled VTD diff in the 5EAT's (and some of the 4EAT's). THAT is the diff to have. Adjustable from 35/65 (f/r) to 50/50.

 

Not all 6MT's are created equal.

[BAC5.2]

So no one knows the spline count?

[camber]

Not sure about the number of splines.

 

DCCD is a bit overated IMO. Especially, if you drive on asphalt. It took years before they were phased out of WRC by much more expensive implementations then what can be found in any production car.

 

IMO, a Front HLSD is 99% of what is missing(performance wise), compared to newer STI's, from the spec. B drivetrain.

[wpgspecb]

Not sure about the number of splines.

 

DCCD is a bit overated IMO. Especially, if you drive on asphalt. It took years before they were phased out of WRC by much more expensive implementations then what can be found in any production car.

 

IMO, a Front HLSD is 99% of what is missing(performance wise), compared to newer STI's, from the spec. B drivetrain.

 

Ok, I'm going to assume that a thread-jack, while it is a bad thing to do to the OP, is SLIGHTLY better than posting a new thread asking a question that has been asked before (although I haven't found it).

 

Car: 2008 Spec.B with TORSEN rear diff.

Transmission: 6MT

Mileage: 37,000kms (warranty until 160,000 or 4 more years)

Mods: Cobb Stage 2 OTS map, Perrin 3" Downpipe, Gimmick 3" CBE (on way), K&N, GFB BOV

 

 

With the configuration of the SpecB, (no dccd, no front lsd) what would be a good choice for me.

 

a. add dccd controller, electronic center diff (used sti or aftermarket) and front LSD.

 

b. add front lsd (used sti or aftermarket)

 

c. add dccd contoller and electronic center diff (no front lsd)

 

 

Most STI owners I know say they leave the DCCD in auto most/all of the time. Is this something I want? Or would I be just as happy adding lsd to the front?

[fishbone]

IMHO those kinds of swaps make sense if you are racing etc or maybe you are big on winter sports and are constantly finding yourself on snowy mountain routes. Otherwise, for a daily driven street car, it's mostly for bragging rights since the stock set-up is fine.