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viscous center locking diff.....


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11 replies to this topic

#1 Numbchux

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Posted 08 April 2006 - 04:01 PM

so I was talking to one of the local subaru gurus.....one of the few that's ever had more than just a loyale in his liftime. He's had a number of XT's and an RX, and a bunch more. anyway, he started a project, and got into EJ series cars before he ever got terribly far, and never finished. but he thinks it could be done. he's got an RX tranny, torn apart, and a Mazda 323 ciscous center diff with mechanical lock that he thinks could very easily be mounted in the RX box so that even with the lock off, the center isn't open....

well, since he has no use for this project anymore, and has offered to give it to me, and, naturally, I said YES. but haven't met up with him to get it just yet.

anyone have any ideas on this? maybe looked into it, or seen both trannies apart and can comment on it? I have never seen the guts of either tranny, so I'm going only by my basic understanding of how they work, and what he told me.

#2 Zefy

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Posted 08 April 2006 - 11:28 PM

actually this might be pretty cool...

from my recent experiment with subaru jim in maple ridge has left me pondering... the centre diff is VERY open when it isn't locked...

so maybe a limited slip would be a grand idea!

this makes me wonder though... a viscous diff only operates at high speeds... so launching from a stop it won't help you... (although you've got a locking centre diff so whats it matter eh?)

if you manage to get it to work(fit) and do some testing i'd be interested...

i wonder how much those mazda diffs cost! only game on the GTX...?

i wonder how hard it would be to fit something like a phantom grip lsd to a RX centre locking diff... even possible? seems like its kinda redundent now...:rolleyes:

maybe if you got a pic of both diffs sitting side by side we can see what we're dealing with...?



#3 mikie

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Posted 09 April 2006 - 02:29 AM

Sorry to be a killjoy but i dont htink it will work- if it is a gtx diff then you have 2 diffs, one inside the other. The outer is the 'centre diff', it is a planatary setup. One side of it drives a gear that goes to the bevel right angle drive to the rear axle. The other side is directly coupled the the housing of the front diff, which is inside. So you have a rather clever compact setup, for a transverse mounted engine. I cant seeing it being converted into a sube easily. But OTOH, modifing a viscous centre diff so it can be locked might be doable.
If its out of another mazda then i am ready to be corrected.

#4 Numbchux

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Posted 09 April 2006 - 12:22 PM

Sorry to be a killjoy but i dont htink it will work- if it is a gtx diff then you have 2 diffs, one inside the other. The outer is the 'centre diff', it is a planatary setup. One side of it drives a gear that goes to the bevel right angle drive to the rear axle. The other side is directly coupled the the housing of the front diff, which is inside. So you have a rather clever compact setup, for a transverse mounted engine. I cant seeing it being converted into a sube easily. But OTOH, modifing a viscous centre diff so it can be locked might be doable.
If its out of another mazda then i am ready to be corrected.


don't worry about being a killjoy. like I said, I haven't seen the innards of either tranny, so I wanted to know just what you told me. thanks man!! hopefully you are thinking of something else

#5 baccaruda

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Posted 09 April 2006 - 09:15 PM

doesn't the legacy AWD have a viscous center diff? BeefARu has something like that in his wagon. I don't know if that's an LSD though.

#6 Numbchux

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Posted 09 April 2006 - 10:33 PM

doesn't the legacy AWD have a viscous center diff? BeefARu has something like that in his wagon. I don't know if that's an LSD though.


yea, all EJ AWD have viscous center LSD. but it's not locking. We want both

#7 Hodaka Rider

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Posted 09 April 2006 - 11:34 PM

this makes me wonder though... a viscous diff only operates at high speeds... so launching from a stop it won't help you... (although you've got a locking centre diff so whats it matter eh?)


Not totally true. My Passat Syncro has a Viscous centre, and it makes launching nice. The fronts start to spin a little, preventing the car from bogging down of the line. This makes for a really nice launch, especially on slightly wet pavement.
Bring revs up -> drop clutch while adding more gas -> front wheels spin a little (traction control helps them both spin at the same speed) -> we're moving out good as the rear locks in and really helps launch it.

#8 baccaruda

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Posted 10 April 2006 - 12:46 AM

aah.

yea, all EJ AWD have viscous center LSD. but it's not locking. We want both



#9 Skip

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Posted 10 April 2006 - 03:29 AM

I believe Chux ment all manual shift EJ AWD's

4EAT's use a clutch pack controlled by the TCU

#10 mikie

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Posted 10 April 2006 - 03:39 AM

You can get a variety of aftermarket and factory centres for the viscous setup. The factory makes 10,15 and 20 kg-something rated viscous diffs, the 10 is standard issue and the 20kg is so near locked it might as well be, its a rally item.

#11 Numbchux

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Posted 10 April 2006 - 04:54 PM

I believe Chux ment all manual shift EJ AWD's

4EAT's use a clutch pack controlled by the TCU


yep, thanks for the clarification!


mikie, I like the sound of that, however, a) I doubt they're available for an EA series tranny and b)does it still have the manual lock option?

#12 robm

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Posted 10 April 2006 - 06:24 PM

Regarding Zefy's post, about the non-locked diff spinning front wheels on launch - I never had it happen on my AWD Corolla with the open centre diff, wet or dry or a foot of fresh wet snow. And it had enough power, about the same as a turbo EA82.

The Loyale, on the other hand, scrabbles like a cat on a hardwood floor in the wet or snow, unless the button is pushed to make it 4WD.

So there must be some drive action happening at the rear.




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