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Gear Ratio Questions & some crazy drive train ideas


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18 replies to this topic

#1 All_talk

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Posted 02 December 2003 - 05:29 PM

Hey Substers

Does any one have a comprehensive list of the trans gear and final drive ratios for all the available trannys? It would be nice if we could compile all the info and post it somewhere.

Now on to the crazy ideas…

Has anyone looked into using the parts from an LSD in the front diff? What about the components from the locking center diff in the rear or front? Maybe with some machine and fab work? 4-wheel LSD or Front/Rear lockers would be really cool. I don’t have the parts or I would look into it myself, maybe we could tear into some broken/worn out trannys and rearends and find out? Or maybe I’m just crazy. :banana:

Gary

#2 StormTrooper

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Posted 02 December 2003 - 06:07 PM

You're not crazy, just highly optimistic!

I want to somehow stuff a 4.44 front diff from a newer gen soob into an oldschool tranny, and of course use a welded rear 4.44 pumkin with oldschool stubs to make for kick rump roast gearing. The prob, as mudrat described exists in getting some parts machined for the front diff. You would need a custom pinion gear shaft to make it work (i think) That to me would be the easiest way to get good gearing for a lifted soob with big ol knobbs. That's why some have done the nissan t-case swap, which entails an entirely contorted drivetrain. Not bashin it, it just seems like a lot more that can go wrong, but I'd like to see the setup first hand.

I think a locked front end on a sube would warrant some serious steering issues...

#3 Qman

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Posted 02 December 2003 - 06:08 PM

The front and rear diffs are different. The front diff uses 12 bolts to hold the ring gear on while the rear uses 10 bolts.

There is a company that offers a front LSD. Basically they modify your open diff. I can't remember the name of the company right now.

McBrat had a list of ratios. It may be on the Ultimate Subaru website.

#4 calebz

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Posted 02 December 2003 - 06:42 PM

I believe the company offering the front LSDs was Phantom Grip

#5 Qman

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Posted 02 December 2003 - 06:48 PM

That's the one!!

#6 All_talk

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Posted 03 December 2003 - 12:57 AM

From what I’ve read the Phantom Grip is not a true LSD, its more of a tightly wedged open diff, it behaves much like a LSD due to the heavy friction load on the gears. Some claim it works quite well, others said it puts extreme load on the diff and could cause breakage or extreme wear (most of this comes form the Datsun guys, I have a 260Z).

I’m not to discouraged buy the differences between the front and rear final drive gear sets, if the spider and side gears are of similar size there might be a way to modify the carrier to hold the LSD internals. I’d also like to see how the center locking diff clutch pack works (I assume it’s a clutch), and if the components could be adapted to the other diffs. And yes a locked diff would certainly create major turning problems on high traction surfaces, but in offroading they are indispensable.

Crazy, most likely… highly optimistic, definitely. Just because it hasn’t been done doesn’t mean it cant be done… with enough know-how, time and money nearly anything is possible (money is the one of the three that always seem to slow me down). And remember… if it were easy, everyone would do it.

If anybody could post some pics of the tranny internals that might suggest if its even worth considering, or maybe I just need to start collecting tranny parts.

A mans gotta have a dream. :D

Gary

#7 torxxx

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Posted 03 December 2003 - 03:37 AM

Why on earth would you want LSD in the front diff?

#8 Rooinater

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Posted 03 December 2003 - 04:24 AM

traction that's why! offroad performance not for the road.

#9 Guest_taprackready_*

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Posted 03 December 2003 - 07:43 AM

Originally posted by torxxx
Why on earth would you want LSD in the front diff?



VW water cooled guys as well as other front wheel drivers have been doing it for years. Quaife is a company that makes awsome LSD equipment for front drivers of mostly european vehicles.

Rockcrawlers and other offroaders also lock up the front and rear on most nearly everthing they drive.

Bill

#10 XSNRG

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Posted 03 December 2003 - 11:01 AM

I wonder if there is any similarities between the EA82 and the Legacy front diffs?

#11 All_talk

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Posted 03 December 2003 - 11:11 AM

Originally posted by XSNRG
I wonder if there is any similarities between the EA82 and the Legacy front diffs?



Good question, if so it might open up some other options.

The Quaife is a high quality unit and would cost you about $1100.00 if they made one to fit the ’80 Subie, which they don’t. And I read up on the Phantom Grip, its just like I described earlier… a friction loaded open diff, they do make one for the R160 for $300 (we can get a factory LSD for much less), but nothing for the front. If the friction loading idea really does work, you should be able to make something to fit the front diff. I have access to a full machine shop including CNCs and heat treating, if someone could loan me a spare front diff, I’d see if I could design something to fit it (I’m a ME, It’s the kinda thing I do for a living). And I’d still like to see the guts of the factory LSD and center locking diff assembly. Anybody here in WA state got a pile of old drive parts?

Gary

#12 StormTrooper

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Posted 03 December 2003 - 01:42 PM

mudrat said there are similarities between the front diffs from a legacy's 4.11 diff and the 3.9(3.7?) Ea82 diffs. But some machining would be in the works, and for a custom job like fabbing a pinion gear with the proper shaft length would cost $$$.

#13 Rooinater

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Posted 03 December 2003 - 02:37 PM

basically lsd's are frictioned opendiffs under spring pressure. that's how it still slips. either using a cone style or there's another style that most lsd's use on all cars.
lsd's are in no way a hard locker, they still slip.

#14 XSNRG

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Posted 03 December 2003 - 03:57 PM

Where's Thorp? I'm in Olympia, I have extra stuff laying around.

#15 All_talk

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Posted 03 December 2003 - 04:29 PM

Hey XSNRG, Thorp is just west of Ellensburg on I-90 (where the big fruit stand is), but I work in Preston (just east of Bellevue/Issaquah) so i'm pretty close.

And I have another question… Could the 1.592 low range gears and 3.90 final drive gear set be transplanted into a D/R full time locking center 4WD tranny (RX)?

I come from the air-cooled VW world where mixin-n-matchin is a way of life, I also have a Datsun Z car which has many mix-n-match options with the later Z and ZX cars. Just wondering about the possibilities with the Subarus.

Gary

#16 torxxx

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Posted 03 December 2003 - 06:01 PM

yeah for offroading why would you want a front diff that slips?
wouldnt you want it locked ?

#17 All_talk

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Posted 03 December 2003 - 06:21 PM

Originally posted by torxxx
yeah for offroading why would you want a front diff that slips?
wouldnt you want it locked ?



True a LSD isn’t as good in the loose stuff as a locked diff or spool, but it’s better than an open diff and, it’s a hell of a lot easier to drive home on the highway than a spool. For a multi purpose rig the LSD is a good compromise.

Gary

#18 Rooinater

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Posted 03 December 2003 - 06:28 PM

an lsd resist slipping due to the friction plate and springs. but still will slip when enough torque is appled. less stress on the drivetrain and doesn't give you quite as bad of steering complications as a locked diff in the front. that's why jeeps and those style rigs are now using selectable lockers. because you can undesignate the locker and it's a open diff and you can turn tighter.

lsd'd don't just slip they do resist it that's why they are better than an open diff.

#19 torxxx

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Posted 03 December 2003 - 06:42 PM

ahhh ok.. gotcha..
Thanks for clarifying




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