AWD lockable vs AWD viscous gearboxes .

bluesteel · Post by **bluesteel** » Mon Apr 07, 2008 11:33 am

cool... i have been looking into the possibilities of 4.44 gearing with the locking diff, and short of getting a new pinion shaft made up, nobody seemed interested

ill hit gee up with a pm

YouTube · Post by **El_Freddo** » Mon Apr 07, 2008 12:04 pm

discopotato03 wrote:From memory the fellow doing my gearbox has a locking box in a brumby (or an L ?) and his is either 4.1 or 4.4

This sounds promising - would love a 4.1 with locked centre...

Bennie

discopotato03 · Post by **discopotato03** » Mon Apr 07, 2008 5:11 pm

With short final drives you also have a few options with 5th gear to try and keep the revs sane at highway speeds .

The 5th gear pair are separate gears so you can run just about any matching set from what I can see but don't know with really late stuff .
The close ratio or shortest 5th works out at 0.87 to 1 .
The L/XT4 5th is 0.78 to 1 .
I have seen mention of some of the single range Turbo Impreza's having a
0.738 (approx 0.74) to 1 so that's another option .

Depending on which ratio 5th your box has the gap 4th - 5th would grow but that's a small price to pay if you need short ratio diffs (numerically high eg 4.44:1) and acceptable cruising revs .
The difference between the lowest and highest 5th gear pairs is approx 16%
so it could just get you a good all rounder even with 4.1 or 4.44 ratio diffs - depending of course on what diameter wheels you run .
Actually overall ratio wise that tallest 5th and the short 4.44 diffs works out almost the same as the shortest 5th and the taller 3.7 diff ie 3.22:1 vs 3.27:1 .

I don't suppose that 3.9 L AWD pinion and crown wheel are for sale ?

Cheers A .

BlackMale · Post by **BlackMale** » Tue Apr 08, 2008 11:10 pm

AndrewT wrote:Hey Jaffa can you post up the gearbox identification number on that gearbox? It's near the starter motor.

Andrew there are (or were) 2. I MAY have them somewhere however they came off when i was degreesing/cleaning the box.

discopotato03 wrote:BTW what's the 3rd option ?

Well i could say that there is the 3.7 option, the 3.9 option and the pinion mod option, which equils 3. (However i was to be honist i was really only think of the 2 - the 3.7 and 3.9 - sorry if this was unclear).

I like your idea of swaping the ratio's around in an attempt to get a little better performance/cruze ratios.
And if this question is for me...

discopotato03 wrote:I don't suppose that 3.9 L AWD pinion and crown wheel are for sale ?

Then ummm, no sorry she's going in my RX

schultzie · Post by **schultzie** » Thu Apr 10, 2008 9:20 pm

well as im about to get one of these boxes i hope it will help transform my car in to a better tarmac warrior.... and im also glad to hear ill stilll be lighting up the steer if i try hard enough...

then ill just need the engine rebuild and suspension... mine will take years but i know mind in the slightest

discopotato03 · Post by **discopotato03** » Fri Apr 11, 2008 7:34 am

If you mean lighting up the rears just remember this .

Those center diff bevel gears are quite small and like any "single spinner center" if one one side is going like buggery and the other not they centrifuge all the oil out . They also get hot so if you keep it up they either sieze solid or if really unlucky split the bevel gears and spread shrapnell throughout the gearbox ruining the gears and bearings .

Gee tells me that usually with these L open center diffs if abused the gears turn blue and lose their heat treating so look after them .
I doubt spares are going to be easy to get so I'd be treating them with kid gloves .

Cheers A .

schultzie · Post by **schultzie** » Fri Apr 11, 2008 9:28 pm

so you dont think i should put 150kw+ through it then...

discopotato03 · Post by **discopotato03** » Sat Apr 12, 2008 9:42 am

That's going to depend on how you use the power or rather torque actually .
Subaru obviously thought they would work ok behind an NA ER27 in an XT6 but they were only single range .
Notice how Subaru don't seem to run DR boxes behind EJ turbos or EJ25's ?
There is obviously is a torque limit with this style of gearbox and Rex people have used quite a few up .
On loose surfaces they should be alright because questionable traction takes a lot of the torque loading off the transmission . I have no doubt a big bootfull in low range (L type) in the lower ratios could seriously stress the box if the driver had no mechanical sympathy .

Rally people in EJ powered cars prefer the EJ type viscous box and in some ways it is the stronger of the two AWD boxes . The output/transfer drive gear is better supported in the long box and there are a greater variety of center diffs available . Depending on your budget I think a Torsen center diff in a viscous box would make a great all rounder .