4wd vs Awd. Best set up for Brumby ej20t

MarkAMO · Post by **MarkAMO** » Wed Jan 19, 2011 12:14 pm

I know there have been discussions on this before but it is hard to get some clear answers.
Basically I'm building up David’s (D3V1L) brumby project. It has an ej20t with a wrx gearbox currently. I'm working on my own custom (and cheap) rear brake conversion at the moment and will post more on that later).

As I would like to eventually turn this into a 4wd like my old brumby, I’m stuck deciding on a gearbox set up. There would seem to be a couple of options for me:

1) Install an L series 5 speed box (I currently have one lying around).
2) Install a forester awd DR box (with viscous centre lsd)
3) Combine some kind of super box of the best worlds with awd and low range 4wd.

I’ve been told that the DR boxes are weaker than wrx boxes (due to fitting the DR set up inside the same casing making the gears smaller) but I was wondering how much stronger are the awd DR gearboxes than the L series ones?
I also noticed that the rear axles on a brumby are thicker than wrx ones?! Does this mean they were very conservative when designing the brumby/L series drive train?
Another point is that it would be a lot better for on road driving awd with an ej20t (although fwd may be the last option).

I understand the 4wd makes a difference off road but how good are the awd DR boxes off road?

Finally is there some kind of way to fit an open-or-locking centre diff into a forester box?

I’m sure a few people have come across these questions before

Cheers,
Marcus

d_generate · Post by **d_generate** » Wed Jan 19, 2011 6:04 pm

It's only 1st gear that's weaker in the AWD boxes (by about 20% but remember they still take the power of a 2.5) and you can get very cheap front LSD's from the States, you can also get 12 or 20kg center diffs (std 4kg) just depends on how far you want to go, I've even had the gearing in mine changed from 3.9 to 4.44.
I don't exactly take it easy in mine either, I'm just a bit careful in 1st and with the new computer etc it's punching out some decent power now.

daza · Post by **daza** » Wed Jan 19, 2011 6:51 pm

I heard a rumor that Crossbred is testing an Ej Awd box with a centre diff lock?
A part time 4wd box is Fwd on road.
With an Ej turbo that's going to suck so bad i reckon it would be dangerous.
Daza.

MarkAMO · Post by **MarkAMO** » Thu Jan 20, 2011 12:10 am

Thanks for the advice.
At the moment I'm leaning towards an awd dr box as the car will spend most time on road and will hopefully source out a viscous center. Bit more pricey but on the other hand I wouldn't need an adapter plate or to modify much in the interior hopefully.

Would any dr gearbox from the ej series bolt onto an ej20t?
Is there much difference between sizes/clearances?

d_generate how does the wrx go off road?;)

d_generate · Post by **d_generate** » Thu Jan 20, 2011 3:56 am

Mine is out of a 92 Liberty and is on an EJ20 WRX, you'll need to change to cable clutch, it's pretty good so far off road but I've only really had it in the sand a few times.
But we've been making lots of changes lately like fitting the new Dobinson springs which have lifted it way higher than the old Forester ones.

78sti · Post by **78sti** » Thu Jan 20, 2011 1:14 pm

As far as I understand the dr boxes are weaker due to the low range reduction gear is before the others, so it increases the torque on the gears. A 50% reduction would have a 50% increase in torque on all the gears. When in high range there should not be much difference in strength.

My ultimate off road gearbox would be a late forester box (lower diff ratios) with l series or scorpion low range 12kg certre and torsion front lsd.

daza · Post by **daza** » Thu Jan 20, 2011 1:28 pm

78sti wrote:My ultimate off road gearbox would be a late forester box (lower diff ratios) with l series or scorpion low range 12kg certre and torsion front lsd.

That would be my recomendation, changing diff ratio in an early box can be expensive and the Torsen front diff is much nicer on road than the CLSD.
I will not have another part time Subaru box, no matter what Subaru it's for.
Daza.

lovey80 · Post by **lovey80** » Sat Jan 22, 2011 5:46 am

The box that is in my Brumby build (subie boys) is a L series 5 speed AWD with the lower LR ratio and cenre difflock all bundled into a EJ casing. I think this is the best of both worlds. On road you have nice AWD but off road you lock the centre diff and off you go.

I believe that Jeff at Crossbred supplied it also and at a very good price........

MarkAMO · Post by **MarkAMO** » Mon Jan 24, 2011 11:18 am

lovey80 that sounds like the perfect set up

What gearboxes did you combine to achieve all that?
I have a wrx box in there at the moment & a 5sp L series box as spare.
What center difflock did you use?
Would love to find out more about it;)

d_generate · Post by **d_generate** » Mon Jan 24, 2011 4:17 pm

You'll need to find a dual range box as the case is different to the WRX. But it does sound perfect, especially with a front LSD.