Building a AWD OFF-ROAD gearbox...., diff lock vs DCCD

guyph_01 · Post by **guyph_01** » Wed Feb 02, 2011 11:12 pm

Hi guys,

For the past few weeks there has been quite a bit of chat about those gearbox option and I myself have been thinking of upgrading to D/R AWD in my L series a few months ago.

From what I have gathered there are a few options.

#1 Is to use a Standard EJ 3.9 D/R AWD box and drop in the diff lock from the S/R FT4wd and use the 1.59 low range from D/R PT. This would eliminate the need of the adaptor plate. (Similar to yours I think only using a gen1 or gen2 Lib box that already have the 3.9 ratio. Not sure but one has 3.7 and the other generation uses 3.9)

#2 Is to simply fit the 1.59 low range from D/R PT in a D/R FT4WD box and use it on an EJ engine with an adaptor plate.

But as you know i'll be luckier to be struck by lightning than finding any of the above diff lock gearboxes.

#3 Is to use an Early Liberty D/R AWD box and put the L series 1.59 low range in a EJ D/R box and installing a DCCD.

What I wanted to know is:
- What would be the advantage of the DCCD over the diff lock. Does it behave the same as the D/R FT4WD box with diff lock?
- Is #1 and #3 feasible
- When using a EJ gearbox in an L series does the tail shaft need to be custom made?

Thx

spike · Post by **spike** » Thu Feb 03, 2011 8:52 am

paul at subarwreck has at least one full time L box, youll pay through the nose (he has a buisness to run!!) but if its what you want
i think he actually has 2 or 3 but i know theres one there

legacytt · Post by **legacytt** » Thu Feb 03, 2011 10:08 am

guyph_01 wrote:
#1 Is to use a Standard EJ 3.9 D/R AWD box and drop in the diff lock from the S/R FT4wd and use the 1.59 low range from D/R PT. This would eliminate the need of the adaptor plate. (Similar to yours I think only using a gen1 or gen2 Lib box that already have the 3.9 ratio. Not sure but one has 3.7 and the other generation uses 3.9)

#2 Is to simply fit the 1.59 low range from D/R PT in a D/R FT4WD box and use it on an EJ engine with an adaptor plate.

But as you know i'll be luckier to be struck by lightning than finding any of the above diff lock gearboxes.

#3 Is to use an Early Liberty D/R AWD box and put the L series 1.59 low range in a EJ D/R box and installing a DCCD.

What I wanted to know is:
- What would be the advantage of the DCCD over the diff lock. Does it behave the same as the D/R FT4WD box with diff lock?
- Is #1 and #3 feasible
- When using a EJ gearbox in an L series does the tail shaft need to be custom made?

Thx

Firstly your 1st option won't work unless you transfer everything from an L series AWD box into the EJ case and keep the L awd rear extension housing with the diff lock. This would eliminate the need for an adaptor and keep all the characteristic of the L AWD. To fit the 1.59 low range you would need to modify the EJ case for the selector etc as outlined in numerous other posts. In reallity it would be easier to go with your option 2 and just use the adaptor.

The third option works as this is what I have now. When the DCCD is locked there is absolutely no slip, in fact at partial lock on the thumb wheel it is allready getting quite tight. I have been using this on quite loose rocky terrain recently and with a plated LSD rear there is loads of traction to spare. The DCCD is great on gravel roads as well, I set it up with partial lock and the grip is fantastic, without the understeer of a fully locked centre so if you can find a well priced DCCD I would recomend that option.

AndrewT · Post by **AndrewT** » Thu Feb 03, 2011 1:33 pm

lol, I thought this was pretty concisely summarized for you a few months ago on perth-wrx.com. It's a hell of alot of stuffing around just to get some drive to your rear wheels for driving on tarmac.
You already have the ultimate for offroad (locked centre) and I can't imagine your front wheel spinning is really *that bad* with only an EJ22 and large tyres to justify upgrading to AWD. Perhaps the wank of DCCD is just too much to resist haha.

To answer one of your questions, yeah to fit an EJ gearbox you need the front section of the tailshaft shortened by 65mm. Also need to cut and shorten the shifter linkage and other rod, and either mess around with getting the EJ clutch cable to work (I haven't done this) or install the hydraulic system which involves welding or bolting a bracket to your clutch pedal and fitting the master cylinder in the firewall and relocating the speedo cable.
Unless you fit it all into an EA casing but I don't know, that probably wouldn't work with DCCD.

guyph_01 · Post by **guyph_01** » Thu Feb 03, 2011 7:04 pm

Yeah Perth WRX hand my dreams shattered for a while:)

Hummmm, As am planning to use the cable operated 92 Liberty EJ22 D/R AWD gearbox.

Also the ej22 will be history soon. EJ25 quad cam should add a bit more spin to the wheels... that's why the AWD obsession.

YouTube · Post by **El_Freddo** » Thu Feb 03, 2011 7:32 pm

Yeah as LegacyTT said - you'll need the entire L AWD internals to make this happen - even then you'd need a 3.9 ratio L AWD which is even harder to find than the 3.7 L AWD gearbox. It can be done with more modifications but you'd want to find someone who's either done it and selling the required unit or can do it for you.

If you're going to split the box to put the "real" L low range in, you might as well case it with the EJ casing so that you have stock EJ clutch etc. Makes replacement clutches easy to source

As for the EJ25, with the tyre size you're running if you don't flog your L it shouldn't be any different to the EJ22 when you move off. If you give it heaps you'll expect to be replacing the front road contacting rubber if you don't hit something from torque steer.

The third option would probably be easiest in terms of replacement parts and it gives you total control over the amount of slip between the front and rear - an interesting situation as you try to work out what is best for wet on road use then all the various road conditions from there... The cost could be the issue here.

Cheers

Bennie

guyph_01 · Post by **guyph_01** » Wed May 25, 2011 9:55 pm

Hi guys,

I didn't want to start a new post.

I have now the opportunity to be able to either go with the DCCD system or get a single range vortex diff lock diff system.

I wanted to know what would be best suited for the car. What would be better and stronger and easier to build? I'm thinking of going with 3.9 ratio. what do you think?

Plz give me as much info/advice as possible as i need to decide and choose one option as the opportunity won't be available for long.

Thx

H-top · Post by **H-top** » Wed May 25, 2011 10:26 pm

DCCD!!!!
35/65 split!! in 3.9 its the same as mine

niterida · Post by **niterida** » Wed May 25, 2011 11:22 pm

DCCD will be absolutely crap for what you are planning to do. You will waste your money and end up regretting that decision. Best sell the DCCD you just bought to me and save yourself a lot of heartache

guyph_01 · Post by **guyph_01** » Wed May 25, 2011 11:43 pm

ok two really far apart point of view. any more??? but seriously??

H-top · Post by **H-top** » Thu May 26, 2011 12:34 am

niterida! you just want it!

daza · Post by **daza** » Thu May 26, 2011 6:56 am

chech with the guys who 've done it, but i didn't think you could change the diff ratio on the L AWD Diff Lock box, and 3.7:1 sux.
Daza.

AndrewT · Post by **AndrewT** » Thu May 26, 2011 10:56 am

How badly do you need a little bit of drive to your rear wheels while driving on tarmac? (AWD)
Because that's the only benifit you are going to see by moving away from a totally standard L series part time gearbox. Unless you go for a solution that can 100% lock the centre you will also reduce your offroading ability at the same time.

My advice is to keep a bog standard L series gearbox - they are the best for offroading - your car is an offroader. FWD is fine for tarmac, at least, it's good enough considering the effort and money it would take to go AWD.
If an AWD L series gearbox with centre diff lock comes up cheap, buy it, slap it in your car.
I wonder what happened to the one I had, it's probably still kicking around WA somewhere. That was a good one - had dual range, vacuum centre diff lock, AWD.

How big are the tyres you are going to be running? That will help determine what final drive ratio would be best.

guyph_01 · Post by **guyph_01** » Thu May 26, 2011 11:06 am

I'm thinking of using 225/70/16.

AndrewT · Post by **AndrewT** » Thu May 26, 2011 11:17 am

Bout 28.4" rolling diameter then.
I would definitely go 3.9 then (because it's easily available in an L box) altho 4.1 would probably be better. 3.7 sucks even with 27" tyres......but you do have an EJ25 which should have the balls to cope.

guyph_01 · Post by **guyph_01** » Thu May 26, 2011 11:26 am

why would 4.11 be better?

Gannon · Post by **Gannon** » Thu May 26, 2011 11:30 am

More reduction

guyph_01 · Post by **guyph_01** » Thu May 26, 2011 11:38 am

how bad would it be driving with the 4.11 and those tyres on the freeway?

guyph_01 · Post by **guyph_01** » Fri May 27, 2011 1:08 am

I can't keep the L box as:
1. I blew my last one and i'm not paying 200+ for another
2. I sold my adaptor plate and redrilled flywheel
3. I already sent my lib clutch kit to scott's to get torqued:)

d_generate · Post by **d_generate** » Fri May 27, 2011 2:42 am

guyph_01 wrote:how bad would it be driving with the 4.11 and those tyres on the freeway?

A hell of a lot better than mine with 4.44's and 205/60/16's ......... but it helps off road, mine's probably about 18-20% better geared for off road than with the original 3.9's, I just wish I had the rock crawler gears like you instead of the poxy 19% reduction my low gives me.

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Building a AWD OFF-ROAD gearbox...., diff lock vs DCCD

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