Frankenbox - Lib offroad gear box

ScubyRoo · Post by **ScubyRoo** » Fri Feb 26, 2010 6:56 pm

Hey guys,

I'm seriously keen to get my transmission sorted so I can permantly leave my bigger weels on. 3" of lift with stock tires just doesn't float my boat ya know?

So I'm thinking for my gen 1 lib, which runs 215/70/16s...

EJ AWD dual range box (gen 2 seems easiest to get)
L range 1.59 low range
4.11 or 4.44 front diff
New 5th gear - suggestions?

So I have a bunch of questions:

Do I also need to change the rear diff to match the front?

What's the best way to source gear box parts? Casing from PAP? Low range gear set - PAP or wreckers?

How about sourcing diffs?

Can some explain what 4.11 or 3.9 or 4.44 actually means?

What difference would I feel between a 4.11 and a 4.44? I know the 4.44 needs modification to fit.

I'm doing this because I want my gearing back so I can a) accellerate and b) get up hills with a trailer at the same speed in the same gear as I used to.

I know changing 5th gears can be a bit contentious, but I liked the lower engine noise on the highway and fuel consumption seems to be about the same or slightly less that came with my big wheels.

Answers to the above questions and ideas on how many $$$ I could be up for would be great!

Thanks in advance for your help!

Cheers,
Owen.

AlpineRaven · Post by **AlpineRaven** » Fri Feb 26, 2010 7:15 pm

Ok,
I strongly recommend to get Gen 1 Liberty box (easier to work with) not Gen 2 as you will need machine the gearsets hence weaker! whereabout Gen 1 box you wont need to machine anything at all..

Rear Diff - yes you do need to match the front diff.

You can install 4.11 or 4.44 diff - not hard there is a few people do have 4.11/4.44 around all you need is to ask specially over WRX or RSLC forums.

Sourcing gearboxes - If you already have low range in yours, you can either use your gearbox or get another Gen 1 Lib gearbox from wreckers (Pick a Part or Jollys/Centre Road has a few of them if you're quick - price - sneaky - $57 to $120 or more.)

You will need doner EA box with 1.59:1 low range section.

5th gear, I have an calculater here to give you an idea which 5th gear you should go for. you need to work out what diff and tyres then you will be able to work out what 5th gear you'll need to go for - again 5th gear will be from turbo box out of Legacy or WRX, has to be upto 98 or 99 gearbox (after '99 that its different size key)

With 4.11 or 4.44 you will need to machine the crown to fit the low range area - 4.44 is very tight fit - but it does fit..

whats the diff between 3.7 - 3.9 - 4.11 - 4.44 (3.7 is smaller lower gearing where 4.44 is higher gearing but again it has to match the gearsets from 1st to 5th)

4.44 is better for creeping or drags but not really good for highway unless you have very tall 5th gear but 4th would be crap.

You could source an turbo box (ie. WRX) with just right ratios with 4.11 or 4.44 just take out the gearsets and put it in dual range box.

Price - depends where you go and get the gearboxes from. I would get a bell mark figure for gearboxes/parts you will need is about $250-$500 ($500 would be turbo box if you require) and or bearings.

Cheers
AP

YouTube · Post by **El_Freddo** » Sun Feb 28, 2010 7:08 pm

AlpineRaven wrote: I strongly recommend to get Gen 1 Liberty box (easier to work with) not Gen 2 as you will need machine the gearsets hence weaker! whereabout Gen 1 box you wont need to machine anything at all..

AP's talking about the input shaft/dual range setup - on the Gen II gearsets the spline from one of the low range gearsets to the gearbox is smaller than the Gen I box = the Gen I being the stronger option.

AlpineRaven wrote:whats the diff between 3.7 - 3.9 - 4.11 - 4.44 (3.7 is smaller lower gearing where 4.44 is higher gearing but again it has to match the gearsets from 1st to 5th)

The matching of 1st to 5th gears to the diff ratio is not as in there are sets of 1st to 5th matched to a diff ratio that must be used together, rather what AP means is that you need to work out what you want to do in your subi with your specific setup and work out what diff ratio/1st to 4th/5th will work best for you. Then you need to find those bits....

AlpineRaven wrote:4.44 is better for creeping or drags but not really good for highway unless you have very tall 5th gear but 4th would be crap.

That sounds odd that its good for drags and for creeping... To explain this a 4.44 diff ratio makes the pinion shaft from the gearbox spin more times than a 4.11/3.9/3.7 to go just as far, 3.7 spinning the least. So 4.44 is good for slow, controlled 4wd crawling, but is also great for quick acceleration but could have you over-revving on the freeway. That's where playing with your 1st to 5th or just your 5th gear ratios can have the best of both worlds.

4.11 and 4.44 from what I understand is found in turbo boxes, but I don't have a clue what model came with what ratio. The 5th speed you're after will probabily be in the same gearbox as the final drive you're after. So basically you'll need three gearboxes to make up the one that you're after. Fun eh?

Cheers

Bennie

ScubyRoo · Post by **ScubyRoo** » Sun Feb 28, 2010 9:07 pm

thanks bennie and AP!

I still don't get the 'number' i.e. '3.7'... is it the ratio reduction between the input and output shafts?

What about sourcing the exact gears from Subaru directly? For instance, if I could source the diffs off forums, maybe I could source the 5th gear from subaru... save me the cost of a third gear box.... unless I choose to use all the gears from that box...

Well with the wheel/tire set up that I have now, more acceleration and offroad ability is what I'm after, so the 4.44 may be the way to go. Plus the revs on the highway in 5th are very low atm... 2.5k at 100kmph. If it remains around 3k I'd be happy. Hey AP, what's this calculator thing? I may be needing it eh?

Cheers,
Owen.

YouTube · Post by **El_Freddo** » Sun Feb 28, 2010 9:21 pm

No worries Owen.

The 3.7 ratio is the decimal value of the ratio. 3.7 is actually 37/10, 3.9 is 39/10, 4.11 is 3.9/11 from memory and I've got no idea what 4.44 is.

While 4.44 may be the best for crawling, its probabily also the hardest to find. I'm going for a 4.11. A 4.11 rear diff is easy to source, just about any auto lib has a 4.11 rear diff.

Also, you'll probabily find it cheaper to source the gearboxes you need to make up the box you want rather than buying the bits from subaru!

The calcualtor thing is an excell spread sheet. Gearboxes are basically a moving mathematical equation with a set end result. With some algebra you should be able to work out what 5th gearset is the one you want with the final drive ratio. It would take some time as you need to work out which 5th gear you have. With your tyre diametre (relating it to speed - distance over time), current diff ratio and engine revs you should be able to find the 5th gear you have now.

The excell spread is a lot better at all this once its setup

or AP sends it your way.

Cheers

Bennie

mattl200 · Post by **mattl200** » Sun Feb 28, 2010 9:30 pm

the 3.7 or 4.44 numbers are a relation on the diff as to rotations of the pinion compared to the crownwheel

ie 3.7 means the pinion rotates 3,7 turnes to every one turn of the crownwheel and 1 rotation of the crownwheel equals one rotation of the wheels assuming full traction on the road

i think 91-93 rs liberty had 4.44 ratios and the 5th gear your looking for but the boxes only came in single range (someone correct me if this is wrong)

brumbyrunner · Post by **brumbyrunner** » Sun Feb 28, 2010 9:37 pm

It is easier (and easier to understand) if you use an existing gearbox and just change crown wheel & pinion to correct the under-gearing that your taller tyres created.
Calculate the difference between your "before" and "after" tyre sizes and apply that % to your current diff ratio to get the gearing back to stock. That way your speedo and engine revs will be the way they used to.
Too easy?

AlpineRaven · Post by **AlpineRaven** » Mon Mar 01, 2010 7:46 am

El_Freddo wrote:No worries Owen.

The 3.7 ratio is the decimal value of the ratio. 3.7 is actually 37/10, 3.9 is 39/10, 4.11 is 3.9/11 from memory and I've got no idea what 4.44 is.

Also, you'll probabily find it cheaper to source the gearboxes you need to make up the box you want rather than buying the bits from subaru!

The calcualtor thing is an excell spread sheet. Gearboxes are basically a moving mathematical equation with a set end result. With some algebra you should be able to work out what 5th gearset is the one you want with the final drive ratio. It would take some time as you need to work out which 5th gear you have. With your tyre diametre (relating it to speed - distance over time), current diff ratio and engine revs you should be able to find the 5th gear you have now.

The excell spread is a lot better at all this once its setup or AP sends it your way.

Cheers

Bennie

Bennie - correction 4.11 is 41/10
4.44 is 44/10 I think... :S

Owen & Bennie, PM me your email address and I'll send you an updated excel for Subaru calculator for the gearbox.

I think early RS Liberty had 3.9 & 3.545 diff.

This is an example (not accurate due U.S.A. Specs)-
5th gear in RS Liberty is 0.781 with 3.9 diff
5th gear in 96 WRX is 0.738 with 4.11 diff.
5th gear in 99 STi WRX is 0.825 with 4.44
5th gear in 96 STi WRX is 0.972 with 3.9
5th gear in 98 Legacy is 0.871 with 4.11

In our Liberty Gen 1 & 2 has 0.871 5th, Gen 1 Lib is 3.9 and Gen 2 Lib has 3.7 diff.

The lowest Subaru 5th gear is 0.738, the highest for 5th is 0.972 (your engine will be screaming at 100!) But you have to work out the 5th if EJ22 will be able to pull at specific RPMs, I don't think you should go anything below 2500rpm at 100 due hilly areas, there is specific revs range/speeds where you would use more fuel, it sounds like anything like below 2500rpm might save fuel but you're actually using more fuel.

When I had 26" tyres on mine, i was doing 2650rpm at 100 i was able to reach 625kms to a tank BEFORE the light came on (did came on at 625kms with remaining 8litres left) where abouts i am now back to factory spec tyres I can do 550kms to light coming on.

Cheers
AP

daza · Post by **daza** » Mon Mar 01, 2010 8:19 am

AlpineRaven wrote:Bennie - correction 4.11 is 41/10
4.44 is 44/10 I think... :S
AP

Na
ElFreddo was right, 4.11 is 39/9 and 4.44 is 41/9

I was running 26.5" tyres with the 4.11s and the gearing felt about standard, now with 27.7" tyres it's not quite like standard but it's still good!
Daza.

AlpineRaven · Post by **AlpineRaven** » Mon Mar 01, 2010 8:39 am

daza wrote:Na
ElFreddo was right, 4.11 is 39/9 and 4.44 is 41/9

I was running 26.5" tyres with the 4.11s and the gearing felt about standard, now with 27.7" tyres it's not quite like standard but it's still good!
Daza.

Ah we learn everyday dont we!
Cheers
AP

ScubyRoo · Post by **ScubyRoo** » Tue May 04, 2010 4:56 pm

brumbyrunner wrote:It is easier (and easier to understand) if you use an existing gearbox and just change crown wheel & pinion to correct the under-gearing that your taller tyres created.
Calculate the difference between your "before" and "after" tyre sizes and apply that % to your current diff ratio to get the gearing back to stock. That way your speedo and engine revs will be the way they used to.
Too easy?

I'm not quite following you there mate - do you mean use the crown wheel and pinion from a different box or a custom set up?

If I were to change all these things and get the larger tires running like stock, if I then went back to smaller tires would the opposite (over gearing) then happen?

vincentvega · Post by **vincentvega** » Tue May 04, 2010 5:08 pm

he means use a CW & pinion from a different box. just pick the ratio that gets you the gearing you want.

of course you would then be under-geared if you run small tires. you have changed your gearing. regardless of what rubber you bolt on

pezimm · Post by **pezimm** » Tue May 04, 2010 6:35 pm

ScubyRoo wrote:thanks bennie and AP!

I still don't get the 'number' i.e. '3.7'... is it the ratio reduction between the input and output shafts?

My 2 cents worth...

Just count the number of teeth on the crown wheel and the pinion shaft, divide crown by pinion and you get the ratio...

Hence:
4.11 should be something like 37/9 - 37 teeth crown, 9 teeth pinion...
39/9 would be 4.33 which is not an available option I take it.
And the 4.44 is most likely 40/9

Cheers,
Pedro.

YouTube · Post by **El_Freddo** » Tue May 04, 2010 9:34 pm

brumbyrunner wrote:It is easier (and easier to understand) if you use an existing gearbox and just change crown wheel & pinion to correct the under-gearing that your taller tyres created.
Calculate the difference between your "before" and "after" tyre sizes and apply that % to your current diff ratio to get the gearing back to stock. That way your speedo and engine revs will be the way they used to.
Too easy?

vincentvega wrote:he means use a CW & pinion from a different box. just pick the ratio that gets you the gearing you want.

of course you would then be under-geared if you run small tires. you have changed your gearing. regardless of what rubber you bolt on

ScubyRoo wrote:I'm not quite following you there mate - do you mean use the crown wheel and pinion from a different box or a custom set up?

If I were to change all these things and get the larger tires running like stock, if I then went back to smaller tires would the opposite (over gearing) then happen?

Owen,

Basically what BR and VV mean is to change JUST the diff ratio and retain your current 1st to 5th gears. Once you work out the diff ratio that's best suited to your application (eg, trying to get it as close to factory revs with the larger tyres by changing the mathematical diff ratio) its a case of finding that ratio (either 4.11 or 4.44) in the gearbox it came in or find the crown wheel and matching pinion shaft that someone's selling. They're pretty much the only two ways of finding the bits you need. Price is anyone's guess.

The other way of doing it, which I think is the way you're thinking atm is to change the diff ratio and the 1st - 4th gearsets and the 5th gearset. That's the complicated and expensive way of doing it for a daily driver/part time offroader. If you were racing like brumby runner you'd look into that sort of gear.

Hope that helps out mate

Cheers

Bennie