1.59 Lo range DCCD 5 speed STI box

Donkeytits1 · Post by **Donkeytits1** » Wed Nov 25, 2015 8:13 pm

Righto I'm embarking on a bit of a project here.

I have a gen 1 liberty sitting in the shed with a standard 5 speed manual I fitted a L series low range in about 2 years ago. All the syncros are shitting themselves, and and I have a plan to transplant a 1st gen EZ30 later on down the track. I have 90% sorted getting hold of a 5 speed STI box and diff with the DCCD - Pretty chuffed with that.

So I have enough bits to do something cool.

Ideally I want to end up with a 6 cyl car with the L series Lo range, locking centre, 65:35 torque split, LSD rear, and gear ratios suitable for daily driving, highway and a bit of offroad.

Concerns are:

The STI box has a 4:44 diff: Heard that there is a clash with that diff and the L series gears. if so, how much needs to be skimmed off the ring gear and does it weaken the diff too much?

The rear diff is an R160. This should be fine with my current EJ22 but with DCCD and a 160kW EZ30 up front am I going to eat it for lunch?

Could I reuse the 3.9 ratio pinions and ring gears of my current box with the new diff centres?

How are the STI gear ratios for normal driving and offroading?

Will need to use my current cases with the Lo range. Are the STI gearsets compatible with my original cases and main shaft?

Will be limited to using a push clutch with my current cases. Can you get a reasonable push clutch to hold back an EZ30?

Haha so thats where I'm at. Thinking I'm just going to jump in and start doing it despite these grey areas, but what do you guys think? Discuss

Green_eyed_liberty · Post by **Green_eyed_liberty** » Wed Nov 25, 2015 9:16 pm

i've got myself a DCCD 5spd for my brumby build too. but mine is 3.9 (it looks very simular to the duelrange forester box)

AndrewT · Post by **AndrewT** » Thu Nov 26, 2015 4:47 pm

Hi Donkey Tits,

Sounds like a cool project! Here are some thoughts of mine:

- Yes you have to use a push clutch if you want to run a dual range 5speed. Only way to use a pull clutch is to use a turbo gearbox (none of which have dual range). The bellhousings are quite different.
- Just use an Exedy heavy duty push clutch kit. Vennom had no issues with one of these holding the power of his EZ30.
- You won't have any issues with an R160 rear diff. These diffs basically never fail - really only when people actually weld them locked. You'd have to try really really hard to damage one.

I can't really answer the other questions about the gearbox internals (clearing low range, ratios etc).

Post by **TOONGA** » Thu Nov 26, 2015 7:10 pm

A thread to read on USMB

http://www.ultimatesubaru.org/forum/top ... ge-please/

TOONGA

vincentvega · Post by **vincentvega** » Thu Nov 26, 2015 9:35 pm

use an exedy HD clutch from a 2.5l

Same dimensions as the 2.2l clutch but more clamp pressure. you will kill the gearbox long before the clutch fails. I fitted one to my car recently and cant really tell the difference in pedal weight compared to a stock clutch.

R160 rear end will be fine. They still use them behind the EZ30

YouTube · Post by **El_Freddo** » Thu Nov 26, 2015 11:06 pm

I don't know the exact amount to shave from the 4.44 diff to clear the L series low range. Search for a thread by Pee_Jay about his gearbox build - I can't remember if his was 4.111 or 4.44 ratio, either way the process is the same. If I had the opportunity I'd be going the 4.44s.

The STi drive gears will be no good as they're not interchangeable with the low range input shaft, well, with a press and a lot of stuffing around you could swap 3rd/4th ratios, 5th is relatively easy to do. For the H6 I'd be looking for the lowest 5th ratio a 0.73 from memory.
If you do go the 4.44s you want the "wide" ratio gear sets, not the short ratio ones, otherwise you'll be in 5th gear by the time you're pulling 40km/h :/

If you're serious about the h6 and this box setup it is possible but I'd be doing it in the phase two (8 bolt) gearbox as the case is revised - stronger, and first/second are thicker and stronger than the phase one box. Basically all Subaru boxes are of the same strength for their generation, STi boxes are no different. It's all in how you drive them.

With your L series low range you're one step away from it fitting in the phase two box, that's fitting the input shaft to the larger phase two input shaft bearing. Pee Jay explains it in his build

Have fun with it. Venom ran a phase one box with the h6 successfully. But he did have some trick LSDs front and rear. Kaaz will not fit in the front! Definitely get a front LSD! It's needed and greatly increases traction when offroad. IMO it's highly underrated by those who don't have a front LSD

All the best. Fire away with hose questions because I know you've instantly got 50 more after reading this!

Cheers

Bennie

Donkeytits1 · Post by **Donkeytits1** » Mon Dec 14, 2015 10:40 pm

Thanks for the response Benny, and everyone else

There's a bit of a hold up on the box. Not sure if it's going to come through

But yeah I have read most of the threads on L series Lo conversions. Wanted to make sure I got that right before I basically binned a reasonable L series 5 speed. So yeah, its purchasing that fatter deep groove ball bearing and machining part of the spline off if its going into a TY754 yeah? Thats not to hard to do. I was surprised I didn't have to do that when it just went into my current box.

So you guys reckon it might be worth doing syncros and bearings on my old gen 1 lib box and just use swap the transfer case parts to get the DCCD? This makes sense if the gears are no stronger. The DCCD then becomes a $1500 DCCD and I have a good gearbox to either bin or sell with a crapy centre diff.

And definitely go a wide range. From what I've calculated, 5th would increase 120kph engine speed from 3422 to 3693 RPM with STI gears and a 4.44. Not a huge change but a bit crap for everyday driving. But if I can swap ring gears and pinions in front and back and go STI with 3.9 this drops to 3200. All ratios are similar to that of the old lib box then except for first, which is longer, going from 14 to 12. Not ideal for offroad. Thoughts?

Also I would love a front LSD. But chasing a DCCD 5 speed with an LSD is like picking and choosing hen's teeth. And an LSD on its own is expensive.

Donkeytits1 · Post by **Donkeytits1** » Mon Dec 14, 2015 10:55 pm

Wait. STI gears will not work with DR cause I can't swap the main shaft over. Bummer. So its $1500 just for the DCCD then essentially. Bearings and syncros it is then.

Post by **TOONGA** » Tue Dec 15, 2015 8:43 am

This thread from page 5 - post 47 onward as to RSR555's hybrid gearbox build

showthread.php?t=18280&page=5

TOONGA

YouTube · Post by **El_Freddo** » Tue Dec 15, 2015 11:18 am

Sell the STi box minus the dccd - still worth good coin to someone with a blown box and their working dccd unit...

Personally I'd chase up a phase two box as it's stronger than the phase one gearbox and the mods are about the same.

Go the 4.44 ratio, change the 5th ratio for your desired cruise revs.

Ring and pinion gears are interchangeable between the phase 1 & 2 gearboxes

Cheers

Bennie

Donkeytits1 · Post by **Donkeytits1** » Wed Dec 16, 2015 5:51 pm

How much stronger is a phase 2 box?

And cheers for the link to that thread TOONGA. Any one know the open torque split of an RXII locker?

...RSR555?

YouTube · Post by **El_Freddo** » Wed Dec 16, 2015 7:37 pm

Donkeytits1 wrote:How much stronger is a phase 2 box?

Your guess is as good as mine in terms of exactly how much stronger, but here's a pic of a gen1 gearset on the left and the SG on the right, this is first gear:

The Gen1 has a mm less thickness in the gear cog to make room for what I think is a silencer device - which is 1mm thick with an extra tooth in it...

Donkeytits1 wrote:And cheers for the link to that thread. Any one know the open torque split of an RXII locker? ...RSR555?

No torque split - it's open until you lock it, then it's just like the stock PT4wd L series box, no slip at all.

For onroad I recommend a front LSD as I could easily spin a front wheel around an intersection with the EJ22 trying to put the power down - all power will go to a wheel in the air when the diff is unlocked.

Cheers

Bennie

Donkeytits1 · Post by **Donkeytits1** » Wed Dec 16, 2015 10:38 pm

The Gen1 has a mm less thickness in the gear cog to make room for what I think is a silencer device

Yep your right. That 'sub gear' is a quietening device. Found this in the 1992 manual (It explains it right at the end of the text)

Looks like the later models (this is from a 2003 manual) had them aswell. But not for European and Australian markets

Anyway, from what I can remember from class the strength of similar gears like this should be roughly a ratio of their widths. From your photo and the thickness of the sub gear (1mm), the phase 2 looks to be about 13mm wide compared to the phase 1 which might be 12 or 11.5. In which case, the phase 2 box is probably 10 to 15% stronger than the phase 1.

I'll have a hunt, but I'm thinking with those numbers it'll be the availability of DCCDs and diffs that will determine whether I go for a TY752 or TY754.

With the RXII, I meant to say torque split, not locking torque. If its got a bevel diff like standard centres I'm guessing its probably 50:50. But if its planetary like the DCCD it could be 65:35 or any other ratio

Donkeytits1 · Post by **Donkeytits1** » Wed Dec 16, 2015 10:52 pm

Oh and whats a good way to get a cheap front LSD you reckon?

Thinking with a 65:35 lockable DCCD a front LSD might be less critical. But, I still want one

. Better to have one than not

Donkeytits1 · Post by **Donkeytits1** » Mon Dec 21, 2015 11:46 pm

Got a hold of a 4.11 TY752V4DAA 5 speed box today for $130 with the ideal 0.780 5th gear.

So it's decided. I'm going with a phase 1 box.

Dual range and cases of my current box, gearsets out of the box I just bought, and hopfully a DCCD and rear LSD from somewhere.

YouTube · Post by **El_Freddo** » Tue Dec 22, 2015 1:49 pm

Sounds like a plan.

A front LSD can be had from eBay. I think I paid $550 for my OBX unit which is a copy of another diff from a well known name brand that I can't remember. After I had it installed I was told it's a good idea to pull it apart, deburr some of the casing lines and put a new spring/washer kit through it. It's just time more than anything!

Shortly after I got my OBX unit factory Torsten units were appearing on eBay for about $700 from memory. I wished I got one of these units as the look like they're fit without any mods.

The OBX hit need the bolt heads to be shaved to clear the L low range...

Cheers

Bennie

Donkeytits1 · Post by **Donkeytits1** » Thu Jan 07, 2016 9:41 am

Got my hands on a DCCD centre and associated transfer case components today!

This together with the 5 speed I got the other week gives me the equivalent of and 5 speed DCCD box with wide ratio gears, which is a great place to start. And getting ti all for the cost of a good second hand standard 5 speed, I'm stoked!

With the parts sourced from my old box, I can now mix and match between 2 gearsets and have the choice between 2 diff ratios: 4.11 or 3.9. I would just need to get a 4.11 rear if I choose to go that way. During the rebuild I'll just need to source shims and bearings which shouldn't be too hard.

Once it's built, I'll need to work out how to drive the DCCD (Once I'm done with chucking sick skidz with the 65% rear torque bias

). Don't need automatic control, so don't need DCCDpro. Hoping I can drive it using standard pulse width modulation. Anyone have a car with a 5 speed DCCD I could take some measurements from?

Let the work commence (soon)!!

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