NA SG Low range conversion.

[Brucinator]

I've got a 2003 (SG) NA manual.

I picked up a spare SG box and have been looking into doing a 1.44 low range conversion. Upon doing some research found that some have done a 4.44 front and rear diff conversion too, using a 0.738 5th gear to keep highway drivability.

Basically was just wondering if someone could help me form a list of parts i'm going to need to get a hold of to do just the 1.44 swap, and maybe also the 4.44 F&R diff swap so i can figure out if that's something that i am going to realistically be able to achieve, or if i should just stick with the 1.44 swap.
I'm competent and mechanically minded but haven't played much with transmissions before so this is going to be a learning curve for me one way or another.

Currently looking at getting:
-1.447 LR gearset (probably from alldrive).
-For the front end, (if i even go down this path) would i just be able to buy a 4.44 gearset+rear diff and swap it straight in after putting the .738 5th gear in?
-Looking at LSD's front and rear while everything's out of the car, advice in this regard would be appreciated too (not worth doing rear LSD if a diff locker becomes available in the next 12 months as i'll just buy that).
-Will be doing throwout bearing and a new clutch while it's out too.

Thanks in advance for reading my wall of text :thumbsup:

 

[Rally]

You will need special tools to swap the diff gears over. Not so much the crown wheel but the pinion. May as well stick with Vlsd rear centre till you are ready to get the locker. Keep in mind that for the locker you will need an R180 diff, and nothing from the R160 save the flange will swap over. As for the front, helical/torsen are the most popular, but plated from say Cusco if they are available would be best. For the 5th gear, contact all drive Subaru. Same with the 1.44 gears, unless you did what I did and buy a broken SF box cheap and grab the gears out of it. Of which there are 2. Have you read my build thread?

 

[Brucinator]

You will need special tools to swap the diff gears over. Not so much the crown wheel but the pinion.

So does the 4.44 gearset out of an XT for example, swap straight over?
Special tools like a press? Or is there special circlips or such things that need to be removed?

May as well stick with Vlsd rear centre till you are ready to get the locker.

Yea i figured so much, but worth asking.

As for the front, helical/torsen are the most popular, but plated from say Cusco if they are available would be best.

I'll look into it. Is there somewhere you know of likely to have the plated Cusco lsd?

Have you read my build thread?

I have, but i'll likely be reading, re-reading and re-reading, again and again over the next few weeks as i go through the planning/prep phase.

 

[Rally]

The gears will swap over easily on the rear diff, but will need to be shaved to clear the 1.44 low range gears.

I don’t know what actual tools are required. Apparently only diff specialists have it, most mechanics won’t.

Speak to someone like Dave from A1 Tuning and Performance. He can source the Cusco diff.

 

[Brucinator]

Really appreciate you taking the time to reply mate. Thank you :thumbsup:

 

[El_Freddo]

No special tools required other than some larger than normal sockets. I reckon the 5th gear swap is harder than the diff ratio swap. Namely bedside when I did mine I used a mate's hydraulic hand press that assembled around the gear to be pulled.
The only real difficult bit with the diff is setting the preload and backlash - both are easy enough to do either with the proper gauge or doing it by eye using the coloured grease and the guide found in most factory manuals.

As Rally said, the front diff's crown wheel will need to be shaved to fit the 1.447:1 low range gears. A bit more shaving and stuffing around could see you with the 1.59:1 L series low range and 4.44:1 diff ratio.

Any Subaru 5 speed manual 4.44:1 ratio diff ring and pinion will fit into the SG's phase two gearbox.

Gearbox work is loads of fun

Cheers

Bennie

 

[jf1sf5]

I wouldn't fit a plated Cusco up front because it needs maintenance, a torsen/helical is more appropriate.

What you forgot in your wish list is a DCCD...very effective modification and easy to do.

 

[Rally]

Good point I had forgotten about re the dccd

 

[havachat]

Firstly the gain you get from changing your diffs to 4.44 is immense, it puts the torque is a better speed /rev range and gives far more flexibility in high range. The SG is then far nicer to drive.
If you change the diffs to 4.44 you will need a new speedo drive. I got the yellow one with 32 teeth.
Also Niazi at All Drive can mill the edge of the front diff crown wheel if you get it off him.
You can also buy the rear diff without the hemisphere and reuse yours to reduce cost.
I bought a SF gear box from a car being wrecked for $200 so it is worth looking around.

 

[Rally]

I wouldn't fit a plated Cusco up front because it needs maintenance, a torsen/helical is more appropriate.

What you forgot in your wish list is a DCCD...very effective modification and easy to do.

All plated diffs require maintenance, which means regular oil changes. I think considering the performance difference between plated and helical, it’s a small price to pay

 

[jf1sf5]

If he is essentially going off road, a front plated is probably a better choice but if he stays mostly on the road, I think that a helical is the way to go.

Plated need more oil change and depending on the use or abuse, the discs wear off and need to be re-setup (sorry, cant find the right word !) meaning to open the gearbox.

 

[Rally]

Yes, that’s the downside. Interesting comparing the Forester with my wrx. The wrx runs the Subaru STI plated rear diff and is used almost only on the skidpan and getting to and from the track. Last year it did less than 2,000km. The diff gets a hell of a road workout and it’s oil goes black very quickly. I have decided to change the oil annually. There have been times out on the skidpan when the diff has opened up and I think it’s because of the dirty oil. The diff has been in there for 6 seasons, half of them double entered so you could say 9 seasons. So far the plates are fine (with clean oil) and haven’t given trouble or feel like they are in need of attention.

The Forrie travels further, and I drained the oil twice in the time I had a plated rear diff and on both occasions it was showing only slight discolouration if any.

Based on this experience I think that off road work is less taxing on the clutch packs of the diff than motorsport and if I can get effectively 9 years and counting out of them then I would expect to get many more from off road use.

 

[Rally]

Yes, that’s the downside. Interesting comparing the Forester with my wrx. The wrx runs the Subaru STI plated rear diff and is used almost only on the skidpan and getting to and from the track. Last year it did less than 2,000km. The diff gets a hell of a road workout and it’s oil goes black very quickly. I have decided to change the oil annually. There have been times out on the skidpan when the diff has opened up and I think it’s because of the dirty oil. The diff has been in there for 6 seasons, half of them double entered so you could say 9 seasons. So far the plates are fine (with clean oil) and haven’t given trouble or feel like they are in need of attention.

The Forrie travels further, and I drained the oil twice in the time I had a plated rear diff and on both occasions it was showing only slight discolouration if any.

Based on this experience I think that off road work is less taxing on the clutch packs of the diff than motorsport and if I can get effectively 9 years and counting out of them then I would expect to get many more from off road use.

 

[Beachworm]

Would you not call off-roading motorsport?

 

[El_Freddo]

Would you not call off-roading motorsport?

No, you're not timed and there's no official competition to thrash your off-roader out in the bush unless YOU want to (not good for the environment).

Motorsport such as what Rally mentions is working the drivetrain almost beyond maximum for 98% of the event if not more. We're talking high temps, loads of friction and a general torturing of the drivetrain.

While we might torture our offroader's drivetrain, it's more than likely in short bursts or events with the aim of being able to still drive some (potentially a long) distance to get home.

Cheers

Bennie

 

[Beachworm]

It's an interesting debate over what activities should be classified as sport and there is quite a wide spread of opinions. The Australian Sports Commission defines a sport as: “a human activity capable of achieving a result requiring physical exertion and/or physical skill, which, by its nature and organization, is competitive and is generally accepted as being a sport.”

I would say that off road driving is a human activity capable of achieving a result. It does require physical exertion (at times and low level) and skill and there are situations where it is competitive. Whether it is generally accepted as a sport, who would know?

The aspect of competition is the one that is questionable in general off-road driving as it is not "organised". Put two blokes in 4 wheel drives at the bottom of a steep hill and there will be an unspoken competition but it isn't organised.

I guess if motorkhanas or hill climbing are sports the off-road equivalent could be mud racing or rallycross. Recreational off-road driving would be equivalent to doing donuts in the industrial estate at midnight except it'll legal (usually).

 

[Rally]

Is off roading a sport? Not really. There are no winners. There are no rules apart from road rules and laws affecting national parks, state forests, etc.

 

[NachaLuva]

Offroading can be sport if it's competitive...

IMO the ultimate offroad gearbox is 4.44 diffs with 5th gear & speedo drive to match, 1.447 low range, Cusco front clutch LSD, DCCD centre with manual controller

For the front LSD, helical is best for onroad manners, a clutch front LSD has terrible power understeer depending on what setting you have it on. Cusco is a direct bolt in, all other clutch LSDs needs to be modified

Clutch LSD is best for offroad as it still sends torque to the wheel on the ground when the other wheel is lifted. To do that with a helical diff, you need to drive through the brakes

 

[Rally]

Clutch type diffs are better than helical, and some are better than others. However, the only time I have needed to be towed out was when the clutch type lsd wasn’t strong enough, even though both wheels were on the ground.