SF 1.447 into SG or Use SF box with SG 1st having 4.11

skep

Forum Member
Joined
Jan 16, 2015
Messages
59
Location
Mornington Peninsular,Victoria, Australia
Car Year
2003
Car Model
Forester xs
Transmission
Manual
SF 1.447 into SG or Use SF box with SG 1st

Hey fellers!! I was going to put my l series 1.59 low range into my sg but dont want the hassle so I have decided to look for a 1.447 one instead. A couple of quick questions, If i buy an sf box can I simply swap my stronger SG 1st (and maybe 5th if I if its higher geared??)gear and synchro/slider over to the SF box? that way I will have the 4.11 to give me a little more persuasion up the steeper stuff, as my front (innie) cv's are pretty much cooked anyway.

I am possibly after a front helicle as well, just wondering if it will fit in either of the ratios better than the other?

Id be keen to swap my L series 1.59 for a 1.447 if anyone is interested as well.

thanks boys!
 
Last edited:
I put an sf low range into my sg box as it was a good balance between end result and difficulty for me.

What car is this going in? SG dual range box should already have 4.11 diffs. XT's which are single range have the lower 4.44, I don't know about other models. If you are changing from an SG to an SF box you will need to swap the front CV's to SF (which doesn't sound like an issue in your case). If you are starting with an older Outback gearbox it would be easier putting SF box in as the CV's already match the SF box. If you are changing diff ratios don't forget to do the rear lol.
 
Its going in the 03 xs forry mate. AAAh got my wires crossed, I thought it had the 3.9 ratios going on for a second :redface:, in that case ill just need the low range gearset and not the entire box! I have a rear diff from my old forry gt that is 4.44, I forget reading if the front ring gear needed to be shaved to fit the 4.44 with the 1.447 or not...

Did you notice much of a difference? I went up a track in low range last year that was running at idle speed for most of the way up here in victoria and found its limits, but bloody hell it was steep. Didnt want to drive down it until my mate told me that thats the track we had come up at the start (Dixsons creek, Vic). So not looking do do anything steeper really, but need it just in case..Cheers
 
Good idea to put a front helical in at the same time. Just make sure the axles will fit. The SF low range is a good thing to do if you are towing or have or plan to do other modifications to enhance off road ability.
 
Hey Skep, I'm in Melbourne, used to live in Frankston & love the Mornington Peninsula. Small world!

Yes, I would keep the SG gearbox & fit the SF low range into it. AFAIK no mods needed to fit it with the 4.111 diffs, but with the 4.44 diffs you'll have to machine off the corner of the crown wheel.

With the box open, it's the perfect time to fit a front LSD for a solid offroad setup :cool:
 
1.447 is a noticeable improvement over the stock SG low range. There's far less clutch slipping in stop start up hill sections and taking off in soft sand. Climbs which were once borderline stalling can be done with a little more rpm. But it's not low enough for crawling over uphill rocky sections where you need to be driving seriously slowly.

Definitely the right time to fit a front lsd if you want more traction.

I can confirm no mods needed to fit 1.447 low with 4.11 diffs. I never found an answer from anybody who has done 1.447 low and 4.44 diffs, but general consensus is you will need to do some shaving.
 
thanks for the quick replies! hmmm might stick with the 4.11's (as I do 120km per day on the freeway)

what do you mean by the axles fitting, rally?

Your 1" lift blocks are holding up well Nacha!!! though havent been offroading in a while! bought an 00 xj but 15 l/per 100 freeway driving has me falling in love with the forry again!!:iconwink:
 
I put the SF 1.447 into my SG. I changed the front and rear diffs to 4.44. I also changed the 5th gear ratio. The front 4.44 crown wheel will have to have a little bit milled off the outside edge.
I originally was only going to do the 1.447 low range until Rick the 'gearbox man' talked me into doing the 4.44 diffs. Having done that I wouldn't do it any other way if I were to do it again.
The fitting off the 4.44 diffs has the effect of lowering the low range to 1.6. In high range the SG is just a better all round car as the torque is used more effectively. So towing is so much better. Also you don't need to change down as much. Off road on climbs quite often I will stay in high range unless I need low range. In low range you no longer need to flog the car and can just climb at a very leisurely pace !!
 
Havachat, on a GPS verified 100kmh, how many revs are you doing in 5th?

Skep, some front axles require a pin to hold them in place and some don't. Some axle set ups the axle itself is female off a small stubby axle, while others are male. The front diff you use needs to be compatible with the axles.
 
Sounds good then with the 4.44 havachat. Might take a little while sourcing the parts as I dont want another couple of boxes lying around the yard just for bits n pieces:raz:


Ah i see!! I the difference axle conundrum is in the diff type itself. I thought it might have been a different assembely in the gearbox housing, then connects into the diff!:redface: makes sense...

I have done some quick calcs on rpm/final drive of 3.9/4.1/4.44 at 100kph and 5th gear being .738 with 60/65/70 tyres...



4.44 .738 60tyre @100kph = rpm2615 (havachat)

4.44 .738 65tyre @100kph = rpm2540

4.44 .738 70tyre @100kph = rpm2475



4.11 .738 60tyre @100kph = rpm2420

4.11 .738 65tyre @100kph = rpm2350

4.11 .738 70tyre @100kph = rpm2275




3.9 .738 60tyre @100kph = rpm2315

3.9 .738 65tyre @100kph = rpm2230

3.9 .738 70tyre @100kph = rpm2160


 
havachat said:
I originally was only going to do the 1.447 low range until Rick the 'gearbox man' talked me into doing the 4.44 diffs. Having done that I wouldn't do it any other way if I were to do it again.
Click to expand...

Oldish thread and all but..
what sort of cost is involved in doing this?
How easy is it to source the parts required?
where do I get them from?!

Anyone? :raz:
 
You can get the 1.447 SF low range from AllDrive Subaru (new) or from a SF Forester gearbox from a wrecker. Try Rising Sun in Brisbane.

The 4.44 diff you can get from a SG XT gearbox, also get the 5th gear (it's longer to match the shorter diff ratio so you don't rev more on the open road). Also get the speedo drive so your speedo is correct. Try Rising Sun for this too

You'll also need a matching 4.44 rear diff, also from a SG XT manual or from a SG NA auto
 
Awesome. thanks for the info. There's an SG at the local wreckers that I think's an auto. Might have to investigate!
 
Thanks Nachaluva for responding to Ben. I got my low range from a SF that had been lowered and was being wrecked. I searched Gumtree for cars being wrecked and got the whole gearbox for $200. Due to a bearing failure I got the rest of the parts off All Drive Subaru, otherwise I would have continued to search the parts out.
Don't forget you need to have the front 4.44 crown wheel milled to take the edge off as they come out of a single range gear box.
With the rear diff if your sphere is going to be reused try and buy the diff without the sphere, but make sure you keep the crown wheel and pinion matched.
 
Front crown wheel and pinion you are looking at about $300, plus another $220 to machine it, plus GST. Go for the 0.738 5th gear. It is out of a turbo gearbox. A 1.6:1 low range billet gearset is due for release in the new year. Pricing for that has not been announced, but won't be cheap.
 
With the 4.44 Diffs, are they both LSD?
If I'm going to go to the effort of pulling out gearboxes and diffs, it makes sense to do it as well as I can and in one hit although I doubt my budget would stretch to installing lockers, unless they're not an incredibly expensive thing to do compared to 'just' swapping diffs and gears out.
 
Last edited:
4.44 is the diff ratio, LSD is the type of diff centre (open or LSD). You can have any combination depending on what car it comes from.

Yours is a SG NA manual, so it will be 4.111 diffs with a 1.19 low range, open front diff & viscous LSD rear diff

No lockers for our R160 are available yet but you can get OEM & aftermarket clutch LSDs which are almost as good
 
Ben Up North said:
With the 4.44 Diffs, are they both LSD?
If I'm going to go to the effort of pulling out gearboxes and diffs, it makes sense to do it as well as I can and in one hit although I doubt my budget would stretch to installing lockers, unless they're not an incredibly expensive thing to do compared to 'just' swapping diffs and gears out.
Click to expand...

Maybe have a look at my build thread, as my starting point is where you are now. Better diffs make a big improvement, absolutely. For rear diffs, plated is the best bet because there is no R160 locker made and R180 if it can be done would be expensive. For the centre diff, DCCD is best. Failing that, viscous diffs with stronger limited slip capability are available. For front, plated is best, although helical and sure trac are available. Some time next year I will be selling my helical front diff. The best time to swap front and centre diffs is as you say, when the box is out.
 
Rally said:
Some time next year I will be selling my helical front diff.
Click to expand...

How fortuitous! I'll be in the market for a replacement diff sometime next year... Let me know!
The diff would feel quite at home seeing as it would be going from one poverty pack to another!
 
You must log in or register to reply here.
Back
Top