SG low range swap

OneSixty

OneSixty

Forum Member
Joined
Apr 16, 2018
Messages
117
Location
Outer Perth Area, Western Australia
Car Year
2003
Car Model
SG Forester 2.5X
Transmission
5 Speed Manual
If you own a SG Forester and use low range you probably know it's useless. I have read a couple of threads already but can't completely understand so i'll just ask.

Can you just swap the low range gears from a 1st gen Forester (SF) into a 2nd gen Forester (SG) with no modification? And how much lower will the low range be?

I have also heard about people putting the L-Series low range into the SG Forester gearbox. Would this be as simple as just swapping it over? If it is i'd be surprised.

And, what other options are there to make the low range more like a "real" 4wd's low range?

Thanks.
 
Yes, the SF low range gears swap straight over. The earlier L series don’t apparently, and some machining is required. SF low range is 1.447 compared to 1.19. Apart from running shorter diff gears that’s about it. Alldrive are trying to develop 1.6 low range gears but are still not available
 
OneSixty said:
If you own a SG Forester and use low range you probably know it's useless.
Click to expand...

I disagree entirely. It's much better than no low range at all.
 
I agree Ben. Only when I began upgrading my diffs did I find the limits of the SG low range. Having said that, I still cannot figure out why Subaru went to all the expense of developing new gears which are in every way worse than what they already had
 
If you go down that path change the diffs to 4.44 and 5th to .738. The low range is then very close to a 1.6. It changes the vehicle driving dynamics in hi range as well so the torque is in a better rev range.
 
Yes, and with a turbo engine that set up means you are on boost pretty much straight away.
 
Not sure about the diff gears, they were on some imprezas. The 5th gear isn’t from an SF.
 
The 4.44 rear diff comes out of an auto SG or an impreza and the front comes from a single range impreza. The front crown wheel will need to have the edge milled to clear the dual range. I got the 5th gear from All Drive Subaroo.
 
Is the Auto SG rear diff still LSD?
 
According to the sales brochure for the SG 1 "all models, manual and auto, are now fitted with a viscous limited slip rear differential".
 
Is it possible to buy the SF low range gears online brand new? Would be nice to buy new ones that are probably cheaper than wrecker prices for a full gear box.
 
Alldrive will sell the SF low range as a kit with gasket goo and anything else you need to do the job. Just contact them for a quote. I suggest ringing instead of Email as they were slack with Email when I contacted them. It's also worth asking if their 1.61 low range is any closer to production. You could also ask them if they can sell a kit for converting from a 4.11 to a 4.44 diff ratio as well if you want a lower diff ratio as well.

https://www.alldrivesubaroo.com.au/gearbox/subaru-transmission/
 
I got my SF low range by buying a complete gearbox from a lowered SF that was being parted out and advertised on Gumtree. I paid $200 for the box and the low range looked like it had never been used! I ended up getting everything else from All Drive as I did a bearing in the gear box and I didn't have time to wait to get the rest of the bits.
To save money and if you are dealing with ADS you can buy the complete rear diff without the sphere and reuse the one from the 4.11 diff.
You will also need to change the speedo drive if doing the diffs. Whilst you can do the low range only, the additional benefit of changing the diff ratios just makes it a better car to drive. If I did it again I would do exactly the same.
 
OneSixty said:
I have also heard about people putting the L-Series low range into the SG Forester gearbox. Would this be as simple as just swapping it over? If it is i'd be surprised.
Click to expand...

No, it’s not a straight pull from the L box and put in the SG box job. The L series is an early form of the phase 1 EJ series gearbox. In fact the input shaft housing of the L series box is a direct swap for the Gen1 series 1 gearbox.

But from the G1S2 phase 1 gearbox up to the phase 2 gearbox you need to create an interference bush to fit the L low range input shaft into the bearing and housing of the input shaft bearing.

For all EJ gearboxes the low range hub on the main shaft also needs some meat removed from its splines.

Then there’s the diff crown wheel. 4.111:1 needs a bit of meat shave from the outer section to clear the low range gears. The 4.44:1 needs more meat removed but apparently doesn’t effect the contact area of the pinion gear.

Read more about it here from Phiz’s conversion years ago.

OneSixty said:
And, what other options are there to make the low range more like a "real" 4wd's low range?
Click to expand...

Only real way to do it is 1.59:1 low range and 4.44:1 diff ratios.

I’ve got an SG box with the low L series low range (the 1.59:1 - the crappy 1.19:1 can be found in the turbo model gearboxes), 4.11:1 diff ratio, front LSD (one side shaved to fit the low range) and L series locking centre diff.

It’s a mint setup, it’s just missing the 4.44:1 diff ratio.

The L series low range is well worth the effort, you’ll love it. While you’ve got the box split “throw in” some auxiliary oil feeders over the low range gear set, mainly for cooling...

Cheers

Bennie
 
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