SF 1.447 low range in SH XT?

I do like that idea @scalman, but how do you sit on highway speeds to get to your 4wd destination? Fuel consumption would go through the roof too!

Do you remember the crazy Russian that made a set of portal hubs for his Foz? There are pics of it here somewhere. It’s was pretty obvious that something was done to the car as it was beyond a normal look for a forester.

Cheers

Bennie
 
yes those mods are not for highways for sure as first those take your speed like 40% lower , so itsj ust loccal driving, or carying those reductors in buch and putting them there.
and i duno why they make them open, why not put all that into sealed box so nothing would go inside like other do on bolt on portal.
so if too much torque and lockers brake cv axles then too low gearing braking gearboxes. just move to other car i guess if you think you need low gear.
 
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I believe the weakest point in the driveline is the axles. When you take into account how much more torque goes through them after you multiple the gear and diff ratios they are the part that should fail. Makes sense that the easiest part to change was designed to be the weakest. Of course a good clutch dump will brake the first thing in the line of fire which will be 1st gear. While the hollow secondary gearbox shaft and pinion shaft have bearings between them, and would only be going at different rates during low range operation, I'd rather have a low range in the stock location as long as it's no more then 2:1.

I'd like to see a custom made 1.73 low range with 19 & 25 teeth on both pairs of gears one day. Made properly with the helix angles going the correct way. If you were to do it the cheap way like I did, you would need to have a thrust bearing between the secondary low range shaft and the gearbox casing to stop the shaft wanting to move, which will still put a lot of force on the gearbox case.... would be better to have the helix angles facing the right way. If you do it the cheap way, you need to start with two SF or SG low range sets and follow Red's dodgy low range recipe.
1) Chuck one of the inputs into a lathe and machine of the gear
2) Chuck the secondary shaft into a lathe and machine of the gear that pairs with the input shaft gear.
3) On your second SF/SG low range put your single gear into the lathe and machine out the inside so that it fits snuggly over the secondary shaft that you machined earlier.
4) Machine out the inside of the secondary shaft gear that pairs with the last gear you machined, so that it fits snuggly over the machined input shaft.
5) Glue the two together with Loctite retaining compound - yes thats right strong glue....
6) Get the right size thrust bearing to fit behind the rear of the secondary shaft and the casing to stop the shaft sliding back (Which it will want to do because the helix angles are facing the wrong way)
7) Fit in gearbox and see how long it lasts.
I was towing a fair bit more then you are supposed to in an SG up quite a long steep hill in low range when I broke mine. Failure was the secondary shaft failing and not the glue, surprisingly. I mostly did it as a proof things would fit and want to make the gears properly at one point. If lathing hardened gears you will either need to use the right bits for hardened steels or deharden them and the reharden afterwards - they are very hard right through.
 
Hello everyone, new here.
Found this thread and thought I would ask here instead of creating a new thread for a similar question.
I have a SH forester NA with the small dual range. I've thinking for a while to improve the low range by fabricating new gears for the low range with a better ratio. Don't have the tools or knowledge myself but there are shops nearby that could do it. If I understood the posts right, I should be able to fit larger gears on the low range for a better ratio right? How much larger is safe to do? Don't need much, just to be able to crawl a rocky hill at the rpm where the engine has better torque. Right now, it's either stall or speed up bouncing arround.
Thanks
 
Does your SH have the 2.5L EJ253 engine, or a 2.0L one?

And :welcome: to the forum :) .
 
It's a 2.0L. And EJ20something according to the car papers. Didn't know there was a 2.5L. Maybe it wasn't sold here in Spain
 
I did not think that the 2.5L made it to Europe. Just wanted to check.

The 1.19:1 LR works very well with the 2.5L as it gets about 80% of its maximum torque at around 1200 rpm, and is still around 90% at 6300 rpm (EJ253, the EJ251 in pre-2006 Foresters is nowhere near as torquey),.
 
It's midnight over here but thanks anyway🙂

That 2.5 sounds really nice. My 2.0 has max torque at about 3500rpm. And it's only torquey between 2800 to 4000rpm give or take. And it's dead when lower than 2500. If I try to go slow over an obstacle or climb a hill, even with LR i only get to about 1500rpm, so I end up speeding till I get to the 3k range and would prefer to be able to go slow over it
 
@nelcat I don't think anyone knows what is a 'safe' ratio to go up to. One place in Aus used to sell a custom 1.58:1 set and another has been saying they have a 1.6:1 'coming soon' for years. If I was making a custom set I'd use the largest ratio's that would fit in the gearbox. But you'd have to go easy when using low range. Otherwise, just try and source a 1.447 set from an earlier model.
 
BriefObsessions said:
@nelcat I don't think anyone knows what is a 'safe' ratio to go up to. One place in Aus used to sell a custom 1.58:1 set and another has been saying they have a 1.6:1 'coming soon' for years. If I was making a custom set I'd use the largest ratio's that would fit in the gearbox. But you'd have to go easy when using low range. Otherwise, just try and source a 1.447 set from an earlier model.
Click to expand...
Agree.

If you plot torque against LR ratio for each model, it's just about a straight line. That is, Subaru is making a 'statement' that this is the safest torque:LR ratio, knowing the strength of their gearboxes better than anyone else.
 
Fair enought with the safe ratio, it's hard to know. I don't really need to push it to the limit. Don't want to break anything. I'm sure the gearbox can hold the max torque of the engine + the low range + some safety factor. So 200Nm*1.2+some more. Something around 1.5 low range is what I was thinking should do fine. I'm guessing from your answers that there is enough room inside the gearbox to put some bigger gears then, am I right? At least those 1.447. Do you happen to know the biggest gear you could fit inside? And the size of the standard 1.2 ones? That would be nice to do some numbers.
I've read about the 1.447 earlier models swap but as far as I know it wasn't as easy as taking the gears from one gearbox and putting them in the other one right? There were other changes to be made about sensors and bearings if I remember correctly.
Thanks alot
 
I'm personally not sure about what other modifications are necessary to fit the 1.447:1 LR. There are threads here about it though.

Whatever you decide, just be aware that the drive train is subjected to far more force with a lower LR ratio. Use it gently!

Same advice goes for anything mechanical really.

My 1968 Landcruiser had 1.996:1 transfer gears and was all but indestructible, regardless. However, it sank like a stone on soft soil, mud or sand. It was also a truck, not a comfortable touring vehicle with some off road capabilities ...
 
Not that I've actually done it, but when I was looking into it I understood the 1.447 low range will fit straight in without mods. You might be thinking of the 1.59 gears from the much older L series wagon, which required a bit of machining.
 
@nelcat: this:
BriefObsessions said:
Not that I've actually done it, but when I was looking into it I understood the 1.447 low range will fit straight in without mods. You might be thinking of the 1.59 gears from the much older L series wagon, which required a bit of machining.
Click to expand...
The 1.447:1 low will drop straight in with the 4.111:1 diff ratio. If you have 4.44:1 diff ratio you will probably need to shave the diff’s crown wheel to fit the 1.447:1 low range.

To do the L series 1.59:1 low range see here. 4.111:1 and 4.44:1 diff ratios need the crown wheel shaved to clear the gears. Biggest problem is finding a donor L series gearbox. MUST be from the NA models, turbo low range = 1.19:1 which is what you already have ;)

Happy hunting.

Cheers

Bennie
 
Well, seems I remembered it wrong then. I might have the two swaps mixed in my head. Never seen or heard about those L series around here, I guess they weren't very popular, so finding donors is likely to be hard.
@El_Freddo how can I tell if I have the 4.111:1 diff ratio or the 4.44:1 without having to open it? I'm not much of an expert in subaru parts. Also do you know if that 1.59:1 has been reliable?
Thank you all for the help
 
Hi @nelcat , the white sticker on your gearbox will tell you what you need to know if you google that code. The L Series (also known as Loyale and Leone) is very common in Australia so its probably the best bet for obtaining the 1.59:1 gear set if you cant get them in Spain.
 
@nelcat - the 1.59:1 is quite reliable when used appropriately. The only times I’ve heard of them breaking is when ppl do clutch dumps, particularly behind turbo EJ converted L series back in the day.

There were apparently some part time dual range gearboxes that came in the EJ, these were typically in Latin American markets from what I understand. I believe these were a 1.6L carby or SPFI fed EJ engine.

If you stumble across one of these (unlikely now) it would be gold for a conversion in your gearbox.

Cheers

Bennie
 
Well, first, thanks for the answers, they've been very helpful. I've done a fast search with the bigger second hand parts websites around without any luck for those L series or the other one from Latin America. Will keep an eye on it but I don't think they have ever been sold here. Importing a used L series gearbox from Australia it's not really a good option. If I take into account the price of the gearbox, shipping, customs and local taxes, and the mechanic to do all the gear swapping...I might as well have someone desing and fabricate new gears with the same ratio for the same price. It's good to know that that gear ratio holds up well if well treated. I will keep looking around but it seems my options are either a custom gear set or a 1.447 swap. That narrows it down quite a bit.
Thank you very much for your help.
 
If you or someone could show in videos comparison low ranges would be best visual info i think.
 
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