Low Range Options

[stilson]

I drive in low range 99% of the time. In fact other than the freeway I only change into High range when I need to shift up a half gear offroad.

I need a low range for the low range.

 

[Ratbag]

HR/LR gear ratio table for the SF & SG 5MT/DR gearboxes

Gidday Folks

Some comparative figures for the SF and SG gear ratios and LR gear sets in tabular form, comparing the Kmh/1000 rpm for HR/LR in each gear in stock cars.

Click on this link to download a legible/printable version ...

I have spent much of today researching and putting this info together in an Excel spreadsheet, then working out the formulae to calculate out all the kmh/1000 rpm in each gear for both HR and LR. The Impreza is in there for a comparison of its gear ratios. The series I SG is there because at one point I mistakenly though that it had a different FD ratio - soon corrected, and I couldn't be bothered removing it and re-doing the Excel to PDF to JPG conversion so that I could upload and display the file.

If I have screwed up any of the figures, please tell me. I am not really all that well today ...

I have used the figures from the various Oz Subaru advertising brochures and the rolling circumference of the various tyres from the tyre calculator here.

Regardless of what people might think on this topic, it looks as if the facts speak for themselves.

I cannot see engine braking being greatly changed by there being a 1.4 kmh/1000 rpm difference in speed between the 2.0L engine with 1.447:1 LR and the 2.5L engine with 1.196:1 LR when both are in 1st/LR.

In fact, perhaps the larger capacity engines should/would have the same or slightly more engine braking as a result of their greater capacity. Since engine braking will be proportional to torque, this should be the case. I am not making a case for this, merely pointing out that one could be made for this being the case in a throttle closed situation.

It is also not the case that I am saying that I wouldn't rather have had a 1.25x:1 or even a 1.3x:1 LR in our SG cars. I would have preferred that myself. However, I suspect that going to 1.447:1 would put too much strain on the whole gearbox assembly when behind (particularly) the EJ-253 donk. I am speaking in general terms here.

While Taza's car is using the EJ-251, it has also had it's piggy-back ECU tuned. This will give it a bit more torque at lower revs than a standard EJ-251. It has been suggested that the EJ-253 could also benefit from having an after-market tune done. Guzzla has reported that this made a big difference to his MY07 XT, and I can't see it being different for the N/A donk. This might be a better alternative than changing the LR gear set. Just FWIW.

One simply has to realise that these cars are not designed for our specific use, and it is more than a little counter-productive for Subaru to be repairing every second (and third, and fourth ... ) car they sell because some nitwit puts it into 1st/LR and does a launch on dry bitumen ... . I have actually done this (carefully ... ) in my car, and while it gets under way in a hurry, it isn't hard to see how one could wreck the tranny doing it a lot ... .

The design of any car is always going to be a question of balance. It is easy to see what Subaru have done with the LR gearing, as I have said before. As the torque and capacity of the engines increased from the L series through to the cars that most of us drive (SF/SG/SH series I), Subaru has dropped the LR ratio to match (in reverse) the increase in torque of the engines.

My friend with the Suzuki Grand Vitara (2.7L V6) reckons that the Zook is probably somewhat more indestructible than Roo2. I tend to agree with his assessment. However, he also reckons that in every other respect the Forester is a better car. More comfortable; quieter; better handling; more poke in LR ... ; better brakes. The Zook is also about as big as SWMBO's SH ...

The chart also shows the huge gap between 4th and 5th HR that we have been discussing.

 

[NachaLuva]

The LWF is great.. even in neutral it revs much more freely.. I feel this will help wiyh fuel economy when cursing.

Its important to have good economy while cursing...gotta let those expletives fly!!! :rotfl:

RB, thanks for the table. Please note the SF is 97-02 & SG 03-08.

While it may not seem like a 1.447 will give much more engine braking than 1.196, it will. & 1.59 more than 1.447. As kiwifoz mentioned, on steep slippery descents you may not be able to touch the brakes without spinning out so every bit counts, no matter how small

 

[Ratbag]

Gidday NL

Thanks for that correction. I will modify the descriptions tomorrow.

But what are we discussing here?

Comparing an SG that has an SF or L series LR? Or an SF with an L series LR? Or some other car with a custom made LR gear set? Or an SF with an EJ-251 with piggy-back ECU with an L series LR fitted?

Any of the above would be like comparing my hot rod 1100 with a standard one; or my Austin Kimberley with its custom made FD with a stock one.

This is why this discussion keeps going around and around in circles.

What I am comparing is the stock standard versions of these cars that have the stock standard factory gearboxes. In this case, the larger capacity engine will have more engine braking in a closed throttle situation, even given its numerically lower LR gear set. The engine braking of any engine will be proportional to the inverse of the torque of the engine at any given revs. This cannot be a direct relationship for all sorts of obvious reasons, but it will be a proportional relationship.

Of course an SG with a 1.447:1 or 1.59 LR gear set will be different from the stock configuration. I am not saying that it will be the same.

What I am saying is that if one is going to do this kind of comparison, then maybe it is incumbent on the person making such statements to demonstrate that it does make a significant difference, rather than merely asserting that it does.

Apart from the endless discussions that go on here, you need to find someone who is prepared to wreck a (relatively) expensive car in order to demonstrate that it can be bashed around to better effect than someone else's car which is worth maybe a couple of grand on the open market. There is always someone, but I suspect that anyone prepared to do this has more money than sense, so their opinion might be just a teensy bit suspect ... :biggrin:.

I know how my car performs. It performs adequately to my needs and wants.

As I said before, if I wanted a LC with a 2:1 LR (as I had when towing a horse float around everywhere, on all sorts of "roads"), that is what I would have bought.

I have been through all the fun of modifying cars a long time ago. These days, I buy a car that suits my needs. If it happens to only have some minor shortcomings, then aren't I lucky that I can buy something that nearly perfectly fits my needs and wants? At my age, I am very happy to have what I want, and for it to serve my needs so well. I don't weep, wail and mourn for its minor shortcomings ....

 

[Red XS]

I use LR like Stilson. I just see the standard box as 10 useable gears for road and sand conditions and don't really see it as a low range. Which is perfect for me as I don't really need that low a gear for dunes, but I still get many choices to use.

Even with the EJ253 I won't do 60Km/h in 5th high as the revs are too low for that speed, (I use 5th Low)

 

[Ratbag]

^ Gidday Red

I don't use LR like this on bitumen. Maybe 1% of the time.

However, on unmade roads I am probably in LR about 30-60% of the time. As you say, the LR gives fantastic flexibility. Having such a flat torque curve, the EJ-253 just makes it very useful and usable.

Roo2 will tow the trailer most places without using LR, but the gearing is different enough to make the LR more appropriate at times. As ST describes it: useful when one needs a half gear change ... :lol: .

Where I had to row Roo1 along with the gear lever, keeping the revs between 4,000 - 6,500 all the time to stay in that engine's sweet spot, Roo2 just does whatever I want it to do. No fuss, no bother. Love that kind of tractability in a car, any car.

 

[NachaLuva]

I avoid LR as much as possible to protect it. Heard of too many LR gearsets being heat damaged

 

[Ratbag]

^ Which models, NL?

There is no particular reason that the LR gear set should be any more stressed than any other lay gear set. The main design requirements are that the main shaft bearings are adequate to the task and that the gears and shafts themselves are strong enough to support the lateral forces put on them.

In fact, the Subaru LR layshaft and gears are in the same position as the layshaft in most of the BMC (Leyland) gearboxes that I have looked at.

Even though the gears themselves are interchangeable, it does not necessarily follow that anything else is - e.g. the housing, thrust washers, shaft end bearings, and the like.

At a logical level, it could well be that Subaru decided that the combination of the higher torque output of the EJ-251/253 engines and dropping the LR ratios to compensate was a solution to the excessive stresses generated by the higher numeric LR ratios of previous models. Just a thought bubble.

The problems that you assert are so common seem to occur mainly when people install the older LR gear sets into newer cars. As Bennie and others have said, it is essential in these circumstances to retrofit an oil feed to ensure that the gears are adequately lubricated.

As none of us here have experience as a Subaru gearbox design engineer, I suggest that any opinions any of us might have on this subject is little more than speculation.

I can say for certain that the limiting factors of my car have little, if anything, to do with its LR ratios ...
I could sit up under my LC, for example ...

And why does the Subaru OM now state that it is alright to drive the series II SG in LR all day, if towing, or on steep, winding roads?

 

[ateday]

I find in my MY03 that it will pull reasonably well in high range from about 1900/2000 rpm, 75/80km/hour in 5th. Below that rpm it complains.
The 1.59 low range is very good under just about all conditions, even with 65 profile tyres.
The 1.19 low was next to useless.
Brakes are sometimes needed on steep downhills. It is excellent on sand dunes as in the Simpson crossing.
I would not like a lower low range because the gearbox/transmission is not designed for it and problems may well result.
Even the torque multiplication affect with the 1.59 is probably stretching it a bit for extended use.

 

[NachaLuva]

The reason is the LR is right at the front of the gearbox up high so it gets starved of oil during a steep ascent at the very time it most needs it, not just for lubrication but also cooling

 

[taza]

And why does the Subaru OM now state that it is alright to drive the series II SG in LR all day, if towing, or on steep, winding roads?

My manual says to use the clutch to shift between the two at safe speeds upto 70kmhr, however ive changed at 130kmhr before... I wouldn't do it again for the stress reason.
It also states that it is there for when more traction is needed that high range cannot offer. It does state that it can be used for towing purposes, low traction, hilly or offroad situations. It does not soecify that it shouldn't be used onroad.

I have found that Subaru offer a stupid amount of variations across their whole range with all their features..
they offer so many good features, non of which are found in one single car. The WRX being one of the worst.

For example; my Forester came out with a piss poor, gutless motor that is only good for a boat anchor. While it offers a 1.447 low range that is atleast adequate. It comes with a single mass flywheel clutch setup, which is far superior to the dual mass setup in almost every way except for uber smooth feel and engagement. While the GT version had a motor that was just worthy of moving the heavy vehicle around but no low range.

 

[guzzla]

I have used the figures from the various Oz Subaru advertising brochures and the rolling circumference of the various tyres from the tyre calculator here.

Wow Ratbag, you are a man from my own OCD world.

When I was looking at purchasing my Forester back in 2007 I did much the same calculations (and at least Subaru still supplies the gear ratio specs unlike many manufacturers - and the mator magazines like Wheels don't give them any more) but I never worked out the low range figures. Seeing them there on paper surprises me that there is as little difference between them and normal range as there is. I can now understand why Subaru has dropped low range completely and gives an extra low 1st gear 3.818 ratio combined with the lower 4.444 diff ratio in the new SJ 2.0 manual Forester. That makes the overall 1st gear combined with the diff ratio on the new Forester of 16.961 compared with the almost identical overall ratio of 16.982 for the SG Forester. Of course the heavier mass, presumably less torque and slightly larger tyre diameter of the SJ Forester would still have to give the advantage to the SG Forester though.

The other surprise is that the new 6 speed gearbox shares a 1.947 2nd gear ratio with the 5 speed gearbox in my XT and that the 6th gear ratio of 0.738 is the same as the 5th gear ratio in my XT and they both share the same 4.444 diff ratio. Between them the SJ fits in 3 gears to play with compared with the 2 in mine. That would be nice, although I rarely feel like I'm short of a suitable gear. I like the fairly wide spacing between 4th and 5th gears in my Forester, which is in contrast to the fairly close spacing my V6 manual Camry had. I feel that Subaru really knew what they were doing when they lowered the 1st and 2nd gear ratios of the WRX gearbox for the XT. Back in 2007 I worked out that the km/h /1000rpm speeds of my XT in gears were 1st 7.9km/h, 2nd 14.0km/h, 3rd 20.0km/h, 4th 28.1km/h and 5th 37km/h. These calculations also seem to match up with the corrected readings I get using the true speeds shown on my Garmin. On the (typically inaccurate) speedo 5th shows 40km/h and 4th shows 30km/h.

Just to show how much lower the 1st gear ratio is in the XT than the X/XS, the X/XS high range diff x gearbox is 14.199, the low range is 16.982 and the XT is almost midway at 15.350. The XT's 215/55 17 tyres have an almost identical circumference to the X/XS's 215/60 16 tyres. I have rarely driven where I've felt I've needed a lower 1st - the place I can remember most being the decent on the couple of steep hills on the Cape Tribulation - Bloomsbury track in Far North QLD - and there I would have liked a 2:1 reduction. Not a nice feeling on a very steep slippery slope relying on the ABS brakes to slow the decent. (Having lived for all these years without ABS there are times when it would be nice to turn it off.) Surprisingly the turbo is quite flexible on light throttle at almost idle speeds in 1st gear.

Sorry for all this OCD stuff......:ebiggrin:

 

[guzzla]

The EJ-253 is happy at those revs, and will happily accelerate from there - not fast, but not labouring either.

In lower gears (either using LR, or just changing to 2nd or 3rd in HR), it is more than happy at 1,200 rpm. Not fast off the mark at those revs, but again, not labouring.

My XT will pull from 1000rpm (or even lower) in 4th or 5th but I never do it because below 1500rpm in 3rd, 4th and 5th the engine is grumbly and rough. Strangely that roughness isn't really obvious in 1st and 2nd gears. I found it such a contrast to my V6 Camry manual which would pull unbelievably smoothly like it was an automatic from a 700rpm idle in its tall 33km/h /1000rpm 4th gear to over 200km/h. Yet the XT is so beautifully smooth from 1500rpm where there is an instant transformation in behaviour.

 

[Ratbag]

Gidday Taza

And why does the Subaru OM now state that it is alright to drive the series II SG in LR all day, if towing, or on steep, winding roads?

My manual says to use the clutch to shift between the two at safe speeds upto 70kmhr, however ive changed at 130kmhr before... I wouldn't do it again for the stress reason.
It also states that it is there for when more traction is needed that high range cannot offer. It does state that it can be used for towing purposes, low traction, hilly or offroad situations. It does not soecify that it shouldn't be used onroad.

I have found that Subaru offer a stupid amount of variations across their whole range with all their features..
they offer so many good features, non of which are found in one single car. The WRX being one of the worst.

For example; my Forester came out with a piss poor, gutless motor that is only good for a boat anchor. While it offers a 1.447 low range that is atleast adequate. It comes with a single mass flywheel clutch setup, which is far superior to the dual mass setup in almost every way except for uber smooth feel and engagement. While the GT version had a motor that was just worthy of moving the heavy vehicle around but no low range.

I agree, and it's not confined to Subarus, or cars, FTM.

About the only way to get a "steak sandwich with the lot" is to buy the top of the range model. Which is precisely what we did when we bought Roo2 and RonnyRoo ... :iconwink: :biggrin:.

I also agree about the seriously underpowered 2.0L Foresters. As I have said (a lot ... ), the Impreza was the same. In the Impreza's case, it also had bad gear ratios and a lousy ECU tune that meant that the engine only really rocked at 4,000+ rpm. Then it really rocked!

Before you rush off and rip the low range gears out of your Forester, I suggest that you give it a fly for a while with the standard SG LR. You need to put a couple of thou on it to really get a feel for it. I know that the EJ-251 is not as torquey as the EJ-253 at low revs, but it's certainly not a basket case either, like your original 2.0L donk or the EJ-18 in my Impreza were.

BTW, Roo2's OM says nothing about changing from HR to LR below any particular speed. It does state not to exceed 188 km/h in 5th/LR ... :ebiggrin: :biggrin: - so does my driver's licence (it's in the very fine print) ... :lol: :rotfl:. In Victoria, that speed causes mandatory, on the spot loss of licence, and one can have one's car confiscated (maybe permanently ... ).

 

[jf1sf5]

Sorry Ratbag but the last few posts are more about engines than LR...:iconwink:

 

[Ratbag]

Gidday JF

Yeah. I noticed that too, mate ... :iconwink:

But at 0012H this AM, I was too knackered to be bothered moving them to the relevant engine thread. Will do it this morning.

From my Batphone

[EDIT]

Done.

[end edit]