Developing better low range for a Subaru

El_Freddo said:
My idea is to slot a high/low range setup between the centre diff and the splines of the driving gears and pinion shaft...

...I can draw up a diagram if it helps ;)

Cheers
Bennie
Click to expand...

If this was feasible and 'affordable' I wonder how that would go on my SVX. Probably blow up the transmission even quicker.

Not that the SVX is ever going to be anywhere close to being a rock climber. :lol:
 
If you do play around at the back of the box, do it on an STI 6 speed gearbox. Stronger, another gear and more readily available front and centre diff options.
 
I can understand the interest in modifying a Subaru gearbox to get a bigger reduction on low range, particularly by those owners with interest/experience/expertise in engineering. It's a challenge to be surmounted but it would make just as much sense to fit a Subaru with a live rear end from a Jeep as it does to think about putting portal axles on a Subaru (or on anything to be honest). It is an impractical modification.

Conventional/traditional 4X4 vehicles solve this problem by adding an additional reduction box to the transfer case. Because Subarus have what is essentially a front drive system with a power takeoff to drive the rear wheels this isn't an option. You can only play around with what you already have if you want your vehicle to still be a Subaru. You should use Subaru parts though adapting them from a recent model onto an early model or vice versa seems OK to me. Pick the strongest bits but make sure they're off a Subaru.

In my younger days I transplanted a later model drivetrain and suspension onto an early model rear engine Renault to run in motorkhanas but every part was Renault. I had a friend who started with a rear engine Renault hill climb car that eventually became a mid engined V8 (Ford) and this seems somehow wrong.

In my opinion this discussion should be about what a Subaru can do or what can be done with a Subaru, not what we can do to make a Subaru more like a traditional 4X4.
 
Red XS said:
4wd's usually stop when shifting into their 2+ reduction low ranges.
Click to expand...

Big 4wds have to stop as they do not have synchros on the low range. The only reason Subarus do not have to do this is that the low range has synchros. Given how small the synchros are it may be more difficult to shift at shorter ratios but I still think it would be possible.

El_Freddo said:
My idea is to slot a high/low range setup between the centre diff and the splines of the driving gears and pinion shaft.
Click to expand...

I had the exact same idea as soon as I opened up a gearbox ages ago. My main concern is that the tiny bearings on the pinion shaft may not cope with prelonged running at different speeds to the lay shaft, particularly with more torque going through them. They might be ok but its something to certainly consider.

I also have a rough concept design for a low range locking centre diff unit that could potentially be packaged into the same space as the current centre diff without need for custom casings, shifters or tailshafts. The concept would be a planetary style low range reduction coupled with a planetary style centre diff (how DCCD works). It would be a fully open diff when unlocked (probably with a rear bias) and true 4wd when locked. The low range ratio would likely be very very low, it might actually be difficult to make it not to low as it is impossible with this design to have a reduction less than 2:1. It may not even be possible to make it strong enough in the Subaru package.

But coming back to reality, that design makes a rear R160 diff lock or even a front locker look as difficult building a paper plane and that still hasn't happened yet. It is something that would take an engineer with ample money and tooling at their disposal months even years to design and build a prototype so unless I win the lotto it ain't going to happen..... A few more % reduction on the input on the other hand is actually something that could.

Beachworm said:
You can only play around with what you already have if you want your vehicle to still be a Subaru. You should use Subaru parts though adapting them from a recent model onto an early model or vice versa seems OK to me. Pick the strongest bits but make sure they're off a Subaru.
Click to expand...

I understand where you are coming from but using that logic you could really do bugger all to your car. With that logic, after market anything is out, so no turbos or exhaust upgrade or even lift kits for that matter as none of these were ever made by Subaru. I don't really see how a low range adaption is any different to a lift kit.
 
The trouble with posting ideas here is that I feel compelled to make them short and to the point and I inevitably fail to explain myself clearly. What I was trying to say is that it is important to retain the essence of the marque when making modifications. This doesn't preclude using aftermarket products, even if there is a Subaru option. What it does preclude, however, is using parts from a different brand of vehicle such as a live rear end from a Toyota or an engine from a Porsche. It also precludes making modifications, even using aftermarket products such as portal axles that destroy the essence of what the vehicle is.


Subarus are unique in that they are extremely competent on road and very competent off road. Making modifications that destroy that versatility is, in my mind, inappropriate. The vehicle ceases to be a Subaru. I see no problem in using a snorkel off a Mitsubishi because there is no Subaru option. Likewise, I see no issue with fitting a bigger, aftermarket turbo or fabricating a modified part for the suspension because none of these destroys the essence of the vehicle being a Subaru.


If you wanted to start from scratch and build a complete gearbox with a satisfactory low range, that is an acceptable modification. It's not Subaru but it simply makes the vehicle more capable off road without compromising its capacity on road and you haven't barstardised ( I use that word in it's correct context) the car by making it a hybrid.


I also accept that this particular point of view might be mine alone and I'm comfortable with that. Everyone else is entitled to see the world that way they want and I'm not suggesting that my paradigm is any better. It's just mine.
 
Ah, that was in response to the posts that were moved (I miss all of that) rather than improved low range modifications to Subaru gearbox. Yes I quite agree. Portals or solid axles on a Subaru defeat the purpose of having a Subaru... I actually had the arguments with someone on YouTube recently. Agreed mods should, where possible be in the spirit of Subaru being a road car and something different to the typical 4wd.
 
Yes, I did have a bit of a look, it's just difficult follow what order the posts were in after they have been moved to different threads. I incorrectly assumed Beachworms post came before the moved posts.
Don't get me wrong I am all for moderation :cool:
 
Rally said:
You wouldn’t know it from watching your off road videos! :lol:

Love watching them of course
Click to expand...
:rotfl::thumbsup:
 
Rally said:
If you do play around at the back of the box, do it on an STI 6 speed gearbox. Stronger, another gear and more readily available front and centre diff options.
Click to expand...


While that may be true it adds further cost - and 6 speeds offroad isn't going to be good for anything... If you could get a lower set of gearsets to mimic that of something near a 5 speed box but with a low 1st ratio it'd be a good way to go... but expensive - again!


Ideally the back of the box is the way to go as it will reduce the stress on the driving gears, reducing the chance of blowing a gear with the low range (been there done that, not fun! I believe it was a worn gear, long story...).

[MENTION=4168]Dedman[/MENTION], those tiny bearings on the pinion shaft shouldn't be carrying any torque loading, they're only there to ensure the pinion and lower layshaft can move independently with relative ease. So, yes, lubrication would need to be looked at to keep these rolling properly and from overheating. In theory they should be fine, in reality it could be a different story and an idea killer :(


Cheers

Bennie
 
You must log in or register to reply here.
Back
Top