Phantom grip

Barry said:
What I'm still trying to work out is, if the rear is open, is there any point in fitting a viscous LSD in the back, or pretty much not, as I understand from my talk with Michael at Scorpion last Friday?
Click to expand...

I thought there was a sticker somewhere on the rear diff. identifying if it was LSD or not??? Maybe this was just on the older models???
 
If it is open, I'd go plated. There are aftermarket ones but some are very noisy when turning- very clunky. Mine is factory and is quiet- I assume the R160 ones would be similar. I cannot see the point of having a really nice crawler low range if all you are doing is spinning wheels due too an open diff. If you already have a viscous LSD then maybe the crawler range would be the next step.
 
Barry said:
if the rear is open, is there any point in fitting a viscous LSD in the back?
Click to expand...

The standard viscous rear LSDs are next to useless. I wouldn't bother.

Rally said:
I cannot see the point of having a really nice crawler low range if all you are doing is spinning wheels due too an open diff.
Click to expand...

True that.

Our rear diff options are pretty limited (nothing nice like auto-lockers or ARB airlockers are available). Best thing that is actually available is probably a plated/clutch LSD. As Tony mentioned, he has a Subaru one in his Impreza (which I have seen in action - very nice!). Another user on here (scaddanr) has a Cusco in his Forester.
 
simxs said:
The standard viscous rear LSDs are next to useless. I wouldn't bother.



True that.

Our rear diff options are pretty limited (nothing nice like auto-lockers or ARB airlockers are available). Best thing that is actually available is probably a plated/clutch LSD. As Tony mentioned, he has a Subaru one in his Impreza (which I have seen in action - very nice!). Another user on here (scaddanr) has a Cusco in his Forester.
Click to expand...


That is all really useful info.

My primary use for lower gearing (still not 'crawlers', as such) is for climbing on relatively steep dirt roads in 'dry' conditions. In those conditions I'd expect both rear wheels 'on ground', and therefore LSD wouldn't operate anyway. Thats as I see it, am I right?
 
If the road is reasonably smooth and even then yes. But on that last trip we did to the Watagans it was reasonably steep and definitely not smooth and even, I found both the low first and the diffs I had to perform without problem. The problem was ground clearance. Even with me right rear wheel high in the air and the left front unweighted, and the front of the car grounded, I still had enough drive and grunt to easily get out. Yet there have been other times- say on the Abercrombie trip, where better diffs would have worked. The number of times when I needed better gearing is less than better traction. We don't have the ground clearance for it on ascents, although it would be good on descents.
 
Barry said:
In those conditions I'd expect both rear wheels 'on ground', and therefore LSD wouldn't operate anyway. Thats as I see it, am I right?
Click to expand...

If the track is steep but the ground is even, quite right, an LSD is probably not of much benefit.

However I find that, since our wheel travel is fairly short compared to larger offroaders, it doesn't take much unevenness of the ground for wheels to become unloaded and start to spin if you are trying to climb a hill or get over a bump. You then need to resort to momentum...

(As an aside, years ago my dad had an original shape Range Rover. While it had a manually lockable centre diff (actuated by inlet manifold vacuum - clever!) it had no cross axle diff locks or LSDs. Because of its very long travel coil springs and lack of anti-roll bars it could go through uneven ground while rarely spinning a wheel. Mind you, it certainly leaned a lot in corners on the road!)
 
simxs said:
If the track is steep but the ground is even, quite right, an LSD is probably not of much benefit.

However I find that, since our wheel travel is fairly short compared to larger offroaders, it doesn't take much unevenness of the ground for wheels to become unloaded and start to spin if you are trying to climb a hill or get over a bump. You then need to resort to momentum...

(As an aside, years ago my dad had an original shape Range Rover. While it had a manually lockable centre diff (actuated by inlet manifold vacuum - clever!) it had no cross axle diff locks or LSDs. Because of its very long travel coil springs and lack of anti-roll bars it could go through uneven ground while rarely spinning a wheel. Mind you, it certainly leaned a lot in corners on the road!)
Click to expand...

I agree that wheel travel is crucial in this regard, hence my current thinking that disconnectable sway bar links would be a real benefit! :lildevil: (I now think of disconnects as 'cheap and easy lockers'! :twisted: )
 
DCCD and Manual cars?

Rally said:
MY99 WRX (modified)- Front- Helical LSD Centre- DCCD. Rear- R180 plated LSD.
MY04 Forester-5 speed Front- Open Centre- Viscous LSD Rear-Viscous LSD

The centre diff in the WRX can pretty much be locked when in manual mode.
Click to expand...

Can the DCCD be fitted to the manual, or will they only fit into / work with the Auto box?
(Is it a matter of space in the case, or do they need specific connections on the wiring loom / other specifics?) They sound :twisted: !
 
I don't know. I guess they should as they do go in the back of the box- but whether there is room in a dual range box is at best a guess. WOuld probably have more chance in an XT. But 5 speed ones are very rare compared to 6 speed. I'd be more inclined at getting an 11kg centre diff- again, assuming they fit. The dccd does need wiring- and the 5 speed ones draw a lot of current compared to 6 speed, and are less sophisticated. Hence why I think the 11kg centre clutch is worth a look. The autos never came with DCCD- although not sure about the latest STI
 
Rally said:
I don't know. I guess they should as they do go in the back of the box- but whether there is room in a dual range box is at best a guess. Would probably have more chance in an XT. But 5 speed ones are very rare compared to 6 speed. I'd be more inclined at getting an 11kg centre diff- again, assuming they fit. The dccd does need wiring- and the 5 speed ones draw a lot of current compared to 6 speed, and are less sophisticated. Hence why I think the 11kg centre clutch is worth a look. The autos never came with DCCD- although not sure about the latest STI
Click to expand...

Thanks mate, apols for the 'quiz program'!:) I'n just really 'green' when It comes to all the Subi variations - so much more than with the old beetle!;)

Of course, WRX ... so hardly going to be auto ... :lol:

Hopefully I'm still a couple of years away from the 'pull down', before which I'd like to have sorted the absolute optimum to fit with the new low range gears.

Was thinking potentially your WRX set up, Front, centre & rear. The description of 'pretty much locked' sounded like gold to me! :lildevil:
 
Though this is getting a bit off topic (centre rather than rear diffs), since Tony has mentioned the other diff options I'd suggest taking a look at the info here: https://autospeed.com/cms/A_108266/article.html. As mentioned when I posted this previously, the correct units for measuring the 'stiffness' of a viscous LSD are kg.m per 100rpm. That is, kg of weight applied at the end of a one metre lever per 100rpm difference in rotation of the front and rear output shafts. (The article suggests measuring torque in kg/m which is incorrect.)
 
Barry said:
Thanks mate, apols for the 'quiz program'!:) I'n just really 'green' when It comes to all the Subi variations - so much more than with the old beetle!;)

Of course, WRX ... so hardly going to be auto ... :lol:

Hopefully I'm still a couple of years away from the 'pull down', before which I'd like to have sorted the absolute optimum to fit with the new low range gears.

Was thinking potentially your WRX set up, Front, centre & rear. The description of 'pretty much locked' sounded like gold to me! :lildevil:
Click to expand...

Pretty much locked referred only to the centre diff. When turning as say in a carpark, the car fights you the whole way and it is like the handbrake is on. When wheels are lifted, there is a momentary slip, but I'm finding it hard to replicate off road conditions on road. I also need another, standard WRX to compare it against. The rear diff is less aggressive than the centre diff in "locked" mode, but more aggressive than VLSD. I have noticed a difference in steering feel with the new front diff- and it is perhaps the only negative aspect of the conversion- albeit only slightly
 
simxs said:
Though this is getting a bit off topic (centre rather than rear diffs), since Tony has mentioned the other diff options I'd suggest taking a look at the info here: https://autospeed.com/cms/A_108266/article.html. As mentioned when I posted this previously, the correct units for measuring the 'stiffness' of a viscous LSD are kg.m per 100rpm. That is, kg of weight applied at the end of a one metre lever per 100rpm difference in rotation of the front and rear output shafts. (The article suggests measuring torque in kg/m which is incorrect.)
Click to expand...
Thanks for that link simxs. From that post I guess that, whatever variation I choose for the centre diff, it can be done separate to opening the case to fit the low ratio gears. Therefore, can do it 'one step at a time'! :)

Rally, yes understood that the 'fully locked' comment was about the centre diff. Ideally I'd like to be able to achieve this with the centre diff when required off road, then return it to normal when on-road. Perhaps a DCCD will approximate this.

OK, will now take my musings to a separate thread...
 
Last edited:
You must log in or register to reply here.
Back
Top