A few off road questions

[Symo Advanced Member Find all posts View Profile Close Symo]

I made a video, will post here when I edit it of dif lock vs unlock on the climb, for what ever reason with the dif locked in L4 the car skewed off line and tried to climb the rise head on when the wheels came off the ground, possibly due to increased torque to the wheels with traction cause wheel spin the moved the vehicle. With the diff left unlocked in LSD mode the car climbed straight with little wheel spin of fuss. The TRC does all the work.

[Fred63 Advanced Member Find all posts View Profile Close Fred63]

A few untruths here, allow me (self proclaimed expert to correct them):

1. The 150 Prado is in H4 permanently
2. The 150/120 Prado uses a Torsen LSD centre, it is neither open nor locked
3. The centre Torsen diff can be locked at the push of a button in either H4 or L4
4. The torque split is always 1:1 (often incorrectly referred to 50:50 - why not call it 200:200? see?)
5. There is about a 10% difference (seat of the pants) difference between unlocked centre and locked centre with TC still on\
6. There is a very slight difference between H4 TRC and L4 A-TRC (H4 retards throttle and brakes wheels, L4 only brakes wheels)
7. 99% of the time if your tyres are down to 18psi you can drive on and off the beach and along it in H4 with both TRC and VSC on and it won't bother you (I have extensively tested this and it so long as you are not half bogged leave it on, but there is no harm in turning it off)
8. I tested climbing a 600mm high vertical drop off in H4, L4, diff unlocked and locked and found the best combo with TWO wheels off the ground was ironically L4 diff UNLOCKED, don't know why.
9. The off road manual clearly states to leave the diff unlocked and only lock it when you are having trouble
10. THe prado will not spin one wheel if it comes of the ground, one rear wheel always has drive (centre diff lcoked or unlocked) the difference is about 10% drive loss in LSD mode.
10. You can tackel 90% of off-road terrain in H4 with TRC and VSC still on
11. L4 is useless on sand, the 410nm or 450nm is more than enough to move the Prado along with ease in H4, L4 will just burn fuel and heat the engine and oil up for zero benefit. (always makes me laugh watching someone revving the crap out their car in L4 and going no where, while someone else idles along slowy behind them in H4 1st or 2nd.

Nice post...

I agree with all points from what I have tried so far.
I will 100% confirm point 8 sandstone step near vertical unlocked as described in my previous post.
pics in this post http://www.pradopoint.com/showthread...l=1#post531947

Fred

[JohnC80 Junior Member Find all posts View Profile Close JohnC80]

Some great info being posted. I'm up the beach in 2 wks time. Even though it's a very easy beach I'm sure I can find some sand to play in. Also hitting glasshouse soon so will test a few things there.

Last beach trip I tried to climb a dune that is about a 50m run with a steep climb. The traction control on dug it in. Low range with and without diff lock was useless. H range and some right foot did the trick. Interestingly, the patrol would crawl up it in low range. Maybe a clearance thing as the prado was riding on it's belly?

Symo you have some great points. How would you tackle a 300m run up a dune that is fairly steep and deep soft sand?

Great posts guys. Thanks again.

[AK7 Senior Member Find all posts View Profile Close AK7]

I'm no expert but from what I'd read, the centre diff unlocked torque split was usually 60/40 rear bias (as r4ndll said). Would be good to see whitepapers on this.

8. I tested climbing a 600mm high vertical drop off in H4, L4, diff unlocked and locked and found the best combo with TWO wheels off the ground was ironically L4 diff UNLOCKED, don't know why.

With a vertical climb, if all wheels have traction, the distance travelled by front wheels versus rear wheels may not be the same, meaning the locked centre diff would be adding unnecessary load to the drivetrain. I'd expect that the difference in rotation speed between front and rear wheels would also change at different points during the climb.

11. L4 is useless on sand, the 410nm or 450nm is more than enough to move the Prado along with ease in H4, L4 will just burn fuel and heat the engine and oil up for zero benefit. (always makes me laugh watching someone revving the crap out their car in L4 and going no where, while someone else idles along slowy behind them in H4 1st or 2nd.

I'm all for using and recommending H4 in sand, but not exclusively. I had a situation a while back going up a steep sandy hill with deep ruts where the car was labouring to get up in H4 with VSC/TRC off, diff lock on and low tyre pressures. I switched to L4, 3rd or 4th gear and it just cruised up. The only thing I can put that down to is that when TRC is "disabled" in H4, it doesn't fully disable, but significantly reduces the effects of TRC (there are several reports on PP that this is how TRC Off in H4 behaves) and is reducing engine power when it gets wheel slip.

John80, there was a great comment a while back regarding the diff lock along the lines that "if the ground moves under your feet, engage the diff lock, otherwise leave it unlocked."

My $0.02 on the dune climb:
H4, 2nd or 3rd gear
VSC and TRC off
Centre Diff Lock on
2nd Start on (Auto)
Tyre pressure 16-18PSI

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

4. The torque split is always 1:1 (often incorrectly referred to 50:50 - why not call it 200:200? see?)
5. There is about a 10% difference (seat of the pants) difference between unlocked centre and locked centre with TC still on\
.

I'm no expert but from what I'd read, the centre diff unlocked torque split was usually 60/40 rear bias (as r4ndll said). Would be good to see whitepapers on this.

From Toyota themselves: http://www.toyota.co.nz/about-toyota...-road-terrain/

"At the heart of Prado's full time 4WD system is a Torsen mechanical limited-slip centre differential.

The Torsen LSD system helps optimise traction.

The torque sensing system can automatically and instantly change the torque split ratio front and rear depending on driving conditions.

Under normal conditions the drive torque is split 40% front, 60% rear and is variable up to 30% front, 70% rear dependant on driving conditions.

For example, the system provides a 30:70 torque split when the vehicle is accelerating around a curve to suppress the chance of under steer and enhance cornering performance.

In more aggressive off road situations, the centre differential can be locked using an electronic system. Locking the centre differential splits drive torque 50:50 between the front and rear axles, making it easier to navigate rough terrain."

Now my 120 doesn't have all that fancy traction control malarkey. I get the option of HH, HL, N, LL on my old school second stick. I get no choice of leaving the centre diff unlocked in Low Range.

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

A few untruths here, allow me (self proclaimed expert to correct them):

1. The 150 Prado is in H4 permanently
2. The 150/120 Prado uses a Torsen LSD centre, it is neither open nor locked
3. The centre Torsen diff can be locked at the push of a button in either H4 or L4
4. The torque split is always 1:1 (often incorrectly referred to 50:50 - why not call it 200:200? see?)
5. There is about a 10% difference (seat of the pants) difference between unlocked centre and locked centre with TC still on\
6. There is a very slight difference between H4 TRC and L4 A-TRC (H4 retards throttle and brakes wheels, L4 only brakes wheels)
7. 99% of the time if your tyres are down to 18psi you can drive on and off the beach and along it in H4 with both TRC and VSC on and it won't bother you (I have extensively tested this and it so long as you are not half bogged leave it on, but there is no harm in turning it off)
8. I tested climbing a 600mm high vertical drop off in H4, L4, diff unlocked and locked and found the best combo with TWO wheels off the ground was ironically L4 diff UNLOCKED, don't know why.
9. The off road manual clearly states to leave the diff unlocked and only lock it when you are having trouble
10. THe prado will not spin one wheel if it comes of the ground, one rear wheel always has drive (centre diff lcoked or unlocked) the difference is about 10% drive loss in LSD mode.
10. You can tackel 90% of off-road terrain in H4 with TRC and VSC still on
11. L4 is useless on sand, the 410nm or 450nm is more than enough to move the Prado along with ease in H4, L4 will just burn fuel and heat the engine and oil up for zero benefit. (always makes me laugh watching someone revving the crap out their car in L4 and going no where, while someone else idles along slowy behind them in H4 1st or 2nd.

Cool, more experts more untruths lol.....

3. In a 120 the odds are there is no button. It's a lever.
4. 50:50 is percentage people refer to %, 1 to 1 is ok but it gets difficult when it's 40/60 how does 1:1 work? 200% doesn't work either.

The rest gets confusing, but some good testing & ideas some cold make for endless arguments /discussions.
Good post

[spike69 Senior Member Find all posts View Profile Close spike69]

From Toyota themselves: http://www.toyota.co.nz/about-toyota...-road-terrain/

"At the heart of Prado's full time 4WD system is a Torsen mechanical limited-slip centre differential.

The Torsen LSD system helps optimise traction.

The torque sensing system can automatically and instantly change the torque split ratio front and rear depending on driving conditions.

Under normal conditions the drive torque is split 40% front, 60% rear and is variable up to 30% front, 70% rear dependant on driving conditions.

For example, the system provides a 30:70 torque split when the vehicle is accelerating around a curve to suppress the chance of under steer and enhance cornering performance.

In more aggressive off road situations, the centre differential can be locked using an electronic system. Locking the centre differential splits drive torque 50:50 between the front and rear axles, making it easier to navigate rough terrain."

Now my 120 doesn't have all that fancy traction control malarkey. I get the option of HH, HL, N, LL on my old school second stick. I get no choice of leaving the centre diff unlocked in Low Range.

Thanks R4ndll, nice to have it from the Toyota horse’s mouth.

Agreed though, I like the simplicity of my 120’s 2nd lever. If I engage HL or LL,the centre diff is locked. Simple!

Maybe one of these days I’ll take a 150 for a spin and try all the various options with TRC, VSC etc. Might get a pleasant surprise…..

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

11. L4 is useless on sand, the 410nm or 450nm is more than enough to move the Prado along with ease in H4, L4 will just burn fuel and heat the engine and oil up for zero benefit. (always makes me laugh watching someone revving the crap out their car in L4 and going no where, while someone else idles along slowy behind them in H4 1st or 2nd.

Well, you've obviously never driven on some of our very, very soft beaches like down Esperance Way and further around the south coast of WA.

Pushing the car in H results in higher fuel consumption and increased trans and exhaust gas temperatures. Running in L places less stress on mechanical components, cooler exhaust and cooler trans.

I've done some testing to see which combination works easiest for the car. And, when in soft sand in L most times the car will not be exceeding 30 or 40km/hr so there will not be any excessive revving. Only lunatics will rip along beaches in H at breakneck speeds, especially more so when tyres are deflated.

Some beaches are so hard you can roller skate along them such as the one at Esperance Bay. So you need to select the best gear and high or low and tyre pressures to suit.

[rooboy Junior Member Find all posts View Profile Close rooboy]

And wait until the little red tranny light starts glowing at you if it's an auto.

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

Well, you've obviously never driven on some of our very, very soft beaches like down Esperance Way and further around the south coast of WA.

Pushing the car in H results in higher fuel consumption and increased trans and exhaust gas temperatures. Running in L places less stress on mechanical components, cooler exhaust and cooler trans.

I've done some testing to see which combination works easiest for the car. And, when in soft sand in L most times the car will not be exceeding 30 or 40km/hr so there will not be any excessive revving. Only lunatics will rip along beaches in H at breakneck speeds, especially more so when tyres are deflated.

Some beaches are so hard you can roller skate along them such as the one at Esperance Bay. So you need to select the best gear and high or low and tyre pressures to suit.

Agree, L4 is definitely the go in soft sand. More capable, easier on vehicle.

Load burns fuel worse than r.pm. H in soft sand & your stressing it out. Trans temps will be very high.

[JohnC80 Junior Member Find all posts View Profile Close JohnC80]

Yep I agree with the load, fuel, soft sand points. Last beach trip which was my first with the new car I kept a constant eye on revs, gear selected and fuel usage. Car certainly didn't like low revs.

As pointed out earlier though, in the soft sand climbing a dune the car did not like the locked centre diff. I never tried unlocked in L.

[Stoo Junior Member Find all posts View Profile Close Stoo]

Why does driving in high range put more stress on the car?

The key to driving in soft sand is obviously to keep up a reasonable speed. I would have thought that 1st gear in low range would be too slow.

I don't understand why using 2nd-3rd gear in low range is better than 1st-2nd gear in high range. Engine RPM is the same, vehicle speed is the same, just a different combination of gears.

The only difference I see is that in low range you need to change gears more often when you want to change speed.

The manual says to use high range when driving on sand and leave the diff unlocked. That's what I do and it seems to work pretty well. I usually turn off the traction control (despite what the manual says) but that is only so I don't have to listen to all the buzzing noises.

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

Dunno if its different in the 150 but I run a scangauge to keep an eye on my AT temps. I mostly run in High Range on sand. A long High range run in soft sand will see the temps climbing. If they get too high for comfort, I just drop into Low Range and the temps will soon drop back down. High Temps = Bad for your AT fluid. LR gives also you more torque at lower speed, which useful in the soft heavy sand.

Don't forget Sand isn't Sand - South Australian beaches are very different to Fraser for eg. You have to drive to the conditions. Hard sand - More likely to use HR. Soft deep sticky sand - More likely to use LR

I don't pretend to fully understand an auto's torque convertor but my understanding is that low range gives you more torque at higher rpm but slower speeds, therefore less slipping of the torque convertor = less generated waste heat = better for the AT fluid and box. I am sure someone will correct me here though

[AK7 Senior Member Find all posts View Profile Close AK7]

From Toyota themselves: http://www.toyota.co.nz/about-toyota...-road-terrain/

Nice! Thanks

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Beaches we have here are way firmer than the fluffy powder in WA, especially at the end of summer. H4 is pretty good most times but I agree when the sand is so soft you are down to 16psi and below L4 is the only sensible choice. And second start.