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+--- Thread: Sand Setting on Evoque (/Thread-Sand-Setting-on-Evoque)
RE: Sand Setting on Evoque - J77 - 08-05-2012 07:03pm
Got it in one.
RE: Sand Setting on Evoque - mark_n - 09-05-2012 04:22am
I wld have thought that any accumulated transmission windup was released when the viscous couplings were themselves released or the transmission put into neutral.
RE: Sand Setting on Evoque - lrdaft - 09-05-2012 06:33am
Evoque doesn't have a viscous it has a haldex unit in the rear diff to provide 4wd not enough time to explain how it works but in sure someone will provide the answer shortly
RE: Sand Setting on Evoque - Donny Dog - 09-05-2012 01:30pm
This appears to give the answer - and, no, it's not a wind-up!!
"The Haldex Electronic Control Unit (ECU) disengages the Haldex clutch in the centre coupling as soon as brakes are applied to allow ABS work properly. When performing tight low-speed turns (e.g. parking) the clutch is disengaged by Electronic Control Unit to avoid "wind-up" in transmission. When Electronic Stability Programs (ESP) are activated the Haldex is disengaged to allow the ESP system to effectively control the vehicle. This applies under acceleration and deceleration conditions".
Presumably similar disengagement is, or in theory could be, performed if the Evoque was left in 'sand' setting and then run on a low-slip surface such as tarmac.
RE: Sand Setting on Evoque - jitenc - 09-05-2012 02:01pm
(08-05-2012 09:59am)XFullFatTim Wrote: Your Evoque, and all 4WD Evoques, use the viscous coupling to determine how much power to send to the rear wheels as well as the fronts. In normal driving something like 95% of the drive goes to the front and 5% to the rear, the viscous coupling can change this to be something like 95% rear and 5% front depending on traction, additionally it can send power from side to side using the ABS and TC to the wheels with most grip.
Launch control, as used in sand mode "locks" the VC and sends equal power to all the wheels. In addition to the VC Evoque and Freelander2 have an intermediate reduction drive, (aka IRD) which acts like a differential. When you go round corners as you know the inside wheels rotate at a differ speed to the outside wheels ( thanks to the differential in the axle) by locking you remove this ability for the wheels to rotate at different speeds, and this manifests itself as damage to the drive system. If you get transmission wind up then there are 2 options to unwind it if you haven't already done damage - reverse round a few corners (inconvenient) or find a slippery surface like wet grass and you might hear the wheel slip or a bang, you hope it isn't a bang!
Try googling transmission wind up or better still take yourself on a Land Rover Experience course as they have a very nice video that explains how diffs, diff locks and limited slip differentials work and what transmission wind up is and how to avoid it.
Sorry I cannot explain very clearly, maybe Richard will do a better job.
Thanks Tim, I think this is the only post that has got me more confused and at the same time interested to see how the whole thing works. I think we need to book a LR Experience for Evoque members only... to mess around in Demo cars... won't really like to mess in mine first...
RE: Sand Setting on Evoque - Biker - 09-05-2012 10:22pm
I'm assuming ESP is de-activated when in sand mode? If that is the case, you can get wind-up. If not, then no worries.
RE: Sand Setting on Evoque - Donny Dog - 09-05-2012 10:45pm
(09-05-2012 10:22pm)Biker Wrote: I'm assuming ESP is de-activated when in sand mode? If that is the case, you can get wind-up. If not, then no worries.
See my earlier post above.
RE: Sand Setting on Evoque - crimson_flames - 16-05-2012 03:11am
So Donny, does that mean its ok to use the sand mode on tarmac and go fast on corners?
RE: Sand Setting on Evoque - Donny Dog - 16-05-2012 08:33am
(16-05-2012 03:11am)crimson_flames Wrote: So Donny, does that mean its ok to use the sand mode on tarmac and go fast on corners?
It doesn't specifically say it disengages at high speed, and I'm in no position to offer any guarantees, but the technology is clearly there to protect the transmission in the cases listed, and I can't see why it wouldn't do so in any circumstance where there was an operational conflict..