Thread: All wheel drive vs 4 wheel drive vs ?

Originally Posted by one_iota

My Defender has a drum brake on the rear driveshaft. As I understand it, if the centre diff is not locked only the rear wheels are braked and so when a rear wheel is lifted the hand brake doesn't work. A chock was provided.

How does the parking brake system work in yours TB?

Technically, only the rear tailshaft is locked when the handbrake is applied. It is still possible for the rear wheels to spin in opposite directions through the rear diff centre. If jacking a rear wheel, engage the centre diff lock so the front axle becomes braked also.

Originally Posted by one_iota

My Defender has a drum brake on the rear driveshaft. As I understand it, if the centre diff is not locked only the rear wheels are braked and so when a rear wheel is lifted the hand brake doesn't work. A chock was provided.

How does the parking brake system work in yours TB?

It's the modern style with a motorised gear on each rear wheel to clamp the brake closed. So each rear wheel gets independently held.

Originally Posted by cjc_td5

Technically, only the rear tailshaft is locked when the handbrake is applied. It is still possible for the rear wheels to spin in opposite directions through the rear diff centre.

I have this happen to me in a series 3 parked on a steep concrete driveway with a 2 tonne trailer on the back. In gear (not 4wd) and handbrake on and holding - vehicle slowly slid down the drive with the rear wheels turning in opposite directions leaving rubber down the drive - was like watching in slow motion as it was so slow but it kept on going until I jumped in and applied the brakes.

Originally Posted by TB

It's the modern style with a motorised gear on each rear wheel to clamp the brake closed. So each rear wheel gets independently held.

The entertaining and informative Simon Jefferson takes us on a discovery tour of the underside of his....the parking brake component is pointed out in passing.

New 2020 Defender Underbody Tour + Review Using Low Ratio + Off Road Mode - YouTube

An update on the situation with the 6-cyl diesels' driveline being in 2WD when parked...

Andrew from TuffAnt did some pretty thorough testing with his D300 and confirmed that this is the case when the TR mode is set to Comfort (the default) or Eco. The front wheels are completely unrestrained when the engine is off and the park brake applied.

However when you select any of the off-road modes (tested GGS, Mud Ruts, Sand and Rock Crawl, but not known about Wade) if that mode is selected when you turn off the vehicle then the front driveline clutches appear to remain locked. This is equivalent to having a locked centre diff but is still an open front diff.

Definitely an improvement and something all owners of those vehicles should be mindful of.

Hi Everyone! Thank you for awesome tread. I presume, since we know D3.0 uses IDD, attached description of IDD transfer case is correct for D3.0 as well. However since Jaguar IDD uses permanent AWD system with standard 90% rear and 10% front torque, dynamically distributing it by IDD when needed and D3.0 has PWD, and needs to engage 2 clutches before IDD comes in force, it makes this system further more complicated then usual Juaguar transfer box - that's where all these "2WD drive only" mistakes come from. Also torque distribution should take longer them 100 ms quoted by Jaguar IDD. Not saying about possible steering problems when front wheels can not move quicker then rear wheels with AWD engaged. I see the only way, they could somehow avoid it is disconnect front axle when from wheels need faster spin then rear one. However JLR does not state D3.0 operates like rear wheel car in turns but instead they insist it works like proper AWD, i.e. no difference with D2.0 and Gas versions. That puzzles me out.

Hi,
I own a defender L663 D300 and have had the time so far to play off road with it (about 17000km off road now, 19,000 on road). The vehicle does a lot of things that are simply not explained to us when we buy it. When doing the old coach road in North QLD, I learned that your more there for the ride than actually worried about how it does it or how to do it. It plays tricks with the drive train and suspension. Also if you jack it up and have all 4 wheels of the ground and spin the wheels fast enough it disengages the front when I estimated it was doing just over 20km/hr (if it was on the ground). I also learned that the suspension moves weight around to compensate when needed. I have experienced this. BTW very disconcerting when the vehicle takes control and you are ignored (breaks and accelerator(brown stain moment)). How is all of this is done LR seems to be keeping close their chest and I would too. What blew me away when dropping over 1m dropoff or driving up it, it makes it so effortless. I have quickly learned that comfort mode is good 99% of the time.

I think when Richard Hammond described it as an off road super computer, he was right. I am now convinced it will go where ever you reasonably want to and in so much comfort. Are there bugs in the software?, you bet, but I have just placed an order for a 3rd.