Rear Wheel Drive or All wheel Drive

[DaveXT]

I mostly leave my Challenger in all wheel drive except when going on longer runs I will slip it into AWD to save fuel.
I went on a longer run recently and found no difference in fuel consumption.
I am sure I will save a little in wear and tear running in RWD but is it worth it
when AWD offers superior grip and handling?
Just throwing it out there!

[900canoes]

2wd on sealed roads unless its raining, then its AWD ... and also for dirt roads.

[Ballfyboy]

Mine has not been in RWD only mode for about 40,000 km. No problems yet...

[Bobkat]

Mine has not been in AWD only mode for about 40,000 km. No problems yet...

Hm, must read manual and find out about this AWD stuff

Been there, done that already and now thinks that this might get the bloody knob away from my knee

[wasarangie]

Dirt roads and if traveling on wet roads mine is in AWD. On highway runs it is in RWD. I find the transfer case lever hits my leg when in AWD,so highway running it is moved to RWD mode. Cannot see a problem running in AWD all the time.

[Marty V]

I drive mine in 2wd all the time unless it really wet... I have to do a U turn on a busy hwy everyday and find the ASC slows me down even in the dry so i usually flick it off while I do that and I can get into the traffic much quicker... When its wet I'll usually fick it into AWD instead...

Apparently Ed Ordinsky who Rallied Mitsubishi's for many years always drove his MMAL supplied Pajero in AWD for the handling/balance and grip but I guess he wasnt paying for his fuel...

[aaron.miller]

I drive mine in 2wd all the time unless it really wet... I have to do a U turn on a busy hwy everyday and find the ASC slows me down even in the dry so i usually flick it off while I do that and I can get into the traffic much quicker... When its wet I'll usually fick it into AWD instead...

Apparently Ed Ordinsky who Rallied Mitsubishi's for many years always drove his MMAL supplied Pajero in AWD for the handling/balance and grip but I guess he wasnt paying for his fuel...

That asc is a killer, several times i have forgotten to turn it off waiting for a gap to turn right across the traffic. I gun it to make it thru the gap and halfway across the asc kicks in and its a oh shit moment. Its only a problem in 2wd.
That being said i would've never even bothered with those gaps in the old disco 2, the challenger is sooo much quicker

Aaron

Aaron

[fuelconsumption]

I mostly leave my Challenger in all wheel drive except when going on longer runs I will slip it into AWD to save fuel.
I went on a longer run recently and found no difference in fuel consumption.

Would it actually save fuel in RWD? AFAIK (and I stand corrected if wrong) the challenger does not have freewheel hubs, so the front diff is always turning whether in RWD or AWD, and I suspect the centre diff also spins in both cases. However, in AWD the drive actually passes through the centre diff while in RWD it does not, so maybe there is a very small fuel saving in RWD.

I am sure I will save a little in wear and tear running in RWD but is it worth it
when AWD offers superior grip and handling?

Tyre wear may even be lower in AWD as the drive is shared evenly between front and rear. However, in AWD there is more wear and tear on the centre diff, front diff, and front CV joints. Personally I normally use RWD, but will engage AWD in wet, slippery or steep on-road conditions, especially when towing.

I note that the AWD 'super-select' is more sophisticated than on my older '93 Pajero, employing a viscous coupling in conjunction with the centre diff, presumeably so the centre diff locks up if wheelspin occurs preferentially at front or rear.

[DaveXT]

Would it actually save fuel in RWD? AFAIK (and I stand corrected if wrong) the challenger does not have freewheel hubs, so the front diff is always turning whether in RWD or AWD, and I suspect the centre diff also spins in both cases. However, in AWD the drive actually passes through the centre diff while in RWD it does not, so maybe there is a very small fuel saving in RWD.




Tyre wear may even be lower in AWD as the drive is shared evenly between front and rear. However, in AWD there is more wear and tear on the centre diff, front diff, and front CV joints. Personally I normally use RWD, but will engage AWD in wet, slippery or steep on-road conditions, especially when towing.

I note that the AWD 'super-select' is more sophisticated than on my older '93 Pajero, employing a viscous coupling in conjunction with the centre diff, presumeably so the centre diff locks up if wheelspin occurs preferentially at front or rear.

There are no free wheeling hubs but I think the front diff disengages at the front diff.
It could be argued that in AWD wear is shared evenly with front and rear diffs and axles etc.

[fuelconsumption]

There are no free wheeling hubs but I think the front diff disengages at the front diff.

That doesn't seem right, because the front propeller shaft definitely rotates when the vehicle is in motion in neutral, in RWD. Bottom line is that the front diff definitely spins (and therefore uses a little more fuel) whenever the front wheels rotate, even when in RWD. For this reason, I personally would prefer the vehicle to have free-wheeling front hubs. The fuel saving is small, and can be judged from the ADR fuel consumption specs for the 2WD and 4WD versions of the Challenger, 8.2 vs 8.3 l/100km.

It could be argued that in AWD wear is shared evenly with front and rear diffs and axles etc.

Correct, but personally I do NOT want my front CV joints carrying a load at all times. CV joints are a right PITA, they wear out, and if you have replaced as many of them as I have, filthy, stinking, rotten things that they are, then you would prefer them to be turning without load most of the time so they may last forever.

[DaveXT]

Bugger I am going to have to climb under mine tomorrow to check the front Shaft!
You are right about the front CVs they will wear more.
I bet the different fuel consumption figures are more about the weight differences between the 2wd and 4wd versions.

[fuelconsumption]

Bugger I am going to have to climb under mine tomorrow to check the front Shaft!

I don't have any sympathy Dave, because it is thanks to you that I was climbing under my vehicle last night checking my front shaft .....

I bet the different fuel consumption figures are more about the weight differences between the 2wd and 4wd versions.

Agreed that the weight difference will also be a player, though the 4WD version weighs only 120kg more, which I would expect to have a negligible effect under highway conditions, yet the highway consumption figures are not identical, but 7.2 vs 7.3. I would bet that, at least on the highway, the slightly lower consumption of the 2WD version is mainly due to the lack of extra diff(s) spinning around, but we will never know for sure. However, if you get under your car after travelling on the highway, the front diff will be noticably warm, despite having a 100 km/hr blast of cold air over it, so it is definitely wasting power. (So now you will have to get under your vehicle yet again cos of me ) I may do some back-of-envelope calcs on this just for fun.

[wasarangie]

There are no free wheeling hubs but I think the front diff disengages at the front diff.

This is correct..

The diff has a clutch that is disconnected via a vacuum actuator. The actuator is on the underside of the diff housing towards the rear of the vehicle.

Could have been deleted on later models though. I remember reading that some people reported not seeing an actuator on the later models. Must then disengage at the transfer box, not sure about that.

In any case I can turn the front driveshaft by hand with the engine running (to release the clutch) in 2WD mode. Vehicle on ground and stationary. With out the engine running it will not have vacuum and trying to engage 4WD.

[fuelconsumption]

This is correct..

The diff has a clutch that is disconnected via a vacuum actuator. The actuator is on the underside of the diff housing towards the rear of the vehicle.

Could have been deleted on later models though. I remember reading that some people reported not seeing an actuator on the later models. Must then disengage at the transfer box, not sure about that.

In any case I can turn the front driveshaft by hand with the engine running (to release the clutch) in 2WD mode. Vehicle on ground and stationary. With out the engine running it will not have vacuum and trying to engage 4WD.

Curiouser and curiouser said Alice. In my 2012 vehicle, I cannot turn the front driveshaft by hand with the engine running (to release the clutch) in 2WD mode. However, it may be that the vehicle needs to be driven a short distance for the said diff-clutch to disengage, or it may be that the later model is different. I will investigate further tonight. Bugger, this probably means I need to take the bashplate off for a closer look.

[DaveXT]

This is correct..

The diff has a clutch that is disconnected via a vacuum actuator. The actuator is on the underside of the diff housing towards the rear of the vehicle.

Could have been deleted on later models though. I remember reading that some people reported not seeing an actuator on the later models. Must then disengage at the transfer box, not sure about that.

In any case I can turn the front driveshaft by hand with the engine running (to release the clutch) in 2WD mode. Vehicle on ground and stationary. With out the engine running it will not have vacuum and trying to engage 4WD.

Thanks you have saved me a crawl! And you are right if you loose vacuum the front diff will engage.
I have noticed if you shut the engine down before coming to a complete stop you will hear a clunk coming from that region.