Best drive mode for rainy weather?

[Plati]

Great information.
I thought the wiki article I posted here said the same thing (with less detail) https://en.wikipedia.org/wiki/ControlTrac

 

[JExpedition07]

For a few years now on Explorer and I believe the F-150 maybe the same time

have a read of this https://www.f150forum.com/f118/awd-vs-automatic-4wd-4a-318140/index6/#post5075900

Post 52 if you lose the direct link

Ah, gotcha. Ford used BorgWarner Transfer Cases on the 3rd gen that are likely regular transfer cases that can lock on demand. I was under the impression they had to lose traction to send power. Clutches would allow for slip. Maybe they brought the new transfer cases in house or a new supplier. This is my T-Case sticker:



I’m curious what year Ford switched systems now. Some members with 2017s also said they believe power goes forward at all times on acceleration.

 

[Plati]

Borg Warner supplied the original system for Ford Expedition and has supplied all versions since. 1998. Electromagnetic Clutch controlled by a microcontroller.

Original patent was priority date 1992
https://patents.google.com/patent/US5485894A/en?oq=5485894

 

[JExpedition07]

Borg Warner supplied the original system for Ford Expedition and has supplied all versions since. 1998. Electromagnetic Clutch controlled by a microcontroller.

Original patent was priority date 1992
https://patents.google.com/patent/US5485894A/en?oq=5485894

I’ll admit I was lazy on the fly and didn’t read all the links posted. It appears only some 1st gen Expeditions waited until traction was lost to send power forward. From 2002 on they transfer power forward in increments and can anticipate traction loss in advance and none of them are old style T-Cases. Thanks for the info as you’ve taught me something I didn’t previously know. Your right they are all clutch packs and allow for slip. This still however doesn’t change 4WD adds no additional traction for braking or turning (unless accelerating around said turn). So our 4WD system is much credit to BorgWarners Torque on Demand system....Here is a vid I found.

 

[shane_th_ee]

Except what’s happening here is that the torque during acceleration applied to the rear wheels is greater than the available traction at the rear wheels, which results in wheel spin/slipping. Having the transfer case in 4A will not increase traction, but it will divide that torque between the front and rear wheels. And a smart system like the one in the Expedition will vary the power distribution to account for a wheel slipping.

 

[Plati]

J ... I've read this stuff for years and still not sure that you're not actually correct about "wait until traction is lost to send power forward". It seems that the sensors measure the rotation of both (front & rear) axles and start sending (additional?) power forward when the rotation is greater in rear than front. It seems to me that the front axle might be "primarily" rotating due to wheel contact with the road vs drive from TCase. Clearly when traction is lost in rear, that happens and drive power is incrementally added to front. I might have some of my terms wrong.

I originally bought my first Expy (1999) new because I read the article in Design News and liked the Borg Warner design. Of course the big draw back then was "on the fly", being able to switch to AWD or out while driving down the road ... or 4WD if stopped, but at least there was no get out and lock hubs dance.

and in that video (which has no sound dammit) they state TOD has increased gas mileage over full time AWD. this implies at times no power to front while in AWD

Dang, now I gotta go back and read all that stuff again. Sometimes it takes (me) a lot of study to really understand.

 

[JohnT]

This stuff is changing fast, if you had told me 10 years ago that a phone based algorithm could match pictures taken on a big fast glass lens using a a pinhole lens I'd have said you were mad.

Now we have huge computing power in cars monitoring sensors, accelerometers, gps etc figuring out whats happeing almost instantly.


I've had the display showing equal power applied to all 4 wheels on a straight dry road at slower speeds but accelerating (not hard)so I don't think it just waits, for given scenarios it seems to preemptively direct power.

In sports mode applying power at any speed while turning seems to push power to all 4 corners. equally cruising at 120km it sends all the power to the rear.

Snow mode softens the throttle, dials down the torque created by the engine at slow speeds and seems to keep 4 way power engaged way longer.

 

[JohnT]

Looks like BMW is going down a similar path


skip to 4:30 if you are impatient

 

[Artie]

So what’s the life expectancy of these clutch packs?

 

[Plati]

So what’s the life expectancy of these clutch packs?

They've been stock since first Expedition in 1998.
Not sure if that answers your question.

I've never heard much about them breaking.
I have heard its a good idea to change the fluid at least by 150K.

 

[JohnT]

If they are anything like the limited slip diffs the only things that kill them are water, heat and wrong oil with friction modifiers such as molybdenum disulfide. The last one usually put in by an inexperienced tech at a fast oil change place.

German ones are likely as fussy as their gearboxes about bronze eating additives, Fords I'm not so sure about.

I suspect if you get to overheating the oil, you've got bigger problems elsewhere brewing in your drive train.

 

[JExpedition07]

They are pretty solid, many have 200k plus on the BorgWarner system and still operate correctly. The vacuum portion of the 4WD system requires the most maintenance over its life. Hub actuators, check valves, solonoids etc.

 

[Artie]

Thanks y’all for all that info! Anytime I hear the word ‘clutch’ I’m assuming it’s a consumable item but this sounds way different than a transmission clutch.

FWIW I run 4A in the rain here. In 2A I sometimes feel wheel slipping on the painted areas of the road like crosswalks and such but not at all in 4A.

 

[Randy Schmidt]

Thanks y’all for all that info! Anytime I hear the word ‘clutch’ I’m assuming it’s a consumable item but this sounds way different than a transmission clutch.

FWIW I run 4A in the rain here. In 2A I sometimes feel wheel slipping on the painted areas of the road like crosswalks and such but not at all in 4A.

Just like Arie, I run 4A when it rains. Maybe for a piece of mind. I really haven't experience any slipping or sliding in 2A, but 4A makes me feel like I am "preventing" any slipping or rear wheel spin.

 

[aggiegrad05]

Just like Arie, I run 4A when it rains. Maybe for a piece of mind. I really haven't experience any slipping or sliding in 2A, but 4A makes me feel like I am "preventing" any slipping or rear wheel spin.

Same. A couple of road trips ago I was on the highway in driving rain (in 4A). I was pulling around a semi and felt some unsteadiness from the rear. Looked down at my power distribution gauge in the cluster and saw the front power increase and the rear settled down. Worked like a champ.

 

[benyl]

I’ll just leave this here.





Sent from my iPad using Tapatalk

 

[JExpedition07]

I’d recommend reading the article and the engineers standpoint. These Jeeps have non proportional adjusting valves and have no ABS. On an relatively old school vehicle test these results are plausible, results would be different on different vehicles. In this case the fronts have more braking power and will lock up before rears, but in 4WD they all are forced to spin the same so they lock up together. Locked wheels have capability to stop faster in a straight line because they act as plows. Keep in mind it can be easier to lose control of the vehicle in this condition and locked up wheels cannot turn at all. Hence why experts say 4WD does not help you stop safer and in many cases faster. Remember ABS does not reduce stopping distance it reduces risk of loss of control. Stopping fast and safe are two different things. Would you rather stop in 200 feet and be in a ditch or in 225 feet and be safe and sound? You have to google the autoweek article, just google something along the lines of “does 4x4 help you stop faster” and it will come up. The link won’t work but it exists.

https://autoweek.com/

 

[JExpedition07]

On our Expeditions with AdvanceTrac RSC and ABS systems they distribute braking power pretty well and go by where it’s needed in these scenarios. The Wheel Speed sensors monitor each wheels rotational speed at all times and tell the ABS system what it needs to know. This is a capability these older jeeps don’t have. I’m curious if BorgWarners system would lock the front and rear when braking in 4A or not? I don’t know. But I’d be willing to guess it doesn’t, and rather when power is reduced it retreats to rear wheel drive and ABS takes over. I could be wrong. Good videos Benyl thanks for that.