4x4 VS 4x2... What is turning?
 

I drove across country in November of which I saw several Dodge trucks without front Hub Caps.... It is obvious that the front drive shaft is constantly turning along with the Wheel axles in 4x2. engaging the 4x4 just activates the transfer case to connect up the front axel. Am I wrong? Anyway, I got to thinking... what is going on with my truck in 4x2 and 4x4? Just curious what is actually turning in 4x2 and in Auto for the front hubs. Thanks.

Front should not be locked in unless Hubs have been manually locked. Look at your hubs and make sure they are in Auto. That way they should not be engaged unless transfer case in in 4 hi or low .

On the Dodge, the front end spins all of the time. There is a center axle disconnect that breaks one of the axle shafts so that the truck steers nicely in 2wd without clunking. But everything spins. This is why I have no interest in Dodges. The freespin kit is pretty serious $$$. I can add a locker, fenders, and tires to my F250 for that cost.

The ESOF Ford have auto hubs. In auto 2wd, nothing up front spins. The driveline is disconnected inside the hubs. If you lock the front hubs, everything spins in 2wd, just like the Dodge. And you'll feel the universals clunking a little in turns.

I leave the front hubs locked in the winter, so I can smoothly shift in and out of 4wd at speed. But the new ESOF, has a clutch that'll spin up the front axle before engaging the hubs, so it will shift smoothly from 2wd to 4wd with the hubs in auto. That's a pretty cool feature, but I still manually lock the hubs in the winter, because how many times can that clutch spin up the front end before it wears out? It's just easier on the truck this way.

The manual hub, manual xfer case, 2008-2015 trucks will grind badly if you try engaging 4wd at speed without locking the front hubs, because the front axle isn't spinning. So I always have to lock those manually. With the auto hubs you have the option to let them automatically engage, or manually do it. I prefer manual, for regular use, and auto for a weekend where I might only use 4wd once, usually at low speed.

Much thanks..... As I only use 4x4 occasionally, I keep them in Auto. A guy up the road keeps his in Locked all winter. Just didn't know what spins and what didn't. Something to ponder for all who reads this thread also. :-jammin

i dont know what year trucks you were seeing but from '14 to present is electric cad. prior to that was a full time locked axle just like if you were to put your hubs in lock permanently. prior to that was vaccum cad. they used free spin hubs as well but its been long time ago.

imo the cad has nothing to do with making the truck turn better. if you read the latest ram literature, they make it a point to say the new cad gives slightly better fuel economy. fuel economy is a big deal these days and if even 1mpg decrease will put you ahead of the competition then you can make tv commercials that 20mill people see and claim class leading fuel milage

this may be why ford bumped up the power by a miniscule amount. class leading power in a tv commercial that millions watch will likely bring in some extra sales

How does the CAD save fuel economy? Everything is still spinning. In fact more may be spinning, the spider gears inside of the diff will spin on acceleration until the other half of the diff catches up with the driven half. The literature ain't from engineering. I had the same setup on my YJ. No change in economy at all, I had a cable to operate the CAD. It stunk. It's not as silly of a design as Fords Dana 50 IFS, but it's up there.

The only positive effect I've felt is you can't feel the universals twitch while steering, because the axle get's spit and separated.

The Dodge Trucks were Hot-Shots pulling loads.... There was no way to disconnect the front hubs due to the big "Nut" in the center of the wheel hub. Soooo, I figure that the Hub was spinning the axle to the front Diff and on back to the transfer case.

What is cad?

ram says theres up to 1mph better with cad. i know its miniscule but maybe over the vehicle life it would eqaul something worth while. if you want details or more info then contact ram about it.

housemouse all rams have large nut. thats what holds the preload on the unit bearings. like a pinion nut etc. hotshot truck could be anything from a 2500 to 5500 series truck. i think 5500 would have 275mm magna steyr front axle but im not sure if its full time or cad. i would guess its full time but i could be wrong

center axle disconnect - alternative to locking hubs. CAD systems are typically used in front drive axles on four wheel drive vehicles. A CAD system works by having an axle shaft (typically the longer shaft) split into two pieces. One piece is connected to the carrier, the other connected to the wheel. This reduces drag on the axle by allowing only the spider and side gears to spin.

I had to look it up. :o

Eventually the carrier catches up, and starts spinning. Otherwise the diff would be "diffing out" the whole time. Which is some bad mojo.

Thanks!!!!!

heres what ive seen with cad. if you drive the vehicle say 50mi the rear end will be hot as expected but the front is mostly cold. i wondered why but never looked into it. while this paper talks about the older vacumm design, im sure the electric version is similar. so now i know why the front diff doesnt get hot in 4x2 and why theres likely a small mpg increase. the carrier/ring/pinion/tcase really isnt turning or if it is its very little. i learn something new everyday. aparently there must also be a synchronizer gadget even in the manual tcase versions to bring it up to speed

Dodge CAD System Explained by 4x4Wire.com

99% of axle heat is the ring and pinion meshing together under load. Pretty much straight up friction. With the xfer case in 2wd, no load, or force is being applied to the front gears.

I can pretty much promise that 4x4wire is wrong unless there's some part I'm missing. My YJ's front drive shaft spun up eventually in 2wd. It takes a bit of force to spin all of those spider gears and diff out the diff. Especially with gear lube in there. Are the spider gears even on a bearing? Nope, that can't be good to keep those spinning. Eventually on the highway, the ring is going to spin. Easy test, put a zip tie on a Dodges front drive shaft so you can hear it tick loudly if it spins.

mounting a gopro camera under there would be interesting to see what it shows

after reading more and thinking about things, it seems to me that with the axle split , the drivers side shaft turns , which then spins the 4 spider gears and then the turns passenger side half shaft, this passenger side half shaft would also spin in reverse to the driver side. just as if you jack up the rear end of any truck with open diff and turn one tire forward and the other goes backward.

for the front driveshaft to turn in the same direction as the vehicle is traveling, like you suggest, wouldnt both front axle shafts have to be turning forward ? i do believe so. if im wrong ill eat crow. with the axle split, the two shafts turn opposite direction