bigdav160

Ask yourself why CAD is on there at all if everything is spinning anyway.

Ok, just to make sure I was not ignorant of how the system works, I just went and put my truck on the lift. The front driveshaft did not move unless I put in 4WD. Then I had my helper drive it through the shop and guess what? The front driveshaft never turned at all. Maybe something is wrong with your truck.

vzdude

O.K. let me get this straight......all the trucks driving around that I see with the front propshaft spinning are all driving in 4wd? Come on dude! With your truck on the lift....spinning the left front tire did not cause your prop shaft to turn at all? I'd be pulling the cover, something aint right! If what you are saying is correct. Your stub shaft (right side inbetween diff and CAD) would be spinning twice as fast as the axle shaft on the passenger side and there would be no way that the vacuum actuator would have enough power to slow it down to engage it! Come on, get realistic!

BTW - my truck is a 3rd gen - no CAD. Worked on thousands of 2nd genners though!

That being said.....why would disconnecting one axle shaft on your 2nd gen. truck keep the differential from spinning? The left axle is still in the differential and spinning, right? If the differeantial is spinning, then the prop shaft is spinning. Guaranteed. If it isn't, you got bigger troubles.

vzdude

OPERATION
The shift motor receives a vacuum signal from the switch mounted on the transfer case when the vehicle operator wants to switch from two wheel drive mode to four wheel drive mode, or vice versa. When this signal is received, the shift motor begins to move the shift fork and collar within the axle housing. In the four wheel drive mode, the shift collar connects the axle intermediate shaft to the axle shaft to supply engine power to both front wheels. In two wheel drive mode, the shift collar is disengaged from the intermediate shaft and the intermediate shaft is allowed to free-spin. When the two shafts are disengaged, the load on the engine is reduced, thereby providing better fuel economy and road handling.

Why would it need to free spin? It's not moving according to you!

PourinDiesel

All 3rd Gen front driveshafts "spin" if the front wheels are turning. There is no axle disconnect on them like some of the older 2nd gen trucks.
The only thing that keeps a 3rd gen from POWERED full time 4 wheel drive is the transfer case.

I know this from taking my truck apart on a regular basis!!

vzdude

Right, this I know. The 2nd gen trucks if really what is being debated right now.

PourinDiesel

Just making things clear since this is in the 3rd gen forum.

welndmn

O1- and older until when ever they stoped using real hubs :P
The other reason besides what Bigdav160 said is from Fluid dynamics. The fluid in the NON-CAD side driving around the carrier can and will push the fluid into the ring gear, and turn the driveshaft.

3rd gens Spin.
Don't believe it? With your truck with all 4 wheels on the ground, try and sping the front shaft.
Now feel free to spend the next few hours figure out what is holding it back

Swayse

I'm glad they did away with CAD, if you go in and out of 4x4 a lot, them things just wore out. I just wish they had made a totally greasable front end, driveshafts, ujoints, ball joints.....

13FOX

Actaully I like the CAD because it will allow me to run 2wd low range with the Posi-Lock kit.

Oh and my 04 shaft turns all the time. 98' shaft never turns until put in 4wd. Also must remember that these truck have an open diff in the front end. Therefore it is possible for the ring gear and pinion and the drive to not move during 2wd operation. However that does not mean there is no movement. There is slight movement at higher speeds when operating in 2wd.

vzdude

I will agree with that for the most part. I am now bowing down and backing off of my "they ALL move all the time"! I spent some time with my buddy's 02 dually 4x4 last night. I will say they have a "tendancy" to move. Most I look at while driving are moving as was my buddy's, but we put a bungee cord tight around the driveshaft and it was able to hold it still, so......I apologize to all that I have debated with! Some might call it argue, but never the less.....! I would rather see them move, in my opinion, because they would be easier to "shift on the fly". Trying to get all the parts spinning the same speed to get engaged would be a lot better on equipment.

IntakeRacing

lol all i know is my 01 driveshaft does not move... lol we had this arguement a different night at the shop that it got so heated i finally drove my truck on the hoist and proved so. big debate that night..

but thank you guys for the answer for the 3rd gens

vzdude

I guess that I have to give a detailed description of "why" I say that they move. On the hoist, NO. No movement. The front wheels aren't turning so why would it? It is diconnected in the transfer case! On the road, at most any kind of speed, there is enough "friction" to persuade the front driveshaft to turn with the wheels. Remember, the left front wheel is constantly connected to the differential, so there is rotational force on it. Does it do it at 2 mph? Who knows, proabably not, but I have watched them going down the road, spinning to beat the band. Can they be stopped- yes- proved that the other night with a bungee cord. My thoughts are, if it is spinning, it has got to be easier to engage the shift on the fly 4x4. If it isn't you would get grinding to no end, trying to get all the pieces to rotate at the same speed. Just my thoughts.

Sunir

I have an '01 and don't know if my front driveshaft moves or not, don't know if I have CAD (no owners manual when I bought the truck) but I'm guessing I do since it's an '01. How do you check for CAD easily?

I was looking into an EMS or Dynatrac free spinning lockout hub kit and I will mention the year of my truck, give them the VIN or whatever, and make sure they provide me the correct kit (CAD or what not is upto them to design around, that's part of their value added engineering in the kit). Will this kit help a lot as in how much EMS and dynatrac claim in terms of reducing the drag and increasing mpg? Also if I unlock the hubs then put the truck into 4WL that will give me 2WL so I'll now have an additional setting, correct?

thanks for the input

97RamBeast

Correct me if im wrong but to answer your question about the CAD, look at the passengerside front axle housing and if you see a housing about midway on the tubing witha few wires and vacuum line running to it then you have CAD. since you have a 01 you should have this.

tool

I had the front driveshaft replaced under warranty on my '99......

Some time later the bolts fell out and it just laid on top of the skid plate and didn't move. It was like that for thousands of miles before I fixed it.

You would have known if it was spinning on the skid plate.