jigdog

lets hear it for JR. Thats one of the reasons you back up after being in 4x4 so you can unlock and unbind (new word) ;D

magnum

Justin---Is the manual like instructions???

KATOOM

The reason you feel a vibration and growl in 4wd is because in '02 DC made some changes to the geometry of the front axle and eliminated the vacumm axle diconnect system on the housing. These changes made means the front driveshaft now spins all the time, the front axle housing was pushed foward around 2", and the pumpkin pinion was rotated down a few degree's. This three changes can cause you to feel a high speed vibration (65+mph). Especially if one of the front u-joints start to go bad from the added stress of the pinion rotation. Any noise you hear is going to be exaggerated by applying power to the front drive shaft since its usually just spinning freely by itself and noise will be transfered by the transfer case. Guys that say they have no vibration with their '02's probably have the vacumm axle disconnect system. DC installed them on '02's untill no more were left then switched to the solid axle housing. You should be able to run your truck in 4wd at any speed (given the road conditions permit) since the front driveshaft is already spinning as fast as the rear, but like others said just because you are in 4wd doesnt mean more control it just means power to all the tires. Yes it can put a strain on the drivetrain, mostly when turning but I really doubt you will hurt anything since these are very strong trucks but try to stay out of 4wd on hard dry ground. AWD cars and truck get around this by using a viscous coupler or transfer cases with differentials in them.

Scotty

I ran in 4x4 for most of the past 3750 kilometers pulling a trailer on snow covered highways. Never got much over 65 mph and was usually in the 50 mph range tops.

Of course this is with one of those fancy dancey new 04 trucks. A bit different then the 2nd gens.

jrs_dodge_diesel

[quote author=Bearfoot2 link=board=4;threadid=23775;start=0#msg224086 date=1071540062]
Well spoken by one who has a 2WD!!
[/quote]

Bearfoot, That expierience comes from my other truck, a F150, which happens to be a 4x4. I wish I could have found a 4x4 Dodge but they are very hard to find here in Dan Diego.

Jigdog

I believe you are referring to the automatic hubs. They are not in a bind but they are locked in. Backing up in 2WD is the only way to unlock them. My F150 had them, I thought the autos were garbage so I ripped them out and put a set of Warn manuals in.

Commatoze

Manual? You mean that red thing in the glove box? You're supposed to read that? Seriously, thanks for all of the answers. Something that KATOOM mentioned that you guys may not have realized, I have the "new" Dana 60 axle, meaning the front driveshaft is spinning full time in and out of 4WD. The vibration isn't there in 2WD. Yesterday, I had an opportunity to take it up to about 80 in 4H on dry pavement. As I mentioned earlier, the vibration came on at about 45, but disappeared around 60 and was very smooth up to the max speed so maybe there's a resonance band it goes thru. So I guess I'll consider it normal drivetrain noise, but keep an eye on it too.

Tartarus

I also have the final issue, always-spinning Dana 60 front axle, and I can tell you exactly what's happening in 4Hi above 45 mph on dry pavement -- I've seen this in 4x4's over a fair number of years.

As others said, locking the axles together creates stress variables along the driveline. Where do you lock the axles together? In the transfer case. What part of the transfer case is most flexible and prone to stress resonance and harmonic vibration? The transfer case chain.

What you're noticing is the chain whipping back and forth, trying to compensate for the stress variables. At certain speeds, the whipping becomes noticeable as the chain moves out of true by a larger and larger amount. Above those speeds, as the vibration settles down, the stress continues to increase, but the physical "length" of the whipping motion is replaced by the intensity, or number of times the chain whips.

All transfer case chains stretch over time. Eventually they may break. By driving in 4Hi at high speeds on dry pavement, y'all are stressing your chains and increasing the wear-out rate. You could go 200K miles. You might break a chain tomorrow. Who knows?

Marine

[quote author=Marine link=board=4;threadid=23775;start=0#msg223896 date=1071521899]
fastest I've travelled in 4WD is 65 down the freeway.
Mike
[/quote]

This, of course, was when it was snow covered.

Mike

Commatoze

[quote author=Tartarus link=board=4;threadid=23775;start=15#msg224325 date=1071584482]

What you're noticing is the chain whipping back and forth, trying to compensate for the stress variables. At certain speeds, the whipping becomes noticeable as the chain moves out of true by a larger and larger amount. .........[/quote]

But as I said in the first post, this vibration was occuring on a snow covered Interstate, which judging by all of the cars I saw spun out in the median over 120 miles, provided more-than-enough slippage for the drivetrain. Is my thinking wrong? Or is it possible as you suggest my chain has stretched over time? Keep in mind that I may do 400 miles a year in 4H, but when I do, it's usually long distances on snow covered highways.

jigdog

katoom question.in the 02 with fulltime front drive shaft spinnung is the chain in the tc spining too?

KATOOM

I dont know if the chain runs without the driveshaft. I would think it does for oil circulation. But I guess that would also depend on which shaft inside the transfercase engages in 4wd. The way the '02 solid axle locks in and out of 4wd is by engaging the front output shaft inside the transfercase. The front axle is whats making the driveshaft spin in 2 HI.

Is there absolutly no vibration at these speeds in 2wd? And how bad is the 4wd vibration. Is it just a slight hum or does it make your rear view mirror moves?

Commatoze

KATOOM, there's no vibration in 2H. The vibration isn't enough to make the mirror vibrate, but I can feel it in the steering wheel, and I can hear the growl in the cab. I had a main driveshaft forward U-joint replaced about 2 weeks ago, and the sound is very similar.

Tartarus

The chain spins all the time. In 2Hi, it "idles" w/o transmitting power. There's always a certain amount of deflection or "whipping", even in 2Hi. It's a question of degree -- where you're gonna get the worst is in 4Hi on dry pavement at 80 mph, say. But you'll get more on snowpack at 65 mph than on snowpack at 25 mph. And the more you get, the faster the chain will stretch and wear. Not saying the chain isn't tough. It's just another wear factor.

KATOOM

I still think its a u-joint problem. Have you put on a leveling kit? Maybe you should check the front u-joints. I dont think its a chain issue. Not saying it isnt but it sounds more like the sounds of u-joint that is stressed, by to much angle or just bad. The front u-joint is supposed to be relatively straight out of the pinion because the u-joint at the transfercase is a c/v joint which cancels out it own angle vibrations. Have you checked any front u-joint s for movement of the pinion for play?