2nd Gen Non-Engine/Transmission 4WD and highway speeds

[ETavernier]

Hi,

I was driving my 98. 5 in 4 hi, (during a snowstorm), between Iron Mountain, MI, and Escanaba, MI at 4 am on my way to work... Escanaba ER; I was travelling at about 70 mph and blew my transfer case. The planetary disintegrated into half a dozen pieces.

My 98. 5 had the entry level juice box, 4 inch exhaust and 50 hp injectors, SBE intake, and post intercooler carbonfiber elbow.

Too much torque?

Too much speed?

I no longer drive at high speed in 4 Hi. . or low!

Eddie

 

[SRath]

If you had the NP241DHD (rather than the 241DLD) they are known to have a retainer that can fail with catastrophic results like you described. A search on the engine/transmission forum should yield a lot of info about it and how to upgrade the poor design.



As for speed, well, if you needed 4wd, then 70 mph was not a safe speed to begin with. If 70 mph traction was available, then you should not have had 4wd engaged.



A combination of pavement dry enough for 70mph and engaging 4wd is just inviting disaster. If nothing else, the 4wd changes your steering characteristics enough to make 70mph dangerous even if the components like your t-case and axle can handle it. And they can.



But consider for a moment your tires: Very few vehicles, 2wd or 4wd, have as much tread on the rear tires as they do the front due to normal wear. When you engage 4wd, the front and rear wheels must either be able to turn at exactly the same speed, which would require them to be exactly the same diameters and air pressures AND you must maintain straight steering (no curves or corners), or they must be able to slip a bit to compensate. They cannot slip on dry, good-traction surfaces, so something else has got to give. Usually your t-case. The faster you drive, the worse you stress the driveline because of all this.



I think you learned the important lesson on your own. But if your replacement t-case is an NP241DHD, get the upgrade, too.

 

[mwilson]

I've shifted mine in and out of 4WD up to 75 MPH many, many times, always with the drivetrain under 'neutral' load engaging and going from positive load to negative load and back to release when disengaging. 75 is crazy, you say? Ever driven down a decent highway and suddenly hit a stretch where the ruts are filled with water? I have, and it ain't fun when the front wheels stop turning. 4WD works wonders maintaining control under unexpectedly sub-par conditions.



Shifting from high to low or from low to high I have done numerous times as the manual states: under 15 MPH, shift with a smooth, steady, continuous motion.



275K miles and 12 years and nary a problem with the t-case.

Same here, the e-bay special has been in 4wd all week so far. 450 miles at 65-75 mph.

Keep all of the front u-joints tight and maintained, change fluids in all gearboxes once a year and remove load from the powertrain before shifting.

If you feel it tightening up, let off.



This new truck is a reg cab with 8ft box and it is downright twitchy in 2wd. Much safer to reach down and pull the lever back one notch.

My Mega is much more stable but still has run at times for miles and miles in 4wd.



To each his own... .

 

[ETavernier]

SRath,

Yes I did have the HD transfer case. I have since sold the truck. I was trqavelling on a long winding highway in the UP of MI, and the snow was 12 inches. Plenty of slippage for the tires as the roads had not yet been plowed> i had travelled the same route hundreeds of times and truly needed the 4 wd only to keep the front end pointed forward.

Eddie

 

[SRath]

I'll bet that DHD just grenaded itself in that case, Eddie. Not uncommon at all. Which is why my NV5600 conversion will also have a trusty, all steel, all gear, NP205 backing it up.



And don't get me wrong, it is pretty fun to run hammer-down in fresh snow with a capable vehicle as long as there are no other vehicles, which is often the case. Rest assured, the axles, even the wimpy pseudo-dana 60 dodge foisted off on us, can handle it if they are in good shape. So can the part-time t-case with no differential built in like the NP203 full-time case had, as long as the wheels can slip a little. But, unknown to you, I think your t-case was not in good shape.



It's wrong to run 70 in those conditions when there is traffic. I say that because you have no control over the other guy's vehicle. And because you can make it extremely difficult for anyone you are passing, from either direction, to maintain control.



Nothing chaps me more than fellow big rig drivers who drive too fast in traffic during bad weather even if they and their rigs are under control and capable. They absolutely blind every one they pass with white-out snow in their wake, even other semis. They terrify already highly-stressed fellow motorists who may not have 80,000 pounds of traction and tall rubber to push the snow aside, or the skill and experience. Some of those motorists are new to driving. Some are elderly. Some are driving lightweight 2wd little pieces of crap with 12 inch wheels and no tread. Most should not be out there at all in such weather. Often, it takes very little to wreck them.



We won't even talk about trying to get stopped...

 

[mwilson]

Here in Maine we are a little different.

75 mph in 4wd is not an oddity but we do not have the heavy traffic that a lot of you have to deal with.

The traffic that is out in a storm are a snow-savvy bunch as a rule.



Maybe this will help explain it... ... .



======================================================

Jeff Foxworthy on Maine :



If you consider it a sport to gather your food by drilling through

18 inches of ice and sitting there all day hoping that the food will swim by,

You might live in Maine



If your local Dairy Queen is closed from November through March,

You might live in Maine



If someone in a store offers you assistance, and they don't work there,

You might live in Maine



If your dad's suntan stops at a line curving around the middle of his forehead,

You might live in Maine



If you know how to say... Wicked. . . Up to camp. . Ayuh. Can't get there from heyah,

You might live in Maine



If vacation means going "up north" for the weekend,

You might live in Maine



If you measure distance in hours,

You might live in Maine



If you know several people, who have hit deer more than once,

You might live in Maine



** If you can drive 65 mph through 2 feet of snow

during a raging blizzard without flinching and keep drinking coffee**

You might live in Maine



If you see people wearing hunting clothes at social events,

You might live in Maine



If you install security lights on your house and garage and leave both unlocked,

You might live in Maine



If you think of the major food groups as beer, fish, and Venison,

You might live in Maine



If you carry jumper cables in your car, and your wife or girlfriend knows how to use them,

You might live in Maine



If there are 7 empty unlocked cars running in the parking lot at Hannafords at any given time,

You might live in Maine



If you design your kid's Halloween costume to fit over a snowsuit,

You might live in Maine



If driving is better in the winter because the potholes are filled with snow,

You might live in Maine



If you know all 4 seasons: almost winter, winter, mud season and of course, road construction,

You might live in Maine



If you can identify a southern or Massachusetts accent,

You might live in Maine



If your idea of creative landscaping is a plastic deer next to your blue spruce,

You might live in Maine



If "Down South" to you means Boston

You might live in Maine



If you find -15 degrees "a little chilly",

You might live in Maine



If you actually understand these jokes, and you forward them to all your Maine friends,

You definitely live in Maine



Mike.

 

[Crazy Horse]

What are your thoughts?

When I lived in Anchorage the transfer case sometimes stayed in 4x for months at a time.



You can easily shift between 2 and 4wd at any speeds on the fly especially with an auto trans.



If your running in 4x and the roads go dry just pusher her back into 2x. Sometimes with a little on and off the trottle will allow you to easier shift it back and forth.



Some people want to baby it shifting back and forth, it's allot easier on everything if you use a firm hand when moving the T-case lever.