Transfer Case Operation Question

[Popeye2347]

Due to the slick, snow covered roads I took my IDI 4x4 to work today and will for the next few days. On the way home I realized I have not read anything about engaging or driving with 4 HI engaged.

Two questions came to mind. First, what is the maximum speed you can engage 4 HI without damage.

Second, can one drive 45-50 mph in 4 HI without damaging the transfer case [or something else]? This assumes a slick driving surface. A slick surface is defined as one where the rear tires break traction easily when the accelerator pedal is floored at the target speed. [I know a dry surface will cause torque 'lock' problems and damage.]

FWIW I was proud of her, just let the GP's heat and then waited for a count of 10, and she started right up-Had to push the acc. pedal about 1/2 way, but first try and she was running. All after sitting outside, not plugged in, in 16*F for 8 hours. She also started last night in +8F, again without block heat.

Be safe, plan for a breakdown, have cold weather survival gear in you transportation, don't forget munchies and a working flashlight. A cell phone is nice too.

 

[Sycostang67]

I've had no problem engaging 4HI while traveling 20-30mph. You should be able to go as fast in 4HI as you do in 2HI. You usually dont want to due to the road conditions though.

 

[Agnem]

As long as your hubs are locked, you can switch between 2 Hi and 4 Hi at any speed. All the parts that will be in motion, ARE in motion already. All your doing is connecting two moving parts that are moving at the same speed in the same direction, together. Don't try and do it if your already spinning on something though. That would be bad. All the wheels would need to be stopped to make the change.

 

[sassyrel]

adn--you can even have the 4x4 in--when the road may be dry in places--i/e youll hit intermittent ice--then dry--you just have to get the tires on slick stuff--every so often,to "unload" the twisting forces in the driveshafts-ford has a faster front gear setup,--and always has--hence the the winding up of the driveshafts--and the breaking of u joints,on dry pavement--had a guy breaking joints one right after the other,he said he left it in lock when he hit the pavement from the fieldi explained to him why not to do that--end of ujoint problem--

 

[SparkandFire]

We used to lock in the 4hi on our service trucks during the winter when I worked on the windfarm. All the dirt roads became muddy and snowy out at the site, so the management told us to put the trucks in 4hi and leave em' there. We drove roughly 40-50 miles per day on pavement (to and from the shop in town) mud, snow, and ice without any ill effects to the 4wd system.

You will wear out u-joints faster than normal up front, but that is simply because you have the whole system in motion when normally there is no movement at all...

We replaced the u-joints up front and in the rear at about the same time, so I guess they wear at the same rate when it's in use at all times.

 

[Popeye2347]

Thanks for ALL of the above information. I have looked over the owner's manual and supplement and, while failed to do a search on this topic,[my bad], I have never seen this topic discussed, hence here it is for all to see.

I had a Jeep Grand Cherokee prior to my IDI and the owner's manual stated pretty much what was said for our Fords-didn't know if it would be the same or not.

Thanks again....

 

[snicklas]

Yep, same as stated above. If you have your lockouts enguaged and the tires are all at the same speed (no wheels spinning and some stopped) you should be just fine. If you had "automatic" lockouts I think you need to be stopped or moving slowly as I have not had setup before, have had manual T-Case and Manual lockouts. If you happen to have ESOF like my Ex does, turn the knob as long as no tires are spinning it will lock everything in at speed, I was running 45-50 this morning and did just this, the computer will even blip the throttle to unload the driveline as it is shifting......

 

[riotwarrior]

Well don't know bout your trucks, but my 90 Bronco BW 1356 T case with manual hubs locked in and a T18 Manual, I shift into and out of 4 hi on the go at any speed so long as no spinning up to 80 85 K at times.

Now 4Lo, gotta stop, pull into low, and stop to get out of low too.

 

[fury9]

And if it pops out you gotta shut it down then pick a gear after you think everything has stopped spinning, at least I do anyway or else it gets to grinding really bad