Posted: 1/22/2011 10:21:23 AM EDT
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In the middle of a 20" snowstorm yesterday, a close friend of mine had a medical emergency and called me for help after calling 911 (I beat the ambulance by about 20 minutes). I put approximately 20 miles on my K1500 locked in 4wd hi at between 70 and 80 MPH. I know most 4wd vehicles say not to exceed 40 or 45 MPH in 4wd, but I haven't seen any bad consequences of this yet. Is there anything I should check or do or watch out for?
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Snowy roads............it'll be fine. You should be changing out the fluids every couple years anyways. I use synthetic ATF myself in mine. Synthetic 80/90 in the axle diffs.
Biggest issues with a vehicle with a X fer case without a center diff is drivetrain bind. If it's still working without funny expensive noises, it's likely fine. |
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What were the road conditions? I assume given the speeds that the roads were dry. If they were wet or snowy, then the risk of damage is much less.
The issue that could cause damage would be binding caused by slight variations in tire size, etc. The transfer case outputs for front and rear are turning at the same speed. If the front and rear axles aren't turning at the same speed (caused by different sized tires, different gear ratios, etc) then there could be binding and damage done inside the transfer case. However, if your truck isn't rednecked up with different gear ratios or tire sizes, I'd say you're probably fine. Probably wouldn't hurt to change the transfer case fluid when it gets warm. I believe an NP241 takes ATF instead of gear oil. I'm simply curious, why were you in 4Hi? Just forgot to take it out? ETA - you responded with road conditions while I was typing my reply. You're fine. Well, at least with regards to damaging your xfer case. Probably not the smartest thing to drive 70mph in snow. Not to lecture, I've just seen it happen a lot - if you don't get there safely, you can't help anyone else. Good luck dude, hope your friend is ok. |
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Wow...bet that was some ride !...If there was going to be an issue, I'd say it would've manifested itself when the needle hit 80 or so ... Maybe treat the xfer case & front diff to a fluid change once the weather clears up... The drive itself actually wasn't that bad. No vehicles on the road at all and convenient 4ft snowbanks to bounce off if the ass end got out of line, lol. Actually I didn't have any control issues at all, I was pretty impressed once I stopped being terrified of what I was going to find when I got to her house. I picked up fluids, etc. today so hopefully I didn't stress the old girl too much. |
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Snowy roads............it'll be fine. You should be changing out the fluids every couple years anyways. I use synthetic ATF myself in mine. Synthetic 80/90 in the axle diffs. Biggest issues with a vehicle with a X fer case without a center diff is drivetrain bind. If it's still working without funny expensive noises, it's likely fine. I do annual changes at least. Front end and TCS/Trans was done in October. The transfer shifts in and out of all ranges fine and so far no odd noises, smells, or behaviors. |
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Thanks everyone. I'll get the fluids changed once I'm done digging out from the storm.
Yeah, my driving was pushing the limit, but I stayed within (barely). No fishtailing or snowplowing to speak of. I did slow some when I needed to for corners and big drifts, but it was a major road and mostly straight and flat. I'm about the only male in my friend's 8 YO son's life since he was born. We spend a lot of time together and he calls me dad. He was down in their basement and fell, both bashing his head pretty well and nicking an artery in his arm when he fell on the sheet metal edge of something. She went to put some laundry in and found him sitting all groggy in a pool of blood. She's a med-surg nurse so when she called in a panic it was time to grab my kit and go. All is well now except the paranoia of watching for post-concussive issues. CT looks good and the docs patched up the arm nicely. He'll be a hit with the girls on Monday, I'm sure. And maybe now I can convince my friend that she needs a 4wd where she lives (although she was so plowed in that I couldn't get in the driveway with my truck either). |
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I'm glad your little buddy is ok. That sounds like a hell of a fall. Yeah, he is all boy, that's for sure. He has a part of the basement as a playroom and got it in his head to use a short stepstool to try and hang some blankets up on the rafters to "wall off" his little man-cave. The stool kicked out on him and he smacked his head against the concrete wall on the way down and landed on an old sheet metal radiator cover that was up against the wall. It could have been a lot worse, but I don't think I have been that scared in a long time. |
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Your little buddy might like to go winter rally driving with you when he's feeling better. 
Glad he's OK . Stay safe Hehehe. He loves driving the truck out in the big field at his house in the snow. He says its even better than the ATV "cause its warmer". |
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If it's bad to drive in 4hi at freeway speeds then I'm fucked cuz I do it all the time. |
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[div]If it's bad to drive in 4hi at freeway speeds then I'm fucked cuz I do it all the time. I've been doing it for many years as well, and it's not been a problem. I have a very long commute and in the snow I also run 55-60 mph in 4-High whenever the conditions permit. Also, when I was living in the Mojave, a group of us would go 4 wheeling in the wide open desert where you could literally drive as fast as your skill allowed for hours at a time. Most of that driving would be done in 4-High with a few steep climbs and deep sandy areas that required 4 Low. Never had any adverse effect on any of our Transfer Cases, and the conditions were brutal with 100-115+ degree heat during the summer. Now, Transmissions, drive-shafts, and differentials, were a different story. At the shop, the only problems I ever see out of properly maintained Transfer Cases -as result of high speed driving- is when they run them in 4-Low for extend periods, and especially in mixed (snow/dry, dirt/paved) conditions. 4-High is not a problem at 55-65 mph, even on long drives. -Or as one of my customers did...drive it on the highway on a fine summer day in 4-Low until it grenaded.
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