Hey all:

I’ve got a 2017 F250 CC LB 6.2 4.30 4x4 with about 2800 miles that has been nothing short of great so far. I have used 4 wheel drive multiple times with no issue at speeds less than 35 mph. On a recent highway trip the roads required the use of 4 high. At about 60mph I take my foot off the gas move the electronic shifter to 4 high and there is an obvious clunk and the truck even jerks a little bit. 4 wheel drive did engage but then there was kind of whistling/airy type sound coming from the drivers side front when engaged. When I take it out of 4 high everything is back to normal. This problem continues to exist and the noise is only noticeable at higher speeds. This definitely does not seem normal to me, every other truck I’ve had shifts to 4 high smoothly as long as your foot is off the gas obviously. Oh and neither hub is locked. I’m planning on taking it to the shop but just wondering if anybody else has run into this at higher speeds in 4 high?

Thanks in in advance for your feedback. This forum has been a huge help with the purchase of my truck.

 

I should probably rephrase the question. This isn’t normal is it?

 

You will find that the truck shifts into 4wd much smoother if you do not lift off the throttle, you don't want to be on the throttle, just let it float into 4wd for the smoothest engagement.

 

This is not to start an argument, but more to consider what happens mechanically, when shifting at speed.

While you can do what you want to your truck, I contend you should not need 4wd at 60mph (to each their own), nor would I ever shift into 4WD at speed. While the truck is supposedly build to do that, I prefer to take it easy on the moving pieces. It would seem to place extremely high stresses on drive train components, to go from 0 to 60 at the flip of a switch.

If I need 4WD, I select it at a stop sign, or before I leave the house. This is my 4th 4WD truck, I've treated them all the same, and have never had 4WD issues.

Back to your question, maybe there's a problem with the front end, a partially engaged front locker. If under warranty, I'd certainly get it looked at unless it's only made noise once.

 

I can hear mine make a slight whine as you say when at speed. All 5 SD that I had did this so I would think it's normal. You sitting onto the transfer case so you would hear it from that side. Just be glad you not my buddy since I know your worried about that because I would go put a bunch of wire ties on that front drive shaft to really make you worry as it would sound like a big fan whining then. LOL

 

I don't think you have anything to worry about.

I concur that maintaining a steady speed while shifting is beneficial.

IMO, using 4WD in extremely slippery conditions does add to the stability and tracking of the vehicle. But, remember you don't stop or turn any better with 4WD.

 

If your hubs are in auto the front drive line does not spin so when you shift in to 4x4 it has to start spinning all that stuff. If they are in lock though there should be a seamless shift in to 4X4 as the front drive line is already spinning. I don't shift my truck in to 4X4 when I'm moving if the hubs aren't locked. Ford says you can do it but I just prefer not to.

 

Thank you all for your responses. Very helpful!

 

Lock your hubs if you plan on going into 4wd at high speeds.

Something has to grind while the front hubs engage. I don't know if the hubs have clutches in them, or just splined gears that grind in. I'll guess, that's why trucks are delivered with the hubs locked.

 

in winter months i would just turn them to lock and leave it there.

i think ford or dana could put their heads together and find a better and more reliable 4x4 system. with vacuum hubs and electric motor on the tcase it just leaves to much room for something to go wrong imo

 

Both my '11 and a '16 we have at work made a whistling sound at speed in 4-hi, and you could feel a noticeable lurch as the front driveline comes up to speed. I think your truck is behaving normally.

That lurch comes from an electromagnetic clutch in the transfer case spinning the front driveline up to speed in less than a second. Completely normal, and it won't hurt a thing.

 

My new 17 makes more noise in 4 wheel drive than any of my many previous duties! Enough that I noticed it immediately. I figure its normal. I drive in winter conditions for 5 months a year and use 4by on the highway all the time as they are generally covered in ice! I always shift in and out at speeds no higher than 60mph. My recently retired 2012 has 300,000km or about 180k miles on all the factory front end 4 wheel parts. And by the way, I feel its driveshaft noise I am hearing?

 

Ah, ha. So there is a clutch in there now to smoothly spin things up. That's great. So we can select 4wd, with hubs in auto, even at speed without grinding? I think I'd still rather have the hubs locked in if all of our highways were frozen of course.

 

Just a correction, I was confusing transfer cases in my above post. The '11-16 models used a variant of the old NP273 that was made by Magna Powertrain. These used a synchro ring, which is similar to the synchros used in manual transmissions to match gear speeds, to spin up the front driveline. I believe the '17+ models use the same type of setup, but I'm not certain, and info is hard to find at this point.

From your owner's guide:

 

Yeah,I read that, just never believed it. I remember the ESOF F150's grinding when the vacuum system failed. My previous trucks were XL manuals. So I follow about the same routine with the ESOF on the '17.