Mattloz

Hey guys I got a 2004 f150 xlt 4x4 3.55 non limited slip and I know that you can't turn while in 4wd unless your on really soft grown but I went to North Carolina and there's gravel roads and I ised 4x4 twice and when I turned everything binds not bad but you can feel it but my brother has a h3 hummer and 4wd all the time why does our cases not allow us to turn. I just want some knowledge

homer

When you say "4wd all the time" do you mean he has an AWD or electronic/automatic 4WD? If it's AWD/electronic 4WD, it's not comparing apples to apples. Many of AWD's have a clutchpack or differential-type setup in the transfer case instead to eliminate driveline windup. In general, AWD vehicles operate much differently. Ford made the F150 Harley Edition with AWD and it has a series of clutch-packs to prevent the windup.

http://www.hummerknowledgebase.com/general/4wdawd.html



Some vehicles have electronic or automatic 4WD... i.e. they don't engage until traction is detected. The Chevy Envoy had this feature. I was pretty impressed with it, a guy I worked with showed me after I asked how it worked. He stepped on it in the snow, we felt the back tires spin for a few seconds then it smoothly engaged the 4WD. This is also different as when he's turning 4WD is disengaged.

I could be wrong but this sounds like what you're comparing.

Mattloz

Correct me If I'm mistaken isn't awd always on and you can not switch between 4 hi amd 4low and 4x4 your able to switch because the hummer its on 4 high then he has 4 high locker and 4 low locker he doses not have 2wd and then I'm guessing ford 4x4 is part time system and do the new fords have the same issue.

homer

That's right. Well........ that depends. Like Subaru is always on. The F150 Harley Edition has AWD and 4HI (forced - see attached image). It actually sounds like his 4HI is operating a differential (similar to F150 Harley AWD), then his 4HI locker is locking that differential (similar to ours), then 4LO is same as ours. I'm not 100% familiar with the Hummer's 4WD system but that's what it sounds like to me.

I had found one link where a guy claimed it's a 40/60 split in 4HI whereas it's 50/50 in others... but that doesn't make sense to me. Other resources I'm finding show it as an open diff in 4HI (similar to what I mentioned with the Harley Edition).

homer

This is from my program, I've set it to a 2006 Hummer H3... It claims it's an open diff in 4HI mode (which makes sense). You'd simply have windup and other issues if it wasn't.

Mattloz

That makes sense I understand now, but if one day I get money to buy self a lift and new tires ( I'm 18) I may through limited slips but I'm guessing that won't effect the 4x4 since other fords alredy have limited slip and won't cause more binding

homer

haha sorry I updated my post. Added more info from my application (has more details).


One thing I don't like on AWD's is I knew someone with a GMC Safari. He didn't want to replace all 4 tires (and didn't rotate properly) so he bought two. Even though the sizes were somewhat the same, they were slightly different. He ended up smoking the differential going down the highway. With 2WD you at least can have different sized tires... but in our case we still need to watch the sizes anyways as we'll still blow the transfer case in any 4WD mode.


I had a 2013 F150 and it has the electronic locking rear differential. I've actually found it works pretty good... as for binding while turning I still had that just the tires were stock so I didn't notice it as much. I haven't driven a GMC/Chevy to say whether they bind more or less though honestly.

Mattloz

Wow that's crazy, well my brother and I are very picky on our cars he just bought new tires (all4) and rotates properly and he has a full size spare (same size that he has now) now I have 285/60/r18 and I have a spare but it's 255/xx/ a i think either a 16 or 17 rim that small differents won't hurnt since I'm in 2wd and have open diffs or can it hurt