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Auto Locking Hubs explanation

129028 Views 24 Replies 14 Participants Last post by  97_7.3_4X4
Ok Ive gone through a lot of threads here and cannot find an answer to my question.

I have a 2001 F250 7.3 Diesel. I just replaced both auto locking hubs and wheel bearings. All tested fine and according to my mechanic, all is working normally. I want to know if 4WD low engagement is the same as getting out of your truck and locking the hubs manually. If I have my hubs in the "auto" position, why do I still have to get out and rotate the hubs into manual. Some people are telling me that because of limited slip differential that I dont have full 4WD until I get out and change the hubs to manual. So my question is why have auto locking hubs if I still have to manually change the hubs.

It seems like I have half 4WD until I lock the hubs myself. Then its great. I've gotten stuck in snow many times thinking I have engaged 4WD when I haven't.
Its frustrating when everyone with 4WD is just plowing past you.

Thx anyone

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Term 3 has a pretty good understanding. 4L and 4H is a gear change in the transfer case. Stick it in low and you'll see. The hubs auto lock but as with any open/limited slip differential the least traction is the easiest to spin and it will. Locking them in locks them both, but this is harder on your components because nothing gives. Auto-lock is fine for 90% of the situations manual lock is your maximum traction but harder on your stuff for driving distances.
OK it sounds like I may have vacuum line leak because I was stuck on ice and it would just spin one front tire but when I manually locked them in either the other one got traction or something because I drove right out. Good info guys.
The vacuum system can take up to one full revolution of the tire to engage the hub. So if you get stuck in two wheel drive, then engage the vacuum 4 wheel drive switch, the hub may not be able to engage. So you would then have to get out and manually lock in the hubs.
Good info. Thanks.
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