1994 Auto Hub Question
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Cargo Master
Joined: Nov 2004
Posts: 2,751
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From: So Oregon
1994 Auto Hub Question
I have the auto hubs in my 94 Explorer XLT 4x4. I took them apart, to do a brake job (rotors and such). Anyway, I can't figure out how these work. There didn't appear to be any vacuum or anything else that would move them. Am I missing it, or is the "auto" 4x4 just an auto transfer case engagement and the hubs are always engaged? What turns the hub to lock? Anything?
Postmaster
Joined: Dec 2001
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From: UT
I don't remember the specifics, but the hub engages when the axleshaft rotates. The rotating axleshaft causes something in the hub to move and engage the cam assembly. So, your observation was correct, there is no vacuum or any "external" mechanism to engage the hub. It's purely mechanical and all internal to the hub.
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Cargo Master
Joined: Nov 2004
Posts: 2,751
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From: So Oregon
Oh, that may be it. I thought it was a vacuum, but it's obviously not, so I couldn't figure out what might make it engage, unless it was always engaged and the *auto* part was only on the transfer case. If it has to do inward of the spindle though, that may be.
Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
The hubs are a pure mechanical genius, when you apply 4x4 the axle turns inside the hub rotating a V shaped cam, N being the low centre. as the axle rotates it rides up the slope and pushes the cam outwards, this engages the spline.
the hub stays engaged as long as there is pressure on the cam, on changing from F to reverse the lock moves to the N position and then rides up the opposite side of the V, to lock again. Disengagement is provided when the T/C is moved to 2Hi and the truck is rolled back against the last movement (typicaly reverse), this centres the cam in the released position, disengaging the hub.
The most common cause of failure is too much or dryed out grease, causing the cam to fail its outward motion, cannot compact grease in outer hub.
Maintenance, remove all old grease, light cover of light grease (no lumps or packing) and a tablespoon of ATF (help agains freezup in cold weather), seal and button up.
Hope this helps,.. P
the hub stays engaged as long as there is pressure on the cam, on changing from F to reverse the lock moves to the N position and then rides up the opposite side of the V, to lock again. Disengagement is provided when the T/C is moved to 2Hi and the truck is rolled back against the last movement (typicaly reverse), this centres the cam in the released position, disengaging the hub.
The most common cause of failure is too much or dryed out grease, causing the cam to fail its outward motion, cannot compact grease in outer hub.
Maintenance, remove all old grease, light cover of light grease (no lumps or packing) and a tablespoon of ATF (help agains freezup in cold weather), seal and button up.
Hope this helps,.. P
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Cargo Master
Joined: Nov 2004
Posts: 2,751
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From: So Oregon
That makes a lot of sense. I bought this 1994 used, just a few months ago. My 4wheel drive wasn't working and I was getting a lot of brake grind. I pulled off the wheel and the driver side rotor was destroyed on the back side with no brake pad material on the inner pad at all. The hub was PACKED with enough grease for both sides and I'm sure that's why the 4wheel drive wasn't working. I think I need a new caliper(s), but didn't have the time and money for it now. Hopefully in another week or two I can change the calipers and the pads won't be too worse for wear. Taking the rotors off allowed me a good look at the hubs and associated parts and I just couldn't figure out how the 4wheel drive worked, but what you said makes sense, and it's a pretty interesting design.
When you put it back together, it can't be put together in the "locked" position can it, without the button on the dash being in 4wheel drive?
When you put it back together, it can't be put together in the "locked" position can it, without the button on the dash being in 4wheel drive?
Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
When you put them back together they will automatically centre in the N position against the spring pressure, centre of V.
The hubs will only engage when you apply pressure on the cam, (front shaft turned by T/C).
A light coat of grease applied with a paint brush will be sufficient, get ALL the old grease out.
The hubs will only engage when you apply pressure on the cam, (front shaft turned by T/C).
A light coat of grease applied with a paint brush will be sufficient, get ALL the old grease out.
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Cargo Master
Joined: Nov 2004
Posts: 2,751
Likes: 3
From: So Oregon
I took it for a test drive and it brakes like new, AND the 4x4 works as good as I could have imagined! The person that owned it before me, or whoever worked on it was a moron. I found more boogered up stuff in there than you would think possible.
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Cargo Master
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From: BC Canada
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