4WD Automatic Hubs

Contributed by Mark Dyster

After reading your web site information on the Ford Explorer, I thought I could offer some additional information. The company that makes the automatic looking hubs on the explorer (Warn Industries) had an article in an Engineering trade magazine several years ago, indicating that they were switching the material they used to make the hubs.

The material they originally used (Nylon 6/6) could not hold up well under two conditions. First, the front disc brakes on the explorer generated more heat than this material could handle. In addition, they tended to wear out when the wheel would encounter a slip-stick situation, which occurs when a spinning tire grabs hold. To improve the automatic hubs, the manufacturer replaced the material with a better grade of plastic. In there wear tests, the old material only lasted several test cycles, while the new material lasted over 400 cycles.

Every true four wheeler I have spoken with told me to replace the automatic hubs with manual locking hubs. The funny thing is, the manual hubs are not available from Ford (for a 91' Explorer), but are available as after market parts from Warn Industries.

Contributed by David Van Horn

Ok. Let me tell ya a long story.

About this time last year, my 92 started making an intermittent buzzing, maybe one incident every month or so. Put it in 4wd, and the buzzing goes away. Hmm..

About a month ago, I took it in to sears for alignment, and when I get it back, I can't drive more than a block without SEVERE buzzing and chattering, again it goes away if I lock the hubs...

Lotsa talking, reading, and searching ensues, where I learn about how the hubs operate, and why they were buzzing. My dealer says $275 each, plus labor to replace, "nope, can't service them.." BS.

Folks, they aren't that hard. When the driveshaft in the front begins to turn, it operates a cam in the hub, that forces a piece to engage between the powered axle and the freewheeling hub. If this piece rubs, then it buzzes.


Why does it rub? Glad you asked! Failure of the ball bearing at the end of the hub! The bearing has too much slop. It rolls fine, but it allows the sliding assembly of half of the cam, and the sliding piece to contact the hub, and thereby turn the axle. This can get so bad, that it tries to engage the hub on the other side!

The ball bearing comes right out if you have a pair of snap-ring pliers, (maybe $10) and the bearings cost me $10.40 for the pair (One in left hub, one in right hub)

Put in the new bearings, clean up the sliding piece with a file, (just take off any burrs created by the rubbing) close it up and drive away!

The original bearing part number is NSK 6200Z, which crosses to a Timken 200S or an FAG 6200.2ZR.C3

Call your local industrial "bearings-r-us", and make sure they have them in stock. According to Midwest Bearing (my guys) they are very common, and they usually stock them.

It's literally a one hour job, you will get greasy, but it's easy, and if you can change a tire, you can do this. All this repair happens in the part of the hub that comes off when you remove the front tire.

So remember the dealer quote, 2 x 275, plus labor (I don't know what they would have charged, but taking two tires off and putting them back on isn't much labor! Or, $10.40 for bearings, $10 for pliers you probably don't have (buy them at the bearing place) and a little gas to run down the parts.

My 4WD is humming again, my wallet is still nice and fat, and EVEN if it doesn't hold up forever (why?) I'm only back to what I had to figure on when I started.!!! :) :) :)

Oh yes.. I DID ask the dealer about replacing those bearings. "nope. you have to buy the whole assembly, the bearings aren't available as a replacement part". True enough, they AREN'T available from FORD..




Updated August 20, 1998

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