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The first-generation Super Duty (1999-2004 F-250, F-350, F-450 and F-550) and the 2000-2005 Excursion use mechanical locking hubs with a two-position dial: AUTO and LOCK. They sit on the outer ends of a Dana 50 or Dana 60 front axle, depending on the truck. They are tough, but after twenty-plus years most of them have stopped doing the AUTO half of their job.
The good news: if the truck pulls with the dials in LOCK, you have already proven most of the drivetrain is fine.
How the AUTO Setting Actually Works
In LOCK, the dial pushes a clutch ring into mesh and the hub is solidly tied to the axle shaft. Nothing has to happen on its own. It is the same idea as any manual locking hub.
In AUTO, the hub waits. When you shift the transfer case into 4WD and the front driveshaft starts turning the axle shafts, an internal cam and clutch mechanism uses that rotation to drive the clutch ring into engagement. Once it grabs, the wheel is driven. In 2WD the axle shaft stops pushing, and most mechanical auto hubs release when you shift back to 2WD and roll the truck backward a short distance. Your owner's manual gives the exact procedure for your truck.
That cam needs clean grease, tight tolerances and a dry interior to work. Take away any one of those and AUTO gets lazy, then unreliable, then quits. LOCK keeps working long after, because it does not depend on the cam at all.
Failure Signs
- No front pull in AUTO, but it pulls fine in LOCK. This is the classic one. The transfer case is engaging and the axle is turning. The hub is just not grabbing.
- Ratcheting or grinding from one front wheel under load. The clutch ring is trying to engage, getting partway in, and skipping out. That noise is wear you can hear, and it chews up the engagement teeth fast.
- One side engages and the other does not. The truck pulls to one side or one front tire spins while the other sits still, even though open-diff behavior should not look like that on good traction.
- AUTO works sometimes. Fine in summer, dead in the cold. Thick, broken-down grease does that.
Diagnosis in Four Steps
1. Lock both dials and test
Turn both hubs to LOCK, shift into 4WD and drive on gravel or wet grass. If the front pulls, the transfer case, front driveshaft and axle are working. You are down to the hubs.
2. If LOCK does not pull either, check the front driveshaft
Have someone watch the front driveshaft while you creep forward in 4WD. If it turns, the transfer case is doing its job. If it does not turn, the problem is upstream. On electronic shift-on-the-fly trucks, start with our Super Duty transfer case shift motor guide.
3. Jack each wheel and check
With the truck safely supported and the case in 2WD, spin one front wheel by hand with the dial in AUTO, then in LOCK. In LOCK you should feel the axle shaft and front driveline drag. In AUTO it should spin free in 2WD. If LOCK feels no different from AUTO, the hub is not engaging even mechanically. Rough, notchy feel or play in the wheel points you toward wheel bearings or axle U-joints instead.
4. Pull the hub and look
Water, gray milky grease, rust flakes or rounded splines tell you the rest. If the splines on the spindle or axle shaft are worn, fix that before installing new hubs. A new hub on a rounded shaft will not last.
Common Causes
| Cause | What You See | Fix |
|---|---|---|
| Worn internal cam or clutch | AUTO dead, LOCK fine, sometimes ratcheting | Replace hubs |
| Broken-down grease | AUTO slow or dead in cold weather | Replace hubs, or clean and regrease as a stopgap |
| Water intrusion | Milky grease, rust, failed O-ring | Replace hubs with new seals |
| Worn spindle or hub splines | Slop, clunk, skipping even in LOCK | Repair splines first, then hubs |
Our opinion: cleaning and regreasing a twenty-year-old auto hub buys you a season, maybe. The cam surfaces are worn, the springs are tired and the seal is hard. At this price the replacement pair is the cheaper job in the long run. For a wider look at engagement problems across other trucks, see locking hubs not engaging: causes and fix.
Replacing the Hubs
Our Super Duty auto locking hub pair is a factory-style AUTO/LOCK dial design, each hub with its own O-ring seal, sold as a left and right pair. It replaces Ford 1C3Z-3B396-CB and crosses to Dorman 600-203. This is a hand-tools job.
- Park on level ground, put the transfer case in 2WD and chock the rear wheels.
- Raise the corner and support it properly. Pull the wheel.
- Remove the hub retaining bolts and pull the old hub straight off.
- Clean the mating face and the splines. Old grease, rust and grit on the face will keep the new O-ring from sealing.
- Put a light coat of grease on the new O-ring.
- Line the hub up on the splines and push it home. Do not force it with the bolts.
- Start every bolt by hand, then snug them evenly in a crisscross pattern to the factory spec.
- Repeat on the other side, then test in both AUTO and LOCK before calling it done.
Why So Many Owners Just Run LOCK
Plenty of Super Duty owners turn the dials to LOCK every time they go into 4WD and never use AUTO at all. It is not laziness. LOCK is positive engagement, it does not depend on a cam grabbing at the right moment, and it does not ratchet under load. If you are plowing, pulling a trailer up a wet ramp or working a muddy job site, LOCK is the right setting anyway.
The catch is remembering to unlock. Running locked in 2WD on pavement spins the whole front driveline for nothing, costs fuel and adds wear. And a hub with a dead cam usually has water and bad grease inside, which eventually hurts LOCK too.
Cost: DIY vs Shop
| Route | Typical Cost | Notes |
|---|---|---|
| DIY, hub pair | $79.99 | Hand tools, an hour or two for both sides |
| Shop install | Roughly $200 to $400 | Typical estimate with parts and labor; rates vary |
| Hubs plus spline or bearing work | Considerably more | Depends on what is worn behind the hub |
If the inspection turns up worn axle shafts, ball joints or bearings, read our Dana 50 and Dana 60 front axle guides before you button it back up.
2005 and Newer Is a Different System
Starting with the 2005 model year, the Super Duty went to vacuum-operated hubs controlled by the 4WD system. The diagnosis is completely different: vacuum lines, check valves and solenoids instead of a cam and clutch. These mechanical AUTO/LOCK hubs do not fit and will not work on those trucks. If you have a 2005 or newer, go to our Super Duty vacuum hub lock problems and fix guide.
Get Your Super Duty Pulling in AUTO Again
Factory-style AUTO/LOCK hub pair with O-ring seals for 1999-2004 Super Duty and 2000-2005 Excursion 4x4. $79.99, ships free from the USA.
Shop Auto Hub Pair → More Drivetrain PartsFAQ
Why does my Super Duty pull in LOCK but not in AUTO?
LOCK mechanically ties the hub to the axle shaft. AUTO relies on an internal cam and clutch that has to grab when the axle starts turning. If the truck pulls in LOCK and not in AUTO, the transfer case and front axle are doing their job and the auto mechanism inside the hub is worn, dry or full of water.
Is it bad to just leave the hubs in LOCK?
No. Running LOCK whenever you are in 4WD is how a lot of owners avoid hub trouble entirely. Leaving them locked full time in 2WD costs some fuel and spins the front driveline, so turn the dials back to AUTO or unlock when you are done with 4WD.
Should I replace one hub or both?
Replace both. They have the same miles, grease and water exposure, and the second one is usually close behind. Our replacement is sold as a left and right pair for that reason.
Will these hubs fit my 2005 or newer Super Duty?
No. Starting with the 2005 model year the Super Duty went to a vacuum-operated hub system. The mechanical AUTO/LOCK hub pair fits 1999-2004 F-250, F-350, F-450 and F-550 Super Duty 4x4 and 2000-2005 Excursion 4x4 only.
What part number replaces the factory Ford hub?
Our auto locking hub pair replaces Ford 1C3Z-3B396-CB and crosses to Dorman 600-203.