I've been hearing what sounds like gear noise from the front end of my 1993 F-150 4x4 with automatic locking hubs. I've repacked the wheel bearings and they looked ok. I get the most noise when slowing down using the brakes. If I use the emergency brake (rear only) the noise is not there. This noise seems to come and go. So I thought it was the automatic locking hubs. I replaced them with manual hubs and the noise is still there, possibly a bit less. This evening I tried to turn the front driveline with the hubs released and found that I couldn't. Thinking that the hubs may be stuck locked, I took the caps off, but they are released. So, any ideas? I've never tried to turn the front drive shaft with the hubs unlocked and the transfer case in 2H before, but assume that it should turn. When I installed the hubs I did try the locks by turning the wheels (one jacked up at a time) and they both locked and unlocked. Also, I had five bolts in the original automatic locking hubs so I didn't need the adaptor. The new hubs were a snug fit, but they seemed to go in ok and have a little bit of back and forth play as the instructions said.

Sorry for such a long question. Hopefully this will be something someone has seen before.

Fred

 

I pulled the front driveline, lubed the slip joint and replaced the u-joints since they were originals. Surprisingly they weren't that bad after ten years. The slip joint was a bit dry and you culd feel some slop when the two parts of the driveshaft were turned separately.

With the driveshaft out, the transfer case output shaft turns freely when the transfer case is in 2WD. But, the force needed to turn the flange on the front differential is uneven. I suspect that one or both of the spindle bearings is bad and I'm getting drag on one or both of the hubs. I can turn the differential flange, but there seems to be more resistance than one would expect. So that could explain the gear noise. One of the shafts is turning in 2WD, sometimes, and that's when it probably makes the gear noise. So tomorrow, the first spindle comes off and its bearing gets replaced.

Fred

 

No one has replied to this thread yet, so I'll continue with updates in hopes that someone else experiences this problem and wants to hear my experience. I pulled out both manual hubs (hard to get out on the right side) and found that the effort to turn the input flange on the differential was reduced somewhat without the hubs, but it was still noticeable. The major source of the drag is apparently the u-joints on the right side (the one with slip joint in the axle). They seem to operate smoothly and there was no slop, so I didn't replace them.

I removed the hub and spindle from the right side and replaced the spindle bearing (B-2110) and both seals, one in the spindle and one on the axle. Both seals were completely shot. They fell apart by pulling on them with my fingers. The Ford manual mentions a plastic spacer which is suppose to be between the axle seal and the spindle, which was not on mine. The bearing looked ok and didn't feel rough when rotated, but it was definitely in need of grease. And after all the work of getting to it, it would be foolish not to replace it.

A quick comment on removal of the spindle. I'm sure glad I used antisieze on the lip the last time I took the spindle off. The first time took several hours of beating with a rubber mallet. This time it took less than five minutes! I haven't had a chance to drive it yet, but the manual hub on the right went in much easier than before, so perhaps the axle lines up a bit better. I did notice that the old spindle bearing was not pressed in evenly. There was about 0.005 0.01 " difference between sides. This doesn't seem like enough to cause a problem, but the new one is as close as I can measure it.

 

Hi, I have been following your investigation. Keep it up!

Not sure what you saw here, turning the front diff's input flange should make one or both front axle shafts turn, if the front wheels are off the ground. If only one axle shaft turns, then jam something under that wheel to "put the brakes on it", to try and get the other axle shaft to turn. Or maybe you were saying when one particular axle shaft turned, that you heard the noise.

When I rebuilt the front end of my '94 Bronco some years ago, I saw that comment about the plastic spacers in the manual. After finally getting a hold of all the parts, I took the wheel assemblies and spindles all apart, only to find that the plastic spacers weren't there, nor could they be. No way would the plastic spacers fit in anywhere. Probably a line of text left in the manual from some previous years. That's what I remember, anyway.

 

I wasn't actually able to confirm that one of the axles was turning in 2WD, but from the sound of the gear noise, it seems like the differential might have been turning sometimes in 2WD. The noise would come and go. My thought was that if there was enough friction in a hub, possibly from a bad spindle bearing letting the axle sag a bit, that the axle could turn and then turn the gears in the differential which might make some gear noise. I had the most gear noise when I still had the auto hubs in. With the manual ones it got quieter and now that I've replaced one spindle bearing, the one on the side that it was hardest to get the manual hub installed in, it seems even quieter. I was hoping that it was the side that was bad. I was just thinking, if I put a mark on both axles and then drive it, I can see if the marks have moved. That should show me if they turned, unless I'm unlucky enough to stop in exactly the same position (pretty unlikely).

I find it interesting that one axle, the one with the slip joint, is harder to turn than the other side. There isn't much of an angle between the differential and the wheels, but there must be enough that one can feel it when turning it by hand with the transfer case in 2WD and the hubs unlocked. It turns easy, then hard, then easy, then hard, as the U-hoints flex. They felt ok, but possibly a little tight. I sure hope I don't have to take everything apart again.

Next week is to be warm again, so I'm going to try to replace the other spindle bearing and seals. Good to hear that you couldn't find a plastic spacer either. I've checked all the drawings I have in three different manuals and none show one. It's just mentioned in the text and as you say, probably left over from the past.

Fred

 

Well, now I'm really stumped! I put pieces of tape on each axle and one the front driveshaft. Then with both hubs unlocked and the transfer case in 2WD, I drove about five miles. I then checked the pieces of tape and saw that everything has moved. I then jacked up the front and supported it on two two jack stands so that the front wheels were about 1" off the ground. I turned each wheel, but neither turned the axle. I then mounted a dial indicator on a piece of metal laying on the ground so that I could measure any movement in the position of the right axle when it was rotated. I have no more than 0.030" of variation at the slip joint when the axle was rotated. It would be nice if it didn't vary at all, but that doesn't seem like too much, so the axle must not be bent and the u-joints must not be too loose. The angle does change as the suspension flexes, so that may be enough friction to cause things to turn.

So, if someone would like to do an experiment and tell me what they find, I'd be grateful. Mark your axles and front driveshaft with tape, then drive a bit and see if they move. Maybe I'm trying to find something that isn't a problem. I still hear a bit of gear noise in 2WD that comes and goes, so I suspect I'm hearing the front differential turn. With replacing u-joints and spindle bearings, and an oil change, and reading OBD-II codes and fixing (cleaning) a dirty EGR valve and doing yard work, this has been a very busy weekend. I'm anxious to get back to work tomorrow so I can relax.

Fred

 

Hi Fred,

I did the tape trick years ago on my Bronco with Autohubs, just to be sure everything was indeed releasing after the front end work I did. That was the road test, after I had first tested it with the front wheels jacked up. None of the tape pieces moved on the road in 2WD. I suspect that one of your hubs may somehow be making contact occasionally, spinning that axle, causing the diff to turn and the other axle shaft and the front drive shaft too. As an experiment, you could pull out all of the guts of both manual hubs, put saran wrap over the open hub recess with a rubber band around the hub, all to keep it clean. Then try the tape idea again.

 

What kind of manual hubs did you buy. OEM or Warn ( or copies of Warn)? All hubs will have some parasitic drag in them. At low speeds this isn't enough to cause the axle to overcome the friction of the grease and seals. But at higher speeds the parasitic drag increases due to increased bearing speeds and drag within the hub itself. This causes the axle to rotate. If you didn't grease the hubs when you put them in, now would be a good time. When you take them apart you will find what I'm talking about. The inner portion that rides on the axleshaft sits inside the outer portion of the hub that locks into the actual hub. Where the inner spider and the outer hub meet they are usually held together by a lock ring. Take them apart and apply grease to this area. This will help the longevity of the hub as well. The OEM hubs don't usually have this area. That is why I prefer the old style OEM's to the newer ones and the Warn style. OEM's will usually last the lifetime of the truck because they don't have the bearing design of the aftermarket ones. I do pretty good to get 75k out of a set of Warn's before they grenade due to wear.

If all this doesn't help I would suspect that the U-Joints need grease or possibly a differential side bearing is failing.

 

The hubs are Mile Marker Model 402. They were the only ones I could find quickly. I sent an EMAIL to Mile Marker and they replied that I need conversion nut kit # 95-32720. I had been told that only the 3 screw auto hubs needed a kit and that Mile Marker didn't need a kit for the auto hub.

When I drove, it was only at low speed (< 45 mph), so I must have significant drag. Any comments about needing a nut kit?

Fred

 

Ok, another update. I EMAIL'd and called Mile Marker and was told by one person that all Fords need the nut kit and by another that I didn't need it. I described the nuts and washer that I have and was told that it is the same as the kit. I put a piece of wooden dowel into the u-joint by the slip joint on the right side so that the axle could not turn. Now the differential is totally quiet. So I now know which side is causing the problem.

Fred

 

I would suspect something awry in the diff. It's not that hard to pull it out and inspect it. A good shop manual should have all the spec's. If you keep looking and don't find the answer don't be surprised. I had a 97 f150 that pulled to the left like mad. After two years of pulling things apart and not finding anything that could cause it, including two trips to chassis shops. I sold the stupid truck with the problem. Actually I traded it in because it was about to grenade the third tranny in 70K miles and I was tired of paying more in repair bills than payments.

 

Well, I think I now know what is causing the drag that makes my differentail turn in 2WD. The front axle on the passenger side was veryhard to turn in 2WD with the hubs unlocked and the one one the driver's side was a little stiff. As an experiment, I sprayed all three front axle u-joints with penetrating oil. I then let them sit overnight and did the same thing the following day.

I then locked the hubs and drove it about a mile in 2WD. Once I unlocked the hubs, the axles and drive line turn a lot easier. I didn't hear the differential noise either, but I didn't drive it a long ways. So, tomorrow I put in two of the three front axle u-joints. I'd like to do the inner one ont he passenger side, but don't think I can get my u-joint tool in there. I suspect that the sticky U-joints, and perhaps worn too, allowed the axle to rest in a bent shape that put some angular stress on the hubs allowing them to turn the axle, even in 2WD.

I replaced the ball joints earlier this summer, so that was the first time I took it apart down to removing the spindle. Then last week I replaced the spindle bearing and seals on the passenger side, so that was the second timeI took it apart. Now tomorrow it will be the third time. I'm actually getting quite good at this. I only had the drivers side apart once when I replaced the ball joints, but at least the hub now has anti-sieze on it, so it will come out easier than the first time.

THE MORAL OF THE STORY, DO EVERYTHING WHEN YOU'RE IN THERE. THE PARTS DON'T COST THAT MUCH COMPARED TO THE TIME NEEDED TO KEEP TEARING IT APART. AND IF IT HAS A LOT OF MILES ON IT, IT DOESN'T HURT TO CHANGE THINGS.

Fred

 

Fred,
Just a suggestion to look out for, the retainer pin ring on your hubs may have lost its pin. This ring is in between the two hub nuts. Check to make sure the pin is still on it and has not been sheared off during installation. Also check the spindle and be sure the bearing is not spinning on the spindle. Lastly, try preloading your bearing on your spindle a little more. By this I mean put your hub assembly back on the spindle, put your first hub nut back on and crank it down until you can not turn the hub at all. Then back the nut off about a 1/4 fo a turn or until the hub spins fairly easy. There should be a slight drag on the hub, but should be able to make a full turn when spun.
I had the same thing happen to my 93' Bronco. Found out that the retainer pin had been sheared off and the hub nut back off a little, making it sound like the rotor was grinding when I was braking.

 

I just got done replaceing the two outter u-joiints on the front axles. Both were very rusty and one was frozen. The center u-joint on the right seems ok and I really didn't want to open the differential. After ten years the u-joints were really tight in the yokes. I ended up using a 3/4" breaker bar on the socket in order to get enough pressure on my u-joint press to get the old ones out.

As to the pins on the lock nuts, that's a good suggestion. I did make the mistake several times ago of not looking at it and put the nut on backwards so the pin got crushed and bent. I ended up having to push it out and find a replacemen to push in. I don't think that the bearing is spinning on the spindle. There is a little darkening on one part of the spindle, nothing much, but visible. I think that was from before I got the truck. I have been tightening the nut until there is significant drag, then backing it off about 1/4 turn. I noticed that the bearing gets a little tighter when you torque on the lock nut. Again, not much, but noticeable.

So, tomorrow I drive it a bit and make sure that the noise is gone. I did notice less noise after replacing the u-joint on sone side, but the worse one was still on the axle. That one was frozen so that the joint only bent in one direction. AFter taking each side apart 3-4 times in the last month or so, I don't want to do any more if I can help it. If anyone needs part numbers for u-joints, bearings or seals, let me know.

Fred

 

Well, here's the last update. I'm finally all set for winter. The two axle u-joints did the trick. The front axles no longer turn in 2WD and I no longer hear any gear noise in 2WD. Apparently the one u-joint that was fronzen left the axle in a crooked position, so it put sideways force on the hub which made enough friction between the inner and outer hub to turn the axle (even in 2WD with the hubs unlocked).

Here's a suggestion that is perfectly obvious, but easy to forget. When replacing the front driveshaft u-joints with greasable ones, the following works best. First thread the zerk into the body of the u-joint before installing it. This forms the threads so it is easier to reinstall. Then remove it. Add a little grease to each cup, then install the u-joints as usual. Once the driveline is back in the truck, install the zerks and grease the u-joints with a grease gun. The zerks will install quite easily with a nut driver. If you don't do this, it's hard to compress the two caps of the u-joints that must fit into the differential and transfer case flanges. The first few tiimes I used a big c-clamp. With the zerks out, they fit into the flanges by hand with no effort. Like I said, this is pretty obvious when you think about it, but easy to forget when you're doing the work.

Fred