Auto hubs grinding (big surprise) - searched

[MANZ]

I searched for a bit about this problem and couldn't find anyone having the exact same symptoms as mine. I'll try my best to describe it ('94 XLT - 105k).

While driving along WITHOUT 4wd engaged, what sounds like the left hub starts to grind like it is trying to engage. This seems to happen only while taking a right turn, and happens intermittently. If I engage the 4wd, it will go in fine (with the usual loud clunk and popping) but then there is an excessive vibration/wobble that is proportional to road speed and the truck tends to pull left. I don't know if the wobble and the hub grinding are related. I was thinking rusty u-joints since I rarely use 4wd. It will come out of 4wd ok, but the hubs will grind for a little while like they arent fully disengaged. I have to go back and forth a few times until they quiet down for a little while.

This morning it happened again, and actually completely engaged the hub (I could tell from the vibration) without ever touching the 4wd button. I had to back up to get it to disengage.

Yes, I know I should put in manual hubs, but I can't figure out why the hub would be attempting to engage if the front axle isn't turning. I have had them out and cleaned and inspected them a few times. No, there is not a bunch of grease in there and everything appears to be in OK shape.

Logic would tell me that the axle is turning somehow (a little at least) to partially engage the hub cam (I don't think the t-case is dragging or engaging at all). Manual hubs still wouldn't solve why the axle is turning somehow.

What the hell is causing this, especially when turning right? Am I missing something obvious? Thanks in advance for any ideas (besides lighter fluid and matches).

 

[MrShorty]

Too much grease in either or both hubs can cause enough drag for the hub to try to engage. The hub is supposed to be "dry," meaning there is little if any grease added to the hub. Often, when packing the wheel bearings, the hub will get filled with grease. Try taking the hubs off and cleaning as much of the grease as you possibly can out of the hub and off of the cam assembly.

 

[JDraper]

The autohubs in my '92 did the exact same thing when they went south. What killed my hubs was the washer that holds the hub components in place had a groove worn into it, which allowed the autohub mechanism to move and engage randomly. I temporarily fixed it by turning the washers around backwards, but eventually went to manual hubs.

 

[MANZ]

Thanks for the replies. Like I said, I know there is no grease in the hubs since I took them apart and cleaned them thoroughly. Interestingly, I was at the dealer some time ago and he showed me a brand new set of hubs in the box and they were not dry as everyone says they should be. The had a decent amount of light colored grease in them from the factory, so I doubt any remaining trace amounts of grease are the cause of my problems.

J Draper - which washer exactly are you talking about? The one that holds the big spring, etc. in the hub?

Any ideas why the hubs would be fine for months and then try to engage by themselves, then maybe nothing for a while again?

 

[jtison]

I never knew about the "no grease" thing either. If it's true, I'm in trouble.

I think the washer JD's talking about would be the one with the spline grooves in it -- the one retained directly by the clip ring. If that were worn, you'd have one heck of a problem keeping that plastic cam seated within tolerance. That would tell me that the plastic cam is pushing out *further* than it's sposed to. Probably not good.

I have a '94 XLT that used to have the same problem. My *symptoms* turned out to be cured by wheel bearing adjustment.

If you look at the service manual, you'll see a pair of "thrust washers" in the auto hub explosion diagram. I went to the Ford dealer looking for them, and was told they were "NR: not required".

OK, so lessee. If the thrust washers aren't there, could it be that the usual advice on wheel bearing adjustment (35 ft-lbs torque, then back off 3/4 turn to 16 *in*-lbs) is faulty, too? Well, it turns out that the hub locknut (that 2-3/8" monster) is limited in where it can sit by a number of grooves (6? 9?) that the key lock piece can fit into.

I tried a few different approaches to wheel bearing adjustment, since bearings are cheap and the autohub parts aren't.

What finally worked was to take that locknut and move it up (tighter) to the next keylock slot (16 in-lbs + one clockwise slot-worth's turn). I drove it for about 5 miles, and it made more scary-sounding noises in a L turn, much like you report. After that 5 miles, bingo, grinding gone. Could it have been just the bearing doing its final re-seating? That's kinda what it sounded like: the grinding wasn't constant: it was a quick "thud-thud-thud" kind of noise, almost like an excessive axial load on the bearing, and the rollers trying to compensate.

This scared me. I pulled (and marked the hub locknut with a scribe!!) the wheel bearings ... no wear, no metal shavings. Repacked the bearings, reinstalled ... bingo, still no more grinding noise. I'm fixed for now, but I expect more autohub trouble down the road ... there's enough play in there to still make me nervous.

Ultimately, I think I'm gonna have to junk the auto hub for a manual. I'm still not sure the autohubs are disengaging when they're supposed to. Many threads on this site refer to these junky autohubs, and that their replacements with manual locking hubs take care of the problems.

I've never heard of excess grease in the hub causing a problem; but then again, I'm not a pro, either. That's really interesting. I guess I could try washing out the hub in a parts washer, making sure it's really dry and lightly re-greasing; but I'm happy for now: no noises, and I think I'll leave well enough alone.

Peace,
--Jim--

 

[JDraper]

...I think the washer JD's talking about would be the one with the spline grooves in it -- the one retained directly by the clip ring. If that were worn, you'd have one heck of a problem keeping that plastic cam seated within tolerance. That would tell me that the plastic cam is pushing out *further* than it's sposed to. Probably not good....

Yep, that's the one. I flipped it backwards and it worked for a while....

 

[MANZ]

Thanks for the info guys. That washer is not worn at all in my case. I did check it thoroughly when it was apart. The lighter fluid and matches idea is sounding better and better to me.

Here's another theory: I was looking at the article on this page about the failing bearing in the end of the hubs causing this exact problem:

http://www.explorerforum.com/Singleton/web/pages/autohubs.html

Have you heard much about that? I don't recall the inner hub assembly being real sloppy in the hubs, but maybe it was enough to cause a problem. After all, those bearings are always turning when the truck is in motion whether the 4wd is engaged or not. I might just try $10 for new bearings and see. What do you think? Thanks.

 

[jtison]

Here's another theory: I was looking at the article on this page about the failing bearing in the end of the hubs causing this exact problem:

http://www.explorerforum.com/Singleton/web/pages/autohubs.html

Have you heard much about that?

Not ever, but then again, all I have is the service manual, which takes the dealer "hear no evil, see no evil, R&R no evil" approach to those hub ends.

I read the link, it makes sense to me. For the cost of a couple of Timkin 200S bearings, you can easily try this out, and all you'd have to lose would be from clueless reassembly. I have the snap ring pliers, I just don't have an explosion diagram to work from. Scary, but I'd try it if taking the wheel bearing slop out hadn't fixed my symptoms ... I was getting desperate.

Re the "no grease" thing: I looked in the service manual -- they call for normal long-life grease in the hub ends. They don't say how much is too much, tho.

If you try it and it works out for you, PLEASE POST.

Peace,
--Jim--

 

[MANZ]

Well, I went ahead and replaced the bearings (they were $18 for the pair though) since I had the time and set of snap ring pliers. Of course, when I took the old ones out they didn't look or feel bad. They didn't really have any more slop than the new ones. I figured why not waste a few more bucks and give it a shot. While I was in there I cleaned them thoroughly (again).

I think I found out what is causing the grinding noise. Basically, the hubs are a ****ty design (I know, big news flash). While supporting the inner hub sleeve with my fingers, I could spin the outer hub assembly and hear it grinding very lightly. One hub was definitely worse than the other. The inner gears are supposed to ride in a recess in between the outer gears when the hubs are not engaged. Evidently, they are not spaced properly since the gears are starting to touch. Loose wheel bearings or goofed up plastic or metal cam parts on the spindle, or excess grease would obviously have no effect in my case.

I couldn't see any obvious cause of this and what would wear to make it start to happen now. I switched the inner gear sets between the hubs to see if it would help any. Very slight improvemet, but still there.

I slapped them on the truck and only drove around the block, but didn't hear any noise yet. I'm sure I will since it was intermittent before, plus I don't think I did anything profound to change it. I'll let you know what happens. If it starts again, I will probably just gut the hubs (since I rarely use 4wd anyway) until I get a set of manuals. The design just sucks, plain and simple. I know eveyone has said it before, but I find it hard to believe that I wore out my hubs by barely ever using them in 105k miles.

 

[jtison]

Thanks! (VERY LONG)

Nice work, thanks for reporting back!

Loose wheel bearings or goofed up plastic or metal cam parts on the spindle, or excess grease would obviously have no effect in my case.

I couldn't see any obvious cause of this and what would wear to make it start to happen now. I switched the inner gear sets between the hubs to see if it would help any. Very slight improvemet, but still there.

There has got to be something wearing in there. Either that, or there's something about that LH side (torque pull, perhaps?) that doesn't match the RH side. Like you, the noises I heard were all from the LH side (although I did experiment with one bearing adjustment that gave me similar -- but not identical -- noises from the R side).

Now I go back and read the service manual again, which tells me:

Buzzing and ratcheting were a constant concern with the older 4x4 vehicles. These noises occurred usually when shifting into four-wheel drive after starting the vehicle sitting cold for several hours. The noises would also occur just after shifting from four-wheel drive to two-wheel drive. Cold weather was another factor that produced the noise concerns. Colder temperatures increased the viscosity of the axle lubricant resulting in a much higher torque requirement for the transfer case which could only rotate the pinion gears just enough to cause the hubs to partially lock which resulted in a racheting noise.

The newer vehicles, however, utilize a synthetic axle lubricant with low viscosity and a transfer case clutch with a higher output. Both innovations allow for 4x4 operation in extreme temperature conditions.

Noise concerns in two-wheel drive just after shifting from four-wheel drive can occur if one of the hublocks fails to disengage. As the vehicle moves forward, the one hublock that has failed to disengage will rotate its axle shaft through the differential and attempt to rotate the other axle shaft in the opposite direction. This is called Differential Motoring Torque. As this torque attempts to turn the other axle shaft through the differential gears, that shaft's hublock will attempt to engage which will result in a ratcheting or buzzing noise.

This type of noise concern is usually found on axles that have very few 4x4 miles on them. As the front axle accumulates 100 to 200 miles of locked hub operation, the axle will break in ....

Emphasis is mine.

So what you've found out is that the relative position of those inner and outer gears are probably the key to having the hubs disengage -- that's a better explanation than anything I've ever heard up til now. I wouldn't discount any cause, from wheel bearing all the way to the end of that hublock -- slop could definitely be a factor. I mean, go ahead, only torque your lug nuts down to 40 ft-lbs and see how bad the noise gets (but don't cuss me when one of your wheels falls off) Maybe it's that dumb plastic cam's job to keep those inner & outer gears separate in the disengaged state ... all I can do is speculate.

BUT ... Ford's Diagnosis & Inspection section says that the first step is to check the viscosity & level of the front axle lubricant, specifically 1.66 liters of F1TZ-19580-A (WSL-M2C191-A), for which the manual says (believe this at your own judgment) there is no replacement or substitute. Dunno 'bout you, but I bought my XLT used with 115K miles on it. I have no way to know if the factory lube was always used. If those noises ever start up again, I'm gonna do this first next time. Guess it's time for a total drain & replacement, anyway.

I do know that those thrust washers are missing on my X, which got me started down this path. The end play from the spindle hub all the way out to the end autohub case HAS to matter -- the axle end has to get out to a certain point for the hubs to engage in the first place, and that inverse motion obviously plays a part in disengagement. Your mileage may vary -- the ratcheting could come from a number of causes, all of which have to do with those inner & outer gears being too close, I'd guess. We might be talking about tolerances measured in thousandths of inches. Who can tell?

Everything I read says to junk these auto hubs and go with the manual locking kind. Yick. $275, no matter how you slice it. And then you gotta keep a pair of Channel Locks in your cab, and get out to lock/unlock. Fun, fun, fun.

Practical experience is always best. Thanks for posting back, MANZ. You've raised a lot of great observations and even better questions. Like: why would the LH side (mine, too) be so prone to the ratcheting, and the RH side seem to be exempt? Or: just what is wearing in that autolock hub end? I think I'm gonna have to <gulp> follow my curiosity and dissect that auto hub. Maybe better still, I'll go to my local salvage yard and see if I can't find a pair for $5 and play with those. I hate risking my daily driver; but now I'm curious as I can be about what the wear part is.

Thanks!

Peace,
--Jim--

 

[MANZ]

Thanks for the input Jim. If you want to diassemble your hubs, go for it and don't sweat it. It is very simple how they come apart and go back together. You will need a set of snap ring pliers (inner and outer) to remove the inner hub assembly and then remove the bearing.

I drove the truck to work today and didn't hear any grinding. I'll keep my fingers crossed, but I'm sure it will start up again since I didn't really correct anything.

I can't say why the one side is more prone to grinding than the other, or even that it really is more prone to it. Could just be coincidence. Like I said, (at least in my case) the grinding is totally caused by the hub misalignment of the inner/outer teeth set while freewheeling. No part of the cam, plastic retainer, or bearing status is causing this since I could hear and feel the grinding with the hub in my hand.

I'll keep you posted if it starts making more noise. Let me know if you yank yours apart and come up with a different hypothesis. Thanks again.

 

[MANZ]

OK, I give up. These hubs just plain suck. I hadn't heard any noise from the hubs since I last juggled the guts around in them, but this morning they started ginding and popping as soon as I pulled out. Many bad words followed - I even made up some new ones.

I plan on just pulling the hubs apart and removing the inner gear sleeve from them until I get around to installing manual hubs so I can at least drive it. I don't use 4wd much anyway if at all, so that is not a big deal. Anyone tried this or see any reason why I can't do this in the short (or maybe long) term? Thanks.

 

[a94exp]

Yes I gutted mine out about 2 weeks ago because of the same problems you guys have been having. No problems with that. Been following your posts with great interest. It looks like I'll probably switch to manual hubs too but thanks for the info you provided in your posts.

 

[Brandons]

Ill be switching to manuals when i blow these hubs, 2 on the truck working, another working one on the parts truck.

 

[MANZ]

Thanks for the replies. I figured it wouldn't be an issue, but just wanted to make sure. I yanked the guts out of the hubs tonight and took it around the block with no problems so I think I am OK for a while. What gets me is that the hubs look fine. Nothing worn as far as the gears, bearings, whatever. The cams on the spindle look good too. Maybe I should call an exorcist.

I've been keeping an eye on ebay for the warn hubs. You can usually get them with the adapter kit for around $140 or so. Anyone know where the best place is to get them? I'm in no rush though. This truck is getting old and is just one little problem after another, so I'm not dying to keep throwing $$ into it.