Auto Hub Washer Fix With Pictures

Note: I lost my picture server for the following pictures. Original pictures and write ups are available on my Windows Live SkyDrive Here.

See original discussion at: http://www.explorerforum.com/forums/showthread.php?t=21469. I probably won't have my picture server after 2006, so I recommend you save the pictures now or perhaps a moderator can put this in the tech section and host the pictures on the main server. (Edit: Pictures are rehosted below.)

I took some pictures while performing the "Beertime9 Washer Fix" on the automatic hubs of my '97 Ranger.

Many folks have noticed problems with their auto hubs, but upon disassembly they can find nothing blatantly wrong with the hubs. Symptoms include a popping or loud pinging sound while 4x4 is engaged or a grinding sound when you attempt to engage 4x4. The sounds are an indication that the hub will not engage or stay fully engaged.

Don discovered that the pot metal cam on the spline gear and the plastic ring inside the hub that the pot metal cam rubs against can wear over time. As they wear down, the cam can no longer push the internal hub mechanism in far enough to engage the hub gears. Wear seems to be only about 1/32" to 1/16", but it's enough to prevent the internal hub splines from engaging, which are only about 3/8" wide to begin with. Ford will tell you that there are no serviceable parts inside the hub. However, adding a washer between the pot metal cam and the plastic ring seems to replace the worn material and allow the auto hub to engage properly.




Here are a couple schematics of the auto hub, although they don't show the guts of the hub. Notice the "cam assembly". That is not the cam I address below.


When the hub is off, look at the aluminum cam (with the three fingers on it). Measure how much space there is between the top of the cam and the top of the spline gear (blue circle). It's about 1/16" in this picture. Your objective is to add a thick enough washer to bring the cam just about flush with the top of the spline gear. Obviously, you don't want it tight. Give it a little wiggle room so that it won't be under pressure when you reinstall the hub. (The picture below shows this same space circled in blue so that you can more easily see what I'm talking about. Of course, you can only take this measurement while the cam and spline gear are installed.) Start by removing the snap ring. You'll see it at the bottom. It's the only thing holding the spline gear and pot metal cam in. Once you have the snap ring off, turn the hub over and thump it on a wooden or padded surface. The only thing holding the spline gear in now is friction with the center post and crud, so sooner or later, it'll fall out.


This is the internal spline with the cam on top. The screwdriver is pointing to little nubs on the tops of the splines. The nubs prevent the cam from coming off the top. It has to slide off the bottom. The blue circle is to exaggerate the gap you'll be measuring while the cam and spline gear are installed.


If you look down inside the hub with the spline gear removed, you'll see the plastic ring. It is held in place by a round metal snap ring (red circle). This is as far as you can disassemble the hub without a press. To disassemble it further, you have to compress the plastic ring (and subsequently the huge spring at the bottom of the hub) far enough to get the round metal snap ring out. The screwdriver is pointing to the wear on the plastic ring. Can you say "planned obsolescence"??!!. What numbskull at Ford decided to use plastic instead of metal? The blue circle indicates the two sets of teeth that engage the outer teeth on the spline gear. When these two sets of teeth mesh, you're in 4x4. See below for a deeper explanation.


On the bottom surface of the cam, you can see the rounded spot that wore into the plastic ring (blue circle). Although I asked some questions in the original thread about whether or not the little teeth sticking up (red circle) were the result of wear, I'm now convinced that the cam was manufactured this way. I can see no way that a plastic ring wore away 1/4" of metal on the cam.


This is the Euclid E-2411A air brake cam bushing that I purchased from a local diesel repair shop for 26 cents. The outer diameter was still a little too wide, so I had to grind it down. It should be no wider than the width of the cam. Preferrably, it should be a smidge smaller so that it doesn't catch on the round metal snap ring. On the left is the original size and on the right is the washer after it was ground down. This washer is about 1/16" thick. I put two of these on each cam. A thickness of 1/8" is what I needed to just about make the top of the cam flush with the top of the spline gear but still allow for some wiggle room (maybe 1/32"). That may be too much or not enough for your situation. I recommend starting with a 1/16" thick washer. If that doesn't work, try different washers. The good news is that if you put a washer on that is too thick, you won't be able to seat the spline gear deep enough in the hub to get the snap ring back on.


The washer takes up the space left by that little bit of wear in the plastic piece. Clean up the inside of of the hub as much as possible and make sure everything has only a LIGHT coating of grease. Put it all back together, making sure that the new washer fits securely between the bottom of the cam and the plastic ring. The cam, new washer, and plastic ring have to move in and out of the hub, so make sure that the washer is not going to catch on anything.


Put the hub on the axle. It should sit flush against the rotor. If it doesn't (screwdriver pointing to gap), rotate the axle to allow all the hub guts to settle together. I incorrectly stated before that there should be a gap here and that the cam is under pressure when installed. Not true. Once everything settles together, you should not have to push against the force of the large hub spring in order to make the hub touch the rotor. Put the tire back on and torque the lug nuts.

With both front tires off the ground, turn the front driveshaft to see if the hubs engage properly. If they do, take it out for a drive to see how they perform under load. Go easy and go slow to start with. Test it in drive and reverse. Listen for the auto hubs engaging and disengaging. If they don't engage--and assuming you don't have other problems--your new washer may be too thick or too thin. Try a different washer.

EXTRA STUFF ON HOW THE HUBS WORK


If you're curious about how the auto hubs work, put the internal spline gear and cam on the axle, making sure that the cam fingers fit into the pockets on the cam assembly. This is the disengaged position. The blue circle shows the finger on the cam sitting in the pocket of the cam assembly.


Turn the front axle to simulate going into 4x4. As you turn the axle, you'll notice that the cam rides up on the cam assembly (blue circle). This is the action that compresses the huge spring inside the hubs and makes the inner teeth inside the hub engage the outer teeth on the spline gear (additional blue circles). This is the engaged position.

I hope that helps. Feel free to add your own thoughts or questions.

Bob

Yay! I'm going to do this to my hubs when I get to it

Bob... nicely done and excellent pictures. I moderate the Transmission and Transfer case forum, and made an offer to my folks there that a top notch photo illustrated thread entitled the poster to a nice FORD Rotunda Mousepad. This ain't my forum but thought you deserved one for this thread. PM me with an address and i will ship you one right after the first of the year. Gratis.

(ps. Elite status gets you beaucoup room on this server to store pictures for your threads, and sounds like you will be a great addition to the board!)

What a simple fix!! Did this today to my hubs and now have 4x4 again! I should state though that when my hub sit flush against the roter, it didn't disengage properly when I put the wheel on and tested it out. So I put on an extra spacer, had a gap and needed slight pressure to make the hub meet the roter - it all sat fine when the wheel went on. It seemed to work fine after that so I left it!
Thanks again for the post. Save $$ on coverting to manuals. And when they were down again, I'll just put in new spacers!!!

This is a very nice thread! Many people have asked questions how to repair auto hubs. I didn't see this thread until now.

I nominate this for a STICKY.

Aloha,Mark

Excellent thread. I just stumbled across it and rehosted the images.

BobK said:

See original discussion at: http://www.explorerforum.com/forums/showthread.php?t=21469. I probably won't have my picture server after 2006, so I recommend you save the pictures now or perhaps a moderator can put this in the tech section and host the pictures on the main server.

I took some pictures while performing the "Beertime9 Washer Fix" on the automatic hubs of my '97 Ranger.

Many folks have noticed problems with their auto hubs, but upon disassembly they can find nothing blatantly wrong with the hubs. Symptoms include a popping or loud pinging sound while 4x4 is engaged or a grinding sound when you attempt to engage 4x4. The sounds are an indication that the hub will not engage or stay fully engaged.

Don discovered that the pot metal cam on the spline gear and the plastic ring inside the hub that the pot metal cam rubs against can wear over time. As they wear down, the cam can no longer push the internal hub mechanism in far enough to engage the hub gears. Wear seems to be only about 1/32" to 1/16", but it's enough to prevent the internal hub splines from engaging, which are only about 3/8" wide to begin with. Ford will tell you that there are no serviceable parts inside the hub. However, adding a washer between the pot metal cam and the plastic ring seems to replace the worn material and allow the auto hub to engage properly.

Here are a couple schematics of the auto hub, although they don't show the guts of the hub. Notice the "cam assembly". That is not the cam I address below.

When the hub is off, look at the aluminum cam (with the three fingers on it). Measure how much space there is between the top of the cam and the top of the spline gear (blue circle). It's about 1/16" in this picture. Your objective is to add a thick enough washer to bring the cam just about flush with the top of the spline gear. Obviously, you don't want it tight. Give it a little wiggle room so that it won't be under pressure when you reinstall the hub. (The picture below shows this same space circled in blue so that you can more easily see what I'm talking about. Of course, you can only take this measurement while the cam and spline gear are installed.) Start by removing the snap ring. You'll see it at the bottom. It's the only thing holding the spline gear and pot metal cam in. Once you have the snap ring off, turn the hub over and thump it on a wooden or padded surface. The only thing holding the spline gear in now is friction with the center post and crud, so sooner or later, it'll fall out.

This is the internal spline with the cam on top. The screwdriver is pointing to little nubs on the tops of the splines. The nubs prevent the cam from coming off the top. It has to slide off the bottom. The blue circle is to exaggerate the gap you'll be measuring while the cam and spline gear are installed.

If you look down inside the hub with the spline gear removed, you'll see the plastic ring. It is held in place by a round metal snap ring (red circle). This is as far as you can disassemble the hub without a press. To disassemble it further, you have to compress the plastic ring (and subsequently the huge spring at the bottom of the hub) far enough to get the round metal snap ring out. The screwdriver is pointing to the wear on the plastic ring. Can you say "planned obsolescence"??!!. What numbskull at Ford decided to use plastic instead of metal? The blue circle indicates the two sets of teeth that engage the outer teeth on the spline gear. When these two sets of teeth mesh, you're in 4x4. See below for a deeper explanation.

On the bottom surface of the cam, you can see the rounded spot that wore into the plastic ring (blue circle). Although I asked some questions in the original thread about whether or not the little teeth sticking up (red circle) were the result of wear, I'm now convinced that the cam was manufactured this way. I can see no way that a plastic ring wore away 1/4" of metal on the cam.

This is the Euclid E-2411A air brake cam bushing that I purchased from a local diesel repair shop for 26 cents. The outer diameter was still a little too wide, so I had to grind it down. It should be no wider than the width of the cam. Preferrably, it should be a smidge smaller so that it doesn't catch on the round metal snap ring. On the left is the original size and on the right is the washer after it was ground down. This washer is about 1/16" thick. I put two of these on each cam. A thickness of 1/8" is what I needed to just about make the top of the cam flush with the top of the spline gear but still allow for some wiggle room (maybe 1/32"). That may be too much or not enough for your situation. I recommend starting with a 1/16" thick washer. If that doesn't work, try different washers. The good news is that if you put a washer on that is too thick, you won't be able to seat the spline gear deep enough in the hub to get the snap ring back on.

The washer takes up the space left by that little bit of wear in the plastic piece. Clean up the inside of of the hub as much as possible and make sure everything has only a LIGHT coating of grease. Put it all back together, making sure that the new washer fits securely between the bottom of the cam and the plastic ring. The cam, new washer, and plastic ring have to move in and out of the hub, so make sure that the washer is not going to catch on anything.

Put the hub on the axle. It should sit flush against the rotor. If it doesn't (screwdriver pointing to gap), rotate the axle to allow all the hub guts to settle together. I incorrectly stated before that there should be a gap here and that the cam is under pressure when installed. Not true. Once everything settles together, you should not have to push against the force of the large hub spring in order to make the hub touch the rotor. Put the tire back on and torque the lug nuts.

With both front tires off the ground, turn the front driveshaft to see if the hubs engage properly. If they do, take it out for a drive to see how they perform under load. Go easy and go slow to start with. Test it in drive and reverse. Listen for the auto hubs engaging and disengaging. If they don't engage--and assuming you don't have other problems--your new washer may be too thick or too thin. Try a different washer.

EXTRA STUFF ON HOW THE HUBS WORK

If you're curious about how the auto hubs work, put the internal spline gear and cam on the axle, making sure that the cam fingers fit into the pockets on the cam assembly. This is the disengaged position. The blue circle shows the finger on the cam sitting in the pocket of the cam assembly.

Turn the front axle to simulate going into 4x4. As you turn the axle, you'll notice that the cam rides up on the cam assembly (blue circle). This is the action that compresses the huge spring inside the hubs and makes the inner teeth inside the hub engage the outer teeth on the spline gear (additional blue circles). This is the engaged position.

I hope that helps. Feel free to add your own thoughts or questions.

Bob

Click to expand...

1 Year Follow Up

I've been running this fix for about a year now with no troubles at all. I only made one change to to original fix. Instead of using the hastily-ground steel washer, my father fabricated a good close-tolerance brass washer for me. I was able to make the fabricated brass washer just a little thicker than the steel washer, which filled in my cam gap a bit better. I figure the brass washer may absorb future wear a little better than steel and will be easier to replace in the future if I ever run into this problem again.

Auto hub washer fix

The fix for the shiftless hub problem looks like a good one that I will use to fix my own useless hubs but I think the plastic washer is unfairly and incorrectly diagnosed as the problem.

When the internal spline (that is keyed to the hub) is driven by the cam into engagement with the driven spline set it is pushed by a set of 3 leaf springs against the large coil spring. If the mating splines aren't quite lined up the leaf springs compress so as to not crush the cam assembly. as soon as the splines are in aggreement the leaf springs push the splines into engagement.

The internal spline that is keyed to the hub and is driven by the cam to transfer power from the driven axle to the hub is captured between two sets of springs. It's position, both at rest and when driven into engagement to lock the hub into 4 wd, is dependant on the strength of those two sets of springs (the leaf springs attached to the plastic washer and the large coil spring). When the hub gets a few years on it I think the leaf springs are giving in to age. This causes the coil spring to force the internal spline to ride higher in the hub (closer to the wheel) than when new. The result is that the cam movement is no longer sufficient to drive the hub spline (internal spline) far enough to engage the inner/outer spline that is driven by the axle.

The washer that is placed between the cam and the plastic washer makes up for the loss of power in the leaf springs. You are limited in how much washer you can use by the fixed "slop" in the cam assembly. Too much washer and you will need to compress the spring sets. To actually "fix" the problem the added washer would need to be placed between the leaf springs and the internal spline. In this position you could add exactly the amount you need to get the internal spline back to its original relationship to the driven spline set. Of course, if you have the snap-ring removed you might as well replace the offending leaf springs.

The plastic washer is pushed to its upper limit by the springs below it and against the round metal snapring. If the plastic washer wears down it gets thinner but the difference is lost in the springs, until the plastic gets so thin it no longer holds. The cam height relative to the inernal/external spline will be the same no matter how thick the plastic washer is. Aditionally the plastic washer can't be worn down across it's whole width as the cam only rides on a part of it's width. If the plastic ring were wearing it would develop a groove and no longer be flat across it's width.

Thanks for the second opinion, Brad. I just got another set of auto hubs that need to be fixed. I'll look harder this time to see if I can understand what you're saying.

If you look into the hub, as you might look into a cup of coffee, you will see the plastic washer pressed up against a cir-clip (or snap-ring). The plastic washer has three leaf springs attached to its underside. These springs push down on the cog, or inner spine. The spline cog is against the bodatious coil spring. The downward movement of this cog causes it to engage with the driven spline on the axle.

Still looking into the hub? Visualize pushing down on the plastic washer with the intent of pushing the spline cog deeper into the hub. You will notice that you must depress the coil spring in order to accomplish this but as you push you will also have to overcome the leaf springs.

The purpose of the leaf springs are to keep the cam assembly from being crushed in case the splines on the spline cog and the splines on the driven spline are not exactly lined up. The problem with them is that they are only about an inch long and years of use cause them to weaken. The coil spring below them is much more robust and so the spline cog will progressively ride higher in the hub. This means that the cam assembly will have to push farther in order to get the spline cog to engage the driven spline on the end of the axle stub.

The washer fix takes some of the built in "slop" of the cam assembly and uses it to allow the cam to push farther. You can add as mush washer thickness as you have slop but at some point you will cause the hub to preload some spring tension and may cause the spline cog to stay in engagement with the driven cog. If you can't push the hub competely onto the axle without drawing up the lug nuts you have reached the end of the slop and are driving the plastic washer and the contents of the hub away from the snap-ring. As the cam assembly spins with the axle this probably isn't a good thing.

The best way to fix this problem would be to unload the hub, pull the snap-ring, and replace the plastic washer with the leaf spring attached to it but you probably can't buy the darned thing.

Best of luck

Brad

PS: I appoligize if this description is hard to follow. I don't know what the proper names are for the components and everyone uses different phrasology. To add to the confusion there are three spline sets in the hub: the outer spline on the axle, the inner/outer spline set that sets over the axle, and the inner spline that is captured in the hub. The success of the hub depends on the factory set (at rest) relationship between the inner spline (spline cog) that is in the hub and the inner/outer spline that is on the axle stub.

Can Anyone tell me...

What is the circumference that these washers need to grinded down to? I have a 1994 Ford Explorer.

Thanks

Sorry, waynar, can't help you there. I saw the guts of an Explorer hub that appeared to have much different dimensions than my '97 Ranger. I measured the diameter of my cam after I removed it from the hub and then ground down the washers for a "custom" fit.

Good post, Brad. I think you hit the nail on the head. To be honest, I couldn't convince myself that the plastic ring had worn down, but I didn't know what else to blame. I'll put some thought into what might be a suitable substitute for the leaf springs. Maybe a big, squishy rubber washer?

Bob K

As long as you have the hub coil spring unloaded (as you would have to in order to get to the leaf spring) you might try fixing the existing springs. (By unloading I mean removing the cir-clip that keeps the springs and cogs held in the hub.)

Once you have the plastic washer out of the hub try bending the leaf springs back to original lift position. I haven't tried this so I don't know how successful it would be and you'd want to be careful not to break one of the three springs as you may not be able to buy another set. Maybe a Ford dealer will sell you just a new set of springs for the hub.

In my case dismantling the hub, cleaning and repacking seems to have fixed my shiftlessness (my wife wants to do the same to me now).

As for a creative replacement, be cautious. Whatever you use has to stand the pounding of the splines mis-meshing as the cogs spin under load. Anything that can't allow the splines to ride each other until the cogs spin into alignment will cause the cams to snap off. It could be a pretty abrupt and unkind end to the day (and leave you a ways from home).

By the way, the outside diameter of the washer you would use as suggested by the original post, in my hub, would be about 2 inches. I lost the paper I had written the measurements down on and I can't remember what the inside measurement is. The pictures show where the washer fits. If you take your hub apart you should be able to measure the space where it fit easier than I could describe that space.

Would anyone be able to supply me with the dimesions of the plastic ring? I haven't pulled apart my hubs yet, but I would like to make the new 1/16 washer before I do. Sizes? 1991 ford exploder

Thank you

Great

Very informative and interesting article. Thank you for it.

Here's a link to more info on this same subject...with lots of additional pictures by someone who also did the fix with a little bit of a twist: http://www.ford-trucks.com/forums/581318-4x4-in-1997-ranger-doesnt-work.html

FEX1991: I wouldn't venture to guess the size of the plastic ring in your 1991. I only have experience with the '97 hubs and don't know if the dimensions have changed over the years. I'd recommend you take them apart...it really should only take 15 minutes or so per hub.

Bob, you are brilliant. For the longest time I've been without 4WD and I followed your instructions adding the Euclid air brake cam bushing. I've got 4WD again! Two thumbs up to you! I am one happy dude! Much Mahalo from Maui!

Well I ended up fixing my autohubs, unfortunately I didn't get to try the washer fix. I ended up finding about 6 pairs of Ford Explorer Auto hubs at my uncles scrapyard, we ended up walking through about 25 Explorers pulling off every hub we could find, I got em all for 250 bucks. LOL

I didn't find any manuals unfortunately otherwise I would have used those.

My hubs work awsome and if they break its a 2 minute fix. lol

4x4 is alot more extreme now lol