Save Those Auto Hubs--Easy Fix With Pictures
 

PART 1

Go here for pdf documents with pictures: https://1drv.ms/f/s!Av4sLhrHRtHyhRleDQK-G5eyQAuo

See original discussion at: https://www.ford-trucks.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. A little bit of time at $1.00 in parts saved my $600 auto hubs.

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.

http://home.vafb.net/~rgknowlton/95-..._Auto_Hub1.jpg
http://home.vafb.net/~rgknowlton/95-..._Auto_Hub2.jpg
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.

http://home.vafb.net/~rgknowlton/Snap_Ring.jpg
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.

http://home.vafb.net/~rgknowlton/Spline_With_Cam2.jpg
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.

http://home.vafb.net/~rgknowlton/Plastic_Ring_Wear2.jpg
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”??!!. Who 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.

http://home.vafb.net/~rgknowlton/Cam1.jpg
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.

MORE TO FOLLOW

PART 2

http://home.vafb.net/~rgknowlton/E-2411A_Washer.jpg
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. Preferably, 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.

http://home.vafb.net/~rgknowlton/Cam_With_Washer2.jpg
The washer takes up the space left by that little bit of wear in the plastic piece. Clean up the inside of the hub as much as possible and make sure everything has a light coating of grease. Things in the hub do continuously rub against each other, so don’t leave it dry. 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.


MORE TO FOLLOW

PART 3

http://home.vafb.net/~rgknowlton/New_Hub_Gap.jpg
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. 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.

MORE TO FOLLOW

PART 4

EXTRA STUFF ON HOW THE HUBS WORK

http://home.vafb.net/~rgknowlton/Spline_On_Axle1.jpg
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.

MORE TO FOLLOW

PART 5

http://home.vafb.net/~rgknowlton/Spline_On_Axle2.jpg
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.

$1.00 in parts saved my hubs and I bet this is a pretty common problem that cajoles folks into buying new hubs. I hope this'll save someone a few bucks. Feel free to add your own thoughts or questions.

Bob

I have a couple thousand miles on this fix so far, including lots of miles in tougher 4x4 country, and no problems. My father fabricated a fancier one piece washer for me, but other than that, I've made no additional changes.

It looks like wear on that skimpy plastic washer inside the hub was the problem after all.

Thanks for the update and glad to hear things are working good.

Do you have a pic of the upgraded washer?

No. Unfortunately, I don't. However, it is the same dimensions as the original washer except it is made of brass. The original washer worked just fine. I just put the fancier one in for kicks.

New Cause for the Problem
 

After some discussion with BradE, it looks like the more likely culprit for this common problem with the auto hubs is not wear on the plastic washer but rather is the small "leaf springs" attached to the bottom of the plastic washer. As the leaf springs weaken with time, the internal cam has to be pushed further and further into the hub to make up the difference. The washer fix is still a solid fix but someone who can come up with a suitable substitute replacement for the "leaf springs" will have a more direct fix.

https://www.ford-trucks.com/forums/showthread.php?p=1353302

this is now in the tech articles

https://www.ford-trucks.com/forums/1...formation.html

Matt

Well, this fix would have saved me about $250 in Manual hubs. Awsome post. It'ld be cool if bob junes could set up a kit with instructions and sell it.

Here's a link to a similar thread that details a little bit different method for doing the fix. It also has a lot of good pictures explaining the auto hubs: https://www.ford-trucks.com/forums/5...esnt-work.html.

Nice work, keys.

Matt,

The link to the hub fix in the tech section is broken. I have the document w/ pictures in .mht and .pdf format if you'd like to repost. PM me with and email address if you'd like me to send them to you.

I'm having the same problem with my 97 Ranger. I dont have a machine shop or diesel shop around. Has anyone used anything else for the washers? I live in Ontario, Canada anyone has a suggestion?
Thanks

The Euclid E-2411A air brake cam bushing (essentially just a washer) is the right part. Use a grinder or some other rotary tool to grind down the outer diameter of the washer to fit the application.