Hi Bob,
The gap I'm talking about is only measureable when the hub is assembled, so you can't actually see it. Hence the silly putty:



When the hub is fully assembled, there should be no gap between the outside of the CAM and the plastic spring spacer (inside the hub). The silly putty shows a 3/16" gap.

It looks like when the hub locks, the hub spring is supposed to be compressed about a 1/4 inch. With this 3/16 inch gap, my spring is only compressed about 1/16 inch, which isn't quite enough lock the hub, but is enough to make some awful popping sounds as it trys to lock.

I think this is clearly explains why adding the spacers would make the hub work again. But the real question is where did this gap come from!
Nothing in my hub is broken or worn any where near 3/16 of an inch.

Here's some pictures of how the CAM works and locks the hub.

I dissasembled the hub and put the inner piece back onto the axle shaft as if the hub were bolted to the rotor.


The outside half of the CAM is fully seated in the inside half of the CAM.
In 2 wheel drive, the only thing that rotates in this picture is the rotor.


When 4x4 is engaged, the axle starts to turn and turns the the outside half of the CAM. (the outside half of the CAM is splined to the axle at all times.)
As the outside half of the CAM rotates and moves out of its pocket, it is also pushed back (away from the rotor).


As the outside CAM moves away from the rotor, it compresses a spring in the hub(not shown) and moves 2 rings of teeth inside the hub (not shown) away from the rotor. These 2 rings of teeth will engage the two rings of teeth shown in this picture (on the right). When the rings of teeth are engaged, the axle is driving the hub, which is bolted to the wheel. Hence 4 wheel drive.


The outside CAM half has rotated about a sixth of a turn and has met up with the little nubbin on the CAM base assembly. The axle is driving the outside CAM half, which is now driving the CAM base assembly...so in 4x4 mode everything shown in the picture is rotating with the axle. The only thing that doesn't turn is the inside CAM half (inside the CAM base assembly). It is locked in place and never moves.
The CAM base assembly holds the outside CAM half away from the inside CAM half which keeps the spring compressed and the teeth engaged and "locks" the hub.


BTW, it took me hours to figure out how the blasted thing works

 

Wow! Nice pictures, Keys. Those are lot more in depth than the two at the end of my write up.

Yep. Your hubs look like a great candidate for the washer fix.

After talking with some smart guys, we think we've determined that the little leaf springs on the bottom of what you call the "plastic spring spacer" start to sag and then leave that gap you're measuring with the silly putty.

If you look at my write up, I bet you'll see that same gap when you have the inner hub gear in place in the hub.

Good luck! I think they'll work great once you fill in that gap with some washers.

 

By the way, since the plastic spring spacer turns with the wheel, I personnally think there should be a smidgen of space between the outside half of the cam and the plastic spring spacer. If the two are tightly held together--i.e. by adding too many "fix" washers--then the plastic spring spacer will constantly rub on the cam when the hub is unlocked.

 

Thanks Bob, I think you're right about leaving a smidgen of space between the cam and the leaf spring plastic spacer.

I have some custom washers coming my way soon.
Can't wait to try them out.

My leaf springs don't really look saggy though.
My leaf springs and the coil spring in the hub are pushing solidly up against that plastic washer and finally held in place by the snap ring.
But let me think about this....so if you're saying the leaf springs are sagging...that really means that in the unlocked position the coil spring is pushing the sliding spline gear farther out of the hub than when it was new (toward the rotor, but of course not past the snap ring)...this compresses the leaf springs more than normal (due to sagging).....and finally, in order to lock the hub we have to push it that much farther back into the hub.
Since I haven't been able to remove the snap ring, the above relies on my understanding that the sliding splined gear is simply sandwiched between the coil spring and the leaf springs.

That being said, it still doesn't explain my 3/16" gap between the leaf spring plastic washer and the cam. The plastic washer is still in the same place it was when the truck was new...up against the snap ring. Since I know that the snap ring hasn't moved, that means the cam had to move away from the plastic washer to create the gap....but how that could happen is a mystery to me!

 

I'm starting to think that the gap between the cam and the plastic ring has always been there. I could see no significant wear on the plastic washer and no significant wear on the cam. That led me to look somewhere inside the hub for the wear.

As you said, if the leaf springs on the bottom of the plastic spacer start to sag, that means the plastic spacer has to be pushed in even further to make up for the space that the new beefy leaf springs used to take up. The gap between the cam and the plastic ring didn't used to be a problem, but now it's a little too much gap to push the plastic ring in far enough. Whatever it is, it doesn't take much. About 3/16" was enough to fix mine.

That's the best I can come up with so far. I have another set of hubs to fix and I'll keep an eye out for a better answer when I tear into them.

 

I'm happy (ecstatic I should say) to report that my spacers arrived (finally)
and seem to have fixed the problem.
My hubs now engage and disengage like they did when I bought the truck!
Making it through this winter will be the true test.

Here's the specs on my spacers, just in case anybody else wants to make some.
I used 2 spacers per wheel to fill up the 3/16" gap.
One spacer went on the spindle nut.
(between the spindle nut and the plastic part of the cam.)
The other spacer went IN the hub. (sits on top of the plastic washer)

On Spindle Nut
---------------
Inner diameter: 1.8"
Outer diameter: 2.3"
Thickness: 1/16"

Note: the OD of the spindle nut is exactly 1.8"
The machine shop made my spacer's ID exactly 1.8"
and it just barely fit over the spindle nut.
Any tighter and it would have been an interference fit. (obviously)
A fit this tight requires a small radius on the inner side of the ID to
match the fillet on the spindle nut.
I just ground down the corner of the spacer ID with a dremel until
the spacer would bottom out on the spindle nut with no gap.


Inside Hub
----------
Inner diameter: 1.7"
Outer diameter: 2.1"
Thickness: 1/8"


You might want to make your spacers slightly thinner.
My two added up to 3/16", but when I assemble the hub,
the hub spring is ever so slightly compressed even when the hubs are unlocked.
I don't think it'll be a problem, but I think a tiny gap would be better.
Probably only talking 1/64" thinner.

 

Keys,

Your one of only a handful of people who have actually done this and wrote about it, and it sounds like you did it a little different than the "standard" way. Any chance you could post some pictures of your assembly? I have another set of hubs that need to be fixed and your method might work better.

 

Here's some pics of my spacers.



I used 2 spacers per side. I wasn't sure if I could get a single 3/16" spacer to fit in the hub under the outside half of the CAM. So I went with a 1/16" spacer on the inside (on the spindle nut) and a 1/8" spacer on the outside.



Above is the In the Hub spacer sitting on the outside half of the CAM.



Above is another view of the In the Hub spacer - actually in the hub.



Above is the Spindle Nut Spacer sitting on top of the inside half of the CAM.



Above is another view of the Spindle Nut Spacer - actually on the Spindle Nut.
The spacer is a tight fit on the spindle nut and therefore does not spin, even when the CAM is spinning. (in 4x4 mode)



Above is the inside half of the CAM with spacer - fully assembled.

NOTE: the spindle nut spacer absolutely can NOT be any thicker than 1/16"
If it were any thicker it would cause the CAM to interfere with the C clip that goes on the axle.

 

It looks like there are two spacers in the pic, a thicker aluminum-colored one on the bottom and a thinner stainless steel one on top. Am I seeing things correctly? I thought you only put one spacer on the inside.

Also, who manufactured your spacers?

 

Hi Bob,

It does look like 2 spacers in the picture...but it is just one. (plain steel)

The faces of the spacer (the stainless steel looking part) were ground to a mirror finish because that is the part that will rub on the other parts.

The edge of the spacer (the aluminum looking part) was not ground smooth, so it still has the more rough cut appearance...which does look like aluminum in the picture.

And the outside corner of the spacer (which looks kind of shiny in the picture) was just rounded off slightly to make sure there weren't any burrs.

As for manufacturer, I got lucky.
There is a machine shop where I work and I found someone
willing to make them for me for the price of a bottle of whiskey and a little patience (a month later).

 

thanks for all the write ups and pics. I did the washer fix on my sons ranger a couple weeks ago and seems to work great. I don't think it will last forever as I had differing amounts of wear from one side to the other. I installed only the 1/16" thick washer on the axle nut on the right side and had to use both the 1/16" and 1/8" washers on the left side to take up the gap. Definetly some weird wearing going on between the plastic washer and the outer cam gear.
Anyway, I had my washers laser cut out of mild steel from a vendor that we use where I work. I have a extra set of washers if anyone is interested. $25.

Brett

 

Did you laser cut your washers to the dimensions Keys posted above?

It would be interesting to hear an update from Keys how the fix has worked over the winter.

This is a valuable thread. If I ever have this problem, this is the solution I will prefer most. Good job guys.

 

Yes, I did follow the dims that Keys gave. They are very accurate.

Thanks
Brett

 

Well guys, its been an entire winter and the 4x4 hub spacer fix is still working great !

We had near record snow here in Mich, so I had plenty of opportunities to engage the hubs. I'd say close to 100 times this winter.
(I don't shovel much, so most of that was just getting out of the driveway )

I was babying it a bit and almost always flipped the switch while at a stand still. But I did engage 4x4 a couple of times while rolling down the road and that was ok too.

Now its time to park the truck and get out the Mustang!

 

More good news, the fix that I did on my sons Ranger is also working great! He has been working at a Ski Resort all winter and driving up and down the canyon everyday and he on the other hand is not so easy on the equipment if you know what I mean.

Thanks again for all the research, photos, and information.