M939 Front Axle Boot replacement.....how I did it.....

[Moto2four]

Hello all,

I have to say, that was a LOT less "painful" than I expected.
My 1984 M923 was oozing grease and the boots were "crispy" to say the least.
Anyway, I elected to replace both even though the driver side was barely leaking.....we all know it was on borrowed time.
The insides of my knuckles were beautiful. Thank goodness whoever took care of my beast put plenty of that tan goo in there. LOL

I used US Made new zipper style from Memphis Equipment.

Removing the oldies and cleaning the surface is very straightforward so won't go into that.

The only "tricky" part is getting the new seal AND the clamp into the groove.

Here's how it worked for me:

1. Wrap the new boot around the axle, zipper it and turn it inside out to better access the groove.
2. Open the new clamp up (screw removed) and wrap it around the axle and boot.
3. Install the clamp screw (at 12:00 as the one that came off was) and install the nut with just barely enough thread to safely hold it in place so it's able to open wide enough Step 5.
4. Slide the boot groove portion into the axle groove.
5. Work the clamp into the boot groove slowly around the circumference. Be patient, it does work.
6. Tighten the screw slightly just enough to hold it in the boot groove and the boot in the axle groove BUT loose enough that the boot can be rotated ever so slightly into position. Not tight enough and it'll all pop out of it's grooves and you'll be redoing Steps 4 and 5. "just tight enough" and you can safely rotate it. It's a "feel" thing.
7. Gently fold the boot toward a few of it's bolt hole positions to check position in reference to the screw holes in the knuckle.
8. If need be, gently rotate the boot to match.
9. Once you're happy with the position, tighten the clamp.
10. I put a glob of RTV on the thread to prevent the nut from backing off (as the one I removed was) and on the zipper as well as where the zipper mates up to the knuckle.
11. If your previous positioning was good, you should be able to pop the boot into position and install the metal retaining ring.
12. Install screws and tighten gently. Don't overtorque and warp the ring! If at all possible, safety wire them.

Maybe this has been posted before? Maybe not.

But since it was a painless process and the results are worth their weight in gold, maybe this post might get someone who is on the fence about tackling it to dive in and give it a shot.

So if I buy the zipper type I don't have to pull the hub and all that crap off? Or am I mistaken?

 

[M35A2-AZ]

No you do not.
Remove the safty wire, screws, metal ring and the old boot. Also the wire ring that holds the boot on.
Then clean the axle area and put the new boot on.
But you need about four hands to do it.

 

[Moto2four]

No you do not.
Remove the safty wire, screws, metal ring and the old boot. Also the wire ring that holds the boot on.
Then clean the axle area and put the new boot on.
But you need about four hands to do it.

That's awesome news!! Thanks

 

[jarhead1086]

I have heard that you can silicone the zipper for added sealing. My inner seal is bad so I am cheating and having a shop change both since its easier for them knocking them out from the opposite side. It is missing the 4 bolts holding my shackle bracket to the frame so I need the front end hoisted up for that at the shop anyway. I am in the process of removing all four of the rear hubs and putting in new seals. I was able to remove the axle nuts from my first two hubs with my hand!! I will feel better knowing I have the proper torque and new seals. No more 90 weight lawn sprinklers in the back. Those bearings run hot with the grease washed out. Thanks for the tips everyone.

 

[NJDEUCE]

Great advice. I just did one a couple weeks ago by myself and I neglected to buy a new clamp. Big mistake! What a PITA to reuse the old one, especially with the buggered up thread!

 

[M35A2-AZ]

I did a boot some weeks back and the wire clamp had the nut welded to the wire clamp, that is the way to go.
A lot easier to start the screw.

 

[jonesal]

The TMs specifically outline how to do the zipper boots. It even gives the specs on the adhesive you are supposed to use on the zipper. The TM requires letting the adhesive set up overnight prior to fastening it on the knuckle. I followed the TM to a T, and they have performed as good as the solid ones, IMO.

Al Jones
'84 M923

 

[tashaak]

When installing the boot does it matter which way the zipper is. Should the zipper be out or in. One of mine is out and one is in,I don't know which is correct. Also what kind of grease is used inside the boots.

 

[Artisan]

When installing the boot does it matter which way the zipper is. Should the zipper be out or in. One of mine is out and one is in,I don't know which is correct. Also what kind of grease is used inside the boots.

The TM says;

Place steering knuckle boot (Figure 3, Item 6) on axle housing (Figure 3, Item 7), with fabric side of zipper
(Figure 3, Item 1) facing steering knuckle (Figure 3, Item 2).

I am referring to TM 9-2320-272-23-3 then navigate to Work package 0409.

____________________________________________________

REGARDING NO GREASE APPEARING WHEN YOU ATTEMPT TO PUMP GREASE INTO UPPER AND LOWER ZERKS "K";

I have some input.

I too have been replacing my boots ad while I had them off I decided to try to lube K zerts and see what I could see.
Well, I too had little luck getting grease to appear inside the hub, then it dawned on me, JACK UP THE TRUCK !

So I put my handy dandy air powered jack under the axle, up till the tire was off the ground, I then grabbed my air
powered Lincoln grease gun w/ Royal Purple loaded and the air compressor at about 130PSI and VIOLA!
I got grease to appear when I pumped into the BOTTOM zert. I tried the top and NO GREASE, so I let
the air out of the jack and lowered the tire to the ground and VIOLA! Grease emenated from the top.

NOTE I PUT THE TWO LOWER BOLTS IN TO HELP STOP FROM LOSING GREASE.

I pumped them both on both sides till I had all new grease showing.



PS, I think the TM says to torque the large bolts that hold the kingpin bushings to;
"Tighten screws 130 to 170 lb-ft"

Now I need to go find some "Silicone Sealant" ...

 

[Artisan]

Gawd I hate these TM's...


I am reading in LO 9-2320-272-12...

Card #4 of 33 says;
I am on PDF page 29 looking at NOTE #7 , it says on the right side;
GAA Front Axle Universal Joints and
Steering Knuckle bearings(
See Note 7) (LV-K-L) (O)

(Here is note 7)
7. FRONT AXLE UNIVERSAL JOINTS AND STEERING KNUCKLE BEARINGS

Every 6,000 miles (9,600 kilometers) or 6 months, whichever occurs first, disassemble and
lubricate front axle shaft and universal joints. Refer to TM 9-2320-272-20-1.

But where is GAA Faront Axle Universal Joints and Steering Knuckle bearings (See Note 7) (LV-K-L) (O) ??????????????????


Also I can not find LV (Localized View) "O"

Can anyone enlighten me as to where to DL TM 9-2320-272-20-1 and where in the LO can I find LV "O" ?

 

[Artisan]

no delete button

 

[Artisan]

For the seeing impaired...

I just saw on my boot, on one side, at what would be the bottom, it says;

THIS SIDE TOWARDS CENTER OF TRUCK.

Indeed that does put the cloth side of the zipper facing the OUTSIDE of the truck.

 

[Floridianson]

Yea your grease zerks could be pluged did you try and grease them before you lowered the truck back on the tire. If not you could try and raise up the truck and grease when not so much pressure on the joint. The two allen pulgs are not used to grease the new style u jounts just the old style that had timken balls. Quick check for water or Diff. oil in boot/ knuckle is just take out one of the four bottom bolts the hold on the bushing plate. You can drain out all water but if the knuckle is full of grease it might be harder to get out after fording so dont over grease the grease zerts and don't fill the knuckle with grease.

 

[Artisan]

So, if I had old style would I pull those little plugs and then use a needle grease gun type?

 

[Floridianson]

Guess that would be one way. If you have a M925 you don't have the old style.

 

[bogshotrods]

The TMs specifically outline how to do the zipper boots. It even gives the specs on the adhesive you are supposed to use on the zipper. The TM requires letting the adhesive set up overnight prior to fastening it on the knuckle. I followed the TM to a T, and they have performed as good as the solid ones, IMO.

Al Jones
'84 M923

Al, do you have a a link to the TM's for this project as I have a bad boot on the front passenger side, picked up a new zippered boot from Erik's Military the other day and will change it when it warms up a bit, thanks

 

[Artisan]

Try
TM 9-2320-272-24-1

Go to PDF page #796 (that is document page # 3-430)

They call it "Adhesive" but ...;
Appendice C #5 says

General-Purpose RTV Silicone Adhesive NSN 8040-00-833-9563

Looks like you can buy it here but you can prob just use RTV from anywhere...
http://www.vetco.net/catalog/product_info.php?products_id=930

Note how the existing part is orientated on the axle, put your new zipper unit
on the SAME exact way, slather up both sides of the zipper and walk
away for a full day. Return and button it up.

It probably says on the rubber THIS SIDE TOWARDS CENTER OF TRUCK

 

[bogshotrods]

Just changed the right front boot today and it went fairly well, but looking at the TM's for lubricating it shows vol 5 WP 0820 and for the life of me I can't figure out what and how much lubricant to put in there. It does show the 2 plugs to put something in but not what to put in there and how much. I did try to pack some wheel bearing grease in before installing the retaining ring back on, so any help would be appreciated

 

[Artisan]

Do a search for a recent thread on grease bogs.
The TM really blows on this subject.
I put NO GREASE in there.
As I see it the only way to grease that u joint is to pull it apart and grease the zert
or, if possible, a long needle thru one or both plug holes.

Fill it w/ grease and you will blow boots. It makes no sense.

 

[bogshotrods]

Thanks, I think you have a good idea on not filling it with grease, it can only lead to blowing the boot again. I think that sure it needs grease but not t extreme, hopefully what packing I did when installing the new boot will be enough. Maybe I'll pull both plugs and stick something like a zip tie in and see how deep the grease is and go from there. The TM's are full of great info but things like this are a pain in the a$$ to find