preventable rear suspension failure

[gringeltaube]

.... I blew out that seal when I first did the conversion. Without the "relief" the seal blew out like a cork in a bottle of seltzer when I was pumping in the grease.

How could that happen? The seal as well as the retainer are installed on the tandem axle spindle, not pressed into the spring seat housing. There is no way these could shift further back.

Why in the world would the military say to install the zerk in the bottom of the trunnion and then "LOOSEN" the cap before pumping in grease ?

Because otherwise the front (outer) bearing would never see any fresh grease.

.... I forgot to add my seal was a hard "plastic" type seal. Not some felt seal.

You are referring to the #7521647 "Retainer, Packing"; not the seal itself. Very likely there was a change of materials for that particular part,over all those years.
BTW: When I upgraded my spring seats I also replaced that old felt and washers with a 4mm thick (PP)plastic disc, plus an O-ring acting as spacer.
All it does is keep the backside opening shielded to the outside, to prevent dirt and small rocks to enter the next cavity where the seal is. And there is always a slight gap left in between that shield and the seat housing; more than enough for the grease to squeeze out.

 

[Floridianson]

[QUOTE=rustystud
Why in the world would the military say to install the zerk in the bottom of the trunnion and then "LOOSEN" the cap.

Ouch bad mistake. Guess you can never say please read the TM's again. I looked for that TM but gave up looking but that was a thought I had but did not think it would really get grease through out the bearings. Really don't know what happened to your problem. Most I have done so far when doing any of the Deuces was maybe six or seven pumps. Myself when I do the service and remove the cap for the first time if there is no sign of moisture / trouble and looks good on the outer bearing I will call the inner good to go and just do the service with cap installed tight. G your pic showed with the grease fitting on top of the cap and my thought at this time it would be in the center of the cap. Someone ask why this happens. Poor grease job when the truck was built, never saw any services and had seal fail or cap water intrusion plus never checked for everything for staying tight?

 

[Floridianson]

G since I have not had a trunnion apart does the stock grease fitting on the bottom inject grease in between the inner and outer bearing / bushings?
Just throwing it out there. If the grease is injected between the two then every time we service it we are pushing new grease back as you said through the bearing /bushing and rear seal and old grease would be pushed forward out into the cap. If we put a grease fitting in the cap then we are pushing used grease from the front into the rear bearing/ bushing. If it is injected between the two then we grease from the bottom fitting and have a plug in the cap we take out to let the bad grease come out of the front bearing / bushing into the cap and as Greg said the tm said just to loosen it enough to let the old come out?

 

[gringeltaube]

This is my reasoning:
1) Since everything is slow motion in there we can actually completely fill (and keep filled-) the whole space, 100%. That way no water will penetrate - and no condensation can occur.
2) When you pump fresh grease in, it normally goes first where there has been the most relative movement/friction. (Old grease tends to thicken, but only in the "quiet" corners, and it doesn't hurt if it stays there.)
3) When pumping fresh grease in from the cap side (provided the cap had a zerk or plug added) there is only one obligatory route left. Grease just has to pass through both bearings.
4) I have always observed that it doesn't take much to come out clean, on the backside.
5) Grease injected into the bottom zerk may get to both bearings - if you are lucky. It is clear that it will come out wherever it finds the least resistance. Similar to what happens with worn U-joints. Of course, if it came out to the front only, then you can always tighten that cap and keep pumping until it starts squeezing out at the backside, too.

 

[Floridianson]

It is a weird the way the engineer designed it but I don't think we have to reinvent the wheel just figure out how to get it rolling.
Remove the cap and do inspection and reseal. Remove the plug in the cap if you have one. If not install one and open it. Start to pump grease in bottom grease fitting till the grease comes out the cap plug hole. Stop replace cap plug and pump maybe a small amount to get some grease into the rear bearing /bushing or till you start to build pressure. My cap does not have a plug but if I install one I could then just open the plug change out the front bearing /bushing grease and not have loosen the cap that I just inspected and resealed.

Post correction sounds better.

 

[gringeltaube]

Agreed. Many ways to "skin the cat"...

At least people should get to know that there is such spot, to put some grease in there.
I have seen too many of these spring seats, completely neglected - running almost dry and everything worn out beyond hope, of course.

 

[Floridianson]

Agreed. Many ways to "skin the cat"...

At least people should get to know that there is such spot, to put some grease in there.
I have seen too many of these spring seats, completely neglected - running almost dry and everything worn out beyond hope, of course.

That's why I have my fingers crossed that mine will be ok when I get a chance to get into her.

 

[rustystud]

How could that happen? The seal as well as the retainer are installed on the tandem axle spindle, not pressed into the spring seat housing. There is no way these could shift further back.
View attachment 747749


Because otherwise the front (outer) bearing would never see any fresh grease.


You are referring to the #7521647 "Retainer, Packing"; not the seal itself. Very likely there was a change of materials for that particular part,over all those years.
BTW: When I upgraded my spring seats I also replaced that old felt and washers with a 4mm thick (PP)plastic disc, plus an O-ring acting as spacer.
All it does is keep the backside opening shielded to the outside, to prevent dirt and small rocks to enter the next cavity where the seal is. And there is always a slight gap left in between that shield and the seat housing; more than enough for the grease to squeeze out.

When I first did mine, I used my "Lincoln Power Grease Pump". I should have paid more attention but I just sat there holding down the switch and that thing pumped in grease like crazy. Before I knew it, it had blown out the seal completely !!!! I tried to "push" the seal back but it was destroyed. Bent up like crazy. So before you start "Bashing" another person here Gerhard, may be you should find out all the particulars ! I like your graphics Gerhard. They are a great help, but sometimes they don't actually match reality. This is one of those times. I'm still looking for my pictures. I know I have them somewhere. It will show what happened better then I can explain. Trust me when I say it would have been great if I could have simply "pushed" in that stupid seal instead of taking that unit completely apart ! That is a hard, hard job I would have gladly passed on.



This is the seal I'm talking about. It had pushed the metal retainer completely out and the rubber of the seal was hanging out torn and loose. There was "No Way" in the world to push it back in.

 

[Floridianson]

Problem power grease gun putting out enough pressure to destroy seal with cavity closed off. Seems like once you get to where the trunnion set up is full of grease it will not need that much more grease to do a service. As I said before when I did get to service it when I first got the truck five or six pumps with a hand grease gun and I stopped. What I might try when I do get to restore the truck. Remove the cap and inspect bearings /bushing, retorque. Since I don't have a plug in my cap install one and reseal /install the cap. Remove the plug and pump grease into the bottom fitting till the grease comes out the cap plug hole. Replace the plug and pump a bit more but not over grease /pressure for the rear bearings/bushing and seal. I would be willing to bet that when you put the plug in the cap and start to add more grease with a hand pump grease gun to fill the rear cavity you will feel the pressure build and it will become harder to pump. When it starts feeling harder to pump the cavity /bearings are greased filled so stop pumping. Rear seal can relieve / handle SOME over pressure / grease. I popped out a high pressure O ring grease seal in a loading / unloading hose at the refinery. I was using a high pressure hand grease gun and I could feel the gun getting harder to pump. I should have stopped. Two more hard pumps and POP goes the weasel. Good thing I did not have to fix it, ( not my job man). Glad I read this thread as it made me think plus learn what and what not to do. Thanks G.

 

[rtadams89]

Why does the trunnion have a plug, instead of just leaving the grease fitting in all the time?

 

[rustystud]

Why does the trunnion have a plug, instead of just leaving the grease fitting in all the time?

It can get damaged when jacking up the truck, or hitting an object when off-roading. Personally I don't think that would ever happen, well maybe the jacking up the truck part could.

 

[Floridianson]

I checked the two Deuces and all my 5 toners they have the grease fiting installed. The five tonners are the same way as the Deuce's no plug in cap. Seems like it would have been easy to install a plug instead of having to loosen the cap to get the grease to flow to the front.
After learning more about the trunnion set up thanks ALL I will just add a plug in cap and grease from the bottom stock fitting. As said before remove plug pump till grease comes out plug, install plug continue to pump till tight or grease comes out the back seal. Clean up the grease that comes out so as not to attract dirt.

PS easer than drilling and tapping for a plug I will get a new self cutting metal screw with fiber washer like this old one and see if it holds.
Pardon my drawing but keeping the system like it was designed just adding a plug in the cap we keep good grease never touching old and pushing it out both ends. As for servicing it will take very little grease to expel old.

 

[Floridianson]

Now look what happens if we put a zert in the cap. We push old grease into what should be a clean grease cavity. The pressure valve might let the old come out but sooner than later the old grease will end up at the rear bearing and seal. Then everytime we grease we just push old out the rear. The zert needs to be in the stock place so with every pump you expel the old out the cap or rear seal. This is not rocket since. Keep the center cavity filled with clean grease!!

 

[gringeltaube]

...........Then everytime we grease we just push old out the rear....

Yes, some old grease... and then clean grease will soon follow. It doesn't take long; try it out...

 

[Floridianson]

Seems like it will take at least two tubes of grease to change out that way plus makes a mess at the seal end. Correct way maybe six pumps to clear cap end six pumps to clear seal end. Lets pretend we went fording and the cap took on water. Now we have to push this water from one end to the other and hope we get it all? The TM tells us to loosen the cap. So after the inspection if you do one and we replace the cap with a new gasket and leave it loose. Pump till grease comes out and tighten the bolts. With a new gasket I would bet that it would seal. Problem is we don't have new gasket so we use a silicone sealer with clean mating services and install the cap and let it dry. Seems like you would not want to push grease through wet silicone as it might not make a good seal if we do the just leave the cap loose. The other way I can think of would be make a good gasket that could handle the little pressure of grease coming out between the the cap and housing if we leave it loose. That way you don't have to plug / drill tap the cap. Sorry but I believe the stock set up the way it was designed is the correct way to push fresh grease just need a plug in the cap or new gasket. People with zert in cap can just remove the zert can still push grease the correct way. Thanks I will stick with plug in cap for the upgrade
Hay G I would normally not try and bump heads with you as I am a sore looser but here I must.
As for Rusty I do believe his high pressure and high volume super power grease weapon could push the seal rubber backwards but not the steel retainer as you said as it can not go anywhere the way it is seated. That plus cap not loose or plug in cap installed.

 

[rustystud]

I knew I had these pictures somewhere. Here is what happened to me greasing my trunnion bearings.




This seal is rubber, "NOT" felt like Gerhard said. I bought this truck right off of "Fort Lewis" so it was never in civilian hands until me. That means the military installed this seal. That also means there is more then likely plenty other deuces with this seal. So if you have these seals and listen to Gringeltaubs advice and pump in grease until it comes out back, you will "blow" out your seals also.
So Gerhard listen to your own advice and "think" before you post.

 

[Floridianson]

G said it had rubber seal and felt retainer post #61. You can see seal and retainer for felt A new rubber seal I believe will give enough to let air out and some grease. Old might not give as much and using a high power greaser pushes the grease to fast for the air/grease to escape. Then the rubber will fold backwards as you proved. After you get the front side full with plug or cap loose go easy on the rear seal is what I would / will do. Hand pump till it feels as though getting tight. If one was to leave the cap just loose enough ( just a hair) to let air / grease out under pressure there should be some grease going to the rear too. Then finish off cap tight for rear.
I am going to stick with my upgrade and found this self drilling sheet metal screw from Ace hardware and even came with the rubber washer. I will put it in the center of the cap and try it out. Your truck as always do what you think is best.

 

[gringeltaube]

When I first did mine, I used my "Lincoln Power Grease Pump". I should have paid more attention but I just sat there holding down the switch and that thing pumped in grease like crazy....

... So if you have these seals and listen to Gringeltaubs advice and pump in grease until it comes out back, you will "blow" out your seals also.
...

OK, what if we added this phrase:...."but if you pump in grease normally (by using a REGULAR HAND PUMP) you will get grease coming out the back, without damaging any seals"...

Think about this, Rusty: how else would the operator be able to "flush" any old grease out of the inner bearing?


Just for fun, I did some (greasing) "tests", today... (I got curious and wanted to see how hard (or easy) it was to actually "blow out" one of those rubber seals/ shields...)
The parts shown in the following pictures all felt very tight, with no play at all. And all of them had the newer, rubber type shield...
Of course, I did not loosen the cap, on purpose and just pumped grease in, from the bottom.

1st one took a while (to compress the obvious air pockets), but what finally came out at the back side was some dark stuff with the consistency of chewing gum (!) Talk about old grease...! I could actually feel the resistance in the pump, but the thing is, that gum did squeeze out, without doing anything to the shield and washers.
I stopped when it started leaking (fresh grease) at the front. So maybe I blew the cap gasket, but not the rear seal.



2nd one, after about 20 pump strokes, just clean grease (no old stuff) started coming out the back, with very little resistance. After wiping it off, the seal looked as good as before. So, again, no sucess... (in popping the seal)



Of course, isolated test results don't prove anything. And I do acknowledge that things can go wrong, eventually. One single case is proof enough.
Every case may be a bit different. Brand new parts - which most of us don't have - might be a tighter fit, shield to housing?
(as always: "your mileage may vary...")

Again, my humble opinion - after years of working on these things: the whole design is far from ideal, and there is very little we can do to improve it.
One thing I always did was to move that grease zerk out of harms way and place it where everyone can see it - easy to reach and inviting" at least... People in my country don't read TMs, not in English, not in Spanish. But even a moron knows what a grease zerk is for, so there is a slight chance at least that they do add some fresh grease, from time to time!
It has yet to happen that one of those seals popped out, almost like exploded, as seen in Rusty's picture..

 

[Welder1]

There is a difference in how fast you inject grease in a system. A powered grease gun can displace seals and even push bushings out if done wrong. Using a hand gun and slow application will minimize chances of doing what Rusty showed with the seal pushed out. it's a matter of paying attention to what you are doing and moving slow. Just my opinion we all have one.



Eddie

 

[Floridianson]

Do believe if you have a grease fitting on cap or use the stock grease fitting you don't need a pressure relief installed. What one might do is start greasing with the trunnions first till resistance is felt in the hand grease gun and stop. Go do the rest of the grease fittings around the truck and then come back to the trunnions and see if it is purging grease yet. As Eddie and G have said slow and steady wins the race give the air/grease time to find it's way out then continue pumping till you get the clean grease coming out. If it's tight force it and if it breaks heck with it it needed to be replaced any way does not work well here. Give the grease time to ease out not try and blow it out of the rear. I will try my mod and will take pics but I have so many things to do as it is. Right now the Deuce is and has been on the back burner.