Ok! So, the weather is taking a huge dump on us (but we need the rain) and there's not much we've been able to accomplish.
We did make a point of getting out between squalls and wiped down and degreased the front axles and disassembled them. Again, this is a greasy process so no pics of that. Sorry.
What I have here is the Bendix Universal Joint.
TM9-1804B, Page 100, provides a broad strokes review of this process. Here, we are not replacing any of the components; merely cleaning and inspecting.
Disassembly begins with removing the lock pin (AKA universal joint groove pin) from the transverse hole. (see photo below) Drift it out with a suitable punch and mallet. If one end is staked, drift it out from the OPPOSITE end (i.e. the staked end comes out first).
Removal of this pin will allow the hidden pin that retains the center ball (it is oriented on the long axis of the axle) to drop out of the ball and into the shortest shaft of your axle.
You can accomplish that by orienting the axle vertically, with the short shaft down, and bumping the lower end onto a block of wood or tapping upward on the end of the short shaft with a soft mallet. The specific placement of the center ball is what locates the four larger ball bearings so that the joint cannot come apart. It's a bit counterintuitive but it works.
Process of reassembly. Note that we have previously marked the components so that they don't get mixed up. 'S' is for the short axle shaft and both shafts of the short axle shaft were marked in this way. All the ball bearings, including the centering ball and pin, were kept with the axle shafts they came from because all these components wore in together as a unit and we plan on reusing them as a unit.
The larger ball bearings were carefully measured and set up as a pair. Measure these on three axis. In this way you are also checking to see of the ball is out-of-round. Very slight variations in size will have very little effect, particularly on a worn joint but out-of-round balls are, or soon will be. a game changer requiring it be replaced. I did the same with the two smaller ball bearings, setting them up as a pair. More on this in a moment. The TM has some very specific information regarding these and it is worthy of review.
Identify the sides of the joint that have the deepest wear. These are the sides that will receive the larger set of ball bearings.
On the issue of cleanliness of parts - Here we see the hole for the pin that secures the centering bearing in its final place. Despite the fact that the exterior of this component is quite clean, the cavity for this pin is quite deep and it still has quite a bit of old lube in it. It's depth is about half the length of a Q-Tip. Get it cleaned out completely because in a moment we are going to be putting that retaining pin in it. With the old grease that's in there it's going to hang up. We are looking for a good, clean, dry cavity for that pin to move freely in because in a moment we are going to rely upon gravity to make that pin fall into its final position. DON'T put lube or oil in there. Leave all your components completely dry.
Pin is installed. You can see it through the transverse hole for the lock pin (Universal joint lock pin).
Place the center ball over the pin and ensure that the hole in the ball, into which the pin will eventually rest, DOES NOT LINE UP WITH THE PIN, as seen here.
When the time comes to line it up you may find that it is difficult to determine how the center ball is oriented. It is perfectly ok to make a few identifying marks on the center ball with permanent marker to help you find it.
Bring the other half of the axle shaft into position. It will rest upon the center ball.
Bring one end of the axle shaft back at an angle . If you are working alone it will probably be easier to bring the short end of the axle shaft back at an axle.
Insert the appropriate ball bearings oriented, by size, to the previous wear on the knuckle; larger set of balls into the pockets with the deepest worn spots. Ensure that the two larger ball bearings are located diagonally across from one another and the two smaller ball bears are located diagonally across from one another. The first three are easy. The fourth, a little more difficult. You will need to extend the joint's length just a little to get it in there.
With that accomplished, rotate the center ball so that its hole is in-line with the pin. Orient the axle so that gravity brings the pin down into the hole. If you have the center ball close, but not quite perfectly oriented, a gentle shake will generally help the pin find it's way into the hole.
With the pin in place you will see that the transverse hole is now open again. Insert the lock pin and drift it into place. The TM calls for staking it to ensure that it doesn't work its way out. That's it!
Last edited by m3a1 on Sun Apr 15, 2018 5:25 pm; edited 5 times in total
Viewers are reminded that what you see may not be what you have. The 3 primary knuckle joints were Bendix, Rzeppa & Spicer. Both Bendix or Rzeppa came from Willys on the M38's. Many of the M38's today have the even later Spicer joints. Be carefull on this topic because shims, bearings and turn angles vary depending on the type you have.
I am attempting to make reference to these components is they are described and named in the TMs in order to make it easier for the reader to use my posts in conjunction with the book. The TMs refer to these as "universal joints" but as we can see, this is a far cry from what we call universal joints nowadays.
If you are following this and it spurs you on to get into one of these on your own, the first thing to remember is - (1) there are mistakes to be made which is part of the learning process (2) you're not really on your own.
You have excellent resources here on willysmjeeps.com (a shameless plug for the site) and the ability to go one-to-one with the members, the Tech Manuals (almost always a great resource and starting point) and dare I say it... the power of the internet!
There is very little to be afraid of on these old trucks. The fact that you are willing to roll up your sleeves and get some grease under your fingernails may be exactly what your truck needs to go another 60-70 years.
In this article, you are going to notice some similarities in the manner in which we hash things out on these forums and you may be surprised how some people habitually cling to time-worn lines of thinking (that might just be wrong and leave us asking all the wrong questions), and the problems associated with 'Group Think' and the fascinating array of options that modern chemistry has presented us with, particularly in dealing with old trucks. So, here we go.
I title this - Steering Knuckle Lubrication - The Great Divide
The Tech Manuals for the M38 call for specific lubrication within the steering knuckle called, GAA, "Grease, Automotive and Artillery." This lubrication is introduced into the steering knuckle through a hole that is blocked off with a pipe plug, much like those we find on most differentials and manual transmissions. The reason for this is to allow you to see that you have a proper amount of lubricant in there. Just like your differential, the fill line is the bottom of the plug hole.
Well, what if I told you that GAA has given way to new types of lubrication and has become an anachronism? What if I told you that it is no longer being used by the military which has found something other than (and very likely better than) GAA to use? What if I told you that the people who have purchased these surpluses of GAA are charging an arm and a leg for it or quite often, will only sell it in bulk amounts. And, what if I told you that rigid adherence to the time-worn and erroneous idea that the information in the Tech Manuals was brought down from the mount by Moses (along with the ten commandments) is entirely the wrong way to think about things with the many options now available to us? Two schools of thought - GAA is sacred stuff -or- GAA is not sacred stuff. Two schools of thought, hence our title The Great Divide.
Crusty old salts who, if they had their way, would have us still enjoying the company of our equine friends, give us their short answer, "Suck it up buttercup, go source some GAA grease, bust out your wallet, do what the book tells ya and tell yer mama I said hello." My response is, "Well, sorry Charlie, I've never been much of a joiner." In saying that, I'm left feeling like I'm left standing on the precipice of a great chasm, staring over at the other side where all the other happy little boys with their golden cans of GAA are standing and they, staring back at me, see me standing there with my tube of "other-than-GAA lube", while waiting for me to step forward and fall into the depths. It's a lonely, sometimes scary place..
This all began with something quite simple. If you have been following along, you have seen how the steering knuckle is assembled with the king pin bearings living in the same space with the axle's universal joint and thus, inevitably sharing the same lubrication, especially with the lower king pin bearing fully submerged. And yet, I was getting advice from old sages who were telling me to lubricate the king pin bearings with wheel bearing grease. Wait! WHAAAAT?!! What happened to the use-GAA-or-die-a-horrible-death thing?
Over the years, some of the original perspective on these assemblies has been lost to the sands of time. The old mechanics pack up their tools one last time and go home, and the new mechanics, when faced with old technology, go with what they know. Such as - a cone bearing must be "packed" and packing involves wheel bearing grease, which is thick, ergo - cone bearings all get wheel bearing grease. Eventually it becomes a sort of institutional group-think and I submit to you that George Patton Jr. put it best. "If everybody is thinking alike, then somebody isn't thinking!"
Now, they both may be cone-type bearings but they do entirely different jobs - wheel bearings are employed at relatively high speeds with 360 degrees of revolution on a vertical plane in a small space where they have only the lubrication they were packed with whereas, king pin bearings are employed at almost NO speed, in a large space where they enjoy almost constantly refreshed lubrication, and are moving only a few degrees at a time on a horizontal plane. They generally look the same and that's about where the similarity ends.
And the principle that a layperson should not blindly mix lubricants is sacred law. Ask any chemist. So I did! Three hours of hashing this out over the phone. THREE HOURS!
I happen to have a buddy, now retired, who spent his professional career as a chemist. Working for Uncle Sam, it was his job to make sure that military vehicles and all sorts of things associated with military vehicles were using the correct stuff. Some of that stuff had wheels and some of it had wings and some of it was so specific that using the wrong stuff meant having to send very expensive pieces back to the factory for re-coating or writing the parts off altogether.
So, I knew when I made the phone call, that his having over twenty years of saying, "Use only what the book tells you to use." would result in getting the suck-it-up-buttercup answer. Oh! I learned a lot about lubrication and a lot of it based on the chemistry of the stuff. Stuff that I felt I needed to know to make some informed decisions because I felt GAA was going to be out of reach for several very practical reasons, not the least of which was availability, not only roadside, but also in the long term. We also reaffirmed that mixing lubricants was still a no-no and could result in some rather serious consequences, particularly when mixing lubes actually degrades the lubricity (I LOVE that word because it sounds so dirty) to the point where it no longer lubricates. He presented that to me as what I would call "a dire warning", so if you do this, you do it at your peril.
But were we approaching the problem from the right direction? We weren't any closer to solving the problem than when I dialed his number. Were we asking the right question? Because sometimes, folks, it isn't always about Mil Spec. Sometimes it's better to work the problem from the civilian perspective.
So, after two hours of chatting, I finally challenged my chemist's standard answer with a simple statement of fact. The M38 has a civilian counterpart using the same front axle group - the CJ3A and, in fact, that axle group (with some minor changes) was used until something like 1971. They don't use GAA but you can bet they using something very similar! So, when I laid that on him....KaBOOM! (His head explodes) Stoney silence at his end of the line while he scooped his brains back into his skull. NOW, the answer was that it would then be okay to use an OEM-approved lubricant. And suddenly, HALLELUJAH!.... the clouds parted.
Luckily for you, dear reader, I am prepared to share with you the straight skinny.
In order for one to find a certified civilian counterpart to GAA, the only bonofide presented on greases that meet GAA specs are markings, either the NSN number for GAA (which changes depending upon the size of the container) or the Mil-PRF number for lubricants with the properties of GAA, and actually finding one on the shelves of most big name auto parts stores is...well, let's just say you'd have better luck finding a unicorn in your sock drawer under the Valentines Day card you forgot to give to your wife.. In short, forget it. Ain't gonna happen and let's face it, you aren't going to drive a hundred miles to a big manufacturer with a huge warehouse of lubricants and ask for two tubes of the stuff even if they did have it. Again...ain't gonna happen! How do I know? I spent hours and hours reading labels at many, many stores. Hours and hours of my life that I'll never get back.
So I asked another question of NAPA, O'Reilly's, Auto Zone and even the Jeep dealership. What was used back then? What was the OEM lube of choice? Nobody knew and the guys at Jeep, likely in an effort to save face (or perhaps with a more noble cause in mind, such as shooing the annoying old guy out of their dealership) waved a tube of very generic chassis grease under my nose and said, "This is IT!" (which was totally wrong) and frankly, none of them had even been around in 1971.
By this time I figured I was going to be completely on my own...it was sink or swim. So, what to use? Here are my parameters -
(1) I want to put the stuff in and forget about the whole affair...maybe forever...because it hurts my brain. I want what is an essentially fire-and-forget lubricant. Something that lasts longer and is better than just plain, everyday, run-of-the-mill grease. I want modern chemistry in my 1951 Jeep!
(2) Because of that, I want something that isn't prone to creating oxidization and other problems for the truck or for the next guy. That left out some very popular lubes which use some very popular chemistry and which, if you knew about it, would probably have many of you scrambling to change out your lubrication. (see line 1).
(3) And I want something that is typically on the shelves of most auto parts stores. If I need to do a roadside repair I want it to be available (which, naturally, totally rules out GAA).
(4) Because I am running an old truck with a good degree of wear and thus a good deal of slop in worn parts, I want a lubricant that resists squeezing out, has good adherence qualities but also has good flow (NLGI #2 - which is generally, the equivilent of peanut butter)
(4) I want something that is sticky and resists slinging but isn't sling-proof because the very first goal is to keep the axle's universal joint well lubricated ...but also to get some lubricant slung onto that top king pin bearing.
(5) And I want something that doesn't thin out when it gets hot. In fact, I want something that might even get thicker when it gets hot.
(6) I want something that is not hydroscopic or prone to washout.
(7) And I want something that meets or exceeds the performance requirements of the manufacturers of really darned expensive farm equipment. In short, I want it ALL
And parameter number 7 is what brings us back around, full circle to the topic of what questions to ask. Are we coming from the right place when we are looking for solutions? We started with Mil Spec, then on to general OEM automotive spec and now, to general OEM farm spec which I think you will quickly agree is a VERY good place to be!
Farm equipment generally has all sorts of things going on when they're in use. They sit for long periods of inactivity, they have high speed, low speed, no speed parts, they are operated with huge variations in temperatures and they are expected to perform under the worst conditions with the least amount of necessary maintenance. Hmmm...that kind of sounds like our old trucks, eh?
By now you're probably waiting to hear what I've selected as my steering knuckle lubricant. C'mon TJ! Let's have it! Well, you're going to have to wait for the big reveal. I think I have the stuff but, at the risk of another three hours of lecture, I have to run it by my chemist first.
Joined: Apr 15, 2005 Posts: 133 Location: Up State SC
Posted: Thu Sep 28, 2017 12:07 pm Post subject:
You can make some - jeep knuckle pudding.
50/50 (+/-) wheel bearing grease and 80-90 gear oil, mix it well. An old yard sale mixer is good. Then spoon it in the housing.
I mixed some up years ago in an old plastic coffee container. Then I filled the knuckle housing back then. It's not leaking out and I check it from time to time and it keeps it's consistency and the joints are able to pick it up and sling it around inside the housing.
What I have selected for lubrication for the steering knuckles of our M38 Jeep is - Lucas Oil X-TRA Heavy Duty Grease about $4/14.5 oz tube
Lucas Oil Products Inc. Makes some interesting claims for this product. One of the most recognizable is that it is formulated to NLGI grade 2 (essentially the consistency of soft peanut butter.) They promote this product in this way - "Lucas X-TRA Heavy Duty Grease is a high quality polyuria grease excelling high temperature applications. It meets or exceeds OEM "Lube for Life" requirements and should last two to four times longer than conventional grease... is specifically designed to: Resist slinging out of fast moving parts, Resist washing out of steering components on wet roads, Resist melting a high temperatures up to 560 degrees Fahrenheit (dropping point), Resist "squeezing out" under heavy loads (Shear stability- One measure of a lubricant’s protective value is its ability to withstand shearing under pressure. Shear stability describes a lubricant’s ability to resist a decrease in viscosity due to exposure to mechanical loads), Maintain a constant film of protection even under irregular maintenance schedules, Good in cold weather; Exceeds performance requirements of John Deere, Deutz, Case-IH, New Holland and Massy Ferguson.
How does this product do with soft or "yellow" metals? Because there are two bronze bushings present I wanted an answer on that - (TM refers to them as bearings in that they support and guide the axle shafts at either end of the axle universal joint). ASTM International proscribes a copper strip corrosion test (D-4048) with results categorized from the production of slight tarnish, to moderate tarnish, to dark tarnish, to actual corrosion. This is relevant because copper is a predominant alloy in bronze and brass. This product tested at level 1B meaning it would produce a slight tarnish. The 1B result is the final and highest level in slight tarnish category, the next category being moderate tarnish. My chemist said this should be perfectly suitable in this regard.
Because it doesn't use soaps as thickeners, such as in traditional greases, this extends the useful life of the product.
You will find the term "cone penetration" coming up again and again in the discussions of grease. This has nothing to do with tapered roller bearing or "cone-type" bearings. "The cone penetration method employs a weighted cone that is dropped into a fixed-size volume of grease for a defined time period. The depth that the cone is able to penetrate the grease is used to rate the grease’s consistency with a scale developed by the National Lubricating Grease Institute (NLGI)."
Finally, as with almost all polyurea greases, Lucas Oil X-TRA Heavy Duty Grease didn't do well in the category of getting thicker with the application of heat or stress. It is just really not how polyurea greases work. That said, it remains stable up to its drop (melting) point and stability is, perhaps, a better option.
So, I'm finally satisfied and now know more about grease than I ever wanted to know. If you are using something different and you are satisfied with the results, then you have also made the right choice.
Joined: Mar 22, 2014 Posts: 75 Location: Simcoe Ontario Canada
Posted: Fri Sep 29, 2017 10:52 am Post subject:
TJ. Thanks for the research on knuckle grease. This has been kicked around for years with the GAA stuff that is not available. A very concise and informed article well researched and written. Post it on G503 for the ensuing uproar and berating of your work.
Cheers Rob M38A1C CDN3
I noticed in all the above that there is no mention of the change in direction that Willys / Kaiser went with their civvy CJ lube charts on the same knuckle lubrication issue. Was this an oversight and just not included or was it not referenced in your research? _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Wes, I actually got away from pursuing the OEM lube charts when my chemist buddy got involved more deeply because one of our parameters was what is "most" available for use so we began to focus more upon what was being offered on the shelves.
I would really love to see what you have if it's available. Please share!
I spent a great deal of time reading the sometimes scholarly discussions (and sometimes not-so-scholarly) on the 503 and quickly realized that I would be better off on my own chiefly because what I am dealing with my truck in terms of wear and tear aren't necessarily going to conform to the book answer which is predicated upon a truck whose parts are in spec to begin with. That, plus I wasn't interested in explaining this any further than I have to guys who are seeking a one-size-fits-all solution because there is no such thing.
I think I met my parameters nicely with my choice and hopefully, shared some thought provoking stuff with everyone along the way. I'm not selling LucasOil products and don't really care if others are using GAA or Mobil1 or corn head or cow slobber. One thing is assured...there are many, many fine and modern lubricants out there for us to choose from. But the real answer is this... if what you are using is working then you've made the right choice and you can sleep well at night.
If we all wanted empirical evidence of what is "best" then we would have to begin that test with trucks that are perfectly matched and within spec, run them in precisely the same manner and tear them apart and compare whatever it was we wanted to compare. I simply wanted to make an informed decision and luckily had the resources to take it a step further than the average Joe...that being my chemist buddy.
The topic of lubricants is really very interesting and in the end, not all that complicated. There are only so many ways to make grease and those formulas all have their highs and lows and their preferred applications.
And here's another thing. No matter how good a product is, if it never gets tested against a certain standard you'll never see it with that particular seal of approval....ergo, if it doesn't meet (insert your standard here) the first question MUST be....was it ever tested? Maybe you'll find an answer to that...maybe you won't. But, if that answer is NO, then it really could end up being better, or the same, or inadequate in some way. There's no way to tell, and of course we haven't even begun talking about how some requirements are written up in such a way that the product ends up being sole-source (and I can assure you that happens!)
I think the trick simply is to define your needs as best you can and then spend about 8 hours on the internet learning as much as you can.
Perhaps the most interesting thing I learned along the way was why motor oil breaks down and it's not all that hard. Short answer (and not really that short)
"Thermal breakdown is a broad term referring to the degradation of molecules as a result of (high) heat. The two most common mechanisms are "thermal degradation" and "oxidative degradation".
Thermal degradation occurs solely as a result of heat and does not require reactants, although it can be catalyzed by metals. In other words, the fluid just gets so hot that molecules begin to breakdown from the heat alone, even in the absence of oxygen. Thermal degradation for lubricant base oils usually begins well over 400°F, so it is not generally a significant factor for motor oils.
Oxidative degradation occurs as a result of molecules reacting with oxygen. It is considered a "thermal" reaction because the rate of oxidation increases rapidly with heat. In fact, the rate of oxidation doubles with each increase in temperature of just 18°F. Oxidation is a major cause of base oil breakdown, which is why all formulations contain good doses of anti-oxidant additives which react preferentially with the oxygen.
Viscosity breakdown simply means a loss of viscosity my any means. The most common means are mechanical shearing of the large polymeric molecules (VI Improvers), oxidation of the polymeric molecules, fuel dilution, and potentially thermal degradation of weaker large molecules."
I would really love to see what you have if it's available. Please share!
I have shared several thousand words on the topic the last ten years and most are easily found when one performs a thorough research of the on line resources.
My point above is that history shows the OEM's started their re-thinking on this issue much earlier then modern day chemist and researchers are willing to give them credit for. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
What got me going down this road was the fact that when I opened mine up, what I found was essentially a doughnut of wheel bearing grease with a big hole in the middle where the axle's u-joint had been spinning and, to be entirely fair, it was not exactly "starved" for lubrication but certainly hungry for it.
It is interesting that OEM was "moving the bar" so to speak but I'd imagine if they began getting away from this early style u-joint the lubrication needs changed somewhat.
Anyway, no doubt there will be guys coming to the site who are facing the same circumstance in their truck as I was in mine so, I was hoping to lend a hand in that department.
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I want what is an essentially fire-and-forget lubricant. Something that lasts longer and is better than just plain, everyday, run-of-the-mill grease. I want
