A father & son M38

m3a1 · Post by **m3a1** » Sat Sep 23, 2017 7:55 am

Thank you! That's the only logical explanation. We'll investigate that and report back to everyone with what we find.

Cheers,
TJ

m3a1 · Post by **m3a1** » Sat Sep 23, 2017 3:01 pm

So, as was pointed out to me by a more learned member (thank you, 45auto) and as you can see here, we have verified the cause of the damage to the king pin bearings. As it turns out, there are four longer bolts (3/8 - 24) that are meant to be used to secure the brake hose guard to the top of the bearing cap. Each brake hose guard requires (two longer bolts x two sides = four longer bolts). Apparently, because the metal of the brake hose guard is rather thick, they employed longer bolts.

If this is something you weren't aware of (like me

) it would be very easy to simply assume they were all the same and just put them back in where-ever, because these aren't much more than about 1/8" longer than the others, with a glob of grease on the end, who would know?

Oddly, the TM9-1804B makes no mention of the different bolt lengths or of the importance of assuring they get returned to the correct holes -page 103, paragraph 91 and page 138, paragraph 109.

However, it is specifically mentioned TM9-8012, page 265, line (5) and page 266, line (6) but, it appears to me the TM provides directions for using the longer bolt (1 5/8") for securing the king pin bearing cap and the shorter bolt (1 1/2") for securing the brake hose guard and that is absolutely incorrect.

Since the holes on the knuckles are threaded all the way through, my guess is that somewhere along the way, a maintenance work order was probably issued instructing that the longer bolts be exchanged for the other, shorter bolts but that is pure supposition.

Anyway - since there are four assemblies, each requiring four bolts total and since there are precisely four longer bolts, it is a mathematical certainty that if even one long bolt goes astray, there will be a damaged bearing. Apologies in advance to you die-hard Willys guys, but that's just a lousy design.

Here are the brake hose guards with the damaged one now straightened. Those are the old shims in the upper left of the picture. Since we are installing new bearings and cups, both sides must be reshimmed from square one. We cannot rely upon the values of the old shims to be correct with new hardware we'll be installing.

I know it's pretty bold talk to claim that a TM is incorrect but here is the proof - An interior view of the uppers, assembled properly with longer bolts securing the brake hose guard, but displayed here without shims so you can get a true sense of the bolt length. As you can see, if a longer bolt finds its way into any spot other than those for securing the brake hose guard, damage is virtually assured.

Here is my son, whittling grime off the bearing caps before cleaning them up on the wire wheel

And here is something you don't see every day. Stretched bolts! That's right, they start out being 3/8 - 24 and end up being approximately 3/8 - 16! That's WAY up there on the weird scale.

4x4M38 · Post by **4x4M38** » Sat Sep 23, 2017 6:35 pm

The tensile strength of that bolt must have been unbelievable!

It's mind boggling that damage to the knuckle wasn't catastrophic
with the torque on that bolt.

Post by **wesk** » Sat Sep 23, 2017 7:25 pm

Not quite that unimaginable. It is very easy to stretch a bolt by over torquing. And we do not know what grade that bolt is.

Most modern engines deliberately stretch their head bolts to obtain a correct and one time only torque setting since they must be discarded after that first & only stretch.

Situations like this instance where relying on old memories instead of attention to detail and using the manuals resulting in damage to the bearings is usually avoidable.

m3a1 · Post by **m3a1** » Sat Sep 23, 2017 7:30 pm

I do! That's a grade 5 bolt!

Well, I think the true strength of the early Jeeps (and I don't necessarily exclude the modern stuff, because I know virtually nothing about them) is that, while each part may not be built like The Rock of Gibraltar, together they really share the load, making for a very robust little truck.

Of course, the WWII Jeeps, with the severe and strict limitations placed upon their design, are not everything they MIGHT have been and (don't hate me for this) they really don't hold a candle to the M38 which is, all in all, a much better product.

Despite all those wonderful qualities, a thoughtless person * using and working on them can inflict a lot of damage and yet, the truck will continue to soldier on just as mine has....warts and all. That's the real testament to the early Jeeps.

*Wes is certainly correct that relying solely on memory will create problems. I've not done it yet, but I'm going back into the TMs to see exactly what is said about this, just to satisfy my curiosity.

By way of example, there's a lot of talk about poor steering quality in these trucks. Looking at this system closely what I see is not a thing wrong with the design.

Now, it may be that poor stewardship, such as I've encountered here on my truck, has created problems that have lent credibility to the poor-steering-narrative and I'm sure mine isn't the only one with the swapped bolts and low standards of maintenance issues. And, of course we ARE driving trucks whose first home was always meant to be off road. So, I think the claims against the steering are a lot of horse hockey.

The M151 is in a similar category. Someone handed these solders a rather large ATV and took their solid axle Jeeps away and they had been racing around in those Jeeps for YEARS. So, naturally, they started driving the 151s around like hot rods as well. In retrospect, the results shouldn't have surprised anyone. They rolled them. The product was improved and they STILL rolled them. The product was improved again and they STILL ROLLED THEM!

Fly an aircraft outside it's design envelope, crack it up and everyone blames the pilot, but with the M151 series, blame was laid at the feet of the designers. I drive my M151A2 almost every day and I stay within the limitations of the truck and (Surprise! Surprise!) NO issues.

Anyway, I'll get off my soapbox. We are getting to one of my favorite places in these projects. Old parts that are now clean and shiny and inspected are beginning to pile up and new parts are starting to pile up. Yippee!

m3a1 · Post by **m3a1** » Sun Sep 24, 2017 7:41 am

Did anyone notice the coarse thread bolt in the picture of the bearing caps and bolts? Yeah....it was being used!

4x4M38 · Post by **4x4M38** » Sun Sep 24, 2017 8:49 am

Did not, but that must be the "dirty little secret " that might lead to a
replacement knuckle, no?

Post by **wesk** » Sun Sep 24, 2017 11:38 am

This one?

Was the mating hole helicoiled to match course or was the course bolt forced into the fine threaded hole?

4x4M38 · Post by **4x4M38** » Sun Sep 24, 2017 3:41 pm

Wes, that is a very astute question assuming Bubba did not give this
jeep the full treatment.

Inquiring minds wish to know?

Were you spared buying a new knuckle?

m3a1 · Post by **m3a1** » Sun Sep 24, 2017 4:24 pm

You already know the answer! Bubba 'bubba'ed' it.

4x4M38 · Post by **4x4M38** » Sun Sep 24, 2017 4:43 pm

Ahhhhh, Man......

One brief chance at doing the right thing,

Then,"Hey, here's a bolt!"

m3a1 · Post by **m3a1** » Sun Sep 24, 2017 7:53 pm

Yep. Between the TMs being either vague, or absolutely wrong...and the poor design....and the mathematical certainty of it all.....AND Bubbas constantly and insistently involved, it seems that proper assembly of this part of these trucks is doomed to failure.

Sheesh.

Post by **wesk** » Sun Sep 24, 2017 9:35 pm

The key word is Bubba. It took me awhile to find the Bubba definition I was looking for. Most only refer to short word for brother used for rednecks and low income, uneducated southern white boys. Here is what I was looking for:

In gunsmithing, a crude attempt with inappropriate tools at repair or modification which results in damage, often serious or even dangerous. Also, a person who does such work, the generic name for any member of that population, or the name of the collective population.

Book or no book, mathematics aside, if a Bubba was wrenching on this jeep then this is what would happen.

4x4M38 · Post by **4x4M38** » Mon Sep 25, 2017 8:40 am

That covers it. Thanks Wes!

The other side of the coin is that Bubba, in whatever
form, has preserved? some of these vehicles,
so that one day a caring soul can bring them back from
extinction.

Post by **wesk** » Mon Sep 25, 2017 9:42 am

I do not believe Bubba and Preserved fit in the same sentence. A better word would be "retained in service" so that restorers in the future would be able to secure, restore and preserve!