4106 Rear Hub Advice

[JohnEd]

I, for one, hope that you will give advice again.  I didn't think that yours was all that bad at all.  Just so long as nobody walks away from this thinking  "I don't have to install an outer seal or pack my rear bearings cause diff oil will get out to the bearings and do the job".  I was told that very thing and my bearings didn't happen to be up to living on diff oil.  Some are, and those can be upgraded.  You need to verify that yours can.  You mentioned the MCI vs GMC and you mentioned that MCI warranted the change but I don't think anyone ever said that GMC did the same.  It is a matter of the bearing size and whether it will stand up to the design loading using the thinner diff lube.  After all, if I were to use a wheel bearing in a much lighter application I could lube with gasoline, conceivably.  And not being smart @$# about it.

I only caught on a few years ago that all those wet hubs didn't start out that way.  I think I would be likely to change over if it were acceptable to the mfr. and didn't void warranty even if mine is out of warranty.  Just for the peace of mind that they approved.  Being cautious in my ignorance.  Especially never having worked in or around the transportation/trucking field.

It doesn't matter if you are correct or not as long as it stimulates discussion and a more factual theory results.  There are many that resent an uninformed opinion. I am not one of them and humility dictates.  Claiming you know when you don't is a far different story.  There are those that ask questions by postulating their own theory and relying on the group to correct it.  We called it "spit balling".

Nice post JD.

Be well,

John

[oldmansax]

Gentlemen:

EDIT: I TYPED THIS WHILE YOU GUYS WERE TYPING YOURS SO SOME POINTS HAVE ALREADY BEEN MADE BUT I AM TOO LAZY TO FIX IT.....tom

I am not interested in this becoming a contest either, or in having disagreements cost us valuable input from each other later. Perhaps we should look at the situation from a different angle.

We are all familiar with Detroit's need for 40wt., low sulfur oil. That was what was used WHEN THE EQUIPMENT WAS ORIGINALLY DESIGNED. At some point, other types of engines were designed & used multi-grade oils. Some used multi-grades in old 2 strokes with varying results.

My point is the older model equipment & manuals reflected what the engineers knew & had access to AT THE TIME. Their methods and practices still work as designed. Are there better practices now?.... Sometimes. In the case of wheel bearings, I personally would use the original method because that is how the equipment was designed & I KNOW that will work. Maybe some newer methods will work too. I do think MIXING the two may cause problems, not always obvious at first.

As an old foggy, I probably remember the older stuff & do a better job on it than I do with the newer stuff, just too tired to learn I guess.. 

I can say this: the first heavy truck I ever pulled a wheel on was a 1950 (or '51, it's been a long time!) Autocar. I am not counting the International gas jobs here. Every truck we ever owned had dry (grease packed) rear wheel bearings until sometime in the late '60s to early '70s. Then I started seeing the wet (oil lubed) rear wheel bearings. There were a few that came with the "new" wet bearings that failed prematurely. Looking back, I think they had a few engineering problems at first. If I ever have the pleasure to meet you guys in person, I will be happy to expand on what we found, "back in the day". Just somebody remind me because I will have forgotten all this conversation by then.. 

If I took a stronger tone than necessary earlier, I apologize.

You young whippersnappers just get my goat sometimes!!!!!

JUST KIDDING!!!! 

TOM

[Just Dallas]

I agree with John ED, (Surprise!) !!!! I think all of us have valid points, none of them entirely right or entirely wrong for every application.
I hope you do volunteer advice again, a spirited discussion among friends is the way we as a species learn from each other.

I had never read the appropriate section (15) of the MC9 manual until you mentioned it, and you are right, that's what it states.
However, here is an interesting concept, I have read the MC8 manual and just to make sure, I looked up the section again. I'll attack a photo of the appropriate paragraph.

This is interesting because it states that you need to add a quart of oil to each hub after R&R, completely different that the MC9 manual states, even though they are the exact same housings and differentials.
The 96A2 and A3 and the 102A, B and C manuals  also state the same MC8 manual.

Maybe MCI just can't make up their minds, LOL

[buddydawg]

I'll attack a photo of the appropriate paragraph.

What did that photograph ever do to you? It thought it was only being appropriate.... lol 

These are the conversations I enjoy the most on here, especially on subjects I know little about.

[JohnEd]

More like a SHOCK.  But then we are bearing down on 2012 and the end of these times....

I wanted to note to all that Da Book says to clean the vent.  What vent, you might ask.  Its the differential vent up on top of the diff and you might just miss that little gem.  That thing being plugged nearly cost me the only eye I got so add that to the long list of things that are seared into my brain.  Must have started out pretty stupid cause there aren't many places on that organ that aren't scorched with some tidbit or other.

Another post as this one is getting hijacked.

John