Waking up a Texas M151A2

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m3a1
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Re: Waking up a Texas M151A2

Unread post by m3a1 » April 18th, 2017, 6:18 pm

Challenge accepted, Rick!

I fixed it so it doesn't leak or make any noise anymore. 8)

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Last edited by m3a1 on May 17th, 2018, 9:03 pm, edited 2 times in total.

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Re: Waking up a Texas M151A2

Unread post by rickf » April 18th, 2017, 7:33 pm

Now, do NOT make the mistake of driving around on the front axle! Anyone here know why?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Waking up a Texas M151A2

Unread post by Surveyor » April 18th, 2017, 9:09 pm

1st guess off the top of my head.... What is if the rear drive shaft is gone then the flange in the rear of the trans can just slide out and you loose all your oil????
1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Waking up a Texas M151A2

Unread post by rickf » April 18th, 2017, 9:19 pm

BINGO!!! Found that one out the hard way, luckily for the environment it happened in the garage, unluckily for me it happened in the garage. :roll:
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Waking up a Texas M151A2

Unread post by m3a1 » April 18th, 2017, 11:51 pm

Here are a few pics related to the job at hand today, which was removing the differential and axle shafts for maintenance. turned out to be a very straightforward job.

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Trying hard to teach the kid not to put anything under a lifted vehicle that you wouldn't want crushed...like the toe of your shoe!
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Bushings not looking too healthy!
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Military method of filling unused holes. Some kind of epoxy stuff.
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Not all holes got the treatment!
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More marginal bushings.
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Interesting views of the piece removed for the ROPS installation.
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And out she comes!
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Here's the wallowed out yoke. Turns out the washer wasn't missing after all but this yoke is shot.
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One way to eliminate rear and noise and leaks. Remove the rear end altogether! *WARNING* Don't try to drive without it. See that yoke/flange way up under there? It is held in place by the presence of the rear drive shaft. Try to drive without the rear differential and the drive shaft and it is possible for that yoke to slide right out, taking all your transmission lubricant with it!
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Last edited by m3a1 on May 17th, 2018, 9:05 pm, edited 4 times in total.

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Re: Waking up a Texas M151A2

Unread post by rickf » April 19th, 2017, 10:01 am

That bad yoke has a wear sleeve on it, it has been replaced before. There may be other issues there. The first bushing you showed does not look all the bad, the last ones are pretty far gone. They will start to dry rot on the exposed part in a year or two but the inner part is what matters. The outer part does nothing. I have seen the plastic bolt fillers before, the "epoxy" looks more like bondo coming through from the other side.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Waking up a Texas M151A2

Unread post by m3a1 » April 19th, 2017, 8:55 pm

Well, let's just say the bushings aren't bad enough that I'm going to deal with them right now (though it would be a good time for it, as far as I've come). Seems that my truck was undercoated solely in the rear area, very likely in an attempt to help quiet the amplification provided by the rear floor. Once it's all back together I'm going to do some experimenting. Seems to me a couple of strategically placed sandbags back there would really quiet things down a great deal.

Cheers,
TJ

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Re: Waking up a Texas M151A2

Unread post by Xloflyr » April 23rd, 2017, 11:06 pm

Hi there - I was the guy you met at the Hot Rod night in Boerne last weekend who also is in the process of restoring a 1970 M151a2 MUTT. I will be anxious to pick your brain on restoration issues and to share our common interests. I'll try to stop and chat in the near future. Great resto pics by the way

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Re: Waking up a Texas M151A2

Unread post by m3a1 » April 27th, 2017, 8:06 pm

PM sent to Xlo'

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Re: Waking up a Texas M151A2

Unread post by m3a1 » May 4th, 2017, 12:53 am

Finally got enough time together today to get into the rear differential. In all, it was an exceptionally easy job. I didn't replace all the sleeves; a decision I made based upon many years of wrenching and partly because I wanted to see if it was actually an absolute necessity. In one case there was clear evidence that the seal was the culprit and that, coupled with the fact that the sleeve showed no real evidence of abnormal wear, led me to a decision to keep the original sleeve since it had the same outer dimensions as the new one. So here we go..

Rear yoke removed...(or flange if you want to use the absolutely correct terminology). Of all four flanges, this was the worst leaker of the bunch. The sleeve was in good shape but, unlike the replacement sleeves, didn't possess the chamfered edge or perhaps it was installed upside down. Some joker simply pushed it in past the seal, taking the outer edge of the seal with it and I'm quite sure it never, ever sealed properly.
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Note the condition of the seal from 3 o'clock to the 6 o'clock position in the picture. It's just shot.
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Slightly better picture with flash..
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Sleeve is showing some polishing but no appreciable wear so I felt it was OK to take a chance with it. It really is no problem removing and replacing these sleeves (provided you have certain tools) but I just want to know how much one can get away with on these. I read a lot about this process and the discussion always seems to be replace everything while you're in there....but what if you're doing a roadside repair? So leaving this particular sleeve on is basically an experiment.
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The flange and housing shows clear evidence of oil loss at the seal which is no surprise considering what we have just seen. Paying attention to where the oil is coming from is a big hint with regards to what actually needs to be addressed mechanically and I'm not a big fan of replacing every part just because I'm in there...
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Here's the old seal, alongside the new seal. The ring, at the top, sits just below the seal. I removed the ring so as to clean out everything as best as I could. Remember, if you take things out, lay them out and make sure you put them back in!

I bisected the metal to the seal with a small quality screwdriver in order to allow space for the seal's metal structure to ease away from the walls of the housing. That worked like a charm. If you look carefully, you can see some square depressions on the top of the seal where the last guy staked the seal making it fit just a bit tighter. They, and I, put some RTV sealer on the outside of the seal's metal housing, before drifting it down into the housing of the differential.

If you are not taking pictures as you go through these jobs, you should be making a mental note of how things looked before you took them apart. Some times things are correct and some times things are not correct (as we will see later in this post. Don't assume the last guy was a hot-shot mechanic, because it ain't necessarily so! The damage on the rubber seal is not from the removal process. It's what happens when someone blindly presses a sleeved flange past a seal, deforming it forever.
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New seal installed. No, I did not stake it. I didn't think it necessary because of the casual use this truck will see for the rest of its life. Normally, I would wipe off excess RTV but down here, a little bit more certainly doesn't hurt anything. Don't forget to lubricate the mating surface of the seal where it will join with the sleeve on the flange. You can do that before you install the seal, or simply apply some with a Q-tip. There isn't sufficient space to get a finger in there!

There really isn't anything magical about these seals. They work by directing lubricant away from the mating surfaces of seal and sleeve. The inner part of the seal directs lubricant back in and the outer part directs whatever is outside the seal back out.
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Another shot of the old seal and those areas of the seal that were folded over when the last guy just shoved the flange in without any thought as to what he was going to be doing to the seal. The method I used to release the seal from the differential worked exceptionally well. It even allowed me to remove it with my fingers. However, care must be taken not to gouge the metal of the differential surrounding the seal.
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I took great care to introduce the sleeved flange back into the new seal because, as I said above, it is not a sleeve with a chamfered edge. I used this little tool somewhat like a shoe-horn to get the seal up around the sleeve before pushing everything in. This really cannot be accomplished on any of the other three seals because they are quite different and do not present sufficient space to accomplish that with a tool.

A very thin layer of lube was laid on the sleeve before installation. You may also have noticed that I'm not cleaning parts to perfection before reinstalling them. This is a working truck, not a show-piece, and I'm here to solve problems not add to my work load by spending hours and hours looking for perfection.
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Here we see lots of RTV! Irrefutable evidence that someone was concerned that lube would migrate up the splined shaft. That's good enough for me, so I reapplied RTV in the same way upon reassembly. This seal is entirely different from the first seal. This type not only seals against the sleeves but also seals to the differential much like a cap, rather than like a cork.
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Here's my method for removing a sleeve. Graze the sleeve with the abrasive wheel until the metal turns blue and stays blue (an indication of thin metal and high heat). When you reach that point, you are almost all the way through and it really doesn't take long to achieve that. This is a time to be patient and work purposefully like a good mechanic should. This is not the time to be greedy or be in a hurry. When you've removed enough of the sleeve it will almost pop right off. No muss, no fuss.
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Remove the cap-type seal with a flat-head screwdriver by gently working around the edges. This is what is under all that (after a thorough cleanup of the functional bits). Take note of the small piece (9 o'clock to 11 o'clock position in the picture) which has been laid in to lock the retaining/'adjusting ring in place. It simply sits in there, trapped in place by the metal cap of the seal. Getting the mating surfaces clean (where the cap of the seal joins with the differential housing) is extremely important. This is where you want RTV to be able to adhere well. If you fail to adequately prepare this surface before reinstalling the seal, you'll very likely end up with another leak. Personally, I like to clean up surfaces like this using a Dremel Tool equipped with a stainless brush followed by several successive wipe-downs with carb cleaner until the rag comes away clean. If you look carefully at the differential housing you can see that oil had been leaking out the bottom of the seal where it joins with the housing, rather than at the flange sleeve.
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The inside of the flange's slinger is proof that it wasn't leaking at the flange sleeve. It's dry as an old bone!
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Remnants of the RTV inside the seal's cap-like structure. Doesn't look like there was much adhesion at all and so, it leaked. I think I could have cleaned this up and re-sealed it and called it good if I had wanted to take the time.
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Remember that flange (I called it a yoke) that was giving me so much trouble before? The one with the wobble? Well, that's it on the right. The new flange is on the left, with a new sleeve installed. Take note of the direction of the arrows and the chamfered edge. That is a properly installed sleeve.

Let me just say this so the message is clear....no amount of finagling would get that old flange to ride tight on the shaft. It was completely out of spec and that is why I replaced it. The new flange went on right and tight without difficulty. By now, I think everyone agrees the reason the old flange developed a wobble was because the axle shafts were not properly maintained and could not lengthen or shorten themselves as the suspension went up and down. That energy had to go somewhere thus, longitudinal forces became lateral forces and worked on the flange until it no longer fit tight against the splined shaft, so it wobbled. I'm very happy this was such an easy fix.

Also, notice the obvious scoring on the sleeve on the original piece? Had that flange been reusable, replacing the sleeve would certainly be justified.
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It certainly didn't help things that the flange was wobbling. Despite the scoring there wasn't as much leaking at the sleeve as you'd think, primarily because these flanges sit quite a bit higher on the differential than the input shafts.
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Opposite side. Evidence of leaking is a little more obvious on this side. Still, not too bad in my opinion. The problem with minor leaks is, what little lube leaks out has a tendency to attract and trap grit and grime which in turn starts wearing on the bits that are supposed to make a seal and then the dominos really begin to fall.
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Plenty of RTV in here and as you can see and there is a place for the extra RTV to go inside the cap where it doesn't necessarily interfere with the inner workings of the differential. Better to apply a little bit more RTV and get a good seal than not to. No real need to worry about where the extra RTV is going. Note the paint marking indicating where the adjusting ring was set and the locking piece at the 12 o'clock position where it is pretty well encased in RTV.
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Nice and dry. The flange is greasy because of the universal joint. However, look how high that seal cap sits on the differential housing. Perhaps you're already curious as to why it is sitting at such an odd angle...because that might be evidence that something ain't right underneath!
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Yup. Things aren't completely kosher under there! The locking piece is completely out of it's space....and yet, they achieved a good, solid seal. My guess is when they put that seal on, they lifted the cap for some reason, which sucked the locking piece out of its proper resting place and then, not realizing what had happened, they put the cap down again and tapped it on. There's a lesson on what NOT to do!!!

Oddly, the new seal, though firmly and properly seated, really wouldn't go down quite as far as the other side. I find that a bit bothersome but I'm pretty sure I've achieved a good seal.
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Ahh....finally, it's starting to come together! See the big socket? It was perfect for tapping those seals down snug.
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A cursory clean-up and some paint makes everything look SO much better! Yeah, I know I made a clean spot. It'll be dirty again, soon enough.
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Did I do a good job? Well, we'll soon see how I did but before I put it all back together I'm going to need a set of shocks. One is completely done in.
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Last edited by m3a1 on May 17th, 2018, 9:07 pm, edited 7 times in total.

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Re: Waking up a Texas M151A2

Unread post by rickf » May 4th, 2017, 8:06 am

And it will still be noisy! :twisted: :twisted: :twisted: :twisted:


Good job, Good write up. I notice that it is an early series differential, what year is the A2?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Waking up a Texas M151A2

Unread post by m3a1 » May 4th, 2017, 11:10 am

1970. Do you want data on the markings on the casting?

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Re: Waking up a Texas M151A2

Unread post by Fil Bonica » May 4th, 2017, 11:30 am

875 series are the older units and they have a tendency to growl even if new and good.
1100 Seies are newer and somewhat quieter.
Over the years I have been on a fruitless search of a quiet diff.
Some are better than others but not that quiet.
Good Luck
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Re: Waking up a Texas M151A2

Unread post by rickf » May 4th, 2017, 12:22 pm

I went from an 800 to 1100 series in mine and it was quieter for about 500 miles and then it equaled out. I am not so sure there is any noticeable difference. Then again, I am deaf anyway. :roll:
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Waking up a Texas M151A2

Unread post by m3a1 » May 4th, 2017, 4:28 pm

Well, it will still be noisy but I'm tired of putting that tray under the truck to catch the gear oil and having sufficient lubricant in it really tones everything down. Hopefully that leaking is over with for a while. But, as I said, I'm thinking of putting a couple of bags of something on the floor in the back. The resonance through the floor pan is most certainly magnifying the sound. If I can stifle that, I'm sure there will be a big difference.

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