M51 removing brake drum

M51clueless

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So I have 1969 M51 dump truck, Losing brake fluid and best I can tell I think it’s on the front axle, I know I have axle seals leaking on the front as well.

My problem is I can’t get the drum off.

Hoping you have a technique

So far I have used a 10 ton puller that I had jerry rig using the 2 available holes on the face of the drum. Had some real pressure in it but no where close to 10 tons

Thanks !
 

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topo

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I 'm working on a military M131 the brakes are the same as your M51 after getting the hub back on I was having trouble turning the hub and wanted to just remove the brake drum .I then removed the 11/16 nuts and put a jack under the back of the drum then put some pressure on it and shocked with a hammer and the drum broke free with the bakes backed off the drum sled off . I had just put new shoes on and was wanting to reuse the old drum and I could not get the brakes to adjust right I had to put on a new drum and will get this one turned .
 

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M51clueless

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I was able to finish my job the other day. One side the drum slid right off. The other side was hard, no real way to get behind the drum to help it off. Ended up putting a couple of the lug nuts back on and used my mondo puller to ease it off, that actually worked well. Used tie down straps to support the drum as I slid it part the way off , then used a couple more to help spread the shoes enough to get the old cylinder off and the new one in. Was so impressed with myself that I got 4 more cylinders to do the rears as well. Might try to put pictures up of that process when I get to it.
 
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M51clueless

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Well I have finished my brake job on the M51, had a learning curve with it, thought would tell my side of it.

To start with I was losing brake fluid, having to watch the level all the time . This is a old system with a single master cylinder. So as soon as the fluid drops out of the master you have NO BRAKES! I am working with the truck on my farm but am hauling up a hill. So super sketchy if they fail.

To start with replaced the two front cylinders, both were leaking, was still losing fluid so replaced the remaining 4. All were bad.

First had to brake the lug nuts free.
I know everyone else knows but I didn’t, the lug nuts on the right side have right hand threads , “righty tightly, lefty loosely “. The truck left side has left hand threads “ lefty tightly...... “
So if your slow like me standing on the pipe that is slid on the biggest breaker bar I have was not helping matters.
At least I didn’t brake a stud.

Once they were loose I jacked the axle and was careful not to let the tire fall over, and moved it out of the way.
Next unbolt the axle

That was pretty easy, once the bolts are out you can hit the top of the axle shaft to brake it free from the hub .
The axle should slide right out.
Now you have a couple of huge nuts to deal with, I had a pipe wrench just big enough, as you disassembled be careful of the order and orientation of nuts, lock washers seals and bearings.

I used a couple of tie down straps to support the hub because I didn’t need to take it all the way off. Then used a couple more straps to spread the shoes
Now your finally ready to remove the old cylinder.

when you reassemble be careful of the load on the bearing, not sure what it is supposed to be, I tightened the nut until it was tight to the bearing, then backed it off a quarter turn, it should not bind the bearing.

After you get the lock washer on the second nut you should get after, as that is what makes sure the wheel stays on the truck.

After l got all the cylinders replaced, I bled the brakes,
Was not happy with the level of the brake pedal, Tried bleed again, no help
Phoned a friend, he told me on old style drum brakes there is a cam nut to adjust the brakes,

Figured out not just one cam nut but TWO nuts per drum. They are at the 10 and 2 o’clock position on either side of the cylinder.
So had to jack to get the tire off the ground, then tighten the cam nut until it grabs the wheel, then back it off til it turns free.
Didn’t seem like I was doing much but when I was thru the brake pedal was spot on!
If you think about the physics of it makes since, one master with about 6 inches of travel, has to displace 6 cylinders with 2 pucks each that’s moving 12 pucks

anyway, that’s what I learned on this project.
 

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Ajax MD

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Everything you said and went through is in the TM's. More importantly, torque values for things like the hub lock nuts are in the TM's so that you don't over torque them and cause premature wear on your wheel bearings.

You did alright but why not make your learning curve a little shallower by using the manuals? They have really saved me some grief.

 

Ajax MD

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M51clueless

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Bearing has no grease!
Speaking of no grease, the fronts were just fine with grease, all of the rears were bathed in axle oil, guess your saying I have multiple problem, first, it’s not supposed to have axle oil out to that bearing on the rear axles and 2nd should be coated with grease.
 

M51clueless

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Speaking of no grease, the fronts were just fine with grease, all of the rears were bathed in axle oil, guess your saying I have multiple problem, first, it’s not supposed to have axle oil out to that bearing on the rear axles and 2nd should be coated with grease.
Btw, I am sure the tm is there, just got frustrated trying to find the reference I was needing
 

microjeep

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TM's are a different breed that take a little getting used to but it will be well worth your time. My dad worked on heavy equipment and I "helped" him as early as when I was 8, even worked as a car, truck, tractor and farm equipment mechanic for about 3 years. Now that I kinda have a handle on how the TM's work I'll always study them before beginning any project no matter how small. And yes they were frustrating at first but hang in there it's worth the effort and WILL save you time ,money and knuckles.
 

Ajax MD

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Speaking of no grease, the fronts were just fine with grease, all of the rears were bathed in axle oil, guess your saying I have multiple problem, first, it’s not supposed to have axle oil out to that bearing on the rear axles and 2nd should be coated with grease.
Correct. On the rear axles, in addition to the "inner grease seal" there is a small keyway or notch that is supposed to be plugged with a piece of cork (yes, really). Often times, people forget the cork and end up washing the grease out of the bearings with gear oil from the differential. I've also seen people use modern sealants like red RTV in the notch instead of the cork plug.

Yeah, it's tedious plowing through the TM's. I find that it's better to research the job ahead of time and print out the relevant pages rather than look stuff up "on the fly."

Here's the link to the M39 series TM's which includes the M51: https://steelsoldiers.com/threads/tms-for-the-m39-series-5-ton.77614/

The -10 series of manuals is the "Operator's Manual" like you'd find in the glove box of your Chevy pickup. (Operator level maintenance)
The -20 series of manuals is more like the Hayne's manual you'd buy at Autozone. (Intermediate level maintenance)
The -30 series of manuals is like the Factory Authorized Technician manuals that the dealer mechanics use. (Depot level)

Any manual containing a -P is a "parts manual." Everything down to the last screw and washer is in that manual. Often, you can Google the NSN and/or the part number and a general description of the part and come up with multiple sources to purchase from.
 

frank8003

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Take your TM of any flavor and open it in your puter.
When it is open as a PDF file then type
Ctrl and f at the same time and you will get a search box in upper right.
There type in whatever it is you seek, ie brakes, steering, axle, or whatever and push enter
It will then show every instance of that search you named anywhere in that TM so you can click and go right to it.
 
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M51clueless

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Tennessee
Thanks ,for the advice . Had decided that the M39 manual was not right for me, but will start studying. as for the grease for the rears, guess I am going to brake down and get those huge sockets. Will have to fugue out the cork plugs.... only Jeep would come up with that.
 
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