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M816 wrecker

Helped out a couple friends today with some heavy lifting. This old tool trailer was used as a parts donor for his other one and is just about ready for scrap. Since I was in the area....

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Went ahead and picked up the last of the heavy parts from my old deuce and a half and loaded it onto the trailer.

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Earlier in the morning had helped another friend with his truck. Needed to lift his engine a few inches for clearance when replacing the front main seal.

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That it is. Wrapping up a upgrade to air brakes later this summer. Also have Jake brakes and some hydraulic work coming up
 
Yea, decided to start using the GI Bill and got occupied with stuff. Sold the blue/silver k20, picked up a little toyota truck that I killed within a few months (yea the little 4 cylinder is indestructible, except for me cruising at 65mph on the highway. Killed 2 that way). About to buy a 1982 GMC 1 ton crew cab with the 6.2/th400/np205 dually and planning to keep that for a long time.

This post is about to get very picture heavy.


This generation military truck comes with single circuit hydraulic brakes, uses air for power assist like vacuum brakes just different. The brakes are strong enough to lock up all 6 tires (even on the wrecker), but there is no emergency backup so with any brake component failure, you have no brakes. Not good. The next generation of these trucks, M939 series, has air brakes that have the standard spring backup which engages the rear brakes when air pressure is lost.

Back in November I struck up a deal for those air brake components. Kicked out the outriggers, blocked up the axles and removed the old hydraulic brake components. Didn't touch the truck all winter after that.



















Had some stability concerns so remounted the tires onto the rear most axle, truck never shifted.






And it remained this way until late March. Used the crane a few times but the truck never moved.
 
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Late March it started warming up and I had some money floating around so started working on the truck again. The old hydraulic brake backing plates have a total of 40 9/16" rivets holding them onto the rear axles, pain in the ass to remove and currently I've only removed them from the middle axle. Later will remove them from the 3rd axle.

So started at the front axle since it's backing plates are bolted on. Went ahead and removed the axle shafts to replace the inner axle seals.



The 5 foot prybar was used as a punch to remove the seal from the opposite side (often the only way to remove the seal retainer)







Then it was grease the axle shafts and stuff them back in










Followed by the drum/hub assembly. These are inboard brake setups so the drum/hub are installed onto the axle together, weighs about 150 pounds.




And the front all assembled. Enlarged a hole through the frame for the air line plumbing.








With the front axle complete proceeded to the middle axle.
 
Wanted a break from the heavy lifting so on to the plumbing. The military wanted double and triple setups with the plumbing which made it way more complicated than it needs to be, I'm going for simple and readily available parts.

Started off under the dash. Installed the brake pedal (treadle valve) and the bulkhead fittings are for multiple airlines, not just the emergency brake plumbing.












Still working on the plumbing so none of this is complete yet. These are wedge style air brakes so on the rear axles there are 2 brake cans and a total of 3 air lines per hub. Running 2 R12 service brake air valves and 1 R14 emergency brake air valve. Also installing a new air tank at the rear of the truck.











 
Man, that is one worth while upgrade! I bet you'll love the feel of the pedal too. I can't believe any one ever signed off to ok the other system. I jotice what you are using for air line also- NICE!

Any air drier going in on it?
 
Will L. said:
Man, that is one worth while upgrade! I bet you'll love the feel of the pedal too. I can't believe any one ever signed off to ok the other system. I jotice what you are using for air line also- NICE!

Any air drier going in on it?
Click to expand...

Very heavy duty air lines going from the valves out to the hubs haha good eye. DOT approved steel braided with the fabric outer layer, 2000 psi rated. Will be very surprised if I accidentally cut one. Up on the chassis is standard poly tubing with push lock fittings.

Will be plumbing in a Bendix air dryer later. Currently planning to mount it inthe the front passenger fender area, mimic the fuel filter setup from the driver side. Have a few tasks it must be mobile for coming up soon.

Once this is done will be relocating the hydraulic pump to the chassis from the crane and the tank as well. Also have a detroit locker to install.
 
More plumbing today, this should just about finish up the air brake plumbing finally besides clamps and holders.

All lines up to the firewall now connected.




Parking brake (PP7) valve now plumbed/mounted.




Air tank is rigged up for now, will make proper mounts for it later.






Air supply lines from the new rear air tank run to their valves.








Only the drain hose needs to be plumbed in. Decided to go with the heavier duty hose (taken after this pic) rather than the polymer hose because this line runs low, to the bottom of the driver step. Rather not cut it on accident.




Weather permitting tomorrow should finish up the driver side hub on the middle axle, last of the plumbing as well.
 
More tasks with the wrecker today but this is all at the lot where it's stored. Unloaded the small flatbed trailer then transferred this generator from a friends pickup down to his trailer.







After that hooked up to the dump truck remains and moved it into the shop so we could work in the shade. Plan is to turn this into a trailer once the remaining big parts are sold (tcase, front axle, etc).



 
And I thought I had some awesome tools...That's great work. Sorry to not have followed along but, been away from most things w/o spark plugs for too long a time. Is this shop where you're working on the '82?
 
Paveltolz said:
And I thought I had some awesome tools...That's great work. Sorry to not have followed along but, been away from most things w/o spark plugs for too long a time. Is this shop where you're working on the '82?
Click to expand...
Yep same location, it's in Lehi. The shop and lot are not mine, belong to a friend. Have taken the wrecker out to 5 mile pass before and it handles itself very well for its size and weight.
 
How do I know? 3 years enlisted time in Mechanized Infantry (Medic) then commissioned and spent 16 years as an Armor Officer, primarily in Armored Cavalry units. Seen a Hercules dead lift an M1A1 Abrams that was buried so deep in that nasty, gooey, sticky red Kentucky clay of Ft. Knox that top of the tracks were covered and there was about 4" deep of it on the floor around the driver's station where it came in through his open hatch. THAT was something to behold!
 
Those 88's are sick. You could tell what it was before you could even see it. Lol
Just the sound, or look for the smoke cloud.

Sent from my SAMSUNG-SM-G890A using Tapatalk
 
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