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M870A1 Acquisition Thread

Supersize121

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Originally the trailer was used with the M123 10 ton tractor as a replacement for the 25 ton M 172 trailers used up to that time. If a tractor with a winch was not available then either a forklift or wrecker would have to be used to operate the trailer. The military now has a RGN or removable goose neck trailer which has a pony motor to operate it so any tractor can pull it. It also has a double drop to get the floor level down so you can get under a 13' 6" bridge. M 870s and 172s have 36" deck height so the Army accepted the designs on the theory they would never have to deploy to any location with overpasses.
Thanks for the additional info. the 36" deck height is going to put me out of bounds. I am glad you mentioned that fact. I so like the look of the M870A1 but I don't want the risk of low bridging. Guess I will have to start looking for the later version (probably not many turned out for sale yet) or possibly a civilian version that would most likely cost a ton that I could refurbish and paint. Guess that is one way of avoiding the 12-24 volt issue as well as the king pin issue. Good thing I didn't search for a 747 trailer, besides being awfully wide the deck height is probably higher than 36". Dang. Thanks for the additional info. Very helpful.
 

simp5782

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Thanks for the additional info. the 36" deck height is going to put me out of bounds. I am glad you mentioned that fact. I so like the look of the M870A1 but I don't want the risk of low bridging. Guess I will have to start looking for the later version (probably not many turned out for sale yet) or possibly a civilian version that would most likely cost a ton that I could refurbish and paint. Guess that is one way of avoiding the 12-24 volt issue as well as the king pin issue. Good thing I didn't search for a 747 trailer, besides being awfully wide the deck height is probably higher than 36". Dang. Thanks for the additional info. Very helpful.
The m870a1 has a 36in deck height behind a 916 or 920 on a 3.5in king pin plate with 10R15 Dayton tires at the neck. Rear of the trailer deck is 41in over the rear most tire.

You can go with a 235 75 17.5 tire on the rear which drops the rear of the trailer down some.

Behind an m915 on 395 tires and a 2inh plate the front of the trailer deck is 31in sloping to the 41in rear height with stock tires.

On a stock height m915 it would be a good bit less on the front. You have to add a winch to the 915 though

There are civilian variants of the 870 that have a drop deck in the middle with the mechanical scissor neck. One just sold on ironplanet
 

Supersize121

New member
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The m870a1 has a 36in deck height behind a 916 or 920 on a 3.5in king pin plate with 10R15 Dayton tires at the neck. Rear of the trailer deck is 41in over the rear most tire.

You can go with a 235 75 17.5 tire on the rear which drops the rear of the trailer down some.

Behind an m915 on 395 tires and a 2inh plate the front of the trailer deck is 31in sloping to the 41in rear height with stock tires.

On a stock height m915 it would be a good bit less on the front. You have to add a winch to the 915 though

There are civilian variants of the 870 that have a drop deck in the middle with the mechanical scissor neck. One just sold on ironplanet
Again, I'm new on here. Such a knowledge base. I will take a look on Iron Planet and see if it shows what it sold for. Sounds like an interesting unit. Could pull it with Civilian tractor or Military. Every time I transport it cost me. If I had my own trailer I could always get rent a tractor until I save my pennies and get the Tractor unit. I still have my license but have not driven in years. Having a trailer like the 870 series solves not having to have wet lines and eventually having the perfect tractor with a winch is a bonus for recovery of a tracked vehicle (or other) if not running for some reason. Thank you
 

simp5782

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Again, I'm new on here. Such a knowledge base. I will take a look on Iron Planet and see if it shows what it sold for. Sounds like an interesting unit. Could pull it with Civilian tractor or Military. Every time I transport it cost me. If I had my own trailer I could always get rent a tractor until I save my pennies and get the Tractor unit. I still have my license but have not driven in years. Having a trailer like the 870 series solves not having to have wet lines and eventually having the perfect tractor with a winch is a bonus for recovery of a tracked vehicle (or other) if not running for some reason. Thank you
You can install hydraulics to run the trailer neck up and down for around $1000. Which is pretty decent for dual cylinders
 

fasttruck

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Reference post 123 and pulling a M 870 with either a M915 or a commercial tractor: These tractors have 48" or so high fifth wheel. The fifth wheel on a 916 or 123 is at least 12" higher and the porportions of the gooseneck reflect this. So with a M915 the front of the deck will be perilously close to the ground. I never tried this particular combination in service as we had a homemade kingpin that allowed us to use a M818 to pull the M870 for lighter loads where it was not necessary to deploy the trailer to the ground.
 

simp5782

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Reference post 123 and pulling a M 870 with either a M915 or a commercial tractor: These tractors have 48" or so high fifth wheel. The fifth wheel on a 916 or 123 is at least 12" higher and the porportions of the gooseneck reflect this. So with a M915 the front of the deck will be perilously close to the ground. I never tried this particular combination in service as we had a homemade kingpin that allowed us to use a M818 to pull the M870 for lighter loads where it was not necessary to deploy the trailer to the ground.
Bottom of the landing skids sit 6 inches off the ground behind a 915 with 395 tires.
 

zebedee

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View attachment 567639

These are the wood deck hold down clamps. Several people on here were interested to see what they look like. I like them in that you do not have to drill any holes into the trailer to hold the deck down.
OK C-B, time to fess up/catch up/update etc.

I have found an A1 (that FuzzyT decided to sell). So, have been rereading threads etc.

The deck board clips - what was your source for these?
and did you ever look closer at the rear outriggers for fabn details? I could work from the hole, but going from original (borrowed from Soni!) would be better.
Cheers.
 
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Castle Bravo

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OK C-B, time to fess up/catch up/update etc.

I have found an A1 (that FuzzyT decided to sell). So, have been rereading threads etc.

The deck board clips - what was your source for these?
and did you ever look closer at the rear outriggers for fabn details? I could work from the hole, but going from original (borrowed from Soni!) would be better.
Cheers.

I'm pretty sure the clips I used were these, but I'm also pretty sure I paid less than a dollar per 7 years ago. They have multiple listings with different amounts. I do remember that I contacted them through eBay to get a different amount than their various listings had, and a better deal, too.

I can get some measurements of the rear outriggers. Soni's weren't originals, they're something he fabbed up. The 870A1 BII does not include any such outriggers.
 

zebedee

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......I can get some measurements of the rear outriggers. Soni's weren't originals, they're something he fabbed up. The 870A1 BII does not include any such outriggers.
Not Bii, but are part of the operators instructions.. "stored in the front locker" or similar words to that effect.
I guess chocs are not on the A1's Bii as they have spring brakes, also why is it only the 'O' has a pry bar!outrigger diag TM.png
 
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zebedee

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Yeah..... tough work. I found a great local guy with a big mobile set up and a load of the "old tyme" tools who was ok with breaking them down for me. Came back a couple of weeks later to mount all the new tyres n flaps after I'd blasted and painted the rims.
 
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