This becomes a hot topic (pun intended) here on the Zone every few years. Rather than pollute Bryant's "I need to move my truck" thread, I figured a new thread about this was in order.
Over the years, I have seen Dave flat tow his M725 800 miles behind his M35 in a single run. Only to have the rear axle walk out of the housing on the way home from the 2005 Texas FE.
I have read about Jon catching his brakes on fire flat towing his M715 behind his D1500 van.
I have seen Bryant flat tow his M715 500 or so miles in a weekend with no trouble for the 2007 Texas FE.
I have also seen Dave almost burn his front bearings and brakes up flat towing the M725 to the 2008 National FE.
Is it luck, chance, a question of truck maintenance or something else that makes a success or flaming failure of a flat tow?
Here is my opinion. While I have seen all of the above. Something I have not seen is any reference in the manuals about flat towing the M715. Maybe Kaiser and the DOD never intended it to be flat towed. After all, the M35 manuals have a section in them about how to flat tow another one and how to be flat towed. Manuals dated 1954 and 1965 have this along with ones published in the 1980's. So it isn't just an oversite for the short production run of our trucks.
But, why did tow bar adaptors get produced? I think the answer to that can be found in the TM for the tow bar itself. The tow bar is designed to be used in conjuction with a wrecker truck. The tow bar provided the spacing and support while the wrecker arm picked up the front of the towed vehicle. Ever wonder why the shackle hooks were made to bolt onto the tow bar adaptors? That is where the wrecker boom attaches to pick up the front. The tow bar TM goes on to say that the tow bar while it can be used to flat tow another vehicle, it really shouldn't for long distances. That of course is in the perfect world of some paper pusher far from the actual use of the equipment.
Practically in our world things aren't so cut and dried. Successful flat tows of M715's I have seen had something in common. The tow bar angled up or was level with the truck pulling. Pulling weight off the front tires when moving. Those that had overheated front brakes and bearings had the tow bar angled down to the towing vehicle. Pulling down on the front tires and adding stressess not designed for.
Take it, argue it, agree with it. I just wanted to write this down before I forgot about it.