XM757 details

Upon several requests, I'll start posting images of the 8x8 to show details of it's many features.

More...

Thanks for the pics, i'm extremely curious to the design of the machine!!

Interesting spring packs and other unique features. Nice score Bjorn, it appears to be in remarkable condition.

Really neat setup indeed. Are those drive axles a standard type (i.e. Dana, GM Corporate, etc), or are they proprietary to the truck?

Here is the data tag, which shows serial number and delivery date.

David Doyle can probably tell a lot from these numbers. If the 0018 means that it's number 18, it could explain at least three oddities found so far, apparently only one fuel tank was used and the battery tray was never occupied. Long battery cables are connected directly to the starter and they are long enough to keep the batteries on the platform behind the cab...doesn't look like a civi fab job. The cables that would normally go from the bulkhead conectors to the battery box are different from what the manuals show. The third oddity is the lack of black-out driving light, there is not even a space for it.

Maddawg, the axles are Rockwell 6.40:1.

That's odd about the BO lamp. The pic in the original XM757 thread labeled "Cab Canvas" shows it hanging off the front of the cab. At first I thought maybe it was because yours has the winch but the pic I posted of Tom's 8x8 doesn't have it either and his doesn't have a winch. Not sure if it did originally or not.

just a thought, the reason for the differerence may be in that Bjrons is a xm757, NOT a m757, it could be that the first few in the prouduction run remained xm so that some more experimentaion could be finished before the standeredized M number, if that is the case, then the xm757 is even rarer then everybody thinks

Good thought Ron, but I don't know about the "M" version, even the manuals I have call it the "X"M757 along with the expansible van XM791. Only the cargo variant is a plain M656.
Never seen an M757 listed. Again, David Doyle is the expert here.

it list it as a m757 in military wheeled vehicles, those tms could be the first print along with the production where it still was refered as xm977, the cargo was the first rig, maybe thay were still working out problems on the 757 and the expando when production started

Possible, my manuals are all dated 1969, same as the truck delivery date.

look on page 394, the 2 cab fronts are a bit different between xm and m

Hello fellas,
I'm writing from a room in Pennsylvania, with basically no reference in hand. However, before I left I email Bjorn photos of what I believe to be XM757 number 1, those photos may shed some light on this. I also have some photos of various of these trucks during testing - I'll take a look at those when I get home - next week.

Regards,
David Doyle

The pictures probably represent a couple of different units..

BTW David, just to get a better copy, I ordered the paper you sent me directly from SAE (Society of Automotive Engineers) and should have it shortly.
If anybody else is interested, go here:
http://www.sae.org/servlets/SiteSea...simplesearch.jsp&qt=680101&ofType=ALL&x=9&y=6

If the link doesn't work, the SAE paper is #680101 "Design of the M656 Cargo truck". About $20.

As usual, it amazes me that you have been able to dig up all this "inside" info, most of us (myself, for sure) don't even know where to start looking.

In order to gain better access to the engine IP and fuel lines, I removed the left front tire. This exposed the massive steering gear. Pictures here. It seems like the thick layers of mud act like a preservative, the surface below is without rust and the original paint shows up everywhere.
Still a lot of cleaning to do.
Whoever drove the truck last had bypassed any fuel filter and ran two fuel hoses (feed and return) to the rear platform to a makeshift fuel tank I guess.

Correction on the filter bypass statement in the previous post. It only looked that way, the fuel filters are different on this engine compared to the ldt models. There is only a primary, which was indeed bypassed and a secondary, which looks like the image shows below. The power steering fluid reservoir occupies the place where the final fuel filter is on ldt engines...

Hmmm...I was right the first time, there was no filter element in the canister.

(13:45) Turned the engine over with the starter and it sounded real good. Not ready to start it yet, got to fix the fuel lines/filters.

The air and fuel lines are copper covered with cotton wire loom.
This loom did not survive very well, especially where leaking gear oil has soaked it. It's rotten and crumbles when handled.
Thinking about replacing it with black plastic loom which is split, so the connections won't have to be taken apart...

Bjorn, Be careful with the split loom. I've seen that stuff wear grooves in frame rails. It would suck to have a hole rubbed in the air line.