1600-20 Spare Mount on M923 Cargo Truck

[Beerslayer]

I don't know why I think I need a spare tire, but since I have seven 1600-20s coming, I might as well see if it can be squeezed between the cab and bed. Carefully measured today, there is ~just 16" between cab and bet. I think it'll fit.

The first mess I had to fix was to actually get the T nut off of the T bolt that was holding the 1100-20 spare in place. It seemed like someone heat shrank the nut onto the bolt. Complicating things was the fact that there was about 1 1/4" of threads in that square nut. I couldn't get it off without twisting the long T bolt off, so I had to disassemble the starboard side of the spare tire carrier assembly, remove the davit, and roll the spare to the starboard side in order to get enough slack to disengage the T bolt from its slot.

It was a real pain.

Once I got it out, I locked the T bolt in my heavy bench vise. I cleaned all the rust off the exposed threads, covered them with Antiseize, and put two propane torches on the T nut to heat and expand it enough to get it to turn.

With a 15" adjustable wrench on the T nut, and it almost red hot, I was still twisting the T bolt almost in two. I rocked it back and forth, and finally it gave a little. Once it started to turn I spun it off as quickly as I could before it shrank again.

Once off and cool, I took a 1/2" tap and chased out the threads. I almost couldn't get a tap through there, the threads were that bad.

I decided that the T nut was OK after the threads were cleaned up, but the structural integrity of the T bolt was in question. It is probably too short anyway for the 1600-20 spare. So here are the parts I managed to remove with about two hours work.

 

[Beerslayer]

A new and longer T bolt will need to be made to accommodate the larger diameter 1600-20 spare. I hope to convince one of my machinist friends to make one for me. I figure a 36" cut of 1/2" steel rod with 12" of thread cut on one end will be flexible enough to work first time.

It should be long enough to reach, have enough on the end to cut off 3" for the T, and have enough adjustment that I can just take the rod as described above, cut it to length, weld the T on the end, and be set to go. The T bolt that came with the truck had a hole in the end with a clip in it, that is supposed to keep it from flying off as the truck bounces down the road. I will stick with that design.

 

[Beerslayer]

The next consideration is the davit.

1. Will it bear the weight of the heavier 1600-20 spare?

2. Is it long enough?

Answer: I don't know. Anyone?

 

[Beerslayer]

Now for your viewing displeasure I have these really boring but technically informative photos showing how much lateral space we have to work with behind the cab of the M923 for a spare tire.

The photo with the tape measure is on the port side, and tells us we have about 10" from the side of the existing spare to the edge of the truck. That is JUST about enough room for the 1600-20 spare IF it weren't for the fact that it is wider and the clampy things that keep the spare from slopping around back there are made for a narrower tire and will need some fab work to make them fit.

So! If that 10" is Not Really Enough, we have this much less palatable option, shown in the photo that is barely recognizable as being anything at all. Essentially, there is about 6" between the spare tire clampy stop thing and the bottom of the muffler support bracket. If absolutely necessary, the clampy thing could be moved to the starboard as much as six inches. [Oh, and I misspelled exhaust on my photo edit. How embarrassing. Especially since I ding people on careless spelling from time to time. Not embarrassing enough to go back and take another photo though as I edited my only copy.] Downside to that is that the whole ****ed thing would have to be removed from the truck in order to get in there to drill holes. Or I suppose one could reach down in there with a torch and burn some holes, but that would be about my last choice.

 

[466Navastar]

all good questions - make sure to take good pics and let us know how it works out

 

[Beerslayer]

all good questions - make sure to take good pics and let us know how it works out

I hate being the first. I prefer to stand on the shoulders of giants.

 

[rrrr]

I bolt and two hours of work, I understand your frustration. Sounds like a great project.

 

[indy4x4fab]

I'm planning on doing the same thing to my 818 with my 16-20 spare. I'll post a couple pictures of how I'm going to have to do it.

 

[MidnightDuramax]

I'm interested in this as well. I hope to have a M923/925 soon with 16.00's on it.

 

[gimpyrobb]

I am turning a 900 series hoist into a crane for my deuce. I am putting solid steel inside the mast tube(with grease zerks) so it swivels. In comparing its consruction to my "cherry picker" it should be capable of 2000lbs. I am mostly worried about lifting a 395 mounted on a hemtt rim, but it should have WAY more capacity than that.

Does the top portion extend easily? Mine was a PITA to get to extend!

 

[quickfarms]

Interesting

 

[Beerslayer]

I am turning a 900 series hoist into a crane for my deuce. I am putting solid steel inside the mast tube(with grease zerks) so it swivels. In comparing its consruction to my "cherry picker" it should be capable of 2000lbs. I am mostly worried about lifting a 395 mounted on a hemtt rim, but it should have WAY more capacity than that.

Does the top portion extend easily? Mine was a PITA to get to extend!

I didn't try to extend mine yet. It was rusty and pitted. Things get all froze up when these things sit with no use.

I like your idea. Pictures?

 

[gimpyrobb]

I will get some soon.

 

[gimpyrobb]

Grabbed some pics. Not shown is the 14x24 half inch steel plate that will go under the bed and the 2klbs winch I have to put on the tip of the extension.

 

[KsM715]

I'm planning on doing the same thing to my 818 with my 16-20 spare. I'll post a couple pictures of how I'm going to have to do it.

M818 with a davit and 11.00 spare. For now, Iplan to go with 14's and will modify what ever needs modifying.


Edit: Gimp, Thats exactly what I am planning on doing when I get my deuce bed cut down and put on the M818. I was hoping some of the trucks Glen has in his yard would have that type of davit, but sadly they dont. The only ones he has are the style with the upright tube welded to the plate.

 

[pctrans]

Why not just use the standard "wider" tire carrier that comes on 900 series trucks equipped with 14.00's??

 

[wsucougarx]

Like this:
TIRE CARRIER 5 TON M925 M923 M35 M52 SUPER SINGLE | eBay

 

[gimpyrobb]

Jeff, so the one in your pics doesn't have a base like mine?

 

[KsM715]

Why not just use the standard "wider" tire carrier that comes on 900 series trucks equipped with 14.00's??

In my case, Glen (91w350) only had trucks with 11.00's on them in his yard, I got the whole setup you see in the pic with my Jeep for less than what they want for just the base plate on ebay. (not to mention what shipping would be on that heavy thing.)

 

[KsM715]

Jeff, so the one in your pics doesn't have a base like mine?

Nope. Looks like this pic.

I did look thru the 900 parts TM and noticed that there are several styles of davits.