Mod'ing a 923A1 Your thoughts, please

[KaiserM109]

I’m trying to decide what to do with my M109A3 deuce and my M923A1 5 ton and I’d like to hear from anyone who might have something to add.

BACKGROUND
I bought the M109A3 with the intentions of fixing up the box as my off-road camper to be used primarily in the Rocky Mountains. HOWEVER, it seems that the military in its wide ranging wisdom put a non-turbo in this truck. I believe from watching GL that the only deuces without a turbo are early M109A3s, probably because it is defined as a REMF (you GIs will know what that is). What that does for me is, even after opening up the injector, it can’t get to 50 MPH on the flats with about 1500 lb. in the box at 5,000 ft. elevation. I need a truck that will work up to 10,000 ft.

I have since acquired two M105 trailers and an MKT-85 that require a deuce or bigger to safely tow them. The poor M109 can hardly get up to 35 pulling the MKT-85.

I bought the M923A1 with the idea that I would put the 109’s box on it. Bringing it home from GL it blew low gear and got towed the last 16 miles (out of 1800!).

CURRENT PROBLEM
My M923A1 runs well, but I’m a bit disappointed in the power from the Cummins 250, but I think it will be good enough at 10,000 ft. I have seen guys talk about things to increase its power. I am rather conservative when it comes to me thinking I’m smarter than the guy that build a particular piece of equipment, but I do plan to at least run the second fuel line to the back cylinder.

HOWEVER, the M923A1 is a whole lot bigger than I expected and its turning radius might be a problem up in the mountains. I have swallowed nearly a whole bottle of ibuprofen to alleviate the painful muscles from climbing up and down to the cab.

All that said, I think I have several choices:

1. Trade something for an M35A3 and put the box on it. That will give me a long wheelbase vehicle with three axles.
2. Bob the frame on the M923A1 with the following changes: 1) move the exhaust to the side instead of behind the cab. 2) put the spare tire on another rack such as one on a platform that folds up behind the box. This will allow me to put the box right behind the cab. 3) Get rid of the back axle and move the remaining rear axle BACK to center it under the box and lengthen the driveshaft.

This will give me a 4x4 with a wheelbase shorter than the total M109.This will turn better and get better MPG.It would hopefully decrease the turning radius.

I am favoring the second solution.Any thoughts?

 

[porkysplace]

Wouldn't just a whole lot easier to put a turbo on the M109 ?

 

[KaiserM109]

Wouldn't just a whole lot easier to put a turbo on the M109 ?

Yes and no. You also have to swap out the governor (not a big deal) but the 109 also needs power steering (also do-able). I once had a nightmare about dying and driving an F100 around a mountain for eternity. Ford didn’t put PS on F100s.

 

[jesusgatos]

Put the M109 box on the M923. Haven't driven any NHC-powered 5-tons, but love the A2's with the 8.3L. If you want to bob it, do that. It's a better truck than the deuces in just about every way though.

 

[KaiserM109]

Put the M109 box on the M923. Haven't driven any NHC-powered 5-tons, but love the A2's with the 8.3L. If you want to bob it, do that. It's a better truck than the deuces in just about every way though.

I agree about the comparison. I drove my M109 home from Ft. Riley, KS, 490 mi., and the M923 from Ft. Benning, GA, 1800 mi, and I definately like driving the M923 better, apart from the fact that the M923 blew out first gear 16 mi. from home.

Added:
I trust the brakes on the M923 better than the air over hydraulic on the deuce. I had an 'oh, s---' moment when they failed in Manhattan, KS during rush hour. There's a guy, who in 2007 owned a brand new green Chevy pickup, that had the same sort of moment before I turned and went down the median strip next to him.

 

[tobyS]

The naturally aspirated 923 will suffer at altitude, like your deuce, I think.

I haven't done it, but I'd like to put an electric blower on that could have a heat coil (plug in), at least for starting but perhaps also running.

I'm with you on the brakes and if you bobbed it, you would be removing a lot of weight that would generally not be needed with your camper box. No heavy weight there. Shedding lbs would be a goal. Sorry about the tranny.

 

[350TacoZilla]

I'm not familiar with how long your box is that your trying to use but if this helps I bobbed my 923 without moving the remaining axle back (basically the rear axle is now where the mid axle was) and cut the bed down to 10'6". I cant believe how much shorter the truck turns now (both the wheelbase is effectively shorter and all the rear tire scrub is gone).

you could also put a turbo on the 250 as long as your conservative about power gains, just to help with altitude.

 

[hndrsonj]

Yes and no. You also have to swap out the governor (not a big deal) but the 109 also needs power steering (also do-able). I once had a nightmare about dying and driving an F100 around a mountain for eternity. Ford didn’t put PS on F100s.

Swap out the governor? Can you elaborate a bit.

 

[tobyS]

350TacoZilla, do you have any rub on the front tires with 16's?

 

[joesco]

Love my M931 powertrain, but would like the A2 with the 8.3 someday, but will wait as the M931 is insured and registered / tagged as an antique vehicle.

 

[nevrenufhp]

...... ...... I once had a nightmare about dying and driving an F100 around a mountain for eternity. Ford didn’t put PS on F100s.

Sure they did, but it wasnt til the later 60s, and as a option. My 67 doesnt have PS, but my nephew's 72 does. I'm more worried about F100 brakes, than the steering.

 

[350TacoZilla]

350TacoZilla, do you have any rub on the front tires with 16's?

I had a decent amount of rub on the pitman arm and the shield for power steering ram so I cut the centers out of a pair of A0 wheels to use as wheel spacers, then just use thimbles and nuts like you would with duals. I dont rub now but still might if truck was twisted up a bit.

 

[KaiserM109]

Swap out the governor? Can you elaborate a bit.

In the TM for the governor the springs have different part numbers. No idea what happens if you miss-match them.

 

[KaiserM109]

An interesting discovery today, if I delete the back axle on my M923A1 and move the exhaust and spare tire out of the way, the M109 box will fit exactly centered over the remaining back axle with 3” between it and the cab. I had to measure that twice to prove that to myself since an M105 trailer centers itself over the axle. The difference is I have to salvage the extra space between the cab and the bed/box.

Proof for all you disbelievers: It is 6’ 6” from the back of the 923’s cab and some brackets to the center of the intermediate axle; the box is 12’ 6” front to back or 6’ 3” from the front to center. That gives me 3”, which is what there is between the box and the deuce cab!!!

That means I don’t have to move the intermediate axle and mess with driveshaft length, brakes, etc., like I estimated I would before. All I have to do is bend the exhaust around so that it matches the intake stack and find another place for the spare. I have a cool idea for that since I also want a fold-up deck behind the box.

If I keep the end of the frame the same way it is on the M109, I will be shortening the frame by 2' 11". That makes the overall length 24', only 2' longer than a deuce.

IT’S A GO!

 

[hndrsonj]

In the TM for the governor the springs have different part numbers. No idea what happens if you miss-match them.

Nothing-mine has been going for almost 10 years without changing them.

 

[jesusgatos]

Only trouble seems like you're really saving yourself is extending some airlines and modifying one driveshaft. Why not just leave the spare tire carrier where it is and move the middle axle back to wherever works best for you? Should still be able to cut down on the overall length by at least 18", seeing as you're going from a 14ft bed to a 12ft box. If you eliminate the spare tire carrier, then you've gotta put that spare tire somewhere else. Where? Hanging off the back? Same overall length...

 

[KaiserM109]

Nothing-mine has been going for almost 10 years without changing them.

Like I said, I have no idea how having the wrong springs in the governor on a deuce affects the truck’s running. Having screwed around with the governor on the LD engine, I doubt it does very much. However, there are several other disadvantages to using a ’66 deuce with a load that probably exceeds 2 1/2 tons when you consider the weight of the box.

Only trouble seems like you're really saving yourself is extending some airlines and modifying one driveshaft. Why not just leave the spare tire carrier where it is and move the middle axle back to wherever works best for you? Should still be able to cut down on the overall length by at least 18", seeing as you're going from a 14ft bed to a 12ft box. If you eliminate the spare tire carrier, then you've gotta put that spare tire somewhere else. Where? Hanging off the back? Same overall length...

Your point is well taken. Here is what I have been thinking:
One of the biggest considerations is the wheelbase. This affects its turning radius which, when you’re dealing with switchbacks in the mountains, is serious. Having a moderate overhang well above the trailer hookup is not really a problem. It doesn’t increase the length from the drive axle to the trailer pivot point and it doesn’t affect the angle from the wheels to the bumper.

Even when the deuce was still in the picture, I have been considering a back deck, kind of like a back porch, made out of expanded metal or tread plate that folds up. If I pivot it in the right place, possibly by creating a pull-out track, or by adding a winch to lift-lower it, I can manage the heavy weight of the tire/wheel and by adding a cheap winch of some type, it makes the spare a lot easier to handle. I haven’t messed with the original rack yet because the govt. in its infinite wisdom put a biased ply in the spare rack with radials on the ground, but getting that 250 lb. tire up in that rack looks like a back-breaker, even with that little arm. We used an engine hoist to put a blown tire into the back.

 

[cx65083]

Ford didn’t put PS on F100s.

Actually, yes they did. It wasn't standard in the beginning and later models it was optional. My 1980 short bed step side F100 had PS.

 

[cx65083]

Sorry. Should have read all posts. Didn't see that nevrenufhp had commented on this point. The brakes on my F100 were just as good as the F150's by 1980.
Looking forward to your build pics!