Repower or not

[W_A_Watson_II]

Thanks Norm, his running boards look just mine, Ha Ha. Yea the frame has a lot of great flex, so I can see eventually fatigue setting. in. Perhaps I'd better go buy that spare basket case for the frame?

Side note, hope you are back on your feet soon, and our prayers are with you.

[rush]

Frame issues?, wow must have been some "really" wild rides. Seems to me the m37 frame is pretty darn stout!!

[lebowski]

I think all the ambulance and radio trucks (M43 style) had an additional frame brace rail added to their mid sections. Next time you see one take a look under there.

[rush]

I think all the ambulance and radio trucks (M43 style) had an additional frame brace rail added to their mid sections. Next time you see one take a look under there.

roger, I have seen it on the longer wheelbase trucks. The drive train manual also show's the rails to be being slightly heavier gauge material.

[MoparNorm]

...
Side note, hope you are back on your feet soon, and our prayers are with you.

Thanks Will!
Doc put me down for one more week, still have 60% of the gas bubble in my eye, still wearing my "I'm explosive!" arm band to warn paramedics and emergency personnel...ha! ha!

[Wulfman]

Creaky Frame Indeed

Driving around the beat up '52 parts rig I just got, the frame definitely creaks when flexed. I refurb'd a '65 CJ5 decades ago and I had the frame boxed - certainly stiffened it up and they were notorious for frames cracking under extreme use.

I do my wheeling up in Northern California - Rubicon and the lessor known but more extreme Fordyce trail (IMHO). When you are crawling through the rocks, you are not shifting, you are looking where to place your wheels and pick your line. Also, faster speeds make drive component failure more likely. The number one rule on the trail is, if you brought it in, you bring it out. That includes your 6Klb truck so I'm building mine for that specific task in mind.

I would highly recommend Ray's disc brake upgrade, atleast up front. I'am also following a thread that discussing using D60 axles inside the stock M37 axles tubes. Now that would be pretty cool to pull off.

[W_A_Watson_II]

I can understand the fatigue failures of flexible frames, but the stiffer you build things the more likely they are to fail suddenly.

I like the flex, and it aids the M's solid axle leaf spring suspension to keep the tires on the ground.

I guess I should look forward to a frame swap on the M some day.

[Wulfman]

Frame Swap

William, you are thinking the same way I am. If you could get the M37 looks on a current gen frame/drivetrain....As Charles often says, if you upgrade component X, it will lead to component Y failing.

Check out this guy's retrofit of an M onto a cut Suburban frame. Getting a bit close to Monster truck IMHO but he did a very nice job.

http://www.cardomain.com/ride/2377952/2#guestbook

[W_A_Watson_II]

WOW, He's doing a nice job, but it looses a lot of the M's looks in the process. Reminds me of some of the car on 4x4 frame conversion you used to see a lot of. I do like what he did for a grille to fit the pusher fan in.

[MasterYota]

Nothing says "hey officer, pull me over!" quite like that truck...

It suffers the same problem that most M37 owners have - what is a good size tire to put under the truck to keep the looks and be functional. That particular rig looks more like a "match-box car" - the proportions are just off.

Good execution on the build up, just not my cup of tea.

As for the engine swap, if all thats required of the engine is to lug the truck around in first gear all day on the trails, and traction is not an issue, then the 230 should work just fine. If you've any plans for a more multi-purpose rig, including trail, highway, distance type work, then swap it out to something better suited.

Just be aware that neither the 230, or the 251 get good mileage. They are not even close to being the most effecient engine choice available today. I used to plow a little snow with mine, and it averaged about 3 gallons a mile...

[MoparNorm]

Just keep in mind that engine selection is a matter of the type of terrain that you are running.
Sand and Mud both rob power making the stock 6 nearly worthless, if you are trying to turn big tires.
Rock Crawling with low gears doesn't require as much HP, just torque.

[rush]

Roger Mopar Norm,

I prefer to stay away from the big mud. I got my mudding fix while I lived down in Alabama, not into it much nowadays. Ill take my jeep to the sand dunes, much lighter rig.

[rush]

Nothing says "hey officer, pull me over!" quite like that truck...

It suffers the same problem that most M37 owners have - what is a good size tire to put under the truck to keep the looks and be functional. That particular rig looks more like a "match-box car" - the proportions are just off.

Good execution on the build up, just not my cup of tea.

As for the engine swap, if all thats required of the engine is to lug the truck around in first gear all day on the trails, and traction is not an issue, then the 230 should work just fine. If you've any plans for a more multi-purpose rig, including trail, highway, distance type work, then swap it out to something better suited.

Just be aware that neither the 230, or the 251 get good mileage. They are not even close to being the most effecient engine choice available today. I used to plow a little snow with mine, and it averaged about 3 gallons a mile...

I was thinking they got some pretty poor mileage, unfortunately for me my first M37 didn't get driven more then a couple miles here and there. So I never got to test it's trail capabilities or mileage. I did drive it from Ft Rucker Al. to Ft. Polk LA. about 500 miles, and remember it was really weak on any grade at all.

I'm betting that the slant six would get double the mileage, and be capable of going down the highway at 55. The NP 435 transmission would go in behind the 225 with the option later for a ranger OD.

[MoparNorm]

...
I'm betting that the slant six would get double the mileage, and be capable of going down the highway at 55. The NP 435 transmission would go in behind the 225 with the option later for a ranger OD.

Just keep in mind that fuel economy AND vehicle speed is a function of the final drive gear ratio. Be it 4, 6, or 8 cylinders, your speed is a controlled by the gear ratio, big horsepower will not change that, but a bigger motor will provide torque for those steep highway grades.

[MasterYota]

Just keep in mind that fuel economy AND vehicle speed is a function of the final drive gear ratio. Be it 4, 6, or 8 cylinders, your speed is a controlled by the gear ratio, big horsepower will not change that, but a bigger motor will provide torque for those steep highway grades.

Plus a higher rpm band will let you downshift sooner, and maintain momentum when climbing hills.

I recall that I was comming home a few years back, and climbing a hill with about an 8% grade, about 1.5 miles long. I was already in 2nd gear and was considering downshifting into first (bull low) just to keep the truck moving. Out of the corner of my eye I saw movement. It was a fully loaded tourist on an 18 speed bicycle. He smiled and waved, and then passed me. By the time I got to the top of the hill, he had rode out of sight. I never did catch up to him after that.
That entire trip was 125 miles, and it took me the better part of 5 hours to accomplish the distance. 3 weeks after that, a V8 was put between the frame rails and I could cruise down the highway with the speed of traffic; uphill and down, and I got 3-4 times the mileage.

For those wanting to keep the flatheat, but upgrade to the bigger engine I'll soon have a runner 251 out of my current M37.