Blueprinting a Build

[AppleTech]

Good day all! Looking for ideas on my next project and think I might take on an M715. My goal is for a good off-roader that I can abuse a bit more than my Cruiser - don't want to have to worry about scratching the paint up I've also been itching to do a diesel conversion of some kind, and using a pre-75 rig will make it easier.

I'd like to be able to do some towing and also get better mileage than my Cruiser's 13mpg, so I'm planning on doing a diesel build - I think this is achievable with the correct ratios chosen. I'm also planning on learning to weld so once I had that training in my pocket I'd take on this project in a year or two. Posting up my thoughts here to bounce the idea off you guys to see what you think.

Engine: Isuzu 4BD1T - 3.9L 4cyl turbodiesel. Easy to tune for more power and they are a bit smoother than Cummins 4BT. I'd set up with intercooling and the factory-available exhaust brake.

Trans: NV4500 using 4bdconversions.com adapter.

TC: Unsure at this time, have to review what options there are to hang off the back of the 4500 or use a divorced unit.

Suspension - I'd like to do a spring over with the ability to run 37"s

Axles: this is where I need some guidance - are the stock D60/D70 reliable enough to run 37"s off-road? I do mostly rock-crawling. Is there a good aftermarket for the stock axles, as far as alternate R/Ps, lockers, etc? (Know I'm a Toyota guy, so I don't know much about US-made axles). I realized I'd need to have some high-angle driveshafts built for this application as well, and I'd like to be able to convert to disc brakes all around.

Modifications: I'd bob the bed and frame probably a 1ft - to 1.5ft, build an in-cab rollcage, fab up some sliders and skid plates for the new drivetrain.

Thoughts welcomed and appreciated!!

[randygar]

37s are pretty close to stock tire size, and you won't have any reliability issues, nor do you need the springover. 39s will run with no rubbing without the springover. If you do the springover, you can fit 44s, and the stock axles will be reliable unless you do unwise things with too large of an engine.

If you want 4-wheel disc brakes, then you're probably better off swapping in newer axles.

There's plenty of aftermarket support for the stock axles, as they're standard dana models, so you have a full choice of lockers (ARB, eaton, detroit, lockright, aussie, several brands of posis,... take your pick), gears, etc. For crawling, the stock 5.88 gears should be great.

You won't need high-angle driveshafts. Toys are little and cramped and have short driveshafts with bad angles. These aren't Toys.

I'm not familiar with that engine, so can't comment there.

Bobbing vehicles is a really, really bad idea. If you want a short vehicle, start with a short vehicle. A full 8ft bed makes a vehicle much more useful, and harming the usefulness of a vehicle is always a bad idea. Keep it a useful truck!

--Randy

[AppleTech]

37s are pretty close to stock tire size, and you won't have any reliability issues, nor do you need the springover. 39s will run with no rubbing without the springover. If you do the springover, you can fit 44s, and the stock axles will be reliable unless you do unwise things with too large of an engine.

If you want 4-wheel disc brakes, then you're probably better off swapping in newer axles.

There's plenty of aftermarket support for the stock axles, as they're standard dana models, so you have a full choice of lockers (ARB, eaton, detroit, lockright, aussie, several brands of posis,... take your pick), gears, etc. For crawling, the stock 5.88 gears should be great.

You won't need high-angle driveshafts. Toys are little and cramped and have short driveshafts with bad angles. These aren't Toys.

I'm not familiar with that engine, so can't comment there.

Bobbing vehicles is a really, really bad idea. If you want a short vehicle, start with a short vehicle. A full 8ft bed makes a vehicle much more useful, and harming the usefulness of a vehicle is always a bad idea. Keep it a useful truck!

--Randy

Thanks for the input! The only reason I would want to bob is to lessen the rear overhang...

[Binford]

Bobbing vehicles is a really, really bad idea. If you want a short vehicle, start with a short vehicle. A full 8ft bed makes a vehicle much more useful, and harming the usefulness of a vehicle is always a bad idea. Keep it a useful truck!

It won't be too useful off road if his tail end keeps hanging up on stuff because of the overhang! Besides, even bobbed, he'll still have a heap more bed space than he'd ever see in a Toy!

[moosejr]

Power Steering,. .you DEFINITELY will want to do power steering, and it is relatively easy as far as the steering gear itself, just swap in a standard saginaw box. I would recommend strengthening the frame mount and bracing it, along with a steering stabilizer. For serious rock play, depending on how big of a tire you use, . you might consider a rock ram also. I have had my M715 on the rubicon, . and the one thing that would have made a huge difference would have been power steering, . .

[AppleTech]

Power Steering,. .you DEFINITELY will want to do power steering, and it is relatively easy as far as the steering gear itself, just swap in a standard saginaw box. I would recommend strengthening the frame mount and bracing it, along with a steering stabilizer. For serious rock play, depending on how big of a tire you use, . you might consider a rock ram also. I have had my M715 on the rubicon, . and the one thing that would have made a huge difference would have been power steering, . .

Ah! I didn't realize that it didn't have PS! One more thing to add to the list

I am also thinking about buying a Volvo C303 (TGB11) because I'm a Volvo nut, but it will cost me about 10K - 15K for a nice rust-free one and then there's parts availability. Diesel swap with that would not be as easy as you'd have to use a smaller motor, and the options aren't as diverse. That also doesn't have PS, but it DOES have portal axles

[randyscycle]

There's plenty of aftermarket support for the stock axles, as they're standard dana models, so you have a full choice of lockers (ARB, eaton, detroit, lockright, aussie, several brands of posis,... take your pick), gears, etc. For crawling, the stock 5.88 gears should be great.

The front axle is a Dana 60, but only in numbers and gears/carrier. The axles are different and smaller and of course the knuckles are closed.

The rear Dana 70 is different from its modern counterpart and the only gears still available are 4.88's as of last check. There is a Detroit locker still available, but I don't think ARB or anyone makes anything to fit the offset carrier of the D70 in the M715.

Keep in mind that the odd wheel pattern limits you for wheels too and the only (one and only) disc conversion is from Ugly Truckling.

That all said, I have been running 38's on my stock axles and brakes for 3 years now with no issues, but the 5.87's do limit my long highway jaunts.

[tndonor]

Just curious why portals? Spring over with 37 inch tires will look goofy woth that much fender exposed. Sprung over with portals......would look like a monster truck with car tires.

38s would clear in stock form spring under for reference.

Just take you time. Look at some buillds similar to what you want to do/end up looking like and go from there.

[AppleTech]

Just curious why portals? Spring over with 37 inch tires will look goofy woth that much fender exposed. Sprung over with portals......would look like a monster truck with car tires.

38s would clear in stock form spring under for reference.

Just take you time. Look at some buillds similar to what you want to do/end up looking like and go from there.

I wasn't saying portals for an M715... that would be silly. I'm just saying the Volvo that I was also considering as my next build comes with portals

-Phil

[97XJSP]

Why not do portals without a lift? Nothing silly about portals!
For reference, I'm running 38.5x11 boggers on stock suspension/ axles with pretty much zero rubbing, even off-road. I would say that the brakes are adequite as well. When properly adjusted, they stop pretty well in my opinion...