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M715 Build, Off-Road Light Wiring, Ford F-150 Lift & Tracks Effectiveness

Posted in How To: Tech Qa on June 9, 2015
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M715 Survive
Q I recently purchased a ’67 Kaiser M715. It has the stock Dana 70 rear axle with a Detroit Locker and the stock closed-knuckle Dana 60 front axle with an open diff. I realize that these axles leave a lot to be desired, especially the front, but I’m trying to keep it looking mostly stock from the outside. I would like to run 38 or 40-inch tires with about 2-4 inches of lift. There’s a brand-new Clifford-built 4.2L engine that supposedly puts out over 300 hp and 400 lb-ft of torque sitting in my garage. I also have a GM 700R4 that was built by Bow Tie Transmissions and a Dana 300 transfer case. I was going to put all of this into a CJ-7, but I am now going to put it into the M715. I like the 5.87:1 gear ratio. I think it will work well with the tire size and Overdrive gear. The front Dana 60 already has manual locking hubs. So now if you have been patient enough to read all of that, here are my questions: Do you know of a locker, preferably selectable, that will work in the Dana 60? I’m having a tough time getting consistent opinions on the internet. Does anybody make stronger axleshafts that can be used in the front axle? I have been reading your magazine for many years and I really enjoy it. Thank you very much for your time. I appreciate any help you can give me.
Jeff Mutnansky
Via email

Editor Hazel responds:
A I had a ’68 M715. I ran a 400hp, 400–lb-ft Chevy 350, Ranger Overdrive, SM465, 3.0:1 Atlas, and stock axles with factory drum brakes. I put a Detroit Locker in the rear, but kept the front open. I kept the factory suspension (even the shocks) and ran 38x13.0-16 Swampers on the original split rims. It was a ton of fun, and I was able to wheel it all over Moab and other places with no problem. I sold the truck a few years ago, but if I kept it I was pretty happy with it, other than the overly stiff rear springs. I was looking into a set of Hell Creek rear springs for a J-series pickup to replace the factory 5⁄4-ton rear springs.

You can cleanly fit 38s on a stock M715 with no lift. You can probably wiggle 40s under there as well without lifting it.

As for your front axle, it’s not a bad unit if you’re OK with the stock 13-inch drum brakes. If you keep them adjusted properly, they’ll stop the truck with 38s or 40s very nicely. The axletubes are kind of thin and prone to bending if you abuse the Jeep, but the closed-knuckle design will keep the mud out.

The diff is just a standard 30-spline Dana 60 unit. It’s very common, and almost every traction device is available for it. The axleshaft metallurgy isn’t as good as ’shafts in modern axles, and the U-joints and coarse-spline stub ’shafts won’t like a bunch of torque and big tires, so my recommendation is to leave the front open. If you do go for a locker, it’d be a smart move to go with a selectable locker like an ARB Air Locker (arbusa.com) or Eaton ELocker (eaton.com). If you only engage the locker when you need it and can limit locker engagement to when the front tires are pointed straight ahead, it’ll go a long way in keeping those old ’shafts alive.

That said, yes, you can replace the axleshafts with more modern units, but it’s a ton of work and not really financially feasible. It’d be less work to grab a dually GM Dana 60 and put it under there if you’re looking for better ’shafts. The biggest bummer there is losing the 6-on-71⁄2 bolt pattern and not being able to run the factory M715 wheels.

Wiring Lights
Q I have five 55-watt tractor lights that I want to put on my Isuzu Trooper. Do you think I need to run a relay between the battery and the switch, or can I just wire them straight to the switch? Also, how important do you think it is to use shrink crimps or water-tight plugs over using the 3M rubber tape with electrical tape on top?
Eric McGrew
Via email

A Adding off-road lighting is an easy upgrade that can greatly increase your off-road visibility at night. Wiring the lights is a lot easier than most people think. However, it’s important to know the draw of the lights prior to selecting wire, switches, and relays. To figure out how many amps a light draws, you can divide the wattage by the voltage being provided to the lights. In your case, your vehicle has a 12V electrical system. If you divide the 55 watts by 12, you get a draw of about 4.6 amps per light. In my opinion, anything over about 2-3 amps should really have a relay. So in this case you’ll definitely need a relay if you want to put all four lights on one switch. Look for a simple 40-amp relay. This will work for all five of your lights and can be found at most auto parts stores for around $7. Use 10-12 gauge wire to feed power to the relay and on the main power lead for the lights. From there you can branch off to 14 or 16 gauge wire to each light. Don’t forget to include a fuse or circuit breaker on the main power wire between the battery and the relay.

The waterproof connectors are a great idea, but they are not absolutely necessary in most cases. Any crimp connector will work fine. Although, if you live in a wet area, it’s a good idea to at least wrap the connections with electrical tape to keep moisture out.

Affordable Ford Inches
Q I have a ’13 Ford F-150 4X4. I would like to update the stock suspension without breaking the bank. Could you recommend either a kit or parts that would do this? Since the truck is garaged, I can’t afford to lift it much more than 21⁄2 inches. Any help you can offer is appreciated.
Mike Henderson
Via email

A There are many companies that offer what are called leveling kits for all of the IFS 1⁄2-ton truck models. What is included in the kits depends on the suspension design and the kind of performance you are looking for. The ’09-’14 Ford F-150 can use a really simple spacer that lowers the top of the suspension strut, providing up to 21⁄2 inches of lift. Companies such as Daystar (daystarweb.com) and Tuff Country (tuffcountry.com) offer these simple spacer lifts for less than $100. These spacers do not alter suspension performance, they only lift the vehicle. If you want to improve the front suspension performance I would recommend going with an aftermarket adjustable strut replacement. Companies such as Pro Comp (procompusa.com) and Fox (ridefox.com) offer complete adjustable-height replacement struts with performance coils. These struts can be adjusted to provide up to 21⁄2 inches in some cases. They are considerably more expensive than the simple strut spacers. The shocks that come with the kits are generally a much higher quality than the stock shocks. As a bonus, the Fox struts are available in several models. The DSC version allows external adjustment of the compression and rebound performance so you can easily tune the suspension to fit your on- and off-road needs.

Tracked Raptor Trailing
Q How effective would Ken Block’s Hoonigan RaptorTRAX be (or not be) for general wheeling, such as rocks (Rubicon trail) or mud (New Oakville, Perkins)?
Bernie Kressner
Appleton, WI

A The Hoonigan (hoonigan.com) RaptorTRAX is pretty much a purpose-built 4x4. It was designed to hit snow drifts and take snowboarders deep into the backcountry. The most noticeable feature of the RaptorTRAX is the Mattracks (mattracks.com) tracks, although the truck has many other modifications done to it. The tracks allow the vehicle to stay on top of soft terrain. Other modifications to the truck include long-travel suspension, a full ’cage, and a supercharged 650hp engine. The truck will do great on pretty much any soft terrain, including snow, sand, and mud. However, it likely would not work all that well on rocks or anywhere the trails are tight, such as on the Rubicon. The truck is very wide, and the tracks are simply not designed for that kind of use. You might even damage them. Now, if you simply unbolted the tracks and bolted on a set of tires, you could likely take the truck more places on- and off-road. However, the truck would still be too wide for any really technical rockcrawling trail work.

Where to Write
Have a 4x4 tech question you want answered in Techline, drop an email to editor@fourwheeler.comor head on over to our forums at fourwheeler.com. All letters become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

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