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Techline: Your Top 4x4 and Off-Road Tech Questions Answered Here

Posted in How To: Tech Qa on March 12, 2018
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Mix-Match Adapt

I love the mag, the online articles, and so on. Thank you! I decided to mall-crawl my ’68 half-cab Bronco that I originally intended to build as a crawler. Early Broncos are becoming too valuable for me to feel good about beating it to death. This left me with nothing to wheel. Since that wasn’t going to work, I recently picked up a ’83 CJ-7 roller with a 383ci stroker GM V-8, military kingpin Dana 60 front axle, and a 14-bolt rear axle with a Detroit Locker. Both axles have 4.56:1 ratio gears. The transmission is a T-19 manual and the transfer case is a Dana 300. It also came with some extras like a Blue Torch Fabworks full width kit on the front, some Poison Spyder rock sliders, and so on, but, it’s basically trash otherwise. The motor and drivetrain are not installed and the tub and frame are Swiss cheese.

To solve this problem, I picked up a buddy’s ’85 CJ that is in much better shape to swap all the goodies into. I’ll be swapping things over one major component at a time, starting with the axles and drivetrain. I plan on building a crawler first and foremost, with (very far into the future) dreams of Moab, Fordyce, and the Rubicon.

Assuming I go with the 383 Chevy V-8 as my powerplant, should I stick with the T-19 and Dana 300 or go with the NP435 and NP205 that I originally bought for the Bronco? I know I’ll need a Chevy NP205, but that’s not a deal breaker. I’m more worried about overall difficulty of the swap, clocking of the NP205, weight, and just fitting it all in nicely.

Yes, there are a million threads on the T-19 versus the NP435 and the Dana 300 versus the NP205, but I’d rather get an answer from true experts that I can trust. My NP435 and NP205 have the lower spline count on the shafts, so they are not as desirable, but I’m OK with upgrading those if need be. I’m aware of the SM420, but I can’t find one. What say you? All advice and opinions are appreciated.
William Covert
Via email

A lot of the drivetrain decisions you need to make will be based on tire size and driving style. The Dana 300 is a great compact transfer case that will typically allow you to retain the factory CJ-7 wheelbase, if that’s the plan. Given that you intend to run a 1-ton Dana 60 front axle and a 14-bolt rear axle, it’s likely safe for me to assume that you plan to run tires that are at least 37 inches tall and possibly much larger. With the power of the 383 V-8, overall weight, direct drive of a low-geared manual transmission, and the assumption of tires larger than 35 inches, I’d be a little nervous about using the Dana 300 transfer case. Could you make it work? Of course, but it will require sane driving and proper driveshaft angles that don’t allow binding under load or when the suspension cycles. This can be tricky, especially with the axlewrap that leaf springs usually allow.

The Dana 300 front and rear outputs are usually the first to fail on a build like this and it’s typically because of driveshaft binding. If you are careless with your driveshaft angles and driving habits, I’d recommend installing heavy-duty 32-spline outputs front and rear on the Dana 300 right away. JB Conversions (jbconversions.com) offers front and rear 32-spline outputs. Advance Adapters (advanceadapters.com) and Novak Conversions (novak-adapt.com) both offer a heavy-duty 32-spline rear output for the Dana 300. Be sure to check the Dana 300 model before ordering parts. There are two versions that came in Jeeps and one International Harvester version. The less common ’80 Jeep Dana 300 can be identified by a shorter rear output housing assembly that measures in at about 3.5 inches. The ’81-’86, and most common Jeep Dana 300, has a rear output assembly that measures in at about 5.5 inches. The International Harvester version of the Dana 300 has a Texas-shaped mounting surface (similar to the Dana 20 and Spicer 18) instead of the round mounting face found on the Jeep Dana 300. Not all parts will interchange, so order your aftermarket outputs carefully.

The NP205 is an extremely heavy-duty transfer case that is more up to the strength level of your other drivetrain components than the Dana 300. However, it’s very large and will likely require that you extend the wheelbase of your CJ-7 to have proper functional suspension movement and driveshaft angles. The only major downfall of the NP205 is the pathetic 1.96:1 low-range gear. This makes the NP205 less desirable for a 4x4 that you plan to do any kind of slow technical rock work with. Of course, there are solutions. Offroad Design (offroaddesign.com) offers several different crawl boxes that can be added in front of your NP205 to get the gearing down lower. You’ll likely need to extend the wheelbase of your Jeep several inches to allow for the added length of an Offroad Design Doubler or Magnum underdrive unit. If you only want to extend the wheelbase a few inches, JB Conversions offers the LoMax kit to convert your NP205 to have a 3:1 low-range gear. This setup would keep the NP205 transfer case at its factory length.

As for the transmission, the T-19 and NP435 are both great. Their adaptability will depend on what they originally came out of. I think you could simplify your swap and reduce costs significantly by sticking with a GM manual transmission, especially if you plan to run the GM NP205 transfer case. The SM420 and parts for it are getting harder to find, so it’s not the best choice. You might want to consider the GM SM465. It came mated to the NP205 from the factory. If you can find this combo used you’ll save a lot of money on adapters and it will bolt right up to your GM engine with a factory bellhousing. Ultimately, trying to adapt your Ford transmissions to your GM motor and transfer case isn’t all that cost effective. Just because you already have the components doesn’t necessarily make them an ideal swap. If you decide to keep the Dana 300, just run the T-19 that it’s already mated to. Make sure it’s a T-19 and not a T-18 before ordering any parts.

Normally, you should mock up the axles first with whatever wheelbase that you have planned for your project. However, in your case, I think you will want to mock the engine, transmission, transfer case, and any crawl boxes into place before settling on a wheelbase. It will take some trial and error and you will likely have to move things around a few times to make it all work properly. Don’t forget to take the radiator, fan, exhaust, driveshaft clearance and angles, steering, and so on into consideration before final welding of all of the engine and suspension mounts. The more thought you put into the planning and fit of your swap ahead of time will result in fewer headaches down the road.

Mopar Legal EFI

Have you heard any rumors from any companies getting CARB certification on the aftermarket EFI systems? MSD did it just for Chevy vehicles. Where’s the love for everyone else? I’ve got a Dodge. I know Ford guys want it too without having to do to a 5.0L setup from the ’80s-’90s. I’ve been keeping an eye out for several years. I bought my Ramcharger in a no-smog county of Nevada. I swapped in a carbureted 360 Magnum when I lived there. I’m in San Diego now and can’t register it here. The factory EFI barrel intake strangles these engines, so I’ve held out for hope of a CARB-certified kit. No one appears to want to invest the money. My truck passes the sniffer with ease but not the visual inspection.
David Mercer
Via facebook.com/JohnCappa4x4

The problem is that the EFI kits are made to be 50-state CARB legal for each engine and vehicle application, not just for each EFI kit. Unfortunately, the demand for smog-legal Dodge 360 EFI just isn’t that high. Of course, as you have noted, other more popular applications have smog-legal EFI kits available. The MSD (msdperformance.com) Atomic EFI carries a CARB number that applies to ’87-and-older model year General Motors passenger cars and pickups originally equipped with a carbureted V-8 gasoline engine. Howell EFI (howellefi.com) has CARB-legal TBI kits available for Jeep CJ, YJ, and Wagoneer models. Howell EFI has an EFI kit specifically for the Mopar 360, but it does not come with a CARB number and is not 50-state legal. It’s really too bad that the state laws get in the way of a modification like this. The computer controlled EFI would certainly run cleaner and more efficient than a carburetor.

Shocking Taco

I have a ’18 Tacoma 4x4. Would you do an Icon, King, or Fox suspension upgrade kit? I’m doing wheels and tires too.
@rubendawg
Via Instagram @cappaworks

The suspension kits you are looking at are all very similar and they will likely perform similarly as well. However, I’d recommend opting for upgraded shocks. Look for shocks with compression adjusters. This will give you the ability to help tune the ride yourself without disassembling the shocks. If you don’t like the idea of messing with knobs and tuning the suspension, any of these kits should be fine.

Military-Style Wheels

Do you know a source for 17-inch military-style beadlock wheels with a decent offset? My M715 has swapped-in axles with an 8-on-6.5 lug pattern.
@jeepkaiser_m715
Via Instagram @cappaworks

If your heart is set on 17-inch wheels, Rock Monster Wheels (rockmonsterwheels.com) offers the same style of double beadlock wheel that you’ll find on many military vehicles. In fact, the Rock Monster Wheels are made by Hutchinson (hutchinsoninc.com), which is the same manufacturer as the military double beadlocks, although the Rock Monster Wheels have a slightly more civilian flavor in design and colors. The aluminum eight-lug Rock Monster Wheels are 17x8.5 with either a 4.50- or 5.28-inch backspacing.

Trail Worthy Fab (trailworthyfab.com) offers custom-built 17x10 Double Duty steel double beadlock wheels. They are available in many different popular and oddball lug patterns including Rockwell, Unimog, and factory M715. The wheels can be ordered with as little as 2 inches of backspacing.

If you are on a budget and want to steer into military surplus, you’ll have to forego the dream of 17-inch wheels. Unfortunately, there aren’t any mass-produced military vehicles that have used a 17-inch wheel. However, the legendary HMMWV came with 16.5x9 steel double beadlock wheels, although they have 7 inches of backspacing, which may not work on your application. There are several versions of the HMMWV wheel. The most desirable are the 12-bolt and 24-bolt radial beadlock wheels. You can purchase military surplus wheels and tires from companies like Boyce Equipment (boyceequipment.com), Government Liquidation (govliquidation.com), and Gov Planet (govplanet.com). Keep in mind that the 16.5-inch-diameter wheels do limit your tire selection options.

If you can’t use the HMMWV wheels because of the 7 inches of backspacing, companies like Trail Worthy Fab specialize in recentering the HMMWV wheels with a more useable backspacing measurement. Lots of other options are available too, such as changing the bolt pattern, rock rings, rim stiffeners, and your choice of powdercoat colors.

Onboard Air Options

I am working on putting onboard air on my ’77 Ford F-150. It’s a daily driver/weekend wheeler. I have everything except I am having trouble finding an air pump/compressor that operates off of 12V power. I have an 11-gallon tank and would mostly be running air tools and filling up the tires occasionally. What would you suggest?
Joseph Vander Werff
Via email

Onboard air is an extremely useful tool to have on a 4x4. It has many uses including airing up tires and powering air tools. The 11-gallon tank you have planned will help with longer work times and faster tire inflations. The good news is that electric compressor performance has improved greatly over the last decade, giving you many options for a 12V compressor. There are a lot to choose from, but you’ll need to dig into the actual performance numbers of a compressor before pulling the trigger.

Amp draw will be an important number to look at, especially if you are still running the factory alternator. Most high-performance 12V electric compressors will pull 25-35 amps, and some alternators found in older 4x4s produce as little as 35 amps at idle. Running the engine ignition, air compressor, and any other electrical accessories for an extended period of time could very easily lead to a dead battery. Seriously consider upgrading to a 100-amp alternator from a company such as Power Master (powermastermotorsports.com) prior to installing an electric air compressor.

If you want to fill tires up to 37 inches and run air tools for short bursts with an 11-gallon tank, you should look for a compressor that puts out at least 1.5 cfm at 90 psi. For larger tires, bigger jobs, or to run air tools that have a higher cfm consumption, such as cutoff tools and die grinders, you may want a more powerful compressor. In this type of application you should look for a compressor that produces at least 2.5 cfm at 90 psi. If you plan on longer run times, you should steer into a compressor with a 100 percent duty cycle, such as the Air Zenith (air-zenith.com) OB2 compressor. It pumps out 2.66 cfm at 90 psi while drawing 34 amps, but more importantly it’s able to hit 200 psi, making your 11-gallon tank even more useful, that is as long as your tank is rated to 200 psi. Other compressor options are available from companies such as ARB (arbusa.com) and VIAIR (viaircorp.com).

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