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Answers To All Your 4x4 Tech Questions

Posted in Features on September 2, 2016
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Ailing Automatic

I have been reading Four Wheeler for many years and have come to the conclusion that you guys and gals are the upmost authority when it comes to off-roading. That is why I’m writing to you with a few questions about modifying my truck. I have a ’84 Dodge Power Ram W150 with a 318 V-8. Other than the aftermarket exhaust and 33-inch tires, it is stock. I blew up the tranny on my last outing in the mud. I would like to convert it over to the best manual transmission and transfer case that they came with. I’m not sure what that would be. It currently has an A727 automatic transmission and an NP208 transfer case. I’m hoping you will be able to help point me in the right direction. Also, if you know of any little things that someone might need to know, like a wire that needs to get connected that normally isn’t, or if I need a specific crossmember to support the manual transmission and transfer case, it would be great if you could pass that on. Thank you for your time.

Russell Miller
Kaukauna, WI

Fortunately, swapping to a manual transmission in an older truck like your ’84 Dodge is a relatively straightforward conversion. There are no engine or chassis management computers to contend with, but let me cover a few things on the automatic. The TorqueFlite A727 transmission is an extremely durable and robust automatic tranny. They were used in 1-ton trucks and really heavy motorhomes behind big-block V-8 engines. Killing one is quite a feat. If the transmission went out suddenly, with no slipping or warning days or weeks in advance, then you likely overheated it. Heat is the number one killer of all automatic transmissions. Once the transmission overheats, the oil burns up and the clutches inside are destroyed, leaving you stranded and in need of a transmission rebuild or replacement. Keeping an automatic transmission cool is just as easy as it is critical. If you suspect the transmission is running warm, you can monitor the temperature via an aftermarket gauge and a sending unit mounted in the transmission pan. For longest transmission life, the fluid should stay below 175 degrees. At 240 degrees, varnishes form inside the transmission. At 260 degrees the seals begin to harden. At 295 degrees the clutch plates start to slip and at 315 degrees the seals and clutches burn out and the oil turns into a carbon muck. Auto Meter (autometer.com) offers many different transmission temperature gauges with either mechanical or electric sending units. Personally, I prefer the mechanical sending units, but they are larger and can be more difficult to mount. I simply don’t trust the small electric wires required for the electric sending unit on the underside of a 4x4 that regularly sees mud, sticks, and brush.

Cooling the transmission can be done in a variety of ways. Companies such as B&M (bmracing.com) and Flex-a-lite (flex-a-lite.com) offer durable and efficient aluminum transmission coolers. Some have their own electric fans that allow the cooler to be mounted nearly anywhere on the vehicle, regardless of airflow. When space is at a premium on the front of the vehicle, I have seen transmission oil coolers with fans mounted in the bed of pickups, underneath the body, or even on the roof of a 4x4. Extremely high-horsepower and ultra-heavy-duty applications may require the massive transmission coolers available from companies like Fluidyne (fluidyne.com)

A deep sump aluminum transmission pan from companies such as B&M, TCI (tciauto.com), and others can also help with cooling. Tilden Motorsports (tildenmotorsports.com) has a Pro Series transmission oil pan available for GM automatic transmissions that features air-flow cooling tubes that help dissipate heat. With a proper temperature gauge, you’ll be able to more easily identify when you have enough transmission cooling capacity.

Driving habits can significantly alter transmission temperature. Lugging the engine can cause the transmission to heat up quickly. The correct gearing will allow the engine to properly spool up in rpm. Automatic transmissions can circulate more oil at higher rpms and the clutches are generally creating less heat. Rather than lug the engine up a hill in Second or Third gear, try manually shifting your automatic to First or Second gear to ramp up the rpm. You will see the transmission temperature quickly drop. While off-road, you can use low range in the transfer case to decrease the load on the transmission, which will help keep it cooler.

Rebuilding the 727, like most three-speed automatics, is extremely cheap when compared to the cost of rebuilding the more complex four-speed automatics. A typical three-speed automatic can often be rebuilt with heavy-duty clutches for less than $500, whereas a four-speed auto rebuild may be two, three, or even four times that.

If you’ve simply had it with the automatic transmission and want a manual, it will cost significantly more to make the swap than to rebuild the TorqueFlite 727 automatic. The easiest transmission for your swap will be the NP435 four-speed manual and NP208 found in ’80-’87 Dodge trucks and Ramchargers. The NP435 and NV241 transfer case in ’87-’93 Dodge truck or Ramchargers is also a good find. If possible, you’ll want access to the entire vehicle so you can pull the transfer case, clutch pedal assembly, clutch linkage, crossmember, bellhousing, clutch fork, and all of the other related components. Access to all of these factory parts will keep you from having to fabricate something in their place. The NP435 will be the most bolt-in manual transmission swap you can make, but it won’t just bolt in. It will require some drilling and cutting. For example, the exhaust on your automatic-equipped truck may not clear the factory clutch linkage. It may be easier and less expensive to fabricate your own hydraulic clutch linkage system.

If you do a lot of high-speed freeway driving, you might consider a five-speed manual transmission such as the NV4500 or NV3500. Both of these transmissions have overdrive gears. The NV4500 is an extremely heavy-duty transmission that can be found in Dodge and GM trucks. Both versions are very adaptable using components from companies like Advance Adapters (advanceadapters.com). Advance Adapters even sells complete remanufactured NV4500 transmissions. The holy grail of factory manual transmission and transfer case combos is the NV4500 mated to an NP205. This combo can be found in some ’92-’93 Dodge 3/4- and 1-ton gas V-8 trucks, but it won’t come cheap unless whoever selling it doesn’t know what they have.

The NV3500 was used in ’94-’01 1/2-ton Dodge trucks and ’94-’04 Dodge Dakotas with the V-8. They all have a bellhousing that matches up to your 318/360 V-8 engine. However, the NV3500 will be mated to a transfer case that has a passenger-side front output that will not work with your driver-side differential front axle. Advance Adapters offers components that can be used to adapt the NV3500 to a transfer case that will work for your application.


Jeep Swap

I have a ’88 Jeep Wrangler with a TBI 2.5L, five-speed transmission, and an NP231 transfer case in it. I use it for all different kinds of wheeling and some street use. I bought a ’88 Chevy C2500 with a TBI 350 V-8 and SM465 that I plan to swap into the Jeep. I got a Dana 300 transfer case too. I plan on using it with a Down East Offroad flip kit to rotate it 180 degrees to feed my driver-side drop Dana 44. I will probably use Novak parts to adapt everything else. The Chevy motor has 190,000 miles on it, so I would likely rebuild it later down the road. At that point, I would warm it up a bit with a cam, maybe heads, and so on. Would I get more power for my money if I sold the Chevy and saved up for a Vortec 350 or 5.3L LS V-8 with fewer miles? Also, are the SM465 and Dana 300 good choices? Will I hate the old, slow-shifting four-speed? I have been reading Four Wheeler since long before I was old enough to drive and always enjoy the articles.

Torin Brick
Via email

The TBI 350 V-8 motor is a great swap candidate for your Jeep. The Vortec 350 has better heads and will make more power than your TBI motor, but at what cost? Do you need the additional power? The 5.3L LS is great for higher rpm use and has a ton of potential if you plan to modify it, but I think the Vortec 350 V-8 is a better all-around 4x4 motor. It makes more torque down low where you need it and has a flatter torque curve. Down the road, the Vortec V-8 will also swap in place of a GM TBI motor a lot more easily than the LS engine, should you decide to go that route.

The factory GM TBI harness can be pared down to work in your Jeep. However, if you aren’t great with wiring, Howell EFI (howellefi.com) offers complete harnesses that will simplify the installation of the GM TBI engine and OE computer.

The SM465 manual transmission and Dana 300 are great choices. Although, the SM465 is a heavy-duty truck transmission with a 6.55:1 First gear. I would not consider it a sporty or quick-shifting transmission. You’ll be disappointed if that is what you expect of it. You might be able to speed up shifting if you can fabricate a version of the Gear Banger shifter that Wild Horses (wildhorses4x4.com) offers for the NP435. Regardless of the shifter mechanism, you likely will not use First gear on the street, so that will speed shifting up a bit.


Making Ford Traction

Thanks for such an awesome mag. I'm asking a question concerning traction. I have a ’86 Ford F-250 with the 6.9L diesel. I want more traction, but I'm broke. I am stuck with two choices. I can either get a locker or get aggressive mud- or all-terrain tires. I can only afford one or the other. Any other help would be wonderful!

Levi Bennett
Via email

When building a 4x4 on a budget, it’s obviously best to start with the modifications that make the biggest improvement. You want more bang for your buck, right? And while both aggressive tires and a locking differential offer vast improvements over stock, there is a clear cut winner. If you are trying to make more traction off-road, and given the choice between more aggressive tires and a locker, I’d take the tires every time. The all-terrain or mud-terrain tire upgrade will help on multiple levels, where the locker really only helps in one area. Let me explain. The more aggressive tires will clearly provide better traction on wet grass and in mud than street tires, even if you back the street tires up with a locker. Another advantage is that you can opt for tires that are one or two sizes larger than stock, increasing the ground clearance of your 4x4. And lastly, most all-terrain or mud-terrain tires will have significantly more robust sidewalls than traditional street tires, making them better at fending off trail punctures.

To make your truck even more capable, consider airing the tires down to 15-25 psi for off-road use. It will increase the tread footprint, tire flotation, and improve the ride quality over rough jumbled surfaces. Watch out though, some older 3/4- and 1-ton trucks have 16.5-inch wheels. These wheels do not have a safety bead, which helps keep the tire seated on the wheel at lower pressures. If you have 16.5-inch wheels, you may want to upgrade to some 17s prior to purchasing new tires.


Coilover Lengths

I’m planning on doing a long-arm link-suspension with coilovers on my ’91 Jeep YJ. How would you set up the coilovers? I was thinking of going with 17-inch-travel Bilstein 9100 Series coilovers, but I want the Jeep to have a low center of gravity. I plan to stretch the wheelbase to around 110 inches.

Drake FerroNyalka
Via facebook.com/JohnCappa4x4

Link-style suspensions with coilover shocks have become incredibly popular, especially for 4x4s regularly used off-road. It’s a bit of work figuring out all the angles and getting the correct geometry, but when you get it right, you can enjoy massive amounts of tunable wheel travel. Choosing the correct coilover shock length can be a bit confusing. More often than not, most people simply feel the urge to purchase the longest shocks they can get their hands on. This is not the best way to go about selecting shocks for any 4x4. The 17-inch shocks are a bit long if you want to keep your Jeep low and don’t want them poking through the hood and rear portion of the tub. The Bilstein (bilsteinus.com) 9100 Series shocks with 17 inches of travel measure about 27 inches collapsed and about 43 1/2 inches when extended. You should have a pretty good idea of what you want the ride height, compression, and droop of your Jeep’s suspension to be before cutting anything apart and ordering coilover shocks. I recommend that you run out to your Jeep with a tape measure and these shock dimensions in mind. You’ll probably find that the 17s won’t help you achieve the low center of gravity goals you have for your Jeep. In most cases, a 17-inch shock is overkill and difficult to package in a Jeep that isn’t lifted to the moon. You’ll also more than likely find that you will reach the limits of the steering linkage or driveshafts long before you can use all 17 inches of shock travel. A 12- or 14-inch coilover shock is generally a more realistic fit on a full-bodied trail Jeep with a low center of gravity.

You may want to consider the new more affordable Bilstein B8 8125 Series coilover shocks. The B8 8125 Series coilover shocks are specifically designed for serious off-road enthusiasts rather than professional racers like the 9100 Series. They are available in 46mm and 60mm diameters with 5 to 16 inches of travel. The 46mm (2 inch) coilovers accept standard 2 1/2-inch I.D. coils and the 60mm (2.65-inch) coilovers accept traditional 3-inch I.D. coils.

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