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Techline: Answers to all your 4x4 tech questions

Posted in How To: Tech Qa on December 16, 2016
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First Things First

What do you believe should be the first several modifications to a 4x4, including safety, considering the vehicle will see semi to hardcore wheeling? I have my own ideas on this and want to see if yours align.
Glenn McConnell

The first thing I do with any new-to-me 4x4 is give the vehicle a once-over. You’ll always find some sketchy stuff or worn-out components. Very rarely does a seller dump a perfectly running and maintained 4x4, at least not in the price range I’m typically looking at. I’ll even look for loose, missing, or incorrect hardware. Poorly done repairs are common. I'll remove or replace any sketchy wiring and worn-out or missing parts. I look for oil, brake fluid, and fuel leaks. I’ll fix fuel and brake fluid leaks right away and inspect oil leaks to see if they are a going to be an issue. I’ll pretty much fix anything that looks wrong or unsafe. If something does go fubar while I’m behind the wheel, I like to know it could be a potential problem before I hit the trail or road. That way I can plan for it. It forces me to carry some pretty obscure spare parts and odd tools that certainly come in handy. It’s very rare that something busts on one of my rigs that wasn’t at least half expected. After that, the kind of trails I plan to hit and if I care about the body or not will dictate the direction of the buildup. I’m a rocker guard fan, so pretty much anything that goes off-road needs rocker guards of some sort in my mind. That’s usually where I’ll start with actual modifications. A lift, tires and wheels, and a rear traction adding device are usually the next steps.

Anti-Amigo Women

Why do chicks not dig my Isuzu Amigo?
John Pytlak

There is actually a pretty simple answer as to why chicks don’t dig your Isuzu Amigo. The problem stems from the fact that most women don’t really care about 4x4s. Oh, there are a few out there, and many of them have their own 4x4s, so they really don’t need you and your Amigo. Now, women that do like off-roading but don’t have their own rig, often have discriminating tastes. They won’t sit in just anything. Personally, I’ve dated women that didn’t even want to be seen in some of my 4x4s. And I’ll admit it: They were some pretty ugly creatures—I’m talking about my 4x4s, not the women. One woman went so far as to ignore me and pretend she didn’t know me when I drove into her neighborhood. Obviously, you won’t get too far with an Amigo and a woman like that. Amigo-friendly women will generally be the more adventurous type who aren’t concerned with brands or labels. If your object of desire is strutting her Jimmy Choo shoes in a wispy Dolce & Gabbana dress, clutching a Fendi bag while filling your nostrils with the latest Dior scent, you really don’t stand a chance. Yes, this is profiling, but if profiling is accurate, it isn’t wrong. To get women in your 4x4, you need to think like a woman. Women are jealous types. Many women absolutely hate other women that have things that they don’t. Truck guys can use this to their advantage. The guys with the biggest, most powerful or best looking trucks never seem to have a problem loading the cab full of bikini-clad ladies at the local mud pit. The only real good news for you is that there aren’t many other Amigo drivers to compete with. Your 4x4 is sort of rare and odd, making it unique. Although, there are Honda Passport, Nissan Patrol, and Daihatsu Rocky drivers vying for the same woman that doesn’t mind being seen in a goofy-looking 4x4. Good luck with your lady search!


Why is it that on my old ’84 CJ-7 I could float the gears without the clutch and get smoother operation, but anytime I used the clutch it wasn't as smooth? Am I ungifted at driving an old worn CJ-7 on 35-inch tires, or am I just way more gifted at floating the gears?
Agustin Jimenez

Floating the gears of a manual transmission is not a new idea. Truckers have been doing it ever since the invention of a synchronized gear. Floating a transmission involves letting up off the throttle just a bit to match the engine speed to the drivetrain speed and then carefully shifting gears without depressing the clutch pedal. Big-rig drivers use this technique to increase the speed of a shift and reduce the amount of stress that can be placed on the driveline when shifting with a clutch. The jerking and chugging caused by a poor shift could easily pitch a driveshaft out of a big rig hauling 60,000 pounds or more. Floating your Jeep transmission really isn’t necessary. The synchros in some Jeep transmissions may wear out prematurely if you make a habit of shifting this way. In an ideal world, you can learn to shift the transmission more smoothly. Use the same tactics as floating gears by matching the driveline speed to the engine speed in the middle of your clutched shift. Don’t ham-fistedly slam the transmission into gear, ease it on in, and slowly release the clutch as you bring in the throttle. Working a manual transmission properly requires a lot of practice. Each and every vehicle with a manual transmission shifts differently and takes some time to get used to.

Over Under

Which is better: a spring-over suspension or a spring-under suspension?
Greg Martinek

Let me ask you which is better, a baseball bat or a Wiffle ball bat? What I mean by that question is that it totally depends on your situation. You generally wouldn’t try and play close quarters indoor ball swinging a real bat around kids’ heads, and you certainly aren’t going to hit any 90 mph fast balls with a plastic hollow bat, right? The same is true of your 4x4. The type of suspension you choose should depend on where you use your 4x4 and how you expect it to perform.

Most leaf-sprung Jeeps came from the factory with spring-under suspensions. A spring under-suspension is often incorrectly associated with being stiff and inflexible. Lifting a spring-under Jeep generally requires the installation of four new leaf springs. To some people, this option sounds too expensive. Garage fabricators quickly figured out that the leaf springs can be moved from under the axles to above the axles, which achieves a presumably inexpensive lift of 5-6 inches and a lot more ground clearance under the axles. Unfortunately, simply putting the springs on top of the axles is the easy and cheap part. The other elements required to make the spring-over lift functional are expensive and sometimes not as easy to implement. Most spring-over lifts require longer front and rear driveshafts, axlewrap control, longer brake lines, complicated steering modifications, and longer shocks, and some front axles require pinion angle and caster changes to work with the increased lift height.

If RTI ramps and traversing slow-speed boulder patches with a low-power engine are your thing, then a spring-over might be the right suspension for you. But if you want a mostly maintenance-free suspension system that is more versatile and can better handle axlewrap, a spring-under suspension is the top choice in my opinion. The idea of a spring-over being cheap is a total myth. The required steering mods can sometimes cost more than an entire over-the-counter spring-under lift kit, and you haven’t even begun to address axle wrap or any of the other common spring-over issues. Ultimately, if you enjoy tinkering with your suspension, want the most articulation possible, and don’t mind replacing bent or broken suspension, steering, and driveshaft components occasionally, then go for the spring-over. For those that want to lift their Jeep and forget about it, go with the traditional lift kit.

Now, having said all that, most leaf-sprung fullsize trucks are spring-over from the factory. Because these suspensions were originally designed this way, they are usually better able to handle axlewrap and other common spring-over issues.

Diesel or Not

What do you think of the VW diesel conversion for a Suzuki Samurai?
Josh Sawyer

There are many different common engine swaps out there for a Suzuki Samurai. The VW diesel swap is an interesting one, and there are several VW diesels to choose from with a wide range of power output. Companies such as Acme Adapters (, Keltec (, and Rocky Road Outfitters ( offer the components and information needed to make the swap. Although, if you plan to make the swap to save on fuel costs, don’t waste your time or effort. An engine swap will almost never pay for itself in fuel economy savings, even if it is a fuel-sipping diesel. But, if you are looking for more low-end torque, greater range, improved durability, and a unique engine swap, then the VW diesel is a great option for your Samurai.

Reversed FSJ Suspension

Is it worth putting a shackle reversal on an FSJ?
Ken Basile

Interestingly enough, none of the fullsize Jeeps ever came with a shackle reversal from the factory. It’s actually a little bit surprising when you consider that the fullsize Jeeps were offered from 1963 through 1991. While the suspension did change a bit over the years, the fundamental design remained mostly unchanged for the lifespan of the FSJ.

It’s usually argued that a front-mounted shackle provides more traction when crawling over obstacles. The idea is that as the springs compress, they move the axle forward, forcing the tires to bite harder into the terrain. Shackle reversal supporters will argue that a shackle reversal provides a smoother ride on- and off-road. It’s contended that as the front tires hit an obstacle, the springs compress and pull the axle backward, away from the obstacle, making for a smoother ride.

In reality, both systems have pros and cons. From the driver seat you probably would not notice that a traditional front-mounted shackle suspension improves climbing ability. There are other important factors, such as running the correct lowered off-road air pressure, that will make much more of a significant difference than having a shackle reversal. Generally, a leaf spring suspension with a shackle reversal will handle more precisely on- and off-road. However, because suspension compression pulls the axle rearward, you need to be very careful about making sure that the front driveshaft does not completely compress, bottom out, and break your transfer case in half. Conversely, with a traditional front-mounted shackle suspension, you’ll need to pay special attention to the steering system. A front-mounted shackle suspension will push the axle forward (as the suspension compresses) and into the draglink, pitman arm, or sway bar links. It’s important to properly locate bumpstops on both suspension types to avoid any undercarriage damage.

Cool It Down

I have a ’99 XJ with a stock 4.0L motor, 231 transfer case, and an AW4 transmission. It rides on 32-inch BFGoodrich T/A KM tires with a 4 1/2-inch lift and stock 3.55 gears. My tech question has to do with overheating while driving up mountains at highway speeds. I live in the foothills of the Smokey Mountains, so long uphill roads are common. As long as I drive in town on semi-flat roads, the engine temperature gauge reads in the normal range, which is 195-200 degrees for an XJ. But, once I start up one of the long grades, my Jeep begins to overheat, which forces me to stop and let it cool down. It has only been in the past year that this has been happening. I have owned the Jeep for six years now. I have flushed the system and replaced the thermostat and the problem still persists. I’m thinking the problem is clogged water jackets or bad water pump. My Jeep is a daily driver in town, but some of the trails I like to run require me to drive over the mountains where I know I'll run the risk of overheating. What advice do you have for nailing down my excessive heat problems?
David Cooper

Because this is happening at highway speeds, it’s safe to say that it is not a fan problem. Although, it could be an airflow problem if you have recently blocked the radiator with a new bumper, winch, off-road lights, a tranny cooler, or some other accessory. If none of this is the case, I would suspect it could be a problem in the cooling system or a head gasket leak. It’s even possible that the problem is the gauge, a leaky radiator cap, or other coolant leak. Inspect the engine and cooling system for leaks and repair as needed.

Before making any other changes or repairs, I highly recommend installing a true temperature gauge with actual numbers, even if only temporarily. An aftermarket gauge will give you the most accurate coolant temperature reading. The factory cold-normal-and-hot gauge is not all that accurate. Your engine could be running at optimum temperature. A poor electrical ground or other wiring issue could cause the gauge to read higher or lower than it should be. I prefer to use mechanical gauges for this sort of exercise. Auto Meter ( offers many different inexpensive quality gauges that can be put to good use. Unfortunately, mechanical gauges typically have very large sending units that can be difficult to install in the engine. Try to find a place to install the new gauge sending unit near the water outlet in route to the radiator, before ordering your gauge. You may need to use an electric gauge if space is at a premium.

If you find that your Jeep is indeed running hot, use an infrared thermometer to see if you can find cool spots in the radiator. Harbor Freight ( offers a few different infrared thermometers, which regularly sell for $10-$60, which can make this job much easier. Radiator tubes that are cold to the touch or only warm when the rest of the radiator is hot will indicate that your radiator is partially clogged. You should replace a clogged radiator immediately.

A leaking head gasket can be identified in a few different ways. Inspect the oil dipstick. If there is water or coolant in the oil, the oil will look like a chocolate milkshake. Check the coolant inside the radiator (once the engine cools). There should be no oil slicks floating around in the coolant. Also, if your engine’s coolant bottle needs to be refilled regularly, you should perform a coolant hydrocarbon test to see if exhaust gasses are entering the cooling system. If any of these tests show signs of a leaking head gasket, you should replace it pronto.

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