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Tech
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Lift Kits and Lift Kit Suspensions
 You see them all the time: Light trucks, Sport Utility Vehicles, Jeeps, and more, coasting down the highway, sitting atop towering truck suspension lift kits and sporting a set of tires so big that a person could live in them. If youre the curious type looking to lift up your own rig, a more important question than How do I get my ride to do that is Why should my ride do that? There are several reasons why people might customize their vehicles with suspension lift kits, as well as quite a bit to know before you get started. If youre a seasoned veteran who has conquered the most vicious terrains and knows your vehicle better than your own mother, there probably isnt much for you to learn here. On the other hand, if youre just getting started and want to familiarize yourself with the basics, read on. |
Why should I lift my ride?
Glad you asked. Equipping vehicles with a suspension lift kits involves much more than buying the sexiest looking truck lift kit and then dropping your ride off at the local mechanic. Actually, chances are good that if thats all you plan to do, lifting your ride might not be right for you in the first place. Installing truck suspension lift kits requires some hard work, a bit of technical savvy and consistent upkeep and attention to your vehicles components. The first determination you need to make when considering suspension lift kits is what you want to do with it. There are essentially two main purposes for installing truck lift kits: style or function. Although the two are somewhat interrelated, its still important to consider which purpose you most wish to pursue, as it will assist you in making the correct modifications to your vehicle.
 Style: Lets face it: Transforming a vehicle into a style statement has been a popular hobby ever since the advent of tailfins and flame decals. As much as we all might chuckle at a hybrid hatchback sitting on 18 wheels, or the family sedan with a wing that resembles the Seattle Space Needle more than a spoiler, we also find our own vehicles having fuzzy dice hanging from the mirror, or a bobbling hula dancer statuette on the dash. As far as style is concerned, adding truck lift kits makes more of an impression than anything else you can do to your ride. Heads turn instantly at the sight of a lifted rig with massive tires that appear to be sprouting fangs and an exhaust system that scares stray puppies into hiding. When it comes to adding suspension lift kits to make a style statement, looking good is the easy part. Sometimes its easy to overlook general, everyday performance in the midst of decking out a ride. For this reason, choosing the right suspension lift kit with attention to comfort, reliability, durability, safety, and not to mention price, should be given just as much consideration as those precious inches you want to add |
Performance: So youve made the jump into tuning your rig for the off-road world, and youre ready to take the plunge to invest in one of many truck lift kits. But before diving headfirst into a custom truck lift kit and gigantic tires, there are a number of issues to address to ensure a correct setup. The first step is to ask yourself what you will be doing the most, whether its slow-speed rock crawling, high-speed desert racing, general purpose 4 wheeling, mud racing, or long distance open country treks. From there, you can narrow down what you need to do in order to customize your vehicle to suit your needs. Whether youre just starting out, or youre the experienced professional, tuning your rig for optimum off-road performance is an expansive hobby with numerous factors to be wary of. The possibilities are limitless, which can sometimes make it hard to determine exactly which suspension lift kits are ideal for what you want. Where do I begin? As if determining which suspension lift kits to purchase werent complicated enough, installing truck lift kits can alter other components in your vehicle, sometimes causing unforeseen issues that could affect performance or be potentially detrimental to the vehicle itself. For example, drive shaft length, steering geometry, brake lines, highway performance and handling, gear ratios, and overall weight are just a few of the factors that could potentially be impacted by adding truck suspension lift kits. Finding ample resources to determine what products you need can be difficult. Speaking with a mechanic can provide some insight. Reading factory service manuals, off-road magazines, internet message boards, manufacturers guides, and a number of other resources can help as well. But by far the most useful way to determine what truck lift kits are right for you and your vehicle is to consult an experienced and knowledgeable person who has a vehicle similar to yours and uses it in the manner similar to what you want to do. Not only can such a person suggest the correct products, but also likely has experience with installation tips and general drivability. In the meantime, here are some of the basic elements of suspension lift kits for you to keep in mind as you plan your modifications.
 What does a Suspension Lift Kit do? 1. Clearance For starters, one of the foremost reasons for installing truck suspension lift kits is to raise the height of your ride off the ground to enable steeper ascent or descent off-road, and higher ground clearance. In general, it makes sense that when driving over boulders, slogging through mud, coasting across the desert, or even just making your way through the occasional forest trail, higher clearance facilitates negotiating certain obstacles. This can often be a tricky bit of artistry to manage, as higher clearance also raises your vehicles center of gravity, which can reduce handling. 2. Larger Tire Fitment The general consensus suggests that larger tires equate to more traction, right? Well, not entirely. While larger tires may provide some improvement to traction in off-road conditions, there are other ways to improve a vehicles traction that are far more efficient than simply bulking up the rubber. Aside from the obvious stylistic discretion, the main reasons for adding larger tires are for higher vehicle clearance for improved performance in mud, deep snow, rocks, and deeply rutted trails. Certain tires designed specifically for off-road conditions can improve traction depending on the circumstances, but the added clearance is the most immediate and direct benefit of larger tires. |
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 Ultimate Jeep! How to Build It: Cherokee/Comanche JeepSpeed Eater |
 How does a full-on desert racing XJ sound? Now add some lockers and a low-geared transfer case and you can go wheeling anywhere. Sounds good to us, but could you make this Cherokee road-worthy as well? If so, then you have a good idea of what our ultimate Cherokee is: an all-around fun-to-drive streetable trophy truck. OK, so maybe this dream Jeep is a little unreasonable, but what if you made it as good as possible at high-speed off-road driving while retaining the ability to drive down a paved road without killing yourself and frightening any nearby traffic. Yeah, thats better, and unlike the JeepSpeed racing class we wont limit our motor modifications or suspension setup. We couldnt race it with them, but it sure would be fun to drive. |
 One problem the Cherokee has is that the unibody construction is anything but rigid. This is OK for most Cherokees. In fact, this flex can be good for wheeltravel, but if youre talking high-speed off-road driving a rigid frame equals control. So how do you stiffen up the chassis of an XJ? Well, we would start by stripping all stock suspension components for better access since its all going to be junked anyways. Next, we would cut into the pseudo-framerails so we could insert square tubing of a similar size. This not only stiffens up the unibody, but will also give us a solid place to mount custom-length control arms for both the front four-link and rear three-link. To hold the front coilovers we would fab up some hoop-style mounts as high as possible in the wheelwell. We may have to trim out some of the sheetmetal to get the desired height, but hey, shocks sticking out of the hood are cool. For the rear we would have to construct a similar shock hoop, which would protrude into the interior of the Jeep. |
 To ensure Jeep speed we would start out with a supercharged 4.0L motor which we would port, polish, and blueprint so everything will flow and turn as efficiently as possible. We could also add a stroker kit to gain a little displacement and make this I-6 the pinnacle of 4.0L performance if so desired. Strapped to the back of our 4.0L would be a TH700-R4 that shifts like a train hit you. We would use adapters from Advance Adapters as well as their Atlas II 4.3 transfer case so we could cruise down the highway at speed as well as creep over the rocks. Axle duty would fall to a custom-made Dana 30 with chrome moly .250-wall axletubes, an Ox Locker, and tons of gusseting. This axle would help us save weight and should be strong enough to turn our 35s. On the ends of our rear suspension arms we would stick a Ford 9-inch with a Detroit Locker. |
 To further strengthen the unibody and to protect ourselves if we ever wad this thing up into a riverbank at high-speed we would build a multipoint interior rollcage in our XJ. The cage would tie into the newly installed framerails as well as the front and rear shock hoops. This would definitely add rigidity as well as some weight but there is no price for safety. Nothing says blasting down a dry washout better than a set of big gaudy race-like fiberglass front fenders, and if you add a fiberglass hood youve saved 50 pounds or so. To continue this weight-saving theme you could start with a two-door Cherokee, replace the rear glass with Speedglass, and add some fiberglass rear fenders for the tires to tuck into during suspension compression. As for the interior we would strip most of it out , add a set of race buckets up front, and a third two-man seat in the back. Call us crazy but we would keep the A/C and beef up the stereo to drown out the tires road noise |
 Tires are like sandwiches: There are many kinds, some are better than others, and you probably have a favorite. For our Cherokee we would pop on a set of 35x12.50x15s from BFGoodrich. These Mud-Terrains may not have the sidewall that bias-ply tires have, but their radial construction allows more high-speed use. In the spirit of a light-truck we would opt for a set of 15x8 forged-aluminum wheels. |
Good, Bad, & What Its For
 Whether its dirt, rocks, or urban wheeling, this Jeep should be at home blasting down fire roads, dry washes, and highways across the country. The lockers and low gearing should make many a slower trail crumble under the 35-inch tires, and the suspension should prove fun on off-road dips and hills as well as your favorite (sub)urban obstacles like stair-steps, parking blocks, and frontyards. |
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Intro: If you're like me you've got an jeep that's becoming more and more of a trail rig and less and less of a road pounder. One of the key things to do when off-road is to air down your tires for better traction. Reducing the pressure creates a greater contact patch in the tire that is able to deform and grab hold of the rocks. The biggest problem with airing down is coming up with a viable way to air back up so that you can drive your rig on the road. Driving on the road with 10-15psi in your tires is not only discouraged it's dangerous. To add to the trouble usually the closest place to the trail head that has air is several miles down the road, leaving you in a quandary as to how to fill your tires back up or get to where you can. And then what about all your air tools you'd love to be able to run on the trail for repairs? One way is the tiny little tire compressors that you can buy at most discount stores. They will pump up your tires but you may be considerably older by the time they actually finish. They are great if you have a tire on your car at home that is a couple psi low but for the big meats on the trail they just don't cut it. There is no way they'd even come close to running air tools. Another option is an electric powered compressor (quickair or others) built for putting out larger amounts of air. These compressors are similar to the discount store compressors in that they run off the 12v power in your jeep. They are built though for serious air and pump out a good bit. With a tank these higher volume compressors should be able to run most air tools. These are a good option but a little pricey. Another option is the Powertank. A CO2 tank built specifically for off-roaders to use for filling tires or running tools. For me this wasn't any option. The initial tank is pricey and I didn't want to have to run out and fill up the tank when it was empty. That leaves one solution. Using the A/C compressor for onboard air. With a tank the A/C compressor can blow up the biggest tires in a matter of seconds and should be able to run most air tools. Many off-roaders have heard about the great air that York compressors provide. The long stroke compressors found in some vehicles can rival shop compressors for amount of output. The problem with the York compressors is that they're pretty big and in the already cramped XJ engine bay there isn't much room. Also you would have to custom fabrication mounting brackets to be able to mount the compressor so that it could be run by a belt off the engine. York's do have a good thing going for them in that they have an internal oil reservoir to lubricate the pump. The Sanden style that come in XJ's from the factory use oil in the refrigerant to lube the internals so we'll have to provide an oiler to provide the lube on the intake side of the compressor. NOTE: making this conversion will render your A/C useless. You will be disconnecting all of the A/C plumbing from the compressor plus you will have to have the refrigerant removed from your system by a certified shop. Time to dig in..... The Install... This conversion will be done on an A/C compressor from a 1988 Jeep. Depending on the year of your jeep the fittings at the compressor end may be a different size. Some experimentation will be needed to find the right fitting if you decide not to hack off and use the fittings already there. Go ahead and open the hood. Disconnect the battery before beginning any work. (this should be done any time you're working under the hood) Before you disconnect any of the Air Conditioning plumbing you need to have the refridgerant drained. If you've been drained then start to remove the fittings from the compressor. This is the point at which you could take a slightly different beginning. Some folks doing this conversion decide to cut the hard lines coming from the connectors on top of the compressor so they can just put hose over top of them and clamp the hose on for the input and ouput from the compressor. I chose to remove the plumbing intact and find brass fittings that would fit onto the A/C compressor. I did not want to cut my plumbing.
 In the photo you will see the brass fittings I used in combination to get from the output size of the compressor to the 3/8" hose. The open port on the right of the photo is the intake side. At the time of this photo I had not addressed the intake filter and oiler. (we'll discuss that more later. I used a 3/4"NPT female to 1/2"NPT female to connect to the compressor. then used a 1/2"Male NPT-3/8 female"NPT fitting to connect to a 1/4" male 1/4"female elbow. Then I used a 1/4"NPT female to 3/8" hose barb to connect to the red hose in the picture. Any combination to get from 3/4"NPT female to the hose diameter will work as long as it doesn't stick up too high to make contact with the hood when closed. When purchasing hose, make sure that you find one with a high heat tolerance as it will be living under the hood with the XJ's infamous VERY hot motor. In the photot you also can see two wires draped across the top of the compressor. These are the clutch engagement leads. Supply 12v to these and the clutch engages and turns the compressor. We'll use these to hook up to the pressure switch later. Not shown are the intake port components. Why aren't they shown? Well because they're not finished. What needs to happen on the intake side is that you need a way to filter the air and then a way to provide oil for the compressor. What I will use is a lawn mower air filter and a standard tool oiler. I will probably purchase an adjustable oiler so that I can provide the right amount of oil (not too much or not too little, but just right...) These can be hooked up with heater hose or another hose capable of resisting oil and heat. They do not have to be pressure hose. Back to the output side. From the output hose you see in the photo then I have connected an air/oil filter serperator to filter out any oil that gets into the air. A check valve and unloader to exhuast the air in the hose to reduce the stress on the compressor when it engages. A pop-up safety valve which will pop if the pressure reaches 150psi. This is purely for safety and is a must on a compressed air system. If for some reason the switch were to fail this will protect the system from exploding. A pressure switch that will turn the compressor on at 80psi and off at 120. And a male quick disconnect to connect my tank to. I have a seperate (not permanantly installed) tank that you can find more info about in this my build a tank article. You will need barbed fittings and hose clamps when you connect to piece of hose. |
 Here you see the lower red hose is the output from the compressor to the filter/seperator and then out to the rest of the system. Put the filter as the first in the output line to protect the rest of your system from getting oil everywhere. |
 In these photos you will see: check valve/unloader - green arrow pop-up safety valve - red arrow male quick connect - purple arrow the pressure switch - blue arrow |
 The Yellow arrow is pointing to a built in unloader valve in the pressure switch. That required more plumbing so i purchased a check valve unloader all in one brass piece. The check valve keeps the air from traveling backwards through the system. It's a one way type valve. Then unloader empties the air on the compressor side of the valve to reduce the effort the compressor needs to start up. The cyan arrow is pointing to the switch on the pressure switch. You can choose 'Auto' or 'Off' Auto will switch the compressor on and off when the pressure changes. Off..well...is off. |
This is a shot of the whole system. You could choose to plumb for a permanant tank or a portable tank like I built. To connect the pressure switch to the clutch you will need to bring 12v power from the battery (you must use a fuse to protect the system) to the switch. The inside of the swtich will have a place to put the 'in' power and then 'out' power lead. Then take the 'out' power lead and connect it to the clutch engagement wires. (see diagram below)
 Once you've gotten everything hooked up and all your hose clamps tight and a tank and some hose to get to your tires you're ready to go!! |
Parts can be gotten from various suppliers. I got mine from these places: Home Depot: Misc. Brass fittings, air filter/seperator, lawn mower filter, tool oiler, quick connects Grainger: check valve/unloader Northern Tool: pressure switch and tire chuck Tractor Supply Co: pop saftey valve |
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