F&S Guide to Truck Suspension and Lifts
Need a more ground clearance or a smoother ride? Check out our guide to off-road truck suspension.
Part 1, Troubleshooting the Suspension: Out of sight, out of mind. That pretty much sums up how most outdoorsmen view the suspension on their 4×4–until the truck starts bottoming out on rutted trails or groaning like some ghoul in a third-rate direct-to-video horror movie. By this point, you’ve no doubt figured out that something is dreadfully wrong with the vehicle’s ride or handling, but you can’t exactly nail down the problem. What do you do?
Look and Listen: You can help a suspension expert if you conduct a “look and listen” inspection of your rig before taking it to the shop. You’ll need a buddy to help you, preferably one who has not spent a lot of time in the vehicle. (This way he’ll be tuned in to problems that have appeared so gradually you no longer notice them.)
According to the folks at Trailmaster Suspension, your inspection should be as follows:
1) Put your buddy behind the wheel while you slip under the front end. Have him turn the key to unlock the steering column (don’t start the engine) and slightly wiggle the wheel back and forth. Is there excessive free play? Do either of you hear small rattles or squeaks? Try to determine the exact location of any noise. Under the truck, does anything appear to be loose? Grab the steering components (tie rods, steering links, and Pitman arm) and give each a good yank. Slight free play–the result of normal wear and tear–is acceptable, but anything more means a trip to the shop. (For our purposes, “slight” is defined as .030 inch, the width of a standard paper clip.)
2) Have your friend turn the steering wheel all the way to each side. You’re now listening for big noises: groans, creaks, and the like. As your friend turns the wheel, your eyes are glued to the major suspension mounting points. Depending on the model, these include ball joints, king pins, control arm bushings, and leading or trailing arm bushings. Track down the source of any noise. The guiding principle here is, “Where there is noise, there is movement, and where there is movement, there are worn or loose parts.”
3) The bounce test checks the condition of the shock absorbers and bushings. Have your buddy crouch next to a corner of the vehicle as you push down quickly on the body. The corner should come to a rest quickly; if it continues to bob up and down, the shocks are shot. Groans or creaks heard by your crouching friend are signs of shocks and/or bushings in distress. Either way, get the truck to an expert.
4) Your buddy should run the test drive while you ride shotgun. Have him run the vehicle at highway speeds, and then slowly over a bumpy road. Be alert for shakes in the steering wheel. This could be due to an out-of-balance tire (not serious) or a slowly disintegrating ball joint (big trouble). In an empty parking lot, turn the vehicle in slow circles, first with the wheel cranked hard right, then hard left. Again, both of you are looking and listening for anything out of the ordinary.
This drill may seem to be a lot of trouble, but it can be done in about 30 minutes. Just don’t wait until the night before the deer opener.
Day-to-Day Matters: Every year many hunters and fishermen spend hard-earned money on new suspension accessories only to complain about the vehicle’s lack of performance. The fundamental mistake is that new components were installed on a vehicle with a worn-out suspension. The problem is difficult to self-diagnose because a suspension slowly loses efficiency over the years. You won’t even notice the day-to-day wear.
“When a customer calls, our first question is, ‘How old is the truck?'” says Bruce Snyder, marketing manager of Trailmaster Suspension. “We want to know if the ball joints, tie rod ends, and other original equipment parts–including the springs, bushings, and shock absorbers–are worn out. You gotta fix those first.”
According to Snyder, two of the most important yet overlooked suspension components are bushings and bumpstops. Bushings are designed to separate metal parts and absorb the energy created by the motion of the suspension. You’ll find them throughout the truck–major locations are leaf springs, shock absorbers, on the sway bar and its end links, suspension control arm mounts, and engine and transmission mounts.
“Most people are shocked to find that worn-out bushings can mean a gradual loss of braking and cornering performance, poor steering control under acceleration, and a loss of some shock absorbing action,” Snyder says. “And they fail to appreciate how fast stock bushings can wear out. That’s because original equipment bushings are made of rubber, which is highly susceptible to oil degradation, chemicals, UV rays, salt, and dry rot.
“The ideal replacement bushing is one made from polyurethane. Bushings made from this material will last longer and perform better, and that means your truck will ride and handle better longer.”
The bumpstop controls or limits upward suspension travel before it encounters the frame. Bumpstops can be found on control arms, leaf springs, and traction bars. Again, replacing the stock rubber bumpstop with a polyurethane bumpstop will deliver an improvement in longevity and performance.
Logging In: Once the truck has been returned to “spec” (meaning it now should ride and handle just as it did when it was new), you can evaluate the overall performance of the suspension in regard to accessories or modifications.
“Let’s say you want to replace the wheels and tires, which is one of the most common upgrades on 4x4s,” Snyder says. “Manufacturers have a broad range of tires–offroad, mud and snow, slick-rock situations, you name it. For best results, you need to match the tires and wheels as closely as possible to the way the truck is used.
“The same holds true for shock absorbers. Shocks really are the personality of the suspension, and like the tires and wheels, should match the way the vehicle is used.”
How do you ensure the proper match?
“Many hunters who are serious about their sport maintain a logbook of all their time in the field,” Snyder says. “Well, you can do the same thing to document the function of your vehicle. If you record the hours you spend behind the wheel, you’ll get a better idea of how the vehicle is really used. You also can make brief notes about the pluses and minuses of the suspension you’re currently riding on–things like when it works best and when it doesn’t.”
The logbook will be an accurate record of the vehicle’s real use. It will tell you where, when, and how the truck is used.(See appendix for a sample logbook.)
With logbook in hand, you can talk knowledgeably about the specific use of the vehicle, which helps suspension experts select the correct accessories. In towing applications, for example, the biggest consideration is stability and load-carrying capacity. The components that Trailmaster would recommend for a truck used in this manner are different from what the company would suggest for a slick-rock offroad application. Likewise, a purpose-built hunting and fishing vehicle that will spend most of the time offroad requires a different setup from a pickup or sport utility that is used by multiple family members for work and sport.
Keep the log in the glove compartment or console where it’s handy. And clip a pen to the front cover, so you’ll use it.
Part 2, The Soft Machine: Is the truck of today too soft? Many hunters and fishermen think so. Let’s look at the situation a friend of mine encountered with his late-model Suburban. Doug is an avid waterfowler, big-game hunter, and fisherman who tends to push his truck to the limit. He’s been bogged down in a South Dakota cornfield while goose hunting, buried in a Nebraska mudhole while deer hunting, and high-centered on a remote Missouri trail while trout fishing. Though most of his towing is done with a small boat, he occasionally tows bigger loads. He is also a gear freak of the first order–which means he tends to overload the truck with all manner of hunting and fishing equipment.
“My frustration is that I picked a 3/4-ton Suburban so I would have extra load-carrying capability,” Doug told me. “But the rear of the truck sags noticeably when it’s fully loaded. And under heavy braking, the nose really dives. What’s going on?”
Welcome to the world of the modern truck. There was a time (back when television cowboys Roy Rogers, Gene Autry, and Hopalong Cassidy ruled the range) when the sport utility was viewed primarily as a work vehicle. It had a Spartan interior, three-speed transmission, and stiff leaf springs fore and aft designed to handle massive loads. The ride wasn’t pretty, but that was the nature of the beast.
These days we ask SUVs and pickups to do much more. The new breed of SUV/pickup owner expects passenger car comforts–that’s why SUVs come with plush interiors, comfy seats, and a ride like grandfather’s Fleetwood. Fine. But that trend leaves hunters and fishermen who drive offroad or tow heavy loads stuck in the middle. By “softening” the modern truck suspension to meet the requirements of new owners, manufacturers have compromised load-carrying capability for those of us who really need it.
Given the kind of performance Doug required of his Suburban, I recommended a suspension upgrade. First, he replaced the original equipment shocks with premium shocks, which utilized a sophisticated design that improved the shock’s ability to respond quickly and efficiently to widely differing driving conditions.
“Though shocks are often considered solely in the context of ride quality, they have an equally important role in traction and steering control,” says Snyder of Trailmaster. “By helping to maintain proper tire-to-road contact, a shock helps improve traction, steering response, and braking effectiveness.”
We opted for a quality shock to get that performance and to ensure it would mate well with the second part of the installation–auxiliary air springs.
Air springs are primarily load-leveling tools. This is a key role; a vehicle that is not level will not handle properly. By restoring the vehicle to level ride height, air springs also help ensure that the stock steel springs and the shocks work in optimum conditions.
Air springs, available for leaf- and coil-spring applications, use compressed air to inflate and deflate an air bladder to achieve the desired ride height. The controls are mounted in the cab for easy operation.
On the coil-spring application, a polyurethane cylinder is inserted into the spring and a feeder hose for the air is inserted into the top of the bladder. The springs can deliver 1,000 pounds of leveling capacity per pair.
There are two types of leaf-spring applications–sleeve and bellows, each of which is constructed of fabric-reinforced rubber, much like a tire. The sleeve type delivers up to 2,500 pounds of leveling capacity per pair. The bellows is a heavy-duty unit: It can handle up to 5,000 pounds of leveling capacity per pair. (Air springs are not available for trucks equipped with torsion bars.) Never exceed the manufacturer’s Gross Vehicle Weight Rating (GVWR), which can be found in the owner’s manual. GVWR is the combined weight of the vehicle, passengers, and payload (your gear).
“Air springs help deliver the versatility that today’s truck owner demands. The system gives you the capability to fine-tune the ride under widely differing road and load characteristics, and it also makes for a more comfortable ride and better handling,” says Snyder.
Doug has had the system in his Suburban for a year now, and he remains impressed with how his truck handles, both on and off road, loaded and unloaded. “What a difference,” he said. “Sway and nose dive? Gone. They simply disappeared once I had this system in place. Last summer I drove to Canada to fish with four buddies. We filled the back of the Suburban to the headliner with camping and fishing gear. We even maxed out the roof rack. But the truck handled fine during the whole trip.
“With this setup, I feel like I can have my cake and eat it, too.” And that says it all.
Balancing Act: When considering any kind of shock and auxiliary air-spring upgrade, keep in mind the concept of balance. You want to match the springs and shocks as closely as possible. Matching light-rate springs with heavy-control shocks is a recipe for disaster.
The tough part is that what works for one type of truck (and owner) may not work for another. The way a truck is used, the speeds at which it is operated, the loads it is required to carry, and the surfaces over which it is typically driven are critical factors in determining balance. That’s why you should consult with a reputable suspension outfit before you buy any aftermarket components.
Installation Notes: If you do a lot of heavy-duty offroading, make sure you tell the auxiliary air-spring installer. He needs to know so he can route and tuck away the air lines to keep them away from offroad obstacles. For our Suburban, the installer ran the lines next to the vehicle’s hydraulic lines and then tied off the lines every 10 inches to guard against sag. Also make sure that the air lines don’t touch hot exhaust parts. Finally, place the fuse for the air compressor in an accessible spot. If you are offroad and damage a line or bag, you’ll need to pop the fuse to shut off the compressor. If you don’t, the air compressor will continue to pump–and that will eventually drain the vehicle battery.
Part 3, Uplifting Story: Jim and I ran into the 7-11 outside El Dorado, Kansas, for hot coffee and a box of powdered sugar doughnuts–the essentials required to ward off the chill of a late-autumn pheasant hunt. Outside a kid in camo was standing in front of his new 4×4, which drew admiring stares because of its monster truck lift.
“Nice job,” I said. “But how does this thing perform offroad? It seems a little top heavy to me.”
“Oh, I had to disconnect the 4-wheel drive when I did the lift,” he said. “Major bummer, but it was the only way I could get the lift I wanted.”
“In that case, why didn’t you just buy a 2-wheel drive?”
He looked at me as if I had just fallen off the turnip truck. “Are you kidding? Around here, man, 4-wheel rules.”
Although the average outdoorsman isn’t searching for a monster lift look, he no doubt realizes the value of a modest lift that can deliver precious inches in ground clearance. It can also allow the installation of beefier tires, for show or go. But be careful. In too many cases a guy can act like our Kansas kid and end up with a 4×4 that can’t do the job.
Here’s how: Let’s say you opt for a 4-inch lift kit and then throw on a set of 35×12.50R16.5 mud-terrain tires with larger diameter wheels. In this case, you’re asking for trouble because you–like Junior–didn’t bother to match the new components to the limitations of the truck’s suspension.
“Think about it,” says Snyder of Trailmaster. “If the truck came with original equipment LT235/75R15 tires, the outside diameter of those tires is 29.1 inches. The wheel is 15 inches in diameter. The truck manufacturer took those dimensions into account when the truck was built. All of the suspension components are designed to work in concert with those numbers, including how the tires fit in the wheel wells.
“But now you have 35-inch mudders, which have an outside diameter of 35 inches. The new wheels have a diameter of 16.5 inches. Do the math. A 4-inch lift kit will leave you 2 inches short in the wheel wells–and I’m only talking about the tires.
“What about the brake lines, hoses, and wiring? In addition, you’ve also moved the axle farther from the frame. Don’t tell me that won’t affect performance. What about control arms, shocks, and all of the rest?
“My point is that you need to ask a lot of questions before you start. The good news is that the aftermarket has come up with plenty of answers.”
Bottom line: You want a lift kit that contains all the right pieces, and each part should be specifically designed to fit your vehicle. For example, Trailmaster has 50 suspension kits (in 2-, 4-, and 6-inch lift configurations) designed to match a wide variety of domestic makes, including Jeep, Chevy, Ford, and Dodge.
“Our 4-inch lift kit for the Chevy Silverado and GMC Sierra 1/2-ton 4×4 pickups provides 4 inches of mechanical lift by lowering all factory suspension mounting points,” Snyder continues. “Included in this system are replacement crossmembers, which connect driver and passenger side lower control arm brackets, replacement tubular-style upper control arms with greasable polyurethane bushings, and premium ball joints with grease fittings.”
The kits also include new center drag link and tie-rod extensions, differential drop brackets, a two-piece front skid pad assembly, heat-treated hardened and plated upper ball joint spacers, torsion bar drop brackets, and all the necessary hardware needed for installation. That’s what I mean by complete.
Shocking Advice: One of the most common upgrades is shock absorbers. Here are some tips to follow when changing them.
* Get rid of the stock shock. If you bought the vehicle used, the shocks are shot. Changing the shocks is especially important if you invest in tires and wheels–which aren’t cheap. If you don’t upgrade the shocks as well, the tires may wear out prematurely.
* A shock absorber expert once told me, “Valving is what sets a good shock apart from a poor shock. With proper valving, the wheel doesn’t hop and bounce. More durable shocks also feature a larger shaft, with a larger oil reservoir. This helps prevent overheating, a typical problem with cheap shocks. When a shock absorber overheats, the oil foams, which prevents the unit from being able to rebound properly. The wheels will start bouncing all over the place, and you won’t know what’s going on. The next morning you take it to the shop, but they can’t find anything wrong. That’s because the shocks have cooled off and the foaming has ceased.”