I'm going to make a statement that will not be popular with the fine people who make trucks and sport utility vehicles: There is not one vehicle offered to the public that comes with a "good" suspension!

It's not that the offerings are poorly designed, or dangerous. Quite the opposite, modern vehicles are strong, well-built and safe. But the suspension systems, in general, leave a lot to be desired.

Here's something to mull over: The "average" shock absorber that comes delivered on your new 4x4 costs the manufacturer under two bucks each! And that's why you get, at best, average performance.

Not only that, spring rates, suspension lever ratios and leverage arms are all designed to yield a near car-like ride and maybe, if you're lucky, absorb a six inch bump reasonably well. The suspension must be a compromise, since the manufacturer doesn't know just how you're going to use your rig.

They do know, however, that most 4x4s spend most of their time on the road, hauling kids groceries and people to and from work. For those of us who use our 4x4s in genuine off-road situations, the shortcomings of a stock vehicle become immediately apparent the first time we wander down a rutted dirt road, loaded with camping gear.

Most of us solve the problems by simply bolting on a good set of after market shocks. The difference between stock shocks and good shocks is amazing. One example: my neighbor, Art, bought a new Ford Explorer and loved it dearly.

When we decided to take a 2000 mile trail ride to the end of Baja and back, I insisted that we install some quality shocks before we attempted the trip. His response was: "Why bother? These seem to work just fine." His off-roading consisted of an occasional trip to ski country on slippery snow-covered roads.

I ordered four low-priced aftermarket shocks, and put a Saturday morning aside. First, I located a nasty, rutted road close to where we lived, and had him drive the Explorer down the road a bit faster than he was used to. The Ford protested mightily, and we experienced harsh bottoming and lots of impact.

Back to the garage, and the four new shocks replaced the stock gas shocks. We went back to the dirt road and Art drove through the same bumps again. This time the response was: "Wow! I can't believe the difference!" After a few passes to build up courage, Art was able to drive through the same bumpy road at 35 miles per hour, with confidence, instead of the miserable 20 mph he experienced with the stock shocks.

Needless to say, during our Baja trip, the shocks paid for themselves a thousand times over.

If you spend most of your time on the road, chances are you can simply bolt on just about any name brand after market shock and notice an improvement. At this point, you can shop by price alone.

Conversely, I know some people who rarely drive off road, and are running ultra-long travel suspension, mostly for the looks and for tire clearance. Common sense does not rule here.

Do you haul heavy loads off road? Or perhaps tow a boat out to a remote fishing spot over bad roads? Then shocks alone will not cut it; you'll have to consider heavier - or helper - springs.

Serious off-roaders will want a complete system, rather than bolting pieces on at random More on that later.

Off-road racers will want the maximum travel allowable according to the rules in their class. How much is a lot? Well, some of the exotic Trophy Trucks are running 34 to 36 inches at the rear and 28 to 30 inches up front. With this kind of setup, you
don't even lift the throttle for an 18 inch bump.

There are times, however, where running less travel is a real advantage when racing off-road. One year, the majority of the Baja 500 course was laid out over tight, twisty fire-roads. Don Adams, the crafty Class 3 veteran, shortened up the travel on his Jeep to 8 inches, front and rear. I was running about 18 inches in the rear and 15 up front in the Off-Road Project Big Oly Bronco.

Don ate the class alive! He was able to corner flat and easy, with no body roll on the slippery roads, while all of us long-travel types fought the steering wheel the whole time. Don won easily by a full hour margin because he was smart.

Racers learn quickly to set the suspension up for the nature of the course. For example, whenever I raced the legendary Mint 400 in Nevada, I knew that the course was riddling with sharp, tire-cutting rocks. So I set the first half of the suspension travel up very soft to reduce the possibly of flats.

At San Felipe in Baja, the course has a lot of deep sandy whoops. For this course, I always ran heavier springs, greater pre-load on the springs, and heavier compression damping. This reduced the tendency of the truck toward bottoming out, and kept me on top of the whoops, rather than riding through them.

SHOCKS: These are oil-filled tubes mounted at each wheel that serve to control the action of the springs. Without shocks, the vehicle would wallow up and down. You can see this in action when you notice an old beater car hopping down the road like a jack rabbit on a pogo stick.

SHOCK DAMPING: The action of the shocks slowing down the motion of the springs is called damping. You'll often see tech articles where the writer calls it dampening. The word dampening means to wet something. The correct word is damping; don't forget it.

REBUILDABLE SHOCKS: Many shocks can be taken apart to allow for changing the fluid, or altering the damping. While more costly than non take-apart shocks, they are definitely the way to go.

COMPRESSION DAMPING: When the shock is squeezed down as it hits a bump, that's called the compression part of the stroke. Compression is the part of the valving in the shock that controls this action.

REBOUND DAMPING: When the shock recoils from a bump (starts stretching out), this is called the rebound stroke. Rebound damping controls this action, and prevents the spring from extending too quickly.

ADIUSTABLE VALVING: If your shock has the capability of changing the compression and/or the rebound damping, you have adjustable valving. The very best shocks have externally adjustable compression and rebound damping. Many other shocks have to be taken apart, and the valving must be altered to change the damping. Some shocks can only have the compression, or the rebound, damping changed. Still others have a single external adjuster that changes both the compression and the rebound at the same time; a concept that defies common sense, in this writer's opinion.

FADE: When shocks get too hot, the damping reduces. This means both the compression and rebound damping decrease. If the fade gets really bad, the shock will act like it's worn out. A well-designed shock will recover its damping when it cools down. How hot can a shock get? When testing, we used a sensitometer to record more than 275 degrees on the shock bodies, certainly enough to burn your fingers, plus.

A shock absorber is, in reality, a heat exchanger. When a spring compresses or rebounds, the job of the shock is to take the energy generated and convert it into heat. The shock must - then get rid of the heat. If it can't transfer the heat to the outside air, shock fluid will get thinner and pass through the valving too quickly to do its job properly. This is fade.

REMOTE RESERVOIRS: This is a separate chamber, usually attached by a high pressure hose, that holds extra shock oil and has a provision for charging the shock with nitrogen or - another inert gas. You can use air to charge a shock, but nitrogen is superior, in that it has no corrosive nature, resists expansion from heat better, and will not attack sealing O-rings. Air has water in it, and the water will contaminate the oil and rust interior parts. Some shocks have the reservoir built into the shock body. I know of several "illegal" shocks built like this, in classes where remote reservoirs are not allowed.

SPRINGS: A spring can take several forms: leaf springs, coils, torsion bars and even air. Yes, air is a spring. Some shocks have a schraeder valve installed, and gas or air can be introduced in the shock, where it becomes a spring. Air is compressible.

COIL-OVER SHOCKS: These are simply shocks that have a spring(s) mounted around the shock body. This makes for a very compact package and also offers the shock body a measure of protection from flying rocks.

SPRING RATE: Rate determines how many pounds of pressure for each inch of travel the spring will yield. Here's a simple way to test your spring rate: Place a bathroom scale on a drill press and then put your spring on the scale. Now press down on the spring by using the press. When the spring moves down one inch, the number on the scales will tell you the rate. If it reads 100 pounds, you have a 100 pound coil spring. For each additional inch the spring moves down, the pressure will go up another hundred pounds. At two inches, it'll read 200 pounds, three inches 300 pounds, and so forth.

MULTI-RATE SPRINGS: While more expensive to build than straight-rate springs, multi-rate springs offer a great deal of versatility. The spring wire is thinner at some points, and thicker at others. The thinner springs are lighter, and the thicker springs are heavier. This means that with a properly designed multi-rate spring, you can have a soft, supple ride on the first part of the travel, then it firms up nicely later in the travel.

SPLIT-RATE COIL SPRINGS: By putting two or more coil springs on a shock body, you can dial in how the shock works. The lighter spring can offer a soft initial stroke, then the spring action will firm up considerable when the light spring is bottoming out and the heaver spring kicks in. Some exotic racing shocks run as
many as three different springs.

PRE-LOAD: This is the amount of tension applied to a spring. If the spring is sitting at full length, it has no pre-load on it. If the spring is compressed two inches at normal ride height, you have two inches of pre-load. Torsion bars can also have the pre-load adjusted by torquing down the lever adjusters on the end of the bars. By altering the pre-load, you can change the ride height of your vehicle.

IMPORTANT NOTE! Changing the preload will not change the spring rate of your spring. If you have a spring with a 300 pound per inch rate and crank the pre-load up to the max, the spring will still yield 300 pounds more resistance for each inch of travel.

SUSPENSION LINKS: Every suspension has pivoting points that allow it to move up and down. The parts between the pivoting points are called links. They can be typical A-arms, arms like the Ford twin-traction beams, exotic four links, radius arms, or even swing arms, much like a motorcycle rear suspension is built.

SUSPENSION LEVER RATIOS: This is an area that's surrounded with confusion, but we'll give you the basic theory behind it. It's best understood by studying a typical dirt bike rear end. On a dirt bike, you have a swing arm with a pivoting point on the front and a wheel at the other end.

Let's say you have pair of shocks mounted straight up and down over the rear wheel, and these shocks have six inches of travel. So when the wheel moves up one inch, the shocks also travel one inch. This yields a 1:1 suspension lever ratio. Now, if you took those same shocks and move them half way up the swing arm (by fabricating new mounting brackets), for every inch the rear wheel moved up, the shocks would only move a half inch. This would give you a 2:1 suspension lever ratio.

Naturally, when you start putting the shock at any sort of an angle, a great deal of math is required to arrive at the true suspension lever ratio.

There are a lot of old wives' tales alive and well regarding suspension. Let's explore some of them:

Shorten your coil spring to reduce the spring rate. WRONG! The way you calculate the spring rate is by measuring the thickness of the coils, the diameter of the coils, the number of coils, etc. If you cut one coil out of a spring with ten coils, you will INCREASE the spring rate by ten percent. Carrying this further, if you had a 100 pound rate spring with ten coils and cut the spring in half, you would end up with a pair of 200 pound-per inch coil springs.
For maximum bump handling, run as many shocks per wheel as you can. WRONG! I've seen guys running four shocks per wheel on a truck, and there's so much compression damping that the wheels will only use half of their potential travel.
Gas shocks are best. WRONG! It's this writers opinion that shocks with internal gas are harsh on the initial part of the stroke, due mostly to overly high pre-load from the pressure of the gas itself. Also, as the shock gets hotter, the pressure of the gas rises, which further increases the internal spring rate.
Bigger shocks are better. TRUE, WITH A QUALIFIER! The bigger and beefier a shock is, the more it'll resist bending and breaking. But a big shock with small oil capacity, or overly restrictive valving, will run hotter and fade more than a properly designed smaller shock. Look for large oil capacity, high rate of shock oil flow and good heat transfer characteristics of the shock body.
Chromed shocks are cool. WRONG! Chrome plating is one of the worst things you can do to a shock body. The next worst thing is to paint it. Both of these things reduce the ability of the shock body to transfer the heat to the outside air, and cool the oil down. Yes, we know that all shocks are sold with paint or some sort of coating, but this is mostly done to make them look good for sales reasons, and to keep the bodies from rusting. Take a look at the better machines the next time you go to the races. You won't find painted shock bodies. Anodizing makes a good heat-efficient protective coating. I use Rancho RS5000s on my truck and I remove the paint from them and give them a light coating of linseed oil about once a month, or after washing the vehicle.
Shock boots increase the life of your shocks. WRONG! I personally never use shock boots. Why? Because the boots will trap water and dust inside, and create a rust trap. Also, if you bottom the shocks harshly on occasion, bits of the shock boot can be driven, into the top wiper seal, creating a quick leak in the seal. With the boots removed, I can wipe the shock shafts clean easily, and keep an eye on the shafts for corrosion and damage. Boots look great, but don't make much sense.
Use Heim joints on shocks. TRUE! These joints allow the shock to move around freely as they travel up and down. Most shocks have a bolt/bushing attachment on one end and often a threaded rod on the other end. Usually, only more expensive racing-type shocks offer Heim joints.
Re-arched springs work. FORGET IT! While it's cheap to re-arch a set of leaf springs to gain some lift, inevitably they'll sack out. You're far better off to purchase a new set of leafs with the desired arch.
Leaf Springs are stronger than coil springs. TRUE! A coil spring is a very compact design that doesn't take up a lot of room, but it's really nothing more than a torsion bar that's all wound up. If you took a regular coil spring and managed to stretch it out straight, you'd be amazed at how long it would be. When the coil is compressed, the spring twists, and a great deal of deflection occurs. However, a long leaf spring deflects very little at any one point. The metal is less stressed, as a rule. The trade-off is, of course, that the leaf spring is much heavier and takes up a great deal of room. When I ran raced trucks with coil springs, I would get about four races out of the coils before they started to get tired and had to be replaced. On the other hand, when I used a quarter elliptical leaf spring setup on my truck, and it went three years with virtually no maintenance required.
Torsion bars break all the time. NOT TRUE! The only time a torsion bar breaks is when very long wheel travel is added to a system and the t-bars become over-stressed. In general, the longer a torsion bar, the longer it will live. A short t-bar with a heavy load is a candidate for breakage, especially if it's heavily pre-loaded. One side note: It's a good idea to protect a torsion bar from flying rocks, as a nick in the surface can lead to failure. A simple protective device is to slit a section of old garden hose and ziptie it in place over the bars.
Use heavy compression damping and light springs. NOT TRUE! You are better off running the heaviest springs that will do the job, combined with just enough damping to get the job done. In general, the higher your compression damping, the hotter the shock will run.
Add-a-leafs work. TRUE! Adding the right combination of leafs to a spring package is one of the cheapest and most effective methods known to increase your spring rate and ride height.
Twin tube shocks are the best. NOT TRUE! A twin tube shock is nothing more than an outer body with another tube inside that houses the shock piston and the valving. Oil is contained in both chambers. Builders of twin-tube shocks claim that their design is superior, in that any damage to the outer tube will not affect the inner tube. This much of their claim is correct, but once again, we have the trade-off to consider. The outer chamber of oil will act as a barrier to efficient heat transfer. All of the heat is generated in that center tubed portion of the shock, and that second layer of oil traps the heat. Think about this: no off-road racing shock is of a twin-tube design. Period. Some of them even have external by-pass attached to the outside of the single-tubed shock body. However, these are expensive items, and it's not uncommon for shocks like this to retail for a thousand bucks each!
All after market shocks are pretty much the same. WRONG! There's a huge difference from brand to brand, and within the models in any product line. Consider the popular Ranchos. Their basic RS-5000 shock is a simple, solid, good working shock that cannot be taken apart, but offers long life. Their top-of-the-line Lightning Rods are completely rebuildable, have external by-pass valving and damping adjustments, and are equipped with a remote reservoir with capabilities for adjusting the gas pressure. Right in the middle of their line, is the 7200 series, which are similar to the RS 5000s, but offer rebuilding and optional remote reservoirs.
Remote reservoirs are for cooling the shock down. NOT TRUE! While having extra oil in the shock will certainly let the shock run a bit cooler, the primary purpose of the reservoir is to allow the shock body to be completely full of oil, thus reducing aeration of the oil. The reservoir is necessary to allow for shaft displacement. As the shock compresses, the shaft takes up more room inside the shock body and the oil has to go somewhere, so it's forced to the reservoir.
Shock oils are pretty much the same. NOT TRUE! Very few shocks come with what I consider a quality fluid. The first time (many years ago) I raced a Class 7 4x4 Isuzu, we used Rancho 7200 series take-apart shocks. After a few hours of hard racing, I experienced shock fade. When I took the shocks apart after the race and put premium Bel-Ray shock fluid in, the shocks proved fade-free in the next race. By the way, serious off-road racers change the shock oil after each race!

BASIC STOCK. If you use your truck or SUV mostly on the road, with only light duty off-roading, chances are you'll be happy by simply installing decent low-cost after market shocks. While you're at it, replace the shock bolts with Grade 8 bolts, for maximum life and safety. Shock bolts take a heck of a lot abuse.

TOWING/HEAVY LOADS. If you drag a boat or camper, have a camper shell, or pack your bed with gear, you'll want good after market shocks and an add-a-leaf spring for the rear. You might even consider a slightly heavier spring or torsion bar up front to match the rear.

BIG TIRES. If you install big tires on your rig, the stock shocks will be horribly over-stressed. Again, installing good shocks is a must, and increased spring rates at both ends should be considered. Think about this: a 35 inch BFG tire weighs in about 20 pounds more than the stock small rubber that comes on most trucks. You must compensate for this increase in unsprung weight.

MEDIUM DUTY OFF-ROADING. I would recommend a suspension lift kit (not a body lift kit), with longer after market shocks to match the increased travel. A good complete kit will come with higher rate springs.

HEAVY DUTY OFF-ROADING. All of the above, plus replacement of the stock bushings with high quality urethane bushings, longer radius arms (where applicable), strengthened arms and links, beefed up pitman arms and steering parts, and of course, a multi-shock arrangement over each wheel. Go for three shocks per wheel at the rear, and at least two per wheel up front.

SERIOUS OFF-ROADING/PRE-RUNNING. All of the above, plus the use of rebuildable shocks, remote reservoirs, limiting straps on the travel and beefed up suspension links. Naturally, the shocks should be dialed in to match the springs and the kind of terrain you'll be running in.

OFF-ROAD RACING. The sky is the limit, as is the thickness of your wallet. Read the rule books and if there are any limits to travel, work right up to the maximum. For example, let's say your class must have no more than 15 inches up front, but travel at the rear is open. Don't go nuts at the rear, as the situation would create an imbalance. Run about 18 to 20 inches in the back, max.


Suspension lever ratio is easy to understand. In this illustration, the shock on the bike will move one inch for every inch the wheel moves, giving you a SLR of one-to-one.	Here we have the shock on the bike moved halfway up the swingarm. With this setup, the shock will only move ½ inch for every inch of wheel travel, giving you a 2:1 SLR. When you have an angled shock, the math gets a lot more complicated.