Two-Wheel Drive Trucks - Building Better Two-BysPosted in How To on May 1, 2000 Comment (0)
We can hear it now: Cant you guys even read the name of your magazine? Why did you put two-wheel drives bla bla bla? Sure, we can read. All trucks have four tires and can be driven off-road, right?
Lets face it, some of the fastest, best handling off-road trucks are two-wheel drives. These are the desert race trucks of SCORE and the closed-course trucks of CORR. Most of us cant afford these $100,000-plus vehicles that belong in Fortune and other youll-never-own-this magazines. Thats not what youll find here. What you will find is the different kinds of lifts for two-bys and the design and function of each.
While a two-by will never compete with the traction that a four-wheel drive offers, it can have its advantages. Less drivetrain maintenance, cheaper initial cost, and cheaper insurance, plus the fact that many 4x4s are destined to never have the transfer case engaged and serve only as street transportation, are all valid reasons for owning a two-by. Two-bys also make great tough truck competitorswhy destroy a perfectly good 4x4?
Now, you can ruin your two-by and turn it into a belly dragging barrio cruiser that gets hung up on speed bumps with groceries in the bed, or you can do the right thing and try to get a little performance and lift out of the suspension. We would rather see the lifted versions. Not all 4x4s hit the dirt, and the same can be said of lifted two-bys. Many are built just for the look of a 4x4. And while we dont condone this activity, its still better than owning a lowered truck or souped-up import car.
IFS Sucks, Normally
Independent front suspension isnt all that bad. However, adding a drive axle to it just increases the likelihood of breaking or bending something. Many manufacturers even brag about how their 4x4s ride like cars (certainly not something we look for in a 4x4), suggesting that the strength of the driveline and suspension is questionable for off-road duty. Lift kits for these 4x4s are usually a sea of brackets and bolts that resembles a jigsaw puzzle or a colorfully painted scrap yard.
Since two-wheel drives dont have transfer cases, front differentials, or front driveshafts to lower or worry about, the lift kits tend to be less bracket-happy. Many of the kits add wheel travel to the front suspension. This is something the 4x4 IFS lift manufacturers cant readily do without replacing or modifying the CV joints in the halfshafts (not cheap).
Have Speed, Wheel Travel
If youve decided to actually use your two-by in the dirt, youll want to look for a kit that offers additional wheel travel. Without a low-range and a front drive axle youre going to have to hit obstacles at speed. The extra wheel travel will absorb the bumps and keep the truck in one piece and on the trail. Of course, you wont be traversing the same bolder-strewn trails as a rock buggy, but you can still have some off-road fun and then drive your truck back to civilization and work the next day.
Often the added wheel travel and speed produces heat in the shocks. Heat causes the shocks to fade and the vehicle to become bouncy and difficult to control. Duals, triples, and more are used to distribute the load and dissipate heat. A shock with a single-tube design will dissipate heat better than other types. Off-road race teams have been using large-diameter reservoir shocks for several years. These shocks are designed and progressively valved for high-speed abuse and wont fade under most circumstances. Only recently has the technology become more affordable from companies like King Off-Road Racing Shocks. These large-diameter shocks generally come in build-your-own-mount lengths, so shock hoops will need to be built to accommodate them. They can also be converted to coilovers if desired. Many manufacturers and custom fabricators offer bolt-on hoops to allow the use of multiple conventional shocks. Check out the two-wheel-drive buyers guide in this issue for products that might fit your truck.
Two-wheel-drive A-arm suspensions are all very similar. The difference lies in how they are sprung. Torsion bars or coils can be used to provide rebound to the suspension. All Chevy and Dodge two-bys use coils. The 97-present Ford F-150s, Toyota Tacomas and Tundras, and 98-present Rangers also use coils and A-arms. Torsion bars can be found on 79-95 Toyota pickups and all Nissans, as well as other imports.
The popularity and total number manufactured of each truck is considered before a company produces a lift for a vehicle. Often the popularity of past models is enough to spark interest in lift production. In this aspect the two-wheel lift market is no different than the 4x4 market. Some trucks have vast options when it comes to lift shopping, while others may be left for the lowered truck crowd.
Basic: The basic suspension lift for a coil-sprung A-arm truck is a set of lifted coils (up to 3 inches) and ball-joint spacers to correct the camber of the front tires. This type of kit generally doesnt offer an increase in wheel travel or performance. The typical street truck is built in this fashion. The aftermarket coils and shocks provide a firmer ride than factory. This is perhaps the cheapest way to safely lift your coil-sprung two-by.
Basic II: A spindle (knuckle) lift is also very low in the hierarchy of lift systems. Most spindle lifts are 3 inches. A replacement knuckle is used to provide lift. Much like a lowering knuckle, a lifted one has a relocated wheel-bearing spindle to provide the height change. Lift spindles do not provide any performance gains and give the same ride as stock. They merely lift the vehicle to provide room for larger tires. This makes them very popular with the street crowd. The stock shocks are often retained but they should be replaced with firmer units to control the larger tires. Spindle lifts are more expensive than the coil swap and ball-joint spacer kits.
Upper Arms: Next in line are a coil swap and new upper control arms. Longer shocks are usually required for this system. The new upper arms provide proper caster and in most cases an additional 1 or 2 inches of wheel travel. Some trucks will require bumpstop relocation. This type of kit is perhaps the least you should consider if you plan to use your truck in the dirt. Most of these kits provide 2 ½ to 3 inches of lift. Lift spindles can be used in conjunction with the arms and coils to provide additional lift.
Full-Tilt: At the top of the bolt-on food chain are the upper and lower replacement arm and coil kits. These provide wheel travel up to 12 inches for severe use. The arms increase the track width of the front end and may require the use of fiberglass fenders or fender trimming to provide room for the tires at full stuff. Bolt-on engine-cage shock-hoops are available and afford mounting for dual shocks and additional damping. Lift spindles can be used with these kits to provide even more clearance.
Cheap: Vehicles equipped with torsion bar A-arm suspension can usually be lifted without purchasing parts. Cranking the torsion bars can provide a small lift. By doing this you are preloading the bars and effectively increasing the spring rate. This will firm up the ride and you will lose downtravel but gain uptravel. This can also cause the ride to be rough. If the bars are tightened too much they will eventually sag and need to be replaced. Some vehicles will not align with the torsions overly tightened.
Cheap II: The next cheapest step is to replace the torsions with a set that has a higher spring rate. The benefits and drawbacks are the same as cranking the stock torsions. However, the aftermarket pieces have a bigger diameter and can handle more abuse and lift without sagging.
Army: Upper control arm kits are available for the torsion bar suspensions much like the coil A-arm trucks. The benefits and drawbacks are the same as the coil trucks. If you use the truck off-road it is a good idea to install heavier torsions. For street use, the stock pieces will work fine as long as the bumpstops are positioned in the proper locations. No spindles are available for these trucks.
Big Inch: Few long-travel torsion bar suspensions are available. The truck that enjoys the most number of kits is the 84-95 Toyota. New upper and lower arms along with a sturdier strut frame provide up to 12 inches of travel. Most multiple shock mounts for this truck are weld-on pieces.
Ford had no idea of the potential of its I-beam suspension when it was first introduced in 1966. Right off the lot the I-beam trucks didnt have much more travel than the A-arm trucks. However, the I-beam suspension is easier and cheaper to lift. Soft coil springs and the lever action provided by the beam made for a great off-road design. From the early 80s to the mid 90s, I-beam suspensions could be found on just about every successful race truck. Even today, most serious prerunners and play trucks use some form of I-beam suspension for its durability, simplicity, and long wheel travel potential. I-beams do have their Achilles heel, though. With the long travel comes excessive amounts of camber and caster change throughout the suspension cycle. This can cause erratic handling if the steering linkages are not considered.
From 1966 to 1979 Ford used the longest equal-length I-beams of any year on its two-wheel-drive F-series trucks. These arms stretched all the way to the opposite framerails. The longer the beams are, the more travel that can be obtained. From 1980 to 1996 Ford used unequal-length I-beams, the driver side being longer. This allows the driver side to provide more travel than the passenger side with less camber change. Needless to say, this can cause some unique handling situations. The 99-present Super Duty trucks also use unequal length I-beams.
Rangers (and Bronco IIs) from 1983 to 1997 also enjoy the long travel benefits of I-beam suspension. Much like the 80-96 fullsizes, the Rangers have a longer beam on the driver side. Rangers are one of the most popular two-wheel-drive trucks to lift, and understandably so. You could get one with a speedy 4.0 V-6 and the same 8.8 rear axle (narrowed) that came in the fullsizes. Match this with the long wheel travel and the relatively low price and high availability of these trucks and youve got yourself a runner. Explorers have a similar design but the parts are not interchangeable.
Stuff It In: The simplest method used to lift coil-sprung I-beam suspensions is installing a larger coil. This can provide up to 2 inches of lift. Some vehicles will not align when set up this way. Adjustable camber bushings can be used to correct alignment in some cases. Coils that provide more than 2 inches of lift can be used if alignment is not a concern as in tough-truck racing.
Stack-it Bracket: Complete bracket lift kits can be used to lift an I-beam truck. These kits are the same kits used for the 4x4 versions of the trucks (83-97 Rangers or 80-96 fullsizes). The factory I-beams and radius arms are retained but lowered with bolt-on brackets. These lifts dont really enhance performance so they should be left for the street crowd. They are available in lifts up to 8 inches. Installation can be a pain since it requires the removal of several large frame rivets, which are replaced with bolts.
Stack-it Bracket Plus: These kits are often the same ones as the bracket kits except that they come with longer replacement radius arms. Thicker brackets are sometimes used as well. This type of kit is the least you should consider if you are planning to hit the dirt. The longer radius arms increase wheel travel and help keep caster change to a minimum during suspension cycling. They also help triangulate and strengthen the suspension assembly. The kits are often referred to as second stage, or Class II, indicating some superiority. They provide 2-3 inches of wheel travel over stock.
Get Bent: Bending or aligning the I-beams for larger coils is a very common practice. Usually 4-inch coils are used but often you can fit 6-inch units, depending on the vehicle. Bending the beams should be done by someone who has experience. An incorrect procedure can cause the beams to fail or make the vehicle impossible to align. One drawback of bending the beams is that the track width of the front end becomes narrower than stock. The radius arms need to be modified for proper caster or, better yet, replaced with longer pieces. This method of lifting affords more wheel travel and strength than the bracket kits. Many manufacturers offer bent beams and modified radius arms in a kit that you supply cores for. These kits can provide up to 15 inches of travel if used in conjunction with bolt-on or custom shock towers.
New Beams: Climbing up the I-beam suspension ladder brings us to production-built beams. Although theyre not one-off creations, theyre still not cheap. The beams are usually made from chrome-moly tubing or plate. Their design allows them to accommodate up to an 8-inch lift coil. Longer radius arms are required for these beams but all the components are bolt-on. Huge amounts of travel up to and beyond 15 inches is possible depending on the shock towers. The static track width that these beams provide is usually a few inches more than stock. When the suspension compresses, the track width will be several inches wider than stock. Fiberglass or trimmed fenders may be necessary to provide full use of the travel.
As with any hobby or sport, sometimes you just cant buy exactly what you want because it isnt available. The same is true when building two-wheel-drive suspensions. For extreme-duty, no-holds-barred abuse, youll need to talk to a custom fabricator. Tell him what you want, and get enrolled in his direct deposit banking. Fabrication work isnt cheap but the outcome is usually just what you wanted or more than you expected. Long-travel A-arms, extralong I-beams, coilover shocks, chrome-moly tubing and gussets, and more are not out of the realm of possibility. If youre building a truck like this, seriously consider a full rollcage from bumper to bumper. Not only will you thank us if you ever need it, but a well-built cage will make the frame more rigid and less prone to bending and breaking.