Editor’s Update June 2022: As part of Off Road Xtreme’s super popular PreRunner Building article series, we wanted to link the collection here for your convenience. You can find all the articles linked as part of this update. PreRunner Building 101: The Basics, PreRunner Building 102: Beginner Vs. Advanced, PreRunner Building 103: Testing And Tuning, and PreRunner Building 104: What Is An Ultimate PreRunner?
Prerunner trucks are extremely popular, even in places where no desert exists. Building one is a process. In case you missed it, the basics were covered in our previous article. We covered the basics of shocks and springs, now we can talk about suspension systems.
In this piece, we’ll go over what separates the beginner prerunner and the advanced prerunner, and what you should prepare for if you ever want to step up to the next level.
Suspension Is Foremost
Many suspension kit suppliers specialize in certain makes. If you like Fords, you can purchase bolt-on kits from shops like Desolate Motorsports or Solo Motorsports that greatly enhance your vehicle’s abilities. Fans of Toyotas have specialists like Total Chaos Fabrication; other manufacturers, like Baja Kits, cover all makes.
These companies all make complete suspension kits that greatly enhance the strength and performance of your vehicle. In order to get more wheel travel, suspension components are made longer or wider. When using factory pivot points, this makes your track width wider. Adding wider fiberglass fenders will cover those tires that are now sticking out, and provide substantially more clearance to boot.
The Snowball Picks Up Speed
At this point, you have a comfortable and capable vehicle that still has much of the factory architecture intact, but what if you want more? The faster you want to go, the more your vehicle will need to be modified. This is the point that most will bring in a professional fabricator to assist them.
Once you make the front suspension wider, you will have to modify the steering components to match. Is your steering box or rack up to the task? How about the pump? And you might need to beef things up with custom drag links made from heavy-duty components. Anytime you make one component stronger, other components in the system need to be built up to match their new counterparts. This is because whenever you make one part stronger, the loads travel to the next weakest point.
Once you modify the track width or the suspension travel, you start down the road of heavy modifications to your vehicle. Most longer A-arm kits will also move the wheel position forward to allow more tire clearance at the firewall. Pushing the wheels forward will intrude on your front bumper. You might get away with trimming it but in most cases, a modified bumper can be purchased or fabricated to replace it. You will need a heavy-duty bumper up front anyways to protect your headlights and radiator, as well as a place to mount additional lighting.
When you start going fast in the dirt, you will quickly out-drive the factory headlights. What does that mean? As you drive, your brain is constantly analyzing the information your eyes are sending. Since the terrain is constantly changing, your brain gets very active.
The less light you have available, the longer it takes for your brain to distinguish features and make a determination on what it is that you are seeing. The better the quality of light, the quicker your brain can process information. It isn’t always a case that you can’t see; sometimes your brain just doesn’t have enough information. If you are driving fast, quality lighting is important.
Adding lights, a radio, and other electronic accessories will require running additional wiring, switches, and specialized electrical components. You can find high-quality parts for those purposes, but there is an underlying issue that many people overlook. Truck manufacturers have done everything possible to save weight. As part of this, one thing they do is reduce the wiring’s gauge, or thickness. On a purpose-built race car, the wiring is contained tightly in a loom and secured to the chassis; factory wiring just isn’t designed for the extreme vibrations and G-forces you will be experiencing.
The thin factory wiring can flex to the point where it breaks inside the casing. There will be no indication of damage on the outside of the wire, but you will have a broken connection inside. Ask a knowledgeable mechanic. This condition has emerged in the last decade or so as the wiring has been downsized. You may end up rewiring the vehicle, and new cars are loaded with electronics. Fully powered accessories are nice to have, but maybe roll-up windows and manual door locks are a better choice if you plan on building a prerunner.
Once you start cutting into your truck, you’ve reached the point of no return. Stronger A-arms will put more of the load on the frame. Once you beef up the mounting points, you will need further bracing, like an engine cage. The same is true in the rear. Most leaf spring trucks mount the shocks to the rearend housing. Once travel goes beyond a certain amount, longer shocks need to be attached. This means you will be intruding into the bed or rear cargo area if you have an SUV, which in turn means a bed cage to mount the shocks.
Now that you have the engine cage and bed cage, you are two thirds of the way to a full cage. You will have to get very comfortable with cutting up your truck at this point. While your roll cage is under construction, you will be pulling the dash, the front windshield, and the rear glass. You will need to cut holes in the firewall, the floor, and the roof of the cab.
Fitting the roll cage into the interior presents problems. The front down tubes will interfere with the A/C ducts in the dash; B-pillar tubes may prevent your front seats from reclining; the factory headliner won’t fit anymore; and the door bars can interfere with window cranks or armrests. Your factory interior is just not designed to accommodate a roll cage, and may have to come out altogether.
Once you are this far down the road, you might as well go all out. If you are still running leaf springs in the rear, they are now holding you back. It’s time to go with a linked rear suspension. That requires more frame bracing, and a revision to the bed cage. In order to make room for the links and new shock mounts, you will probably end up cutting the frame off and redoing the entire rear half of the truck. And now that you have cut your truck in half, you’d better have a good fab shop or be skilled enough yourself to put it back together right. It’s also the the time to design a fuel cell and the pumps, rollover valve, and filters that go with it. Oh, and did your budget include plumbing, coolers, wiring, and hardware? Because it ought to.
Since you are converting the rear suspension to a linked design, you will have to modify the rear axle housing. There is no sense in using the factory housing, axles, or differential. Any gusseting or link mounts that you would add to a stock housing would rip right off because the axle tubes are too thin. You need something you can weld to and that will stand up to the pounding. You will need some type of locking rear diff, or a fully locked spool. Of course, with all of the additional clearance you have after removing what was left of your factory bed, you can now mount larger tires that will require bigger brakes all around, as well as a gearing change.
Now you have a fairly capable truck that can handle some high-speed travel. Unfortunately, you probably added substantial weight, so it can’t get out of its own way. You will soon discover that your factory transmission and driveshaft are not up to the constant shock loads created when the rear tires go through the whoops. Your driveline components will need to be modified in order to withstand any kind of horsepower increase considering the huge contact patch you have with your 40-inch tires. Do yourself a favor and upgrade the driveline before you increase the horsepower. Trophy Trucks carry a spare driveshaft around, but they have Trophy Truck budgets and salaried employees to replace the broken parts.
You now have a pretty good feel for what it takes to build a prerunner. This is why people who have the means start from nothing more than a bare cab. If you are going to end up with a thinly disguised Trophy Truck, it just makes sense. Building in stages will also work, and is the way most people go about it. The best part is that it’s your vehicle, and you can do whatever you want with it. The ultimate goal should be to get out and enjoy it, however you like.