Weak link: Lack of torque
Models affected: All pickups and 4Runners equipped with the 20R, 22R, or 22RE engine
What happens: Toyota drivetrains are stout and will live forever behind the 129 lb-ft of torque produced by the 22R motor. This lack of torque leaves something to be desired, though, when traversing tough trails.
Sturdy fix: Instead of swapping in a larger motor and sacrificing the weight balance, fuel economy, and simplicity of the drivetrain, many owners opt to add a second transfer case with an adapter from Marlin Crawler. This allows twice the torque multiplication and also relieves the angle on the front driveshaft. Another path to lower gearing is numerically lower gears that can be installed in your existing transfer case, such as those available from Advance Adapters. If your budget allows, consider a replacement 20/22R engine. LC Engineering sells all sorts of replacement parts for these engines, as well as complete assemblies specially tuned for off-pavement use.
Contact: Marlin Crawler, Advance Adapters, and LC Engineering
Weak link: Stock two-core radiator
Models affected: '84-'95 pickups and 4Runners equipped with the 22R or 22RE engine
What happens: The stock two-core radiator found in 22RE-equipped pickups and 4Runners is adequate for most uses, but when idling down the trail all day with only limited airflow, the coolant temperature can start to rise.
Sturdy fix: An easy upgrade involves using a three-core radiator from an '86-'87 22RTE turbo pickup. This radiator is a direct replacement for '84-'88 pickups and 4Runners, and offers additional cooling.
Contact: Your local Toyota dealer
Weak link: Frame around the steering box
Models affected: '86-'95 pickups and 4Runners
What happens: Though not as common as with Jeeps and Chevys, large, heavy tires can tax Toyota steering components and cause the frame to crack around the steering box.
Sturdy fix: Front Range Off Road Fabrication sells a kit that can be welded to both sides of the frame to sandwich this area with thicker, stronger material. The plates are tapered to prevent stressing adjacent areas on the frame and fit '86-'95 steering boxes.
Contact: Front Range Off Road Fabrication
Weak link: Starter brushes
Models affected: All pickups and 4Runners
What happens: After cranking the engine over for hundreds of thousands of miles, the starter motor can begin to spin slower and slower. Eventually this can leave you stranded on the trail without the ability to turn over the engine.
Sturdy fix: This problem is often just a matter of worn contacts, which can be replaced with factory parts for a fraction of the cost of a new or rebuilt starter. This problem is so common that 4Crawler Off Road stocks starter contacts for all models of Toyota pickups and 4Runners.
Contact: 4Crawler Off Road
Weak link: Front shock towers
Models affected: '79-'85 pickups and 4Runners
What happens: Toyota front shock towers are not tall enough to fit long-travel shocks. With supple leaf springs and longer brake lines, the shocks become the limiting factor and the shock mounts can rip off the frame if they have to support the weight of the axle and wheel.
Sturdy fix: Marlin Crawler has designed replacement shock hoops made of 1 1/2-inch-round, 0.120-wall tubing that are stronger than the stock pieces and allow for much longer shocks. The new hoops weld to the frame and include tubular gussets for even greater strength.
Contact: Marlin Crawler
Weak link: Birfield joints
Models affected: '79-'85 pickups and 4Runners
What happens: Instead of using U-joints on the steering axle, Toyota used a closed-knuckle design with so-called Birfield joints. For many years, the Birfields have been considered the weakest link in the Toyota drivetrain. They are messy to repair and prone to breakage, particularly during sharp turns or while backing up.
Sturdy fix: Now troublesome stock Birfields can be replaced with heat-treated Longfields from Longfield Super Axles. These upgraded Birfields have undergone a special process to make the part less brittle, and thus less prone to cracking under severe loads.
Contact: Longfield Super Axles