Toyota Pickups & 4Runners - Weak Links, Strong Fixes

Weak link: Front brakes on solid-axle vehicles
Models affected: '79-'85 pickups and 4Runners
What happens: Solid-axle-equipped vehicles have non-vented front brake rotors with small calipers. After adding large, heavy tires, these brakes only provide marginal stopping power.
Sturdy fix: Fortunately, there are factory parts that offer improved braking performance. Larger calipers from an '86-or-newer pickup or 4Runner can be used with vented rotors from an '81-'87 FJ-60 Land Cruiser on solid front axles. A larger-bore master cylinder from an '88-or-newer V-6 Toyota is also a bolt-on replacement. Additionally, all of these upgrades will still fit beneath your 15-inch wheels.
Contact: Your local parts store or wrecking yard

Weak link: L-series transmissions
Models affected: '79-'83 pickups
What happens: The L-series transmissions used in '79-'83 HiLux pickups are not nearly as strong as later-model W-series transmissions. They are prone to bearing failure, and their short length makes for a steep front driveshaft angle.
Sturdy fix: A later-model W56 transmission will bolt right to the stock motor and transfer case, but it is 4 1/2 inches longer and requires driveshaft work and a new clutch. Front Range Off Road Fabrication produces transfer-case crossmembers to accommodate the increased length. If all of this sounds like too much work, Marlin Crawler offers heavy-duty L-series transmissions featuring larger bearings and helical-cut gears that are reported to be 30-percent stronger than the stock tranny.
Contact: Front Range Off Road Fabrication and Marlin Crawler

Weak link: U-bolts and spring plates
Models affected: All pickups and 4Runners
What happens: From the factory, Toyota leaf springs are connected to the axles with U-bolts that are pointed towards the ground. Not only does this rob ground clearance, but the U-bolts can become bent or deformed after coming in contact with trail obstacles, after which time they are nearly impossible to remove.
Sturdy fix: All-Pro Off Road sells a kit that flips the U-bolts so they are facing upward and free from harm. The kit includes 1/4-inch spring plates and new U-bolts, as well as relocated lower shock mounts that must be welded to the axlehousing.
Contact: All-Pro Off Road

Weak link: Differential breathers
Models affected: All pickups and 4Runners
What happens: From the factory, Toyota differentials only have a breather cap to allow for heat expansion. When making stream crossings, water can enter the differentials and serve you up a foamy gear-oil milkshake. If left unchecked, this can cause thousands of dollars of damage to the differentials.
Sturdy fix: In order to prevent this problem, a hose barb can be used to replace the stock breather and a length of rubber hose is attached to the barb and routed to a higher location. The fitting off of a Toyota Celica intake manifold (PN 90404-51319) has the same thread pitch as the stock axle breather and works perfectly.
Contact: Your local Toyota dealer

This is the fourth installment of a series that will examine some of the common problems of popular four-wheel-drive vehicles and how to fix 'em. Past installments included Chevy fullsize trucks and SUVs (May '04), Ford fullsize trucks and SUVs (Aug. '04), and Dodge fullsize trucks and SUVs (Apr. '05). In future issues we're going to put the spotlight on Jeep and other four-wheel-drive trucks and SUVs.