1979-1995 Toyota 4x4 Builder's Guide - How To Trail Your Toyota

Transfer Case
From 1979 to 1995, several varieties of Toyota transfer cases were used. Most of the cases were geardriven, though two chaindriven units were also used. Geared cases used a 2.28:1 low-gear ratio but used two differently splined inputs (21-spline and 23-spline) depending on the model year it was installed. The 23-spline input in the geardriven case was used behind the 22RTE Turbo four-cylinder and can be interchanged with the 21-spline input in any geardriven case. The 23-spline input will hold up to higher horsepower and is ideal for V6- and V8-converted Toyotas. Chaindrive cases used a 2.57:1 low-gear ratio and came with 23- and 26-spline inputs depending on the year. The later-model chaindriven cases were paired with the V6 engine and can be identified by its five bolts used to secure the rear cover. The rear cover on geardriven cases is secured with seven bolts. Toyota transfer cases used both top-shift and forward-shift configurations. Most cases are forward-shift but top-shift is more desirable for projects and modifying. Marlin Crawler offers a kit to convert forward-shift cases to a top-shift.

Low gears are about the easiest upgrade to increasing a vehicle's capability. A number of manufacturers offer low transfer case gears. Advance Adapters offers its Trail Tamer gears in 2.06:1, 4.7:1, and 5.0:1 ratios. The gearing in a stock- or low-geared transfer case can be further reduced by pairing it with a gear-reduction housing, or "crawl box," that bolts between the transmission and the T-case. The crawl box will hold one set of T-case gears and the stock T-case will hold a second set of gears. Together the gears combine to create a multitude of available gear ratios that culminate to a very respectable crawl ratio. A number of aftermarket manufacturers offer crawl boxes and complete dual-transfer case setups, including Marlin Crawler and Inchworm Gear. You can also assemble your own double T-case using an adapter plate from Inchworm Gear, Advance Adapters, or Marlin Crawler, and the front housing from a spare Toyota T-case. You'll likely still want a low-gear set for the rear case to increase the low gearing possibilities.

Another transfer case upgrade that should be included with a dual-case setup is a heavy-duty transfer case crossmember. A twin stick shifter is also a helpful transfer case upgrade. The twin stick shifter allows the T-case to be shifted to 2WD Low, which is helpful in making tight turns in rigs equipped with a front locker.

Transmissions
Some early trucks used a four-speed manual transmission for a short time, but it was soon replaced by the five-speed. The '79-'83 five-speed transmission is weaker than later-model units and has a nonremovable cast-iron bellhousing. EFI trucks in 1984 came with a stouter five-speed with a removable aluminum bellhousing and four different versions of these were used through 1995 behind four-cylinder engines. From 1986-1995, two other versions of the five-speed transmission (R150F and R151F) were used along with the four-cylinder Turbo and the 3.0L V6. One automatic transmission was utilized for all Toyota trucks and 4Runners, and it was factory-married with a transfer case unlike all those used with the five-speed manual trans. If an engine or transmission swap is planned for an auto-equipped Toyota, you will also require a geardriven transfer case. Most of the late-model five-speeds are viable candidates for use behind a V6 or V8 engine swap, but the W56 five-speed used in '85-'88 EFI pickups and 4Runners is generally one of the more sought-after. Advance Adapters offers a variety of adapters to facilitate such a conversion as well as adapters to fit alternative transmission candidates such as a 700-R auto or Ford T-18 manual transmission. Toyota manual transmission strength can also be enhanced through the installation of a heavy-duty clutch and flywheel.