3. Transfer Cases & Adapters Toyota Trucks

Throughout the years Toyota used basically two types of transfer cases: chain or gear-driven. All gear-driven cases have the same bolt pattern with a 2.28:1 low gear ratio. They did, however, use two input splines which were 21 and 23. The chain-driven transfer case offered two input splines which were 23 and 26. The bolt pattern on these cases differed from the gear-driven transfer case. These chain-driven transfer cases have a 2.57:1 low gear ratio. This section first helps you to identify your transfer case. In addition, it will cover the modifications necessary when installing a different transmission or the Trail Tamers gears. One of the easiest ways to identify the difference between a chain or gear-driven transfer case is by looking under your vehicle. The transfer case rear cover is either bolted on with 5 bolts (chain) or 7 bolts (gear).  

For further assistance in identifying the different transfer cases Toyota used, we reference the stock transmissions use in these vehicles. These transmission codes are normally found in the engine compartment on vehicles 1979-83, or the driver’s side door jam on vehicles 1984 & newer.

1979-1980 4-SPEED with GEAR-DRIVEN 21 SPLINE TRANSFER CASE:
The first Toyota 4WD was produced in 1979. 1979-80 vehicles used a manual 4 speed (tranny code L43). This transmission was coupled to a gear-driven 21 spline transfer case.

The input shaft on this transfer case was odd because it did not have a standard spline relief as did all other Toyota 21 spline gear-driven transfer cases. On these transfer cases, some grinding is required on the input shaft for proper fit on our adapters. When adapting to this transfer case, the shifter linkage will stay mounted on the transfer case. If installing the Toyota low gears in this transfer case, you will be required to modify the shift forks. Some internal grinding on the case may be necessary for this gearing upgrades.  

1981-1983 5-SPEED with GEAR-DRIVEN 21 SPLINE TRANSFER CASE:
1981-82 tranny code L45 4-speed, 1981-82 tranny code L50 5-speed and 1983 tranny code L52 5-speed. All three transmissions used in these years were all integral (one piece bellhousing and transmission). The overall length of these transmissions varied. When adapting a new engine & transmission on these year vehicles, driveline modifications should be expected. These transmissions were coupled to a gear-driven 21 spline transfer case.

Although there were three different transmissions used, there was only one model transfer case used. The transfer case shifter is mounted on the top of this transfer case. The gears on this transfer case are categorized as “noisy run gears”. If installing the Toyota low gears in this transfer case, you will be required to modify the shift forks. Some internal grinding on this case will be necessary.

1984-1988 (Carbureted) 5-SPEED with GEAR-DRIVEN 21 SPLINE TRANSFER CASE:
1984-88 tranny G52 & G54 5-speed. These transmissions were normally coupled to a carbureted 4 cylinder. These transmissions offered a removable bellhousing, allowing these transmissions to be retained for engine swaps. These transmissions were coupled to a gear-driven 21 spline transfer case.

Although there were two different transmissions used in these years, only one model transfer case was used. The transfer case shifter was mounted on the stock 5-speed tailhousing. Our transfer case adapters will allow you to retain this same transfer case shifter configuration. This transfer case also used a retainer clip to secure the two front bearings. This clip must be removed when using one of our adapters. If installing the Toyota low gears in this transfer case, some internal grinding on the case may be necessary.

1985-1988 (E.F.I. 4 cylinder) 5-SPEED with GEAR-DRIVEN 21 SPLINE TRANSFER CASE:
1985-88 tranny code W56 5 speed. This transmission was normally coupled to an electronic fuel injected 4 cylinder. The bellhousing on this transmission is removable, allowing this transmission to be retained for engine swaps. This transmission was coupled to a gear-driven 21 spline transfer case.

The transfer case shifter linkage is mounted on top of the transfer case. Since it has “quiet run gears” and the correct transfer case shifter configuration, this box is the best suited transfer case to use for a donor Crawler unit. If installing the Toyota low gears in this transfer case, you will need to modify the shift forks. Some internal grinding on the transfer case may be necessary for this upgrade. This transfer case also used a retainer clip to secure the two front bearings. This clip must be removed when installing one of our transfer case adapters.  

1989-1995 (E.F.I. 4 cylinder) 5-SPEED with GEAR-DRIVEN 21 SPLINE TRANSFER CASE:
1989-95 tranny code W56 5 speed. This transmission was normally coupled to an electronic fuel injected 4 cylinder. The bellhousing on this transmission is removable, allowing this transmission to be retained for engine swaps. This transmission was coupled to a gear-driven 21 spline transfer case.

In 1989, the transfer case shifter linkage was relocated on the 5 speed tailhousing. The shifter mechanism for both the transfer case and the transmission were one unit. When using this transfer case with any of our transfer case adapters, you must either modify or replace your transfer case. By changing the shifter rods from a 1984-88 (Carbureted 4 cyl.) transfer case or using Toyota part numbers 36314-35020 (high-low rod) and 36313-35020 (front drive rod), you will be able to retain your stock transfer case. The other option is to purchase a 1984-88 (Carbureted 4 cyl.) transfer case.

This transfer case also used a retainer clip to secure the two front bearings. This clip must be removed when using one of our transfer case adapters. If installing the Toyota low gears in this transfer case, some internal grinding on the case may be necessary.  

1986-1987 (Turbo E.F.I. 4 cylinder) 5-SPEED with GEAR-DRIVEN 23 SPLINE TRANSFER CASE:
The transmission code is R151F, and this unit is used in conjunction with the turbocharged 4 cylinder. This 5-speed has a removable bellhousing, allowing this transmission to be retained for engine swaps. This transmission was coupled to a gear-driven 23 spline transfer case.

This transfer case is identical to the 21 spline transfer case except Toyota used a larger diameter 23 spline input. This input can be interchanged with any of the 21 spline cases. On high horsepower engines or vehicles with large tires, you can interchange this 23 spline input into a 21 spline case if you are concerned about strength. The transfer case shifter is located on the transmission tailhousing. Our adapter housings will allow you to retain this shifter configuration.

This transfer case also used a retainer clip to secure the two front bearings. This clip must be removed when using one of our transfer case adapters. If installing the Toyota low gears in this transfer case, some internal grinding on the case may be necessary.

 TOYOTA  ATLAS   

CHAIN-DRIVEN 23 SPLINE TRANSFER CASE 1988-1994:
In 1988, Toyota introduced a different style of transfer case, changing to a chain-driven design. This 23 spline transfer case is most common in late model Toyotas and is normally used in conjunction with a V6 engine. The transmission code is R150F.  

This transfer case is completely different than the gear-driven version. You can identify this transfer case by the number of bolts (5 bolts) that hold the rear tailhousing to the main case. The adapter selection to retain this transfer case is not as extensive as is our gear-driven transfer case options. Driveshaft modifications are normally required. No reduction gears are available for this style transfer case, nor do we offer any crawler box be installed in front of this unit.

CHAIN-DRIVEN 26 SPLINE TRANSFER CASE 1989-1995:
This 26 spline transfer case is not real common. It is normally found in Toyotas with 4 cylinders having a transmission code of G58. This vehicle also has a vacuum disconnect differential (VDD). The shifter handle for this chain-driven transfer case is found on the transmission tailhousing. Our adapters do not have provisions for this shifter configuration. Therefore, if you are using this transfer case with our adapter, you must change the transfer case shift rails and top cover. Driveshaft modifications are normally required. No reduction gears are available for this style transfer case, nor do we offer any crawler box be installed in front of this unit.

Transfer Case Support:

The transfer case support runs directly underneath the transfer case. Depending on the transmission you plan on installing and the transmission you are removing will determine whether or not the crossmember support will need to be relocated and if driveline modifications are required. Most Toyotas have a boxed-in frame rail which makes it difficult to move the crossmember back if needed. On conversions requiring the transfer case to be relocated further back, we offer an adjustable crossmember plate to assist you. This plate can be ordered under P/N 713125-C.

Toyotas that were originally equipped with a V6 engine will require crossmember modifications. When using our motor mounts, we provide P/N 713125-C which is an extension plate that bolts directly between the transfer case and crossmember. Some floorboard modifications on these vehicles are also necessary for the transfer case shifter handle.

Toyotas 1984-95, originally equipped with a 4 cylinder, had a stock drivetrain length of approximately 25-3/8”. When installing a new transmission and transfer case adapter longer than the stock drivetrain, you may have driveshaft modifications. Part No. 713125-C can be used in the relocation of your stock transfer case. Floorboard modifications may also be necessary for proper clearance on the transfer case handle. On some applications, the engine can also be cheated forward to retain the transfer case in the stock location; however, radiator and fan clearance become an issue.

Toyotas 1979 to 1983, originally equipped with the 4 speed or 5 speed transmission varied in transmission lengths. When performing an engine and transmission conversion, most of these vehicles will be required to relocate the transfer case and have driveshaft modifications. Part No. 713125-C can be used to relocate your stock transfer case. Floorboard modifications may also be necessary for proper clearance on the transfer case handle. If you are using this plate, it will allow up to 6” of movement towards the rear axle.

ADVANCE CRAWLING SYSTEMS
Tx2 Crawler Adapters:
Because of larger tires with a stock drivetrain, most Toyota trucks are not geared low enough. A double transfer case crawler adapter can be an easy solution to your gearing problems. Low gearing allows you control crawl over obstacles; and keeping the vehicle under control saves on wear & tear and, in many cases, less breakages.

We are pleased to release as part of our Advance Crawling Systems our all new redesigned Tx2. Designed for 1979-95 Toyota truck gear-driven transfer cases (21 or 23 spline), this new double bearing design is ideal to help with gear support and deflection. Tx2 kits have a casting length of only 2.375” long.

This gear box takes the stock Toyota transfer case from a low gear ratio of 2.28:1, to a 5.20:1 low gear ratio. The stock gear-driven Toyota transfer case is assembled from the factory in 3 basic portions. By using the front section of the transfer case as a donor box, our adapter will allow you to install this reduction box between your transmission and transfer case. When installing this unit, driveline and floorboard modifications are required. Since the stock transfer case is also being relocated further back, an extended speedometer cable will be necessary. The kits we offer fit both the 21 & 23 spline gear-driven transfer cases.
50-5905D - Tx2 Crawler Adapter for 21 spline gear-driven T/C     
50-5906D - Tx2 Crawler Adapter for 23 spline gear-driven T/C
716186-C - Speedometer cable extension

The 1979-83 Carbureted and the 1985-88 EFI T/Cs have the shifter on the transfer case with a 4 bolt cast iron base of 3-1/8" x 4-3/8". When using one of these cases as a donor box, your shifters would measure 6-1/2" apart.

1984-88 Carbureted and 1986-87 EFI Turbo T/Cs have the T/C shifter located on the transmission tailhousing with a 4 bolt aluminum base of 3-1/4" x 4". When using one of these cases as a donor box, your shifters would measure 11" apart.

The 1989-95 EFI T/C shifter is located on the transmission tailhousing. This transfer case has a 6 bolt aluminum base that houses both the transfer case & transmission shift handles. This aluminum base is 4" x 8". When using one of these cases as a donor box, your shifter’s would measure 10" apart.

Note #1 - The rear T/case must be a top shifting style (1979-83 Carbureted or 1985-88 EFI).
Note #2 - The reduction gear box can retain the original T/C shift rod location to match to the existing transmission, or the reduction box can be changed out to the 1979-83 carbureted or 1985-88 EFI box (T/C shift lever on reduction box).
Note #3 - Shift rods, forks & driveshaft flanges are interchangeable between all years shown.

Heavy-Duty Toyota Transfer Case Front Housing:
On the 4.77 gears, the stock case must be machined or ground to provide clearance for the cluster gear. You can grind the necessary clearance; however, it is recommended to machine the case for this clearance.  If your not sure about this grinding or the machining process, we now offer a new heavy duty front Toyota housing. Our new Toyota HD housing can be used as a crawler box with stock Toyota gears or with our low gear sets. It can also be used as a new front housing for the lower gear sets listed above. This housing will save you time and money. When installing our low gears into a stock Toyota housing, grinding & machining on the stock case is required. Our housing has been engineered with additional clearance for our gear sets. Thus, hours of grinding & expensive machining labor are eliminated. This housing is made from 356-T6 heat-treated aluminum alloy with an average thickness of .550”. A “stock” housing is die cast aluminum and only has an average wall thickness of .200”. 51-5911