BRONCO DANA 20
The early Ford Broncos have always been popular vehicles for conversions and modifications. These vehicles were normally equipped with a 6-cylinder or V8 engines, and mated up to a 3 speed transmissions. With this transmission, Ford used two different lengths of adapter housings when coupling this three-speed to the stock transfer case either 6-1/2” or 9-3/8”. Vehicles equipped with a V8 had a 9-3/8” tailhousing, which set the bellhousing further into the engine compartment. Vehicles with six cylinder engines had a 6-1/2” tailhousing. . This shorter adapter compensated for the longer engine. In 1973, Ford began offering the C4 automatic. A special tailhousing and output shaft was manufactured to couple this transmission to the stock transfer case. Ford no longer makes the C4 adapter.
The 1966 to 1977 vehicles were equipped with a Bronco Dana 20 transfer case. This transfer case has the front driveshaft on the driver’s side of the vehicle and has a 6 spline input gear. Ford has always used a spud shaft that coupled this 6 spline transmission to the 28 spline transfercase.
The transmission-to-transfer case adapters used both a dowel pin and an alignment retainer. The spud shaft is supported in this retainer with a bearing. The adapter kits we manufacture utilize this type of design. In some applications, we also retain the stock spud shaft*. This transfer case has a 2.46:1 low gear ratio. In early 1973, Ford switched to a 2.34:1 low gear ratio.
*We offer a stock Bronco replacement spud shaft under 52-2710.
These transfer cases used two different shifter designs known as either the “J” pattern or “T” handle. The “T” handle was used from 1966 to 1972, the “J” pattern was used from 1973 to 1977.
The “T” handle shifter is a fairly simple shifting mechanism, to retain it with an adapter, it only requires a pivot point for mounting. The “J” shifter requires the shift handle to be mounted in a location relatively close to its stock position. Retaining this shifter in its stock location is hard to accomplish when adapting the various transmissions to the Dana 20. Vehicle owners with “J” shifter are recommended to either change the transfer case shifter rods and go to a “T” style shifter or to contact one of the Bronco specialty shops that offer a twin stick replacement for the “J” shifter. A twin stick shifter that replaces the “J” style should work with most of our adapters.
The adapter housings we manufacture normally utilize the stock Ford Bronco crossmember with the stock rubber supports. On new transmission assemblies longer than stock, this crossmember may need to be relocated. Adistionally, there are a few adapters that require this crossmember to be modified. These modifications are noted in detail on the specific adapter instruction sheet.
ATLAS TRANSFER CASE:
When replacing the Bronco Dana 20 transfer case, an Atlas transfercase is an ideal upgrade. The Atlas comes with a new adapter to mate a new input that matches the Dana 20 transfer case bolt pattern and case rotation exactlt. Most adapters kit listed in the Bronco conversion options can be used when coupling to the Atlas transfercase.
We offer six low gear ratios:
- Atlas15
- Atlas20
- Atlas30
- Atlas38
- Atlas43
- Atlas50
Allthough we do offer numerous input splines to fit the various transmissions, we do not offer a Atlas 4 speed with a 28 spline input. The Atlas offers the same rotation as stock plus some higher ones; however, the frame rails will need some modifications.
Click here for more Atlas installation information.
If you have questions about Atlas transfer cases or want more information about modifications to your 1966 to 1977 Ford Bronco Dana 20, please reach out to Advance Adapters. We’re here to help ensure that your purchase and upgrades are accurate and help you achieve your off-roading and modification goals! Fill out our contact form and a representative will reach out to you quickly. We’ve been experts in the outdoor lifestyle since 1971, and our customer-focused support keeps our customers coming back, year after year.
