AdaptersAdapting the
Borg Warner T18 & T19 Transmissions
to the
Dana Spicer Models 18 & 20 Transfer Cases
Our T18 to Dana 18 & Dana 20 conversion makes for a strong, refined, compact geartrain assembly for broad use in severe terrain or refined roads. It is one of the most persistently popular manual shift transmission conversions into Jeeps, providing a very compact geartrain, an excellent crawling gear, compatiability with several engines and simple installation.
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The Adapter
The Novak T18 / T19 to Jeep transfer cases adapter is very compact at only 1" long for a combined transmission and adapter length of 12.9". The adapter itself is cast and machined of a high-grade aluminum alloy, featuring thick flanges and a heavy cross-section.
Transmission Versions
Any version (Ford, Jeep, IH - 2wd or 4wd) and year of the Borg Warner T18 and T19 can be adapted to these transfer cases. There are no advantages between the 2wd vs. 4wd versions of this transmission.
Transfer Case Versions
All Jeep models of the Dana Spicer 18 and Dana Spicer 20 transfer cases are compatible with this adapter assembly. IH versions of these transfer cases are also compatible.
Transfer Case Input Gear
Our transmission mainshaft is splined for either six-spline input gears, or ten-spline input gears.
- Six-spline gears are predominately most common, as found with the Jeep T84, T90, T86, T89, T98, T18, T15 & T150.
- The rare ten-spline version is only availalble on the 1966 - 1974 transfer cases against the Jeep T14 transmission.
- Factory Jeep TH400 to Dana 20 combinations had a fifteen-spline input gear, which must be replaced by a compatible six-spline version.
International Harvester Dana 20's that had the TF-727 automatic had a 23-spline input gear, which must be replaced by a compatible six-spline version.
Consult our informative Dana gears interchange chart if necessary.
All Warn type overdrives are compatible with this conversion. Spline count information is the same.
Transfer Case Bore Size
The diameter of the transfer case center input locating bore will be either 3-5/32" or 4".
Most Dana 18's have a 3-5/32" bore, including those found against the T84, T90, T89 or T98. - Some Dana 18's have a 4" bore, including those found against the T86 & T14 transmissions (Buick V6 engines), 1966-1971.
- All Dana 20's have a 4" bore, regardless of the transmission they were joined to.
Transmission Mainshaft Replacement
Included with the kit is a new mainshaft for the Borg Warner transmission. Replacement is largely straightforward and instructions are included. We also recommend our basic gasket & seal kit, or our all-inclusive master rebuild kit, depending on your assessment of your transmission's condition. See our T18 parts page for information on these items.
Transfer Case Strength and Condition
The Dana transfer cases are very well matched to the T18. They are uncommonly strong, compact and servicable. They are capable of power ranging up through V6s, V8s and even the Chevy Big Blocks.
It is not requisite that you rebuild your transfer case to successfully complete the conversion, but it may be a good time to do so if your transfer case leaks or has many miles of service. We've made our Dana 18 & 20 gaskets & seals kits and our all- inclusive master rebuild kits available for this purpose.
Engine Compatabilities & Engine Mounting
AMC Jeep engines are compatible with the Ford T18 & T19 transmissions. See Adapting Ford Transmissions to AMC Bellhousings.
AMC (258, 304, etc.) engines may be left in the factory location in virtually all T18 installations.
A T18 or T19 installation is sometimes done in conjunction with an engine conversion into the Jeep. These engines include the Chevrolet Small Block V6 & V8, from Generations I, II, & III, 1955-2006. Carbureted, TBI and TPI engines are all compatible with this transmission. See Adapting Ford Transmissions to GM Bellhousings.
Ford engines are also natively compatible with the Ford versions of these transmissions. Dodge engines are natively compatible with the Dodge versions of these transmissions.
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| Novak's MM Series engine mounts, featuring excellent vibration dampening, superior strength and impressive adjustability - adjustable even after the engine is installed. The design and strength and affordability of our mounts are second to none. |
Engine Crank to Transmission Pilot Bushing
Many manual transmissions will be married to stock as well as conversion engines, and a custom pilot bushing will be required in many instances. Some common choices with the T18 / T19 transmissions are listed below:
>Bushing, pilot, AMC cranks to Ford T18>Bushing, pilot, GM Gen. I-III (1955-2000) cranks to Ford T18>Bushing, pilot, Ford Small Block, stockFor pilot bushings not listed, see our full collection. |
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Transmission Rear Mount
This transfer case adapter's design is ready to accept our industry standard urethane isolator mount, available for purchase (below). This is our preferred rear mount unit. Our kit is designed for it, and its usage is essential to protect powertrain components from the flex and jar typical of any automobile, but especially Jeeps.
Whether you are assembling onto a stock cross member / skidpan or if you are setting up a high-clearance skid plate, you will find it to be a clean and simple process.
Clocking Information & Driveshaft Clearance
The Novak adapter excels in design and features the best transfer case clocking available with the Ford T18 & T19 transmission.
To install this adapter on the transmission, it will be necessary to drill and tap an additional hole in the rear face of the transmission case. A drill, 13/32" and 5/16" drills and a 3/8"-16 tap will be required. This process is simple and instructions, as always, are included. This method makes the resulting transfer case clocking angle better than otherwise available on the aftermarket, and more like the factory setup. Other adapters yeild a transfer case that is clocked down and likely to offer clearance problems under the Jeep chassis.
Transfer Case Shifter
This transmission conversion will allow for the retention of the factory Dana 18 twin-stick shifters, Dana 18 single-stick shifter, and many of the Dana 20 shifters. Very minor grinding of the earlier Dana 18 dual-shifter mount may be necessary. Some tube-mounted Dana 20 shifters may need to be modified, or possibly replaced with the Twin-Stix Shifter Kit.
Transmission Shifter
Use of the OEM style transmission shifter for the T18 is easily done. The installer may opt to bend the stick to fit the particular Jeep application.
We can supply a new, straight stick that replaces the factory unit. This stick can be custom bent to the driver's preference and will sometimes restore a more solid feeling to the shifting of a T18 or T19.
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| Super short! The Novak adapter helps pack a whole lot of four-speed punch into a small space, making for longer rear driveshafts and better u-joint angles. |
Yoke & Driveshaft Clearance
Use of the factory size driveshaft and yoke is recommended, but there is room for larger units if desired. Our adapter design has maximized clearance between the transmission and yoke. No transmission modifications are required for clearance on this wise.
Driveshafts
Driveshaft length changes are sometimes required, as this geartrain combination is typically shorter than most factory Jeep combinations. Some potential conversion engine installations sit further ahead than OEM engines in the Jeep's bay and will allow for better driveshaft angles, especially when done with this very short combination.
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| A turn-key T18 or T19, professionally built, adapted and delivered to your door - ready for a variety of engines and Jeep transfer cases. Read more... |
Some of our customers, fearful at the perceived expense of new or modified driveshafts, attempt to let the existing driveshafts dictate engine, transmission and transfer case location, sometimes to the detriment of the project. Driveshaft modifications are usually inexpensive when performed by driveline, RV or tractor implement specialists. New driveshafts are an option but seldom a requirement in regards to the actual successful conversion. Jeeps that require extensive travel or specialty-built driveshafts have this option available through several fabricators across the nation.
Axles
Use of factory axles is completely acceptable with this conversion. Axle upgrades are not necessary, but they may be chosen for reasons external to this transmission upgrade.