Chevrolet & GM Standard Shift Bellhousings
Jeep Borg-Warner T18 Transmission
This adapter assembly makes for a strong and convenient adaptation of classic standard shift GM bellhousings to the T18 four-speed transmission, as was the optional transmission found in 1976-1980 CJ Jeeps.
This plate style adapter is cast and machined of a high-grade aluminum alloy, featuring an integrated precision machined bearing retainer. Included are the GM bellhousing locator / throwout sleeve, seal and hardware.
The T18 only from the 1976 - 1979 Jeep CJ's with an input shaft stickout length of ~7" (measured from pilot tip of shaft to front face of transmission case) is compatible with this conversion. The similar T18 transmissions from other Jeeps of this era feature longer input shafts and different gearing, and are not candidates for this kind of conversion.
If you are adapting to an earlier Jeep CJ T18 or FSJ T18, jump here.
The adapter is easily and quickly installed onto the T18. Due to design constraints, the transmission's two top ears will require slight elongation with a round or rotary file. This process is simple and will not compromise the strenth of the flange.
GM bellhousings typically feature either a 4-11/16" rear face bore or a 5-1/8" rear face bore, the latter typically only from Chevy / GM trucks from 1968-1991. Our adapter will work with both. If you are uncertain of your bellhousing bore, choose the 5-1/8" press-on spacer ring that can be used or omitted to cover either situation. The ring is easily returnable for credit if not used in the installer's application.
|The classic Chevrolet bellhousing, with the four-bolt rear pattern. Buick, Olds, Pontiac and other bellhousings with the same rear face are equally compatible.|
If you're using a GM bellhousing that has a 5-1/8" bore, you will require the following sizing ring:
Choosing Your Pilot Bushing
Your pilot bushing choice will depend on your particular GM engine. See our Pilot Bushings page to select this critical component for your conversion.
For GM engines prior to the Gen. III+ Series (LS & Vortec, 1997- present), you will use your GM / Chevrolet flywheel as per factory to your engine, which can be either the 153 tooth version or 168 tooth versions.
If you are using a GM Gen. III+ engine, we strongly recommend the use of our extended height LS / Vortec flywheel to normalize the clutch system. It features 168 teeth and is compatible only with 12" clutches.
|This is the right and recommended GM Gen. III+ flywheel to use to standardize the clutch assembly, and acheive proper clutch geometry and release action.|
This conversion uses readily available clutch components based on GM pressure plates and their geometries. However, because the 1976-1979 Jeep T18 features an 1-1/16" x 10 spline input shaft, a Ford style disc is required. Use of a GM 1-1/8" spline disc will cause serious wear, balance and strength issues. As such, these components are often best purchased as singles (offered below) instead of as kits.
Whether you choose to use the smaller (10-1/2" to 11") or the larger (12") clutch assembly is your preference. Jeep CJ's are typically lighter vehicles and the smaller clutches are generally adequate and offer easy clutch pedal pressure. The larger clutches have more holding power and still have very reasonable pedal pressure when using the diaphram style pressure plate. A more detailed discussion on this topic is available here in Novak's Knowledge Base.
Use a standard GM style pressure plate that matches your particular flywheel, be it the 11" version for 153 tooth flywheels, or the 12" version for 168 tooth flywheels.
Use a Ford style clutch disc for its compatible 1-1/16" x 10 spline hub. If your existing Jeep T18 disc (typically ~11") is in good condition, it can be used between the GM flywheel and pressure plate.
Clutch Release System
Both factory mechanical and factory hydraulic clutch release systems can be made fully compatible with this conversion. A more involved discussion of this topic can be read here.
Installers using mechanical releases should use Novak's #RAGM release fork, which features the correct leverage ratio for a GM pressure plate in these Jeeps.
Individuals wishing to use their factory hydraulic master cylinder or who wish to upgrade to a hydraulic system can use Novak's #HCR hydraulic clutch retrofit assembly in conjunction with a master cylinder from a 1980-1986 Jeep CJ (7/8") or 1987-1990 Jeep YJ (3/4"). Custom firewall installation and clutch pedal modification may be required. Select your slave cylinder diameter to match.
|Hydraulic clutch retrofits make for smooth, non-binding and easily adjustable clutch release systems.|
The dwindling number of off-the-shelf release bearings and the bearings provided in the many full clutch kits on the market are, counterintuitively, not always the right length bearings for that particular pressure plate and can cause a clutch that will not fully release due to too short of a bearing, or a burned up bearing when they're too long and constantly riding the fingers.
Novak's fully adjustable release bearing handily solves this concern, and is recommended for this conversion.
|Novak's adjustable GM release bearing is the ultimate answer to setting up an optimal conversion or factory style clutch system.|
Engines & Engine Mounting
The Novak engine mounting system offers the best designs on the market for strength, ease and flexibility of installation. Whether you are installing a classic Small Block, a V6 or a Generation III powerplant, we've got you covered.
In any scenario, it is critical that the engine be installed (as the Jeep engines usually are) with an offset of 1" to 1-1/2" to the driver's side. Other engine mounts on the market - especially the bolt-in versions - do not take this into account and make other placement decisions for the installer that do not take the full powertrain into account. Novak offers what we have found to be the most intelligent engine mounting system for Jeeps available, allowing the installer to make an easy and satisfying decision as to powertrain placement with the new engine, T18 transmission and Dana 20 transfer case all considered.
|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.|
For your GM engine, we will suggest the use of our RadLock high-performance conversion radiators, which are rugged, easy to install and are extremely efficient in cooling in even the most demanding environments.
|Our RadLock radiators offer a highly efficient and extremely durable cooling solution for your GM conversion engine.|
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 engine upgrade.
|GM V8 engines, Generation I through Generation III+ are popular choices as are the Chevy V6s. The Buick V6 is also a good choice.|