Chevrolet & GM Standard Shift Engine Bellhousings
Jeep Aisin-Warner AX15 & New Venture 3550 Transmissions
This adapter assembly makes for a strong and convenient adaptation of classic, standard shift GM bellhousings to the AX15 five-speed transmission, as was the transmission found in 1988(-1/2)-1999 YJ, XJ, MJ, ZJ and TJ Jeeps, as well as the New Venture 3550 as found in 2000-2004 TJ Jeeps.
Nearly all GM Generation I-III engines are compatible with this conversion, including Chevrolet Small Blocks, Gen III+ V8's, Chevrolet V6's and Chevrolet I6 engines. Buick, Olds, Pontiac and other GM engines are compatible with this adapter assembly if you have a standard shift classic GM bellhousing and flywheel for your engine.
This plate style adapter is machined from a billet of aluminum alloy and it features an integrated, precision machined bearing retainer. Included are the GM bellhousing locator / throwout sleeve and mounting hardware.
AX15 & NV3550 Versions
All AX15's from 1988-1999 and NV3550's from 2000-2004 are compatible with this conversion.
The adapter is easily and quickly installed onto the transmission. 1994-1999 versions of the AX15 and the 2000-2004 NV3550 will simply need to have their bearing retainer snout cut or machined off to allow space for the provided GM retainer to be installed. Instructions are included.
For NV3550 installations, it may be necessary to drill or otherwise machine a clearance hole into the bellhousing rear face to allow for clearance of the NV3550's protruding shifter boss. This is not a difficult task and will not weaken the bellhousing.
A GM style bearing retainer is provided with each adapter kit so that you can use any of the common GM thowout bearings. You can even use nearly any stock GM clutch disc and pressure plate with this installation.
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.
Whether you choose to use the smaller (10-1/2" to 11") or the larger (12") clutch assembly is your preference. Jeep Wranglers 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.
If your existing Jeep 4.0L disc (typically ~11") is in good condition, it can be used between the GM flywheel and pressure plate.
Full Clutch Kit
For a full premium clutch assembly:
Clutch Release System
The factory hydraulic clutch release systems can be made fully compatible with this conversion and should be retained. A more involved discussion of this topic can be read here.
Individuals wishing to use their factory hydraulic master cylinder can use Novak's #HCR hydraulic clutch retrofit assembly in conjunction with a their YJ, TJ, or XJ's master cylinder. We recommend you select a 3/4" 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, your transmission and the NP / NVG transfer case all considered.
|Novak's engine mounts, featuring excellent vibration dampening, superior strength and adjustability. 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.|
Novak's universal and adjustable rear mount assembly for the AX15 & NV3550 transmissions is ideal for these conversion situations. See it here.
|The classic Chevrolet bellhousing, with the four-bolt rear pattern. Buick, Olds, Pontiac and other bellhousings with the same rear face are equally compatible.
We can provide you with a new bellhousing if you require one. Please inquire.