Adapting the

1976-1986 AMC Bellhousings

to the

Jeep AX15 Transmission

This conversion kit joins the popular AX15 overdrive transmission to the series of AMC bellhousings made between 1976 and 1986 for a variety of OEM transmissions. This affordable and straightforward method allows the installer to retain the bellhousing they already own, and in many cases, the existing clutch and its release system.

The adapter is precision designed and expertly CNC machined from alloy aluminum. Its thick cross-section provides ample thread engagement and high structural integrity. Precision indexing is achieved through locating dowels to the transmission and bearing retainer to the bellhousing. This adapter is just under 1” thick and the transmission is 16.5” long giving a 17.5” overall length from the front face of the adapter to transfer case mounting flange. The OEM AX15 bellhousing and associated shaft stickout of 7.5” is 1” longer than a standard 6.5” AMC bellhousing which lines things up perfectly with the adapter plate installed giving standard dimensions to the front of the adapted assembly. 10 input splines at 1-1/8” diameter and a pilot diameter of either 0.59" (early) or 0.75" (late) are accommodated by the correct pilot bushing and clutch specified below.

The adapter installs onto these transmissions with no change of input gear or other transmission internals. Cutting the transmission input shaft is not required as the adapter spaces the transmission properly for the GM crank and clutch assembly. A new pilot bushing is required for this assembly. See Related Products below for the one matching your Ford engine.

Kit Contents

Included are the adapter plate, bearing retainer (which serves as a centering index for the GM bellhousing and clutch release bearing sleeve) and required hardware.

Applications & Compatibility

Bellhousing Compatibility

This adapter assembly is compatible with the following AMC bellhousings:

• T150 & T18 version (1976-1979)
• If you have this version, existing holes will be used and clearanced for new fasteners
• SR4, T4 & T5 version (1980-1986)
• If you have this version, it will be necessary to drill and clearance for new fasteners
• T176 version (1980-1986)
• If you have this version, existing holes will be used and clearanced for new fasteners

If you don't have one of the above bellhousings, but have the factory 1994-2004 4.0L to AX15 / NV3550 bellhousing (image, below), Novak recommends this installation method.

Compatible Jeeps

This conversion is compatible with CJ7 and longer Jeeps. CJ5 Jeeps do not have a long enough wheelbase for these longer, five-speed transmissions.

These are strong transmissions and Full Size Jeeps such as Wagoneers, J-Trucks, etc. are conversion candidates for them unless used for more aggressive driving or heavy work situations.

Compatible Engines

All AMC engines made from 1972-2006 are compatible with the above bellhousings and therefore this conversion, including the 232, 258 & 4.0L I6 as well as the 304, 360 & 401 V8's.

The Jeep / GM Iron Duke 2.5L bellhousing is also compatible with this conversion; some ancillary pieces will vary a bit but the adapting process is the same.

Flywheel

The factory flywheels on all of the above engines are acceptable. Most will accept the recommended 10-1/2” clutch. There are instances of larger clutches in some trucks. If you have one of these applications the clutch diameter will need to match. The Iron Duke will also need the clutch matching its flywheel.

Clutch

The factory pressure plates, whether three-finger or diaphragm, are compatible with this adaptation. However, 1976-1979 (T150 & T18) clutch disc hubs have a 1-1/16" spline diameter that is not compatible with the 1-1/8" input shafts of the AX15 & NV3550. The proper clutch disc will be required and can be purchased separately below, or combined with a new pressure plate.

The factory clutch release arms and their linkages can be retained, including mechanical bellcrank style linkages, or hydraulic clutch release systems, whether factory or aftermarket retrofit.

Transmission Versions

All versions of the AX15 & NV3550 are compatible. However, 1994 and later AX15's and all NV3550s will require a minor modification to their input bearing retainer. Earlier AX15s that featured the concentric internal throwout slave bearing do not require this modification. This is also compatible with Novak’s new, upgraded, stronger AX15 transmissions which come assembled to the extent possible with all parts ordered together. They can be seen here.

Related Products

Installation Requirements

Tools

A drill, 29/64” bit, and various smaller bits are required, in addition to typical mechanic's hand tools.

NV3550 Installation Caveat

Note that NV3550 transmissions have a shift rail boss that protrudes through the adapter, and will require that the bellhousing be milled for clearance. The adapter can be used as a template to mark for this operation.

Powertrain Placement

Transmission placement is largely determined by factory engine location. It is not necessary in typical conversions to change the engine position. Setting the powertrain to the proper factory or conversion pitch angle - usually tilted down ~5 degrees (3-7 acceptable) is recommended.

Engines & Engine Mounting

If converting to an AMC V8 in conjunction with this upgrade, Novak engine mounts are available to ease its installation.

If converting to an AMC or Jeep I6, various aftermarket companies make engine mounts for a variety of Jeeps.

Driveshafts

Driveshaft length changes are often required. Most conversions to these transmissions will require that the rear driveshaft be modified to be shorter and front driveshaft longer.

Some installers, concerned about the expense of new or modified driveshafts, attempt to let the existing driveshafts dictate engine, transmission and transfer case location, often to the detriment of the project. Our recommendation is to prioritize the correct position of drivetrain components over saving a few dollars which is usually regretted in the long run with compromised positioning.

Driveshaft modifications and rebalancing can be affordable when performed by driveline, RV or tractor implement specialists. New driveshafts are an option, but not necessarily a requirement in regards to the actual successful conversion if your existing driveshafts are in good condition.

Jeeps that require extensive travel or specialty-built driveshafts have this option available through several fabricators across the nation. These are normally specified after placement of the new transmission and measured at vehicle ride height. As the rear driveline gets shorter, it is often advantageous to us a Double Cardan or “CV style” rear shaft with the correct geometry at the axle to minimize vibrations and possible binding.

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.

Also See

• Adapting AX15 & NV3550 transmissions to AMC Engines
• AMC V8 Universal MMX Series Engine Mounts for Jeeps and Other Vehicles
• The Novak Guide to the AMC / Jeep V8 Engines
• The Novak Guide to the AMC / Jeep I6 Engines
• The Novak Guide to the Aisin-Warner AX15 Transmission
• The Novak Guide to the Jeep NVG 3550 Transmission