Pilot Bushings for
AMC Engines
A precisely sized pilot bushing is essential to proper manual transmission installation. It supports and aligns the transmission input shaft on center during clutch release.
Not all AMC engines feature the same crank bores. There are three AMC crank configurations:
- Early AMC V8, 1967-1971. Note that these engines aren't really native to Jeeps as Jeep was using Willys & Buick engines during this era and early AMC motors only apply to transplant engines.
- Early engines, 1971 and previous featured a ~1.8" diameter protruding step (see image to the right) instead of an inset recess like later AMC engines.
- AMC I6 & V8, 1972-1991
- These engines feature a ~1.8" diameter recessed centering bore for auto transmission torque converter centering, then a ~1-1/16" diameter manual transmission pilot bushing bore further into the crank. Some Novak pilot bushings use the larger rear bore for conversion transmissions with shorter input shafts.
- Mopar 4.0L I6, 1992-2006
- These cranks feature the same ~1.8" recessed bore for auto transmission torque converter centering, but their manual transmission pilot bushing bore further into the crank shrunk to ~1" diameter (likely to match other Dodge crank bores of this time). Some Novak pilot bushings use the larger rear bore for conversion transmissions with shorter input shafts.
An early AMC crank with the small step rear bore.
1972+ AMC crank with the recessed rear bore.
1992+ 4.0L similar; pilot bushing installed.
Check your Crank
Jeep builders should be aware that the AMC engine in their posession may have been close to a crossover year or have been rebuilt with a crank from a different era. It's not uncommon for engine rebuild shops to keep extra cranks around, and a crank from an early AMC V8 could end up in a later engine, and vice versa. We urge installers to scrutinize and measure the crank bores before ordering a pilot bushing.
Also be aware that on AMC engines originally equipped with a TH400 automatic transmission there may be a thin centering ring (AMC Jeep #5352374) that will need to be removed to install the Novak pilot bushing. If the bore measure ~1.7" instead of the expected ~1.8" youâÂÂve got the bushing that needs to be removed.
... to GM Transmissions
Frequently adapted GM transmissions to AMC engines include the SM420 & SM465. These transmissions have a ~19/32" pilot tip diameter.
These pilot bushings install in the rear step of the crank.
... to Ford Transmissions
Includes Ford truck T18, T19 & NP435, which have a ~17mm pilot tip diameter.
This also applies to the Jeep T18's which have been retrofitted with our T18-ISK.
These pilot bushings install in the rear step of the crank.
... to T14 & T15 Transmissions
Two pilot sizes are used on the T14 transmission early (1967-1971) at ~19/32" and late (1972-1975) at ~3/4". All T15 transmissions used the ~3/4" pilot.
Installs in the inner crank bore.
... to Jeep T150 & T18 Transmissions
Early 1972-1975 Jeep T18 transmissions used a ~3/4" pilot diameter. Later 1976-1979 Jeep T18 and T150 transmissions used ~17mm pilot diameter. The 1976-1979 T150 has a long pilot tip which can locate in either the inner or rear bore of an AMC crank. These pilot bushings are for the inner bore.
... to SR4, T4, T5, T176 Transmissions
The Jeep SR4, T4, T5 & T176 transmissions have a pilot diameter of ~19/32".
These pilot bushings install in the inner bore of the crank.
... to AX15 & NV3550 Transmissions
Two pilot tip sizes are used on the AX15 transmission input shaft: 1988-1991 AX15's had a ~19/32" diameter and ~1992+ at ~3/4" diameter. However, check yours before ordering. All NV3550's feature a ~3/4" pilot tip.
Installation Requirements
Removal of the old bushing and cleaning the crank bore is required prior to installation. There are a number of official and unofficial methods out there to remove the old bushing/bearing. Hydraulic removal using inserted grease behind
the bushing (or wet paper towel, etc. and a precisely sized rod is a classic. Our preferred method is a slide puller available from your local parts store as a rental tool if you donâÂÂt own one.
A proper drift tool or driver is recommended for installation. Do not coat oiled bronze in grease, as this plugs its pores and will not lubricate properly afterwards. Installation as the bushing comes is acceptable, though soaking it for a day or longer in clean engine oil prior to installation is preferred. Freezing the bushing and lightly warming the crank can ease the installation. Pilot bushing and transmission input and main shaft damage are inevitable if the bellhousing and transmission are not centered concentric and parallel to the engine face. We recommend the use of a dial indicator to verify that your bellhousing and engine are centered on the bellhousing bore. See The Novak Guide to Clutches, Linkages and Bellhousings for directions on this method.