A precisely sized pilot bushing is essential to proper manual transmission installation. We generally recommend a bronze bushing for Jeep applications (when available) as they seem to better endure the harsh environment of a clutch housing. However, with proper installation a needle roller bearing is acceptable, so long as the transmission input shaft hardness is up to the hardness of the needle bearing.
Novak pilot bushings are made from quality Oilite bronze alloy, or in the case of a bearing, a quality needle roller assembly. Often, in adapted applications, a custom outer diameter, inner diameter or even a pressed in sleeve are used to meet the needs of that particular application.
Two pilot tip sizes are used on the AX15 transmission input shaft:
It’s always a good idea to verify the actual size as there is no guarantee that the transmission or input shaft are original and especially on the border years, the cutoff isn’t always exactly clean on that year. If your AX15 is the external slave style, it should have the the ~3/4” diameter.
Jeep/Mopar 4.0L engines from 1992-2006 typically (but not always) have a 1" inner crank bore, whereas the previous 4.0L and 258 cranks feature a ~1-1/16" crank bore. We have had customers who felt certain of the vintage of their engine (or its crank, in the case of remanufactured long-blocks or custom builds) only to find their pilot bushing bore to be a different diameter than expected. We recommend you measure your crank bore prior to ordering, to be sure of the correct pilot bushing choice.
You may consider purchasing an additional pilot bushing if you are unsure of your installation abilities or of the diameter of your crank bore or pilot tip diameter.
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 don’t 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.