Reply to "transmission bronze oil lite pilot bushing"

Scott, it's not a 'small' amount of iron in those things. Two of the 3 common Oilite bushing formulations use at least 75% iron powder in their makeup and thus are strongly magnetic. These are not 'bronze' bushings, they are sintered IRON bushings, with a little copper and no tin. Copper and tin make up bronze alloys. Below from Wikipedia:


Oilite SAE 841:
87-90.5% copper, 9.5-10.5% tin, max 1% iron, 1% 'other'. Soaked in engine oil after mfg.

Super Oilite:
18-22% copper, no tin, 76-80% iron, 2% 'other'. Soaked in Turbine oil after mfg.

Super Oilite 16: 18-22% copper, no tin, 74-78% iron, 2% graphite, 2% 'other'. Soaked in Turbine oil after mfg.

Some pilot bushing wear comes from mis-drilled or mis-machined bellhousings so the register surfaces are not perfectly parallel to the crank, which is why speed shops sell offset bellhousing dowels so they can be trued up using a dial indicator. There are also deflections in any clutch input shaft whenever you are in the lower gears and power flows down from the mainshaft to the countershaft. If there were no side-forces or mistakes in parts alignment, real bronze pilot bushings would never wear out..... but we know they do, fairly quickly, so there must be some side-forces for whatever reason.

Given the extreme cost of ZF replacement parts, I'd rather error on the side of caution. So I NEVER use nor recommend ball or roller bearings as pilots, and I avoid using 'iron' bushings in any engine. YMMV....