Tachometer Drive Gear 735889M1 42818 Fits Massey Ferguson 20 35 50 65 135 165 230

What It Is

The Tachometer Drive Gear (part numbers 735889M1, 42818) drives the tachometer cable on Massey Ferguson tractors, converting engine rotation into a readable RPM signal. It’s specifically for older MF models with mechanical (cable-driven) tachometers.

Fitment & Compatibility

Before buying, confirm your tractor model and engine type. This gear fits Massey Ferguson 20, 35, 50, 65, 135, 165, and 230 series, but only those with a mechanical tachometer drive port. Check your existing gear’s tooth count and shaft diameter—this is an aftermarket replacement for OEM part 735889M1. Measure the gear shaft length (typically ~1.5 inches) and ensure it matches your drive housing. Not compatible with electronic tachometers or later MF models with digital gauges.

Key Things to Know

• Quality: Aftermarket, but rated 4.4/5 from 13 reviews—most users report it fits and works as OEM. Inspect for burrs or rough edges before install.
• Installation: Moderate difficulty. Requires removing the tachometer cable and possibly the timing cover. Have a service manual handy for proper alignment.
• Common gotcha: If the gear is stripped, check the drive housing for wear—replacing just the gear may not fix a worn housing.
• Lubrication: Apply a thin layer of grease to the gear teeth and shaft during install to reduce wear.

Should You Buy It

Buy this if you have a mechanical-tach MF 20–230 series tractor with a stripped or broken tachometer drive gear and you’re comfortable with basic engine disassembly. At $16.99, it’s a cheap fix for a common failure, but skip it if your drive housing is damaged or you need an OEM part for a warranty restoration.