2 Pack 131-5399 (15T) Pinion Gear Compatible with 30" Rear Drive Toro Time Master & Newer 22" Personal Pace Rear Drive mowers, Fits 10641 10641C 10642 10642C 10644C

What It Is

This is a 2-pack of 15-tooth pinion gears (OEM part 131-5399) that drive the rear wheels on self-propelled Toro mowers. It’s designed for Toro’s Personal Pace and Time Master rear-wheel-drive systems, replacing worn gears that cause slipping or loss of drive.

Fitment & Compatibility

Check these before buying:

• Deck size & model: Fits Toro 30" Time Master (models 10641, 10641C, 10642, 10642C, 10644C) and newer 22" Personal Pace rear-drive mowers.
• Tooth count: Must be 15 teeth. Count yours if unsure—13-tooth or 17-tooth versions exist for other models.
• Shaft diameter: OEM gear has a 5/16" hex bore. Measure your old gear’s bore to confirm.
• OEM vs aftermarket: This is a non-OEM replacement, but matches 131-5399 dimensions. Not for front-wheel-drive models or older 21" Personal Pace mowers.

Key Things to Know

• Common failure point: These gears wear down over time, especially on uneven terrain or with heavy use. Slipping wheels or jerky drive are typical signs.
• Installation difficulty: Moderate. Requires removing the wheel, drive plate, and retaining clip. No special tools, but patience needed for clip removal.
• Comes as a pair: You get two gears, so replace both sides at once for even wear. One gear often fails first.
• Lubrication tip: Apply a thin layer of white lithium grease to the gear teeth and shaft before installation to reduce future wear.

Should You Buy It

If your Toro rear-drive mower is losing traction or the drive feels inconsistent, this gear pack is a cheap, proven fix. It’s ideal for DIYers comfortable with basic disassembly—just confirm your model and tooth count first. At $6 for two, it’s a no-brainer over paying $40+ for a new drive system.