2 Pack AUC10057 Traction Drive Belt Flat Idler Pulley Compatible with John-Deere AUC10057 Z535R Z540R Z540M Z535M Z525E

What It Is

This is a 2-pack of flat idler pulleys (part AUC10057) that guide and tension the traction drive belt on select John Deere ZTrak zero-turn mowers. It replaces a worn or seized pulley to keep the drive belt tracking correctly and prevent premature belt wear.

Fitment & Compatibility

Direct fit for: John Deere Z535R, Z540R, Z540M, Z535M, Z525E models (check your serial number range—most 2015+ models use this pulley).
What to measure: The pulley should be 4.0 inches outside diameter with a 3/4-inch bore and a flat (not grooved) face.
OEM equivalent: Replaces John Deere part AUC10057. Aftermarket, but matches OEM dimensions.
Before buying: Confirm your mower’s deck size (48–60 inches is common for these models). Verify the pulley is used on the drive belt, not the deck belt—check your parts diagram.

Key Things to Know

• Build quality: Solid steel construction with a sealed bearing. Much better than some cheap plastic alternatives that warp under heat.
• Installation difficulty: Moderate. You’ll need a socket set and possibly a puller if the old pulley is seized on the spindle. Expect 30–45 minutes.
• Common gotcha: The pulley nut is often torqued to 25–35 ft-lbs. Use thread locker on reinstall.
• Pack value: Two pulleys for ~$54 is a good deal—you’ll have a spare or can replace both sides at once.

Should You Buy It

If your John Deere ZTrak is listed above and you’re getting belt squeal, slipping, or uneven wear, this is a reliable, cost-effective fix. The high rating and sealed bearings make it a solid choice for DIY repair over OEM (which can cost 2–3x more per pulley).