Excavator Track Wear: How to Measure It and When to Replace Undercarriage Parts

📅 Published: August 9, 2026✍️ By CN Machinery

An excavator's undercarriage can account for a surprisingly large share of its lifetime running costs. The good news is that undercarriage wear is slow, predictable and easy to measure — which means it can be managed instead of suffered. The key is knowing which parts wear, how to check them, and when replacement becomes cheaper than running on.

1. Which Undercarriage Parts Wear — and How

Every component of the track assembly wears in its own way:

• Track shoes — the grouser bars (the ridges that grip the ground) slowly wear down, and the shoe plates can bend or crack in rocky ground. Worn shoes lose traction and push more load through the whole assembly.
• Track links, pins and bushings — as pins and bushings wear, the chain stretches, measured as "track pitch elongation". A stretched chain whips, wears faster and damages the sprockets.
• Rollers and idlers — the running surfaces wear and the diameter shrinks; leaking seals mean a roller or idler is running dry and should be replaced or rebuilt.
• Sprockets — the teeth wear into a hook shape as the chain stretches; the sprocket is usually rotated or replaced when tooth wear becomes pronounced.

Working conditions decide the wear rate: sand acts like sandpaper and wears bushings fast, rock impacts bend shoes and crack links, while packed clay can hide wear and overload the final drives. Regular cleaning and correct tension slow everything down — see our undercarriage maintenance guide for the daily routine that protects these parts.

2. How to Measure Wear Yourself

You do not need specialist equipment to track undercarriage wear — a caliper, a straightedge and a wear gauge are enough for most checks. Measure the same points every 250 to 500 operating hours and keep a simple record:

• Grouser height — measure the remaining height of the track shoe bars; compare it with the new-part figure, and plan replacement as it approaches roughly half of the original height.
• Bushing outside diameter — worn bushings are the main cause of chain stretch; measuring a few bushings around the chain gives you the average wear rate.
• Track tension and sag — with the machine on level ground, check the sag between the top of the track and the bottom of the track frame. Excessive sag means the chain is stretched and the adjuster has run out of travel.
• Sprocket tooth profile — a hooked or sharpened tooth shape signals advanced wear, often combined with chain stretch.

If you are buying a used machine, the same measurements are the fastest way to judge how much life is left in the running gear — our used machinery inspection checklist shows where the undercarriage fits in the full inspection.

3. When to Replace — and How to Do It Smartly

Replacement timing is a cost calculation. Many operators extend chain life by turning pins and bushings (rotating them 180 degrees) at around half wear — a service that a workshop can do once, and that effectively gives the chain a second life. When the chain is stretched past the limit and the sprockets are hooked, continuing to run only accelerates wear on everything else, and a broken link on site costs far more than a planned replacement.

A few rules keep the bill down:

• Replace in sets — fitting new shoes or links onto a badly worn chain wastes the new parts. Match new components to the condition of the rest of the assembly.
• Rotate sprockets — many sprockets can be turned around to use the unworn side, doubling their life.
• Buy quality aftermarket parts — reputable aftermarket undercarriage parts are built to OEM specifications at a fraction of the price, and for popular machines they are stocked for fast delivery.

When the time comes, order complete sets — shoes, links, pins, bushings, rollers, idlers and sprockets — from one source so the components are matched. Tell your supplier the machine model, serial number and track chain pitch, and they will confirm the correct parts before anything is shipped. If you are sourcing several part lines at once, our guide to choosing an excavator parts supplier helps you vet who you buy from.