How To Replace Tracks On A Bobcat 331 Model?

Changing the tracks on a Bobcat 331 is not the hard part. With the machine chocked on level ground, a jack, a pry bar and a tensioning tool, the swap itself is a morning's work. The part that costs money is the decision in front of it: whether the sprocket, idler and rollers underneath are still fit to carry a new track, because a worn sprocket will destroy a new belt faster than the old one wore out.

Last updated: October 5, 2026

This guide covers the four checks to make before anything comes apart, the tools and safety setup, how the tensioner releases, how the old track comes off, and what has to match before you order the replacement.

Before the track comes off: four checks

Do these with the old track still on, because once it is off you cannot read the wear patterns it left behind.

Record the fitment. Write down the width, pitch and link count of the track you are removing, plus any part number moulded into it. These three dimensions are what the replacement has to match, and they are easier to read on a dirty track than to reconstruct later from a catalogue. Look at the sprocket teeth. Teeth worn into hooks, or a tooth profile that no longer sits squarely in the link, will climb a new track and stretch it out of pitch. Turn the idler and every roller. A roller that is flat-spotted, seized or weeping oil is a roller that will fail under the new track; a worn idler face lets the track run off line. Check the tensioner. If the track lost tension on its own before you started, the seal is usually the reason, and it is worth fixing while the track is off rather than after.

If the sprocket or the idler is at the end of its life, replace it in the same job. Fitting a new track to a worn drive sprocket is the single most common way to short-circuit the life of the part you just paid for.

What you need on the ground

The tool list is short and none of it is special. A hydraulic jack rated well above the machine's weight, axle stands or heavy blocking, a track tension gauge, two pry bars, a sledgehammer and a punch for the master link, a grease gun for the tensioner, heavy-duty gloves and eye protection.

The safety setup matters more than the tools. Park on level, firm ground, lower the bucket and any attachment to the ground, engage the parking brake, and chock the machine so it cannot roll - a track change means lifting one side of a machine that weighs several tonnes, and an unchocked machine can move while a track is off. Then release the hydraulic pressure before you start working around the undercarriage, per the machine's manual, so nothing can move under stored pressure while your hands are in the frame.

Releasing tension

Track tension on this class of machine is held by a grease-filled cylinder that pushes the idler forward. To release it, clean the area around the grease fitting first - grit forced into the cylinder is what kills tensioners - then open the fitting slowly and let the grease escape until the track goes slack. Never crack the fitting open under load with your hand directly behind it, and never stand in line with the idler while the tension comes off.

Once the track is slack, support it with blocks before you break the master link. A slack track on a raised machine is heavy and it moves unpredictably when the link releases; the blocking is what stops it dropping on the frame, the ground or you.

Removing the old track

Clean the undercarriage first with a pressure washer. Working on a packed undercarriage hides the wear you are looking for, and loose material falls into the frame as soon as you start.

Drive the master link pin out with the sledgehammer and punch, with the track supported and the machine chocked. With the link open, walk the track off the sprocket and idler by rotating the wheels by hand - a small amount at a time, keeping the track from twisting. Once the track is clear of the top, lift the side of the machine at the track frame with the jack and use the pry bars to work the belt off the rollers in short sections, alternating sides so the track does not jam against a roller flange. A track that is fought off in one pull is a track that takes a roller or an idler with it.

While the track is off, inspect what it was hiding: scoring on the roller faces, play in the roller bearings, and the condition of the sprocket teeth you can now see properly.

Fitting the new track and setting tension

Slide the new belt over the sprocket first, then feed it around the idler and onto the rollers, keeping the direction marking correct and the belt square to the frame. Join the master link, and apply anti-seize compound to the pin threads during reassembly - it is a small habit that makes the next removal easier.

Tension is set with the grease gun, which pushes the idler forward and tightens the track. The target figure is specific to the machine and belongs in the manual; the method is the same everywhere. Lift the machine so the track hangs clear, measure the sag at the mid-point between the sprocket and the idler at the height the manual specifies, and over the number of links it names. Then check the other side: the two tracks wear and stretch at different rates, and a machine with one tight track and one loose track steers badly and wears the tighter one out first.

Before the machine goes back to work, run it a short distance and watch the track track straight. A new track that runs off line is reporting an alignment or sprocket problem, and it is cheaper to find that in the yard than on a job.

What has to match before you order

Three dimensions decide whether a track fits, and none of them can be guessed from the model name: the width, the pitch - the distance between link centres, which has to match the sprocket - and the link count. The belt AFT stocks for this class of machine is a 300x52.5Nx80 for the 331 and its siblings, and the listing names the models it fits rather than a range; if your machine has been re-tracked before, trust the markings on the track you removed over the catalogue.

Two further items are worth having in writing: a part-number cross-reference for your machine, and the warranty terms as a period plus an operating-hours cap, whichever comes first. Wear parts beyond the track itself are worth ordering in the same job when the inspection above shows they are due - the same catalogue carries rollers, idlers and sprockets across machine brands, including a sprocket 2606341 for Caterpillar and a front idler 21W-30-00014 for Komatsu, which is what it means in practice to have undercarriage parts available rather than one track size in isolation.

This article is part of the rubber tracks guide, which covers how the size code works, tread patterns, compounds and buying a set in Canada.

FAQs

Can I reuse the old pins and the master link?

Only if they are free of scoring, corrosion and stretch. The master link is the part of the belt that works hardest, so a pin that is even slightly worn is worth replacing while the track is off the machine - it costs very little compared with doing the job twice.

How tight should the tracks be on a Bobcat 331?

Exactly the figure in the machine's manual, measured the way the manual specifies: with the machine lifted, at the mid-point between the sprocket and the idler, at the stated height and over the stated number of links. Too loose and the track slaps and can derail; too tight and it loads the sprocket, idler and wheel bearings. Check both sides.

Do both tracks need replacing at the same time?

Not always, but think about wear states rather than about budget. If both tracks have run the same hours on the same ground, fitting one leaves the machine steering against an old belt, and the new one does more than its share of the work. If one track was damaged early on an otherwise sound set, a single replacement is reasonable.

Can I fit a wider track than the machine came with?

A wider track lowers ground pressure and can suit soft ground, but it changes how the machine pivots and has to match the undercarriage and sprocket. Width, pitch and link count still have to agree with the machine, so treat any change of width as a fitment question for the supplier rather than a free upgrade.

How long do rubber tracks last on an excavator?

Long enough that the honest answer depends on your own ground and discipline: what the machine crosses, whether tension is kept to the manual's figure, and whether worn rollers and sprockets are replaced before they reach the new belt. Keep the hours, terrain and dimensions of every set you fit and you will know your own expected life after two sets.