Lawn Mower: Mower Won't Track Straight

The wheel bracket serves two purposes on a lawnmower. First, the axle and wheel are attached to it. Second, it works with the wheel adjuster to move the wheel up or down so the height of the cut can be adjusted. The bracket sometimes attaches directly to the deck and other times attaches to a rod that extends through the deck, allowing both the right and left brackets to attach to it. If your mower won’t track in a straight line, you will want to inspect the wheel bracket for damage or wear. A bent wheel bracket will cause the wheel to be at an angle to the deck. This will cause the wheel to pull in the direction it is bent. The wheel bracket can wear out where it attaches to the deck. This will cause the bracket to skip side-to-side, causing the mower to pull to one side or the other. Replacing the wheel bracket is usually a pretty easy repair. Start by removing the wheel from the bad wheel bracket. The wheel is typically attached with either a nut, or sometimes a clamp ring. Once the wheel is removed, the nut or bolt that attaches the bracket to the mower can be removed next. Take note of any spacer washers that are present so you can re-install them in the correct locations. Install the new bracket in the reverse order.

The wheels on your lawnmower must be pointing straight forward for your lawnmower to track straight. Anything that causes a wheel to point away from straight will cause the mower to pull to the side. Sometimes the wheel will wear down where the axle passes through it. Some wheels have plastic hubs where the axle passes through. These designs are especially prone to wear over time. Models with metal inserts or bearings will be trouble free for longer. If your mower isn’t tracking straight, inspect the wheels closely. If you can easily move the wheel side-to-side with your hand, the hub is likely worn and the wheel should be replaced. Also, look for cracks on the hub or spots where you can see that the axle has worn through. If your mower’s wheels use bearings, look for a failed bearing that is coming apart. Fixing a bad wheel is a simple repair. If the wheel has a hub cap, use a screwdriver to remove it. The wheel is typically attached to the wheel bracket with a nut or sometimes a split ring. Remove the fastener and pull the wheel from the axle. Note the location of any spacer washers so you can correctly re-install them later. Once the wheel is removed, use a rag to clean the axle. If the wheel you are replacing is a drive wheel it will have a gear attached or cast into it. If both the gear on the wheel and the drive gear on the mower are metal, you can apply a small amount of thick grease to the gears. If one or both gears are plastic, don’t use any grease. The grease will capture dirt, which will quickly wear down a plastic gear. Plastic gears are best left dry. Install the new wheel along with any spacer washers you previously removed and secure the wheel with the fastener.

The deck is the central component of your lawnmower. All the other major assemblies of the mower attach to it, including the wheels. If your mower won’t track in a straight line, you should inspect the deck for damage. Before focusing exclusively on the deck while trying to resolve a tracking issue, you will want to first look at the wheel brackets and the wheels themselves, as they are more likely culprits. If the wheels and brackets check out okay, then move on to the deck. There are several common deck problems that could cause the mower to not track straight. Inspect the location where the wheel bracket attaches to the deck and make sure the hole isn’t wallowed too big. If the mower has a metal deck, make sure that it is not bent, causing the wheel to point at an angle. Rust can also weaken the deck, causing it to flex or bend. The steps to replace a mower deck vary greatly by brand and model. In any case, it is not a simple repair and will require some previous experience and a decent set of tools. If you are a novice do-it-yourselfer, this might be a repair you want to leave to a pro. If you have the tools and are up for the challenge you can save yourself a lot of money. The repair consists of stripping all the mower’s components off the deck. This includes the engine, the transmission, the handle assembly, the wheel assemblies, and any other shrouds or covers. While breaking the mower down, make sure you keep track of the fasteners and make notes of things like cable routing and the order of spacers, so the reassembly will go smoothly.