Concrete Saw: Blade Wobbles

A bearing is a device used to enable rotational movement, while reducing friction and handling stress. Due to constant stress a bearing receives, they tend to wear out and can cause the blade to wobble. If your concrete saw is giving off a growling, humming, rumbling or screeching sound, it is a good indicator a bearing needs to be replaced.
To start, take off both belt covers. Depending on your model, one could be the recoil. Relax the tension on the belt by turning the tension nut counter clockwise until it stops. Next, disconnect the water line. Locate the nut holding the pulley in place and remove it. It’s best to use an impact wrench for this, however, if you don’t have one handy, you can also hold the pulley in place with channel locks. Separate the two halves of the unit. Locate the arbor on the other side. To remove it, insert a screwdriver in the backside to hold the blade steady as you take it out. Take off the arbor, blade, flanges and spacers as well as the blade cover. Remove the cutting device assembly by clearing off any snap rings, bolts or screws to do so – this will be different on all models.
You can either replace this whole unit, which houses the bearings, or push the bearings out carefully to ensure you do not damage the housing. For any bearing that needs replacement, install evenly into the housing.
Once completed, you are ready to reassemble the unit. In order, reinstall the blade cover, inner flange, spacer, blade, outer flange/spacer and the arbor and tighten. Next, reattach the pulley tight and reassemble the two halves back together. Reconnect the water line. Reinstall the belt by walking it back on both pulleys and reapply the tension by turning the tension nut clockwise until it stops. Lastly, reinstall your concrete saw’s belt cover/recoil.

If the blade is not spinning true, it has to be replaced. Begin by either removing the spark plug wire or ensuring your saw’s switch is in the off position. This is to prevent an accidental start up. Next, insert a screwdriver in the small hole on one side of the blade and then rotate the blade until the screwdriver locks into place. On the other side, use a proper size wrench and remove the bolt that secures the blade in place. Remove the plate and the old blade and install your new one. Reinstall the plate and thread the nut back on. To stop the blade from rotating, place a screwdriver in the rear hole and use a wrench to tighten the nut down.

The arbor bolt holds the flange against the blade, securing the blade in place. If this bolt becomes damaged on the threads, or the flange, it may not spin true and cause the blade to wobble. This is also dangerous as it could walk itself off the shaft, allowing the blade to come loose. Remove the arbor bolt and inspect it. If there are any signs of wear or damage, replace it immediately.

The flange locks on the blade, securing it in place. If the flange is warped, or damaged, it will not be able to apply even pressure on the blade – causing the blade to wobble. Start by removing the arbor nut, blade, and any spacers and pull both flanges off. Lay the flange on a flat surface and push down on every spot along the edge, carefully looking for signs of movement. If you notice the flange rocks up ever so slightly, then it is not truly flat. Replace with a new flange and reinstall the arbor bolt.

Pulleys are what the belt or belts ride on to transmit power from the engine to the saw blade. If a pulley starts to wobble, it is usually caused from wear and will need to be replaced.
To replace the drive pulley, or saw pulley, start by removing the starter (or the belt cover) on the engine side of your saw. Then, remove the belt cover on the blade side. Relax the tension on the belt by turning the tension nut counter clockwise until it stops. Walk the belt off the blade pulley by turning the blade with your hand. Now, walk the belt off the clutch pulley by turning the clutch drum. Remove the nut holding the pulley in place. For this step, it’s best to use an impact wrench or you can try to lock the pulley in place by using a wrench or pulley remover – this method will vary on each model.
Remove the old pulley and clean the shaft. Install the new pulley and secure it down tight. Next, reinstall the belt by walking it back on the pulley and reapply the tension by turning the nut clockwise until it stops. Reinstall the belt cover on the blade side then the cover, or starter, on the engine side.

The shaft, or axel, is what the blade rides on. If the axel is not straight, or is warped, it will cause a wobble. To check this, remove the arbor by inserting a screwdriver in the backside to hold the blade steady as you loosen the arbor with a wrench. Remove the blade, flanges, spacers and the shaft. Place the shaft on a flat surface and roll it around, carefully inspecting it for a wobble. If you notice even a slight sign of a wobble, it needs to be replaced. Once completed, reinstall the outer and inner flanges and spacers back on the saw, then the arbor and tighten. Located on the opposite side of the arbor, insert a small screwdriver in the port to hold the blade steady as you tighten.

A spacer absorbs any slack between the blade and the flange, centering the blade. If the spacer is not truly flat, it can cause the blade to wobble. To check, remove the arbor by inserting a screwdriver in the access port to hold the blade still while loosening off the arbor with a wrench. Take off the arbor, flange and spacer. Lay the spacer on a flat surface and check for flatness by pushing down, all around, inspecting it for any movement. If you observe any sign of movement, it is not flat and needs to be replaced. Install a new spacer, followed by the flange, and reinstall the arbor bolt by tightening it down as you hold it steady with a screwdriver in the access port.