Of every tool that comes through here for a brush replacement, angle grinders come up the most often. The combination of high RPM, continuous load and dusty operating conditions is hard on every wear part, and brushes take the brunt of it. A grinder that has started losing power, sparking heavily or cutting out under load is almost always asking for new brushes before anything else.
The first sign is usually loss of speed under load. A grinder that used to bite into steel now slows the moment the disc touches the work. The second is bright sparking through the rear vents — a small amount of blue spark is normal at full speed, but anything brighter, longer or more orange points to brushes worn past the safe minimum. The third is intermittent stop-start running, especially when the tool is tilted. That last one is the spring no longer pushing a worn brush firmly enough against the commutator.
Brush dimensions on an angle grinder typically run from 5×8×12mm on smaller 115mm grinders up to 6.5×13.5×17mm on 230mm machines. Fitment is by tool model, not just brand — a Makita GA9020 needs a different brush from a Makita 9558NB, even though both are 230mm grinders. The fastest route is to start from the brand. We carry direct fitments under Makita angle grinder carbon brushes, DeWalt angle grinder brushes, Bosch grinder brushes and Hitachi and HiKOKI grinder brushes, with the full hub at carbon brushes for power tools.
If you have the grinder open for brushes, it is worth checking the spindle bearings while you're in there. Worn brushes mask bearing noise, and a small additional spend on replacement bearings at the same time saves a second strip-down. While the disc is off, check the disc itself — a glazed or out-of-round cutting disc is doing as much damage to the grinder as worn brushes ever did. The cutting tools range covers fresh discs in the common 115mm, 125mm and 230mm sizes.
Brushes are a five-minute job on most grinders. Two screw-in caps either side of the motor housing release the springs; the old brushes lift out, the new ones drop in the same orientation. Run the tool at no load for thirty seconds to seat the new faces before going back to work.