We have said it before, but it is worth revisiting. Don’t grind your gears. If they are grinding, seek help. Modify technique or repair your clutch or transmission before you ruin the rest of the gears. Simple advice, often disregarded.
Above is the overdrive screen from a 1971 MGB we are restoring this week. This screen was so covered with bits of the other gears that we replaced the overdrive with a rebuilt unit straight away. Overdrive cars share the same oil reservoir with the rest of the gearbox, so if you grind up your first gear, for example, your overdrive will ingest all the shards. Big Healeys have the same challenge, as do classic Minis, which share the engine oil with the gearbox. Basically, any metal bits you shower into your oil while shifting will cause problems elsewhere.
So go easy. Keep the grinding in your mouth, not in your gearbox!