I picked up a jdm ZILLION SV TW 5:5:1 lefty reel from digitaka, the plan is to use it for cranking 1oz deep divers. Since it’s a jdm version, it has aluminum gears, would constantly throwing 1oz deep divers strain or damage the aluminum gears? And does anyone know if a 5:5:1 lefty brass gear set is available as a replacement? Any info would be appreciated.

Thanks

Unlikely to damage them with any normal use. Current Daiwa anodized hyperdrive main gears have much harder surface than brass will work-harden, higher through-thickness yield strength resists brinnelling (mashing), and much deeper anodizing than older alloy gears people have complained about (mostly older Shimano, AA6065 vs 7075).

Up front, Daiwa didn't make any Zillion HD-P, and no 5.5 brass hyperdrive gears. Zillion HD starts at at 6.3 gears. (USM Zillion G also starts at 6.3 brass gears).

I have a 5-year-salt JDM Zillion with 8.5 gears, bought at the beginning of January '21 when they were first available, and fished hard. Last fall, I noticed a (very) slight smoothness difference between the long-use reel and my new 7-geared SLPW-Zillion (based on HD with brass hyperdrive gears) - and only noticed the difference because I was fishing both reels side by side. (SLPW-Z only offered 7.1 and 8.5 gears).

One way to look at this, both brass and stainless improve with use, by work hardening a new wear surface. This mechanism doesn't exist in aluminum alloys, which will slowly wear through the hard-anodized thickness. The hard-anodized gears are more tolerant of abuse loads up front than both brass and stainless - e.g. using it to tow your boat with your deep diving crankbait on a stump.

This winter I swapped gears on the long-use '21 Zillion for a new brass hyperdrive 8.5 gearset from Zillion HD. While I was buying, bought a second set to stash and eventually swap into my Zillion Silver Wolf, when I decide it needs them. While pinion normally works gear-ratio-times harder than main gear, all Zillions use stainless pinions, which work harden to levels preventing any pinion wear, and improve with use.