ZF63A 1.6:1 Hurth ZF Marine: My Rant for the Day

This HSW 630 Hurth/ZF transmission was labeled as a Mercruiser and looks like it's from the early 1980s. On these HSW630-style units, replace the filter every couple of years, since the O-rings go flat and can suck air no matter how tight the cover is tightened. ZF raised pressure on the 630/63 over time and later branded the updated version the ZF68. Covered: ZF/Hurth ZF63A, ZF68 | Part numbers: not stated | Ratio: 1.6:1 Parts and rebuilt units: https://www.halemarine.com For this model: https://www.halemarine.com/index.php?... Learn more: https://www.halemarine.com/index.php?... Questions? Call Chris at 804-333-3677 (Mon-Fri 9-3 ET) or email sales@halemarine.com. We buy Velvet Drive and ZF core transmissions.