Hurth Gearboxes in Australia

Hurth gearboxes are behind a great many older Australian cruising yachts and small inboards, and the first thing owners want to know is whether they are supported. They are.

Where you find them

HBW 50, 100 and 150 — the mechanical cone-clutch transmissions fitted behind small and medium auxiliaries across decades of production cruisers.

Still supported

Hurth was absorbed into the ZF Marine range, and the designs are generally still supported through those channels — see ZF marine gearboxes and ZF distributors.

For an owner that means a Hurth box is a normal service item rather than an orphan, which is not true of every component of that age.

The cone clutch, and how to treat it

The HBW family uses a mechanical cone clutch engaged directly by the control lever, rather than the hydraulic clutch packs of a larger box. That has consequences:

It is simple, with fewer things to go wrong and no oil pump to fail.

It is unforgiving of being slammed between gears at speed. Engagement should be made at idle, deliberately. Repeated harsh shifting is the commonest cause of avoidable wear.

Cable adjustment matters more than on a hydraulic box. A control cable short of full travel means the cone never fully engages, which slips and wears. It is also the cheapest thing to check when engagement feels wrong.

What to check

• Oil type and level — the plate on the box is the authority, and it is not always engine oil
• Oil condition — milky means water, usually a cooler; dark and burnt means slip
• Control cable travel, at the lever and at the box
• Alignment, which is the most common non-wear cause of failure on any marine gearbox

See how to check and change marine gearbox oil.

Frequently asked questions

Are Hurth gearboxes still supported? Yes. The designs were absorbed into the ZF Marine range and are generally still supported through those channels.

Why does my Hurth slip? Often a control cable short of full travel, low oil, or the wrong oil, before clutch wear. Check the cheap causes first.

Can I shift at speed? No. A cone clutch should be engaged at idle, deliberately. Harsh shifting is the main avoidable cause of wear.

What oil does it take? The plate on the box says. It is not always engine oil, and the wrong fluid causes clutch problems.

Is it worth rebuilding? Often, on a sound boat. Establish parts availability for your specific model first.