Hynautic K-28 Fixed-Mount Balanced Steering Cylinder - 1.5" Bore x 12" Stroke (2 Ball Joint Ends)

Hynautic K-28 Fixed-Mount Balanced Steering Cylinder - 1.5" Bore x 12" Stroke (2 Ball Joint Ends)

The Hynautic K28 is a double rod end, tie-rod constructed hydraulic steering cylinder designed for rigid mounting on an immovable surface. This configuration uses two ball joint rod ends to help accommodate alignment changes through the steering arc.

IMPORTANT NOTE: Image is of a K-22, not the double ball joint K-28.

Special Note: The K28 is available again as its own brand, manufactured in the USA, the cylinder will differ in some visual aspects but is the same part.

Features

• Balanced, double rod end cylinder for consistent steering response
• Rigid fixed-mount design for inboard steering installations
• Two ball joint rod ends for alignment compensation
• Four total hydraulic ports - two 1/4-18 NPTF ports per end (pressure and relief)
• Integrated bleed screws - mount with bleeds facing up to simplify purging

Specifications

Dimensions and Clearance

Compatibility and Service Parts

• Ball joint assembly: 670030 (2 required)
• Rubber boot: 170001 (note: not used on K-28 and K-29)
• Cylinder seal kits:
  • Pre-1983 K-21 through K-29 cylinders: KS-04
  • Post-1983 (after Aug 1983) K-21 through K-29 cylinders: KS-06

Installation Tips

• Mount the cylinder so the bleed screws face up to make purging easier.
• Confirm the steering arm geometry allows full travel without binding at either lock.
• Use marine-rated hydraulic fluid specified for the system and follow factory fill and bleed procedures.
• After installation, cycle steering lock-to-lock and inspect all fittings for seepage under load.

Maintenance Guidelines

• Inspect rod ends and mounting hardware for play, corrosion, and cracking each season.
• Keep the cylinder rod clean and free of nicks to protect internal seals.
• Address any external leakage promptly - small leaks can introduce air and cause spongy steering.
• If steering feels uneven or bypassing is suspected, reseal or rebuild the cylinder to restore performance.

FAQs

Is the K-28 balanced?
Yes. The K-28 is a balanced (double rod end) cylinder, designed for equal volume on both sides of the piston for consistent steering response.

How do I know if I need KS-04 or KS-06?
KS-04 is for K-21 through K-29 cylinders built prior to 1983. KS-06 is for K-21 through K-29 cylinders built after August 1983. If in doubt, contact Tech Support with photos of the end cap and rod end.

What if I am unsure this is the correct cylinder?
Use the Stock Inquiry form and include your current cylinder model, photos of the end caps/ports, and your boat details so we can help confirm fitment.

Downloads and Resources

• Hynautic K-22 / K-27 / K-28 / K-29 Brass Cylinder Fact Sheet (PDF)
• Hynautic Steering Cylinder Bleeding Instructions (PDF)
• Hynautic Cylinder Rebuild Service - Bronze (Send us your cylinder)

Questions?

• Tech Support: Tech Support Page
• Check Stock: Stock Inquiry Page
• Shipping Quote: Request Quote Page

Seatech Marine Products, Inc. is an authorized dealer, service center and installer for Hynautic.