Hynautic K-27 Fixed-Mount Balanced Steering Cylinder – 1.5″ Bore x 10″ Stroke (2 Ball Joint Ends)
The Hynautic K27 is a double rod end, tie-rod constructed hydraulic steering cylinder designed for rigid mounting on an immovable surface. The K-27 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-27.
Special Note: The K27 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 to help compensate for alignment changes
- Four total hydraulic ports – two 1/4″ NPTF ports per end (pressure and relief)
- Integrated bleed screws to simplify purging (mount with bleeds facing up)
Specifications
| Specification | Value |
|---|---|
| Model | K-27 |
| Cylinder Type | Fixed mount, balanced (double rod end), tie-rod construction |
| Bore | 1.50″ |
| Stroke | 10.00″ |
| Displacement | 13.20 cu in |
| Rated Working Pressure | 950 psi |
| Proof / Burst (Reference) | Proof 4500 psi / Burst approx. 6800 psi |
| Output Force (Reference) | 1260 lbs @ 950 psi |
| Ports | 1/4″ NPTF – two per end (pressure and relief) |
| Seals (Reference) | Buna-N with TFE backup |
Dimensions and Clearance
| Dimension | Value | Notes |
|---|---|---|
| A (Rod centered) | 34.12″ | Reference length per factory fact sheet |
| Stroke (F) | 10.00″ | Travel of the cylinder |
| Maximum space required | 44.12″ | Reference calculation: A + Stroke (verify installed envelope with rod end hardware) |
Compatibility and Service Parts
- Ball joints: The K-27 uses two ball joint rod ends. If you are converting a K-22-style setup to two ball joints, the HP6039 ball joint is commonly used.
- 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
If you are unsure which kit you need, send photos of the cylinder end cap and rod end through Tech Support.
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
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.
Can I replace just the ball joints?
Yes. If the cylinder body is in good condition, worn rod-end ball joints can often be serviced without replacing the entire cylinder.
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
Important Notes
- No sales tax on purchases outside of California
- Buy now, pay later options available (Affirm or PayPal Pay Later)
- International, USVI, Puerto Rican, Hawaiian and Alaskan customers – if shipping looks high at checkout, email us for a quote: [email protected]
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