JSI Jack Screw Series (Inch)
Inch JSI / JSXInch male-male adjusters. Standard carbon steel (JSI, zinc-plated) or premium chromoly steel (JSX) for high-load or vibration applications.
Male-Male Threaded Adjusters for Rod End Linkage
Jack Screw Adjusters for Rod Ends (Male-Male)
Not a lifting screw jack: here, a jack screw is a double-male threaded adjuster that joins two female-threaded rod ends. Turn the body to set linkage length while the assembly remains installed. SYZ offers zinc-plated carbon steel JSI / JSI-M and chromoly JSX / JSX-M, inch 10-32 to 1-12 and metric M5 to M16, with RH/LH thread options.
JSI / JSI-M
Inch + Metric
Carbon / Chromoly
JSI / JSX Options
RH & LH
Adjustable Thread
30 + 6
Configurations
ISO 9001:2015 Certified
Factory Direct Sourcing
36 standard sizes
Inch 10-32–1-12 · Metric M5–M16
OEM-Grade Tolerances
Overview
What Is a Jack Screw?
A jack screw is a double-male threaded adjuster used to fine-tune the length of a rod-end linkage.
With a female-threaded rod end threaded onto each male end (and locked with jam nuts), turning the jack screw body lengthens or shortens the assembly — a compact alternative to a full turnbuckle for precise preload and alignment.
Turnbuckle Effect: By combining one right-hand (RH) and one left-hand (LH) threaded end, rotating the central jack screw body moves both ends inward or outward simultaneously. This allows rapid length adjustment while the linkage remains mounted on the machine or vehicle.
Product Specs
Product Series Breakdown
Available in carbon steel and high-strength alloy chromoly options in both inch and metric standards.
JSI-M Jack Screw Series (Metric)
Metric JSI-M / JSX-MMetric male-male adjusters. Available in zinc-plated carbon steel (JSI-M) or high-strength chromoly (JSX-M) for European metric assemblies.
Selection and Sizing Guide
- • Inch assemblies: Select JSI (carbon steel) or JSX (chromoly, higher strength).
- • Metric assemblies: Select JSI-M (carbon steel) or JSX-M (chromoly).
- • Threads & Jam Nuts: Match thread size and hand to your rod ends. Always add jam nuts to lock the settings securely against vibration.
Link Construction
Choose the Right Linkage Adjuster
This page covers the male-male jack screw. The full comparison with turnbuckles and tube adapters is maintained on the turnbuckles and hex-bar adjusters page.
Jack screw: male-male
Female-threaded rod ends screw onto both exposed ends. Use it where compact length adjustment and access to the central body matter.
Need a female-female body?
Use the turnbuckle / hex-bar adjuster family when male rod ends must thread into a hollow body, or the tube adapter family when the adjuster is welded into structural tubing.
Applications
Where Jack Screws Perform
Precision length fine-tuning for high-load linkage systems.
Alignment & Preload
Fine adjustment of sway bar linkages, agricultural implement linkages, and control linkages where geometry is critical.
Motorsport Suspension
Chromoly JSX series is ideal for race car suspension adjustment links, steering tie-rods, and adjustable control arms.
Machinery Controls
Actuator rod-length tuning and machinery linkage setting in conveyor setups and packaging machinery.
FAQ
Common Questions
What is a jack screw used for?
To adjust the length of a rod-end linkage: thread a female-threaded rod end onto each male end of the jack screw, and turn the central body to lengthen or shorten the assembly, then lock with jam nuts.
Carbon steel or chromoly jack screw?
We offer JSI/JSI-M in standard carbon steel (zinc-plated) for general industrial adjusters, or JSX/JSX-M in high-strength chromoly steel for higher-load suspension or steering applications.
How is a jack screw different from a turnbuckle?
A jack screw is a compact male-male adjuster (rod ends screw onto it); a turnbuckle is a female-female hollow body (rod ends screw into it). Both use opposing right-hand and left-hand threads for adjustments on the vehicle.
Are jack screws available in inch and metric?
Yes. Inch JSI covers 10-32 through 1-12 in 30 standard sizes, while metric JSI-M covers M5×0.8 through M16×2.0 in 6 sizes.
Do I need jam nuts with a jack screw?
Yes. Jam nuts are required on both ends to lock the rod ends against the jack screw body. Without them, vibration will back the threads out, changing the linkage length and weakening the joint.
Engineering Tools
Calculators for This Product Family
Check engagement length for loaded threaded connections.
Factory Direct
Request a Jack Screw Quote
Send us your thread specs, material selection, and quantity requirements. We will provide pricing within 24 hours.