Consistent Wall · Superior Strength · Excellent Concentricity
Chromoly DOM Tubing
4130 chromoly drawn over mandrel — the tube fabricators reach for when a link has to be strong, light and weldable. SYZ supplies 23 standard cut-to-length sizes ready to pair with SYZ tube adapters and rod ends, plus custom OD, wall, shape and length for racing chassis, off-road suspension and OEM tube programs.
Material & Process
What Is DOM Tubing?
DOM (Drawn Over Mandrel) tubing is steel tube finished by a precision cold-drawing pass over a mandrel. The draw removes the weld flash, works the inner and outer surfaces, and leaves a smooth finish, uniform wall thickness and exceptional dimensional accuracy — which is exactly what you want when a tube has to slide over a stepped adapter and weld up concentric.
Standard DOM can be made from plain carbon steel such as 1020 or 1026. Our production focuses on 4130 chromoly DOM tubing — lighter for its strength, higher in tensile capability and far better in fatigue resistance. That is what makes it the default for racing chassis, off-road roll cages and other performance-critical structures rather than general mechanical duty.
Buyers search for this material under both names: “chromoly tubing” describes the alloy, “DOM tubing” describes how it was made. They are not alternatives to each other — SYZ tubing is both.
DOM is a process, not a material. This trips up a lot of quotes. “DOM” tells you the tube was drawn over a mandrel; it tells you nothing about the alloy. Ask any supplier which grade their DOM is — ours is specifically 4130 chromoly alloy steel, which is what gives the weldability, toughness and tolerance combination the spec sheets below describe.
DOM is also not seamless. DOM starts life as an electric-resistance-welded (ERW) tube and is then cold drawn, which works the seam until it is practically invisible and brings the weld area up to full tube strength. It is frequently miscalled “seamless” — it is not, and honest suppliers say so. For most chassis and linkage work that distinction does not hurt you; where a sanctioning body’s rulebook specifies the tube type, check the wording before you order.
ERW vs DOM vs Seamless how the three tube types actually differ
| Tube Type | How It Is Made | Seam | Dimensional Control | Typical Use |
|---|---|---|---|---|
| ERW | Strip roll-formed and electric-resistance welded, no further drawing | Visible weld seam, flash may remain inside | Loosest | General structural and non-critical fabrication |
| DOM | ERW tube cold drawn over a mandrel — flash removed, wall and bore worked | Seam worked until practically invisible, strength restored | Tightest of the three, smooth bore | Suspension links, cages, cylinders, machined tube parts |
| Seamless | Pierced or extruded from a solid billet | None | Varies — needs further cold drawing to match DOM | Pressure duty and applications where a seam is disallowed |
General industry definitions, provided so you can compare quotes on a like-for-like basis. SYZ supplies the DOM row in 4130 chromoly; other grades and processes are available on a project basis.
Why Chromoly
Why Chromoly DOM Rather Than Carbon DOM?
Combining DOM precision with chromoly’s strength-to-weight ratio is what makes the difference on racing, off-road and structural builds.
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High Tensile & Yield StrengthWithstands demanding loads and structural stress without stepping up to a heavier wall.
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Lightweight but StrongA better strength-to-weight ratio than carbon steel DOM — the reason it dominates motorsport fabrication.
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Excellent Weldability & DuctilitySuited to precision TIG welding, bending and forming — see the fabrication guide below for filler and procedure notes.
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Superior Fatigue & Impact ResistanceHolds integrity under repeated stress and impact — the failure mode that actually kills suspension links.
| Feature | Carbon DOM | Chromoly DOM |
|---|---|---|
| Strength | Standard | Higher tensile and yield strength |
| Weight | Heavier | Lighter at equal or higher strength |
| Fatigue Resistance | Moderate | Excellent |
| Application | General mechanical use | Racing / off-road / performance builds |
Carbon DOM (1020 / 1026) remains available on request where cost matters more than weight — tell us the application and we will quote the grade that fits.
Sizes & Specifications
Standard Program and Custom Capability
Two ways to buy. The CMT standard program is stocked geometry cut to length, ready to pair with SYZ tube adapters — order by part number. Beyond that, our tube mill and machining capability covers a wider envelope of diameters, walls, shapes and lengths on a made-to-order basis.
1020 / 1026 carbon on request
oval · D-shaped · tapered
CMT Series — All 23 Standard Sizes 4130 chromoly · cut to length · dimensions in inches
| Part Number | Tubing OD × Wall | ID (calculated) | Length Range | Weight Range |
|---|---|---|---|---|
| CMT-6-058 | 0.375 × 0.058 | 0.259 | 6.0 – 50.0 | 0.116 – 0.928 |
| CMT-8-058 | 0.500 × 0.058 | 0.384 | 6.0 – 50.0 | 0.155 – 1.240 |
| CMT-8-065 | 0.500 × 0.065 | 0.370 | 6.0 – 50.0 | 0.173 – 1.384 |
| CMT-10-058 | 0.625 × 0.058 | 0.509 | 6.0 – 50.0 | 0.193 – 1.634 |
| CMT-10-065 | 0.625 × 0.065 | 0.495 | 6.0 – 50.0 | 0.217 – 1.736 |
| CMT-12-058 | 0.750 × 0.058 | 0.634 | 6.0 – 50.0 | 0.232 – 1.856 |
| CMT-12-065 | 0.750 × 0.065 | 0.620 | 6.0 – 50.0 | 0.260 – 2.080 |
| CMT-12-095 | 0.750 × 0.095 | 0.560 | 6.0 – 50.0 | 0.380 – 3.040 |
| CMT-12-125 | 0.750 × 0.125 | 0.500 | 6.0 – 50.0 | 0.480 – 3.840 |
| CMT-14-058 | 0.875 × 0.058 | 0.759 | 6.0 – 50.0 | 0.271 – 2.168 |
| CMT-14-065 | 0.875 × 0.065 | 0.745 | 6.0 – 50.0 | 0.304 – 2.432 |
| CMT-14-083 | 0.875 × 0.083 | 0.709 | 6.0 – 50.0 | 0.388 – 3.104 |
| CMT-16-058 | 1.000 × 0.058 | 0.884 | 6.0 – 50.0 | 0.310 – 2.480 |
| CMT-16-065 | 1.000 × 0.065 | 0.870 | 6.0 – 50.0 | 0.347 – 3.123 |
| CMT-16-083 | 1.000 × 0.083 | 0.834 | 6.0 – 50.0 | 0.443 – 3.544 |
| CMT-16-095 | 1.000 × 0.095 | 0.810 | 6.0 – 50.0 | 0.507 – 4.056 |
| CMT-18-058 | 1.125 × 0.058 | 1.009 | 6.0 – 50.0 | 0.348 – 2.784 |
| CMT-18-083 | 1.125 × 0.083 | 0.959 | 6.0 – 50.0 | 0.498 – 3.984 |
| CMT-18-095 | 1.125 × 0.095 | 0.935 | 6.0 – 50.0 | 0.571 – 4.568 |
| CMT-20-058 | 1.250 × 0.058 | 1.134 | 6.0 – 50.0 | 0.388 – 3.104 |
| CMT-20-065 | 1.250 × 0.065 | 1.120 | 6.0 – 50.0 | 0.434 – 3.472 |
| CMT-20-095 | 1.250 × 0.095 | 1.060 | 6.0 – 50.0 | 0.634 – 5.072 |
| CMT-22-120 | 1.375 × 0.120 | 1.135 | 6.0 – 50.0 | 0.881 – 7.048 |
Material: 4130 chromoly steel (4140 and 4340 available on a project basis). Cut length tolerance ±.090″. The ID column is calculated as OD − 2 × wall — use it to match the stepped OD of a weld-in tube adapter. Weight range is per the size chart across the 6″–50″ cut range. Special sizes available; see the full spec page to filter and quote by part number.
Popular Heavy-Wall Round Sizes made-to-order, beyond the CMT stock range
| OD | Wall | ID |
|---|---|---|
| 1″ | .120″ | .760″ |
| 1-1/4″ | .120″ | 1.010″ |
| 1-1/2″ | .120″ | 1.260″ |
| 1-1/2″ | 1/4″ | 1.000″ |
| 1-3/4″ | .120″ | 1.510″ |
| 2″ | .120″ | 1.760″ |
| 2″ | 1/4″ | 1.500″ |
| 2-1/2″ | 1/4″ | 2.000″ |
The sizes fabricators ask for most once they go past the standard program — cage tube, heavy 4-link and radius arm stock.
Tube Shapes
Most DOM tubing is round: it gives the best torsional strength and the most uniform wall, which is why it is the default for suspension arms, roll cages and chassis structures. Square and rectangular DOM is available for frames, supports and mounting assemblies. For special applications, oval, D-shaped and tapered profiles can be produced through secondary forming or CNC machining on request.
Build Guide
Weld-Up Linkage Fabrication Guide
Chromoly tubing is the structural body of a linkage. Here is how to spec and build a complete adjustable link.
- 01
Size the System Together
Pick the rod end thread size first. Then select a tube adapter whose stepped outer diameter matches the tube’s inner diameter — ID = OD − 2 × wall, and the ID column in the table above already does that arithmetic for every standard size. A tight sliding fit is what gives you a concentric, strong weld.
- 02
Leave Adjustment Range
Cut the tube so there is still full thread engagement inside the adapters at both your shortest and your longest setting. Standard practice is an opposing RH/LH thread pair so the link adjusts on the vehicle like a turnbuckle — then lock it with a jam nut at each end.
- 03
Remove Bearings Before Welding
Always back the rod ends out before welding the adapters. Weld heat ruins the heat treatment of the ball socket and destroys PTFE self-lubricating liners. Thread them back in only after the metal has cooled.
- 04
Weld It Properly
4130 is normally supplied and fabricated in the normalized condition and TIG welds cleanly. Filler choice matters: a mild-steel filler such as ER70S-2 gives a ductile, forgiving weld and is the usual pick for cages and chassis; a higher-strength filler such as ER80S-D2 is used where more joint strength is wanted. Avoid 4130 filler rod unless the assembly will actually be heat treated after welding — it produces a hard, crack-sensitive weld. Let the joint cool slowly and do not quench it.
Wall thickness decisions: wall is the primary lever for impact resistance and buckling. Go heavy (.120″ and up) for severe off-road suspension links; stay light (.058″ or .095″) to save weight on throttle rods, shifter linkage and light-duty control rods.
Wrench hex flats: round tube gives a wrench nothing to grip. Welding on a weld-on wrench hex makes adjustment far easier once the link is installed on the vehicle.
Check the rulebook first: sanctioning bodies commonly specify seamless or DOM tube for roll cages and prohibit plain ERW, and they often set minimum OD and wall by vehicle weight. Confirm the class rules before you cut — it is a cheap step that saves a rebuild.
Applications
Where Chromoly DOM Tubing Performs
High-stress suspension linkage, safety structures, custom automotive builds and repeat OEM tube supply.
Suspension Link Fabrication
4-link systems, radius arms, track bars, panhard rods, braces and threaded tube assemblies — anywhere strength-to-weight ratio decides the design.
Roll Cages & Safety Structures
A standard material choice for roll cages, cage extensions, gusseted tube structures and motorsport safety fabrication that depends on 4130 chromoly performance.
Steering & Tie-Rod Tubes
Steering links, tie-rod tubes, sway bar end links and adjustment assemblies where clean tube geometry and weld-ready material simplify production.
Agricultural Fabrication
Fabricated agricultural machine structures, implement linkages and brackets that need strong, consistent, cut-to-length steel tube supply season after season.
Industrial Frames & Fixtures
Machine frames, fixtures and structural weldments where consistent outside diameter and wall thickness are a production requirement rather than a nicety.
OEM Tube Supply Programs
Repeat tube dimensions, controlled cut lengths and project-based special sizes — with the machining, bending and finishing handled before it ships.
Beyond Tubing
One-Stop Processing & Manufacturing
Innovation does not come from following the standard — it comes from setting it. Plenty of engineering problems need tubing that is not in anyone’s catalogue, so we develop it with you: performance, weight or assembly simplicity, from prototype to mass production.
In-House Processing
CNC cutting, bending, machining and welding — the tube arrives ready to assemble rather than ready to re-work.
Prototype to Mass Production
Engineering support from drawings or physical samples, with reverse engineering where no drawing exists. One supplier from first article through repeat orders.
Finishing & Assembly
Surface finishing, plating and coating plus sub-assembly service, so the tube ships as a finished part in your packaging. OEM / ODM projects welcome.
Everything Else the Link Needs
Beyond the Part
Engineering, OEM & Delivery Support
From concept to container, the technical and commercial support that lets a tube drop straight into your product.
Accelerate development with the technical data you need to integrate and validate with confidence.
- PDF datasheets for every series and size
- 3D STEP files for instant CAD integration
- 2D CAD drawings (DWG, DXF) for detailing
From concept to global delivery, in five stages.
- Requirement analysis — application, performance metrics, target cost
- Design & 3D modeling — ideas into CAD drawings and models
- Prototyping & validation — rapid samples, fit and function testing
- Tooling & mass production — approved sample to volume
- Quality assurance — inspection at every stage
Products that arrive safe, secure and ready for your market.
- White-label box packaging — clean, brand-ready
- Multi-language manuals for global end users
- Tailored logistics with reliable worldwide support
About SYZ Rod Ends
Precision Manufacturing Since 1999
We specialise in durable, high-performance custom metal components for demanding industrial and automotive applications. Our own facility in Ningbo, together with two closely-affiliated production bases in Jiangsu, runs advanced CNC machining centres, heat-treatment lines and automated inspection systems, so every part meets strict performance, reliability and safety standards under ISO 9001:2015 certification (Cert. No. 11425Q49262R0S).
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FAQ
Common Questions
What is the difference between chromoly tubing and DOM tubing?
Is DOM tubing seamless?
What sizes of chromoly tubing are available?
What materials are available for DOM tubing?
Is chromoly tubing weldable?
What wall thickness should I use for off-road suspension?
Can you cut tubing to a custom length?
Can I order custom tube shapes such as square or oval?
Can you produce tubing to my drawings or samples?
Do you provide surface treatment or finishing options?
What documents and quality reports can you provide?
How do I match tubing to a tube adapter?
Factory Direct
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Specify your OD, wall thickness, cut length and quantity — or send a drawing. We come back within 24 hours with pricing and lead time.