CNC Turned Alloy Steel Automotive Suspension Bolts
These are custom suspension bolts, shoulder bolts and pivot pins turned from alloy or carbon steel bar. Bearing shanks are ground or finish turned, threads are cut or rolled, and parts are heat treated and plated. They are made for automotive suspension, steering and chassis applications where a standard catalog bolt does not have the right shank length, diameter or head form.
- Material
- Carbon Steel
- Tolerance
- to ±0.005 mm
- MOQ
- 1 piece
- Prototype lead time
- 3–7 days
- 4140 chromoly or 1045 steel, heat treated
- Rolled threads available for fatigue-loaded bolts
- Precision shank diameters for bushing pivots
- Zinc plating or black oxide corrosion protection
Item ref. 1600078491834 ·
| Process | CNC turning, milling of heads, thread cutting or rolling, heat treatment |
|---|---|
| Materials | Alloy steel 4140, carbon steel 1045, stainless 304/316 |
| Surface Finish | Zinc plating (clear/blue), black oxide, nickel plating |
| Threads | Metric and UNC/UNF, 6g/2A class; gauge-checked |
| Tolerance | ±0.05 mm standard; down to ±0.005 mm on critical features |
| MOQ | 1 piece; prototypes through mid-volume runs |
| Drawing Formats | STEP, IGES, X_T, STL, DWG, DXF, PDF |
| Lead Time | Prototypes typically 3–7 working days; production usually 10–20 |
| Inspection | FAI, in-process checks, 100% critical dimensions; CMM |
Manufacturing
How we make this part
Process, material options and inspection for cnc turned alloy steel automotive suspension bolts.
Blanks are turned on CNC lathes with the shank, shoulder and thread relief formed in one setup, then hex or flange heads are milled. Threads are single-point turned for low volumes; for higher quantities they can be rolled, which keeps grain flow continuous and improves fatigue life. Shanks that act as bushing pivots are finished to a tight diameter and smooth surface.
4140 chromoly is the usual choice: quenched and tempered to roughly 28–38 HRC it gives high tensile strength and good toughness. 1045 is a lower-cost medium-carbon option for lightly loaded bolts. Stainless 304 or 316 suits corrosion-exposed hardware but is weaker unless hardened grades are used. Zinc plating with a clear or blue passivate, or black oxide with oil, are typical finishes.
Thread fit is checked with ring gauges, shank diameters with micrometers, and hardness is tested after heat treatment. Critical dimensions are inspected on each batch and reports can be provided. Applications include control arm pivot bolts, shock mounting bolts, leaf spring shackle bolts and steering linkage pins where an exact grip length matters.
FAQ
Frequently asked questions
What strength grade can your custom suspension bolts reach?
With 4140 steel quenched and tempered, bolts can be produced to properties comparable to property class 10.9 or 12.9, depending on the specified hardness. Please state the required grade or hardness range on the drawing. We confirm hardness after heat treatment and can supply test results with the shipment.
Do zinc-plated high-strength bolts need hydrogen embrittlement relief?
Yes. Electroplating can introduce hydrogen into steel, and bolts above roughly 39 HRC are at risk of delayed cracking. For hardened bolts, plating is followed by a baking step to drive the hydrogen out. If your design allows, black oxide or a zinc flake coating avoids the issue.
How do I get a quote for cnc turned alloy steel automotive suspension bolts?
Send a 3D model (STEP or IGES) and a 2D drawing with tolerances, material, finish and quantity through the quote form or by email. An engineer replies within 24 hours on business days with price, lead time and any DFM suggestions.
Request a quote
Quote this part
Attach drawings or send several parts at once from the full quote form.
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