Thread Diameter
The nominal size of the bolt family. This is what determines the matching hole and hardware size.
How: Measure across the widest outside edge of the threaded shaft — not the bolt head. Use calipers if you have them.
How to Measure Metric Hardware Before You Order
Before you order custom hardware, confirm three measurements: thread diameter, thread pitch, and thread length.
Use a metric ruler, calipers, a thread checker, or a JDC bolt gauge to match your original hardware as closely as possible. Once you know the size, you can use the JDC Kit Builder to choose the section, head style, finish, and quantity you need.
Watch the Measuring Tutorial
Need a visual walkthrough before ordering custom hardware?
This video walks through bolt diameter, thread pitch, thread length, nuts, and washers so you can order the correct size the first time.
Measure Your Hardware
Check out this guide to identify thread diameter, thread pitch, and thread length before assembling your custom hardware kit.
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Diameter
Pitch
Length
Thread Pitch
The distance between threads. Bolts can share the same diameter but use different pitch.
How: Measure peak-to-peak between two adjacent threads. A pitch gauge is ideal; calipers also work on a clean bolt.
Thread Length
How far the bolt reaches into the assembly. Measure with the bolt out, not installed.
Length note: For most bolts, measure from the underside of the head to the end of the threaded shaft. Countersunk bolts are measured differently because the head sits into the surface.
Measurement checklist
Confirm thread diameter, thread pitch, and thread length before choosing replacement hardware.
Before you order
Whenever possible, measure the original hardware outside the vehicle and confirm the pitch before tightening.
Ready to build?
Use your confirmed measurements in the JDC Kit Builder to choose the section, bolt style, finish, and quantity.
Ready to build?
Open Kit Builder
Use your measurements in the JDC Kit Builder
Once you know the diameter, pitch, and length, open the kit builder to choose your section, bolt style, finish, and quantity.
What About Nuts & Washers?
Nuts match the bolt diameter and thread pitch. Washers match the bolt diameter, but the outside diameter depends on the area you need to cover.
If you already removed the original bolt, use it as the reference when choosing the matching nut or washer.
Common JDC Bolt Head Styles
Use this as a quick visual reference before choosing replacement hardware in the kit builder.
- Flush-Fit Allen Head: low-profile custom finish
- Allen Head: clean socket-head style with strong tool engagement
- Flush-Fit Hex Flange: flush look with flange-style seating
- Hex Flange: OEM-inspired fit with a built-in washer surface
- Button Head: rounded, low-profile appearance
- Countersunk: sits into a chamfered or countersunk surface
Tools That Make Measuring Easier
Want to double-check your measurements?
These tools help confirm thread diameter, pitch, and length before you order custom hardware.
ボルト・ネジ測定ゲージツール
$ 15.00
JDC ビレット アルミ ボルト ゲージ - ボルトの測定に役立つ完璧なツールです。
$ 40.00
JDC チタン ボルト ゲージ - ボルトの測定に役立つ完璧なツールです。
販売価格$ 100.00通常価格
$ 140.00