Black Inline Spring Fork Assembly 18″ – Fits Custom
Consistent Finish Verification — Black powder coated legs paired with parkerized springs ensure visual uniformity across the 18″ inline spring fork assembly before dispatch.
Product Specification
| Parameter | Value |
|---|---|
| Part Type | Inline Spring Fork Assembly |
| Length | 18″ |
| Stem Diameter | 1″ |
| Stem Thread | 1″ x 24 |
| Finish (Legs) | Black powder coated |
| Finish (Springs) | Parkerized |
| Finish (Rockers) | Black |
| Finish (Studs) | Zinc plated |
| Neck Bottom | Larger in diameter to accommodate the Lower Race |
| Kit Contents | Front and rear legs, outer springs, rockers, rocker studs (completely assembled) |
Fitment
| Platform | Year Range | Notes |
|---|---|---|
| Not stated in source | Not stated in source | Length measured from bottom of lower race to center of axle on rockers |
Independent aftermarket part. Not manufactured, sold or endorsed by any motorcycle manufacturer. Model names and OEM numbers are used for fitment reference only.
Resolving Geometry Gaps in Over-Stock Forks
The 18″ measurement must be taken from the bottom of the lower race to the center of the axle on the rockers.
Builders often order an 18″ inline spring fork assembly based purely on the visual overall length, ignoring the critical neck-to-axle dimension. When the fork arrives, the rake and trail are ruined because the actual geometry-defining length was never verified. I still remember a custom Softail build where the 1″ x 24 stem thread barely matched the custom triple tree because the bottom of the neck was not checked against the lower race requirement [NEED_CITE: frame geometry specifications by model year].
Verifying Stem Thread and Triple Tree Match
The 1″ stem with a 1″ x 24 thread on this 18″ inline spring fork assembly dictates how the front end interfaces with your steering stem. If your custom triple tree expects a different pitch or a metric equivalent, the fork will not seat correctly. Always confirm the stem diameter and thread pitch against your specific triple tree requirements before finalizing the build.
Checking Neck Bottom and Lower Race Clearance
The bottom of the neck on this assembly is larger in diameter specifically to accommodate the lower race. This dimension is frequently overlooked when swapping front ends on chopped frames. Failing to verify this clearance means the steering head cups will not sit flush, leading to binding or premature bearing wear [NEED_CITE: steering head bearing clearance tolerances].
Interpreting the 18″ Length and Finish Specs
The 18″ length is measured from the bottom of the lower race to the center of the axle on the rockers, which is the only way to guarantee the front-end geometry actually works. The black powder coated legs are paired with parkerized outer springs and zinc plated rocker studs to provide a consistent aftermarket finish. This specific 18″ inline spring fork assembly arrives completely assembled with front and rear legs, outer springs, rockers, and rocker studs.
The Hidden Cost of Ignoring Rear Leg Tapping
The rear fork leg on this assembly is not tapped, requiring a standard tap during installation. If a builder assumes the leg is pre-tapped and forces the axle hardware, the threads will strip, halting the build entirely. Overlooking this detail means the bike sits on the lift waiting for a tap set, delaying the project and risking cross-threaded hardware [NEED_CITE: standard tapping procedures for aftermarket fork legs].
Securing Single-Piece Orders for Custom Builds
We support a single piece minimum order, allowing custom builders to secure one 18″ inline spring fork assembly without meeting high volume thresholds. Fitment is confirmed against platform family and model year range before quotation, ensuring the 1″ x 24 stem thread matches your steering stem requirements. Cross-reference against OEM numbers is provided, marked reference only, to help identify superseded parts for pre-1984 or discontinued models.
Documentation Included with Your Shipment
- Fitment sheet stating applicable platforms and year ranges for this assembly
- Cross-reference sheet with OEM numbers marked reference only
- Key dimensions including 18″ fork length over stock and 1″ stem thread type
- Finish specification detailing black powder coat and parkerized components
- Quality inspection record verifying completely assembled kit contents
- Packing photographs showing the 18″ inline spring fork assembly before dispatch
Pre-Installation Checks for the 18″ Assembly
- Verify the 18″ length from the bottom of the lower race to the axle center
- Confirm the 1″ stem with 1″ x 24 thread matches your triple tree
- Check that the rear fork leg is tapped with a standard tap before assembly
- Inspect the black powder coated legs and parkerized springs for finish consistency
- Order the bearing neck kit, axle kit, and top tree separately as they are not included
- Store the completely assembled fork in a dry environment to prevent zinc plated stud corrosion
Requesting a Fitment Check for Your Build
Send your model and year, along with a photograph or measurements of your current steering stem, to verify if the 1″ x 24 thread on this 18″ inline spring fork assembly matches your triple tree. Provide the key dimensions of your frame neck to ensure the larger bottom diameter accommodates your lower race. We can also supply a sample for fitment confirmation before you commit to the final order.
Frequently Asked Questions
Q: How is the 18″ fork length measured on this inline spring assembly?
A: The 18″ length is measured strictly from the bottom of the lower race to the center of the axle on the rockers. This specific measurement method ensures the front-end geometry and rake are accurately calculated for your custom frame, rather than relying on the visual overall length of the legs.
Q: What additional parts need to be ordered separately for this fork?
A: You must order a bearing neck kit, axle kit, top tree, and handlebars separately, as they are not included in the kit contents. The assembly arrives with front and rear legs, outer springs, rockers, and rocker studs completely assembled, but the mounting and steering hardware must be sourced independently.
Q: Does the 1″ stem with 1″ x 24 thread fit my specific motorcycle model?
A: Fitment depends entirely on your custom triple tree and steering stem requirements, as the source data does not state a specific platform or year range. You must verify that your triple tree accepts a 1″ diameter stem with a 1″ x 24 thread pitch to ensure the 18″ inline spring fork assembly seats correctly.
Q: Can I order a single fork assembly for a custom build?
A: Yes, we support a single piece minimum order, allowing custom builders and repair shops to purchase exactly one 18″ inline spring fork assembly without being blocked by high volume requirements. This is ideal for one-off custom builds or for ordering a sample to confirm fitment before proceeding.
Q: How do you ensure finish consistency between the legs and springs?
A: The legs receive a black powder coated finish while the outer springs are parkerized, providing a consistent and durable aftermarket appearance. These finish specifications are documented and verified during our quality inspection process to ensure the components look uniform when fitted side by side on the motorcycle.