Fitment Checked Girder Spring Fork for Custom Builds
Single Piece Order Available — Build your custom project without bulk minimums, with this custom girder spring fork available for individual purchase and fitment verification.
Product Specification
| Parameter | Value |
|---|---|
| Part Type | Girder Spring Fork |
| Finish | Chrome |
| Stem Diameter | 1″ |
| Axle Hole Diameter | 3/4″ |
| Top and Bottom Link Hole Size | 5/8″ |
| Length (Lower Triple Tree to Axle) | 36″ |
| Required Axle Length | 7-3/4″ |
| Axle Spacing (Outside to Outside) | 6-3/16″ |
| Axle Spacing (Inside to Inside) | 5-3/16″ |
Fitment
| Platform | Year Range | Notes |
|---|---|---|
| Custom builds | Confirm with model and year | Universal custom application; recreation of a 1975 design. Verify triple tree spacing and axle dimensions. |
Independent aftermarket part. Not manufactured, sold or endorsed by any motorcycle manufacturer. Model names and OEM numbers are used for fitment reference only.
Undefined Axle Spacing Ruins Taper Spring Function
Parallel Links Require Exact Triple Tree and Stem Spacing
I still remember a custom builder receiving a replica 1975 Durfee Girder Spring Fork that completely failed to compress. He assumed the 36-inch length was fine without checking the exact spacing. Because the triple trees were not spaced correctly, the fork links were not parallel, ruining the taper spring function [NEED_CITE: mechanical principles of parallel link suspension geometry]. Now I always verify the distance from the bottom of the lower tree to the axle position and check the 1-inch stem spacing before any custom girder spring fork leaves our bench.
Verifying Lower Tree to Axle Distance
When evaluating a custom girder spring fork for your build, the 36-inch measurement from the lower triple tree to the axle position dictates your front-end profile. This specific dimension determines how the front wheel sits relative to the frame neck. Measuring your existing setup or frame jig against this exact length ensures the visual proportions match your design intent without requiring mid-build modifications.
Checking Stem and Link Hole Dimensions
The 1-inch outer diameter stem and 5/8-inch top and bottom link holes define how this custom girder spring fork interfaces with your steering neck and linkage hardware. If your frame neck requires a different stem diameter, or if your linkage pins do not match the 5/8-inch specification, the unit will not mount correctly. Always compare these hole sizes against your frame drawings or physical measurements before finalizing the order [NEED_CITE: steering stem and linkage pin diameter variations across custom frames].
Interpreting Axle and Hub Spacing Requirements
This fork requires a specific 7-3/4-inch axle with a 3/4-inch diameter to match the 3/4-inch axle holes. The axle spacing is set at 6-3/16-inch outside to outside and 5-3/16-inch inside to inside. These measurements must align perfectly with your front hub width. If the hub spacing is wider or narrower than these specifications, the wheel will not seat properly between the sliders, leading to binding or unsafe alignment.
Hidden Costs of Incorrect Front-End Sizing
Ordering a front end without confirming the axle spacing or stem diameter often results in the bike sitting on the shop floor for weeks. Builders end up paying for custom machining to alter triple tree widths or sourcing new axles to match mismatched hub dimensions. When a custom girder spring fork arrives with the wrong stem spacing, the links bind, and the taper springs wear out prematurely, forcing a complete teardown and re-sourcing of hardware [NEED_CITE: shop labor costs associated with front-end fitment corrections].
Sourcing Front-End Depth for Custom Projects
We produce front-end and chassis parts in our own facility, allowing us to offer this custom girder spring fork with verified dimensions rather than unconfirmed catalog guesses. Our minimum order starts at one piece, meaning you can order a single unit for a one-off build without negotiating bulk quantities. Every unit is checked for the 36-inch length and 1-inch stem spacing to ensure the links will run parallel once installed on your specific neck.
Documentation and Fitment Verification
- Fitment sheet stating applicable platforms and confirming the 36-inch overall length.
- Cross-reference sheet with OEM numbers marked reference only for your records.
- Key dimensions detailing the 7-3/4-inch required axle and 5/8-inch link holes.
- Finish specification confirming the chrome plating details for your build.
- Quality inspection record verifying the axle spacing measurements before dispatch.
Receiving and Pre-Installation Checks
- Measure the 36-inch distance from the lower triple tree to the axle position upon arrival.
- Verify the 1-inch stem diameter and check for the included large spacer under the top tree.
- Confirm the 6-3/16-inch outside axle spacing matches your front hub width.
- Inspect the chrome finish for any transit damage before beginning assembly.
- Ensure the 5/8-inch link holes align freely with your linkage pins without force.
- Store the unit in a dry environment to protect the chrome and internal spring components.
Requesting a Fitment Check
Send your model and year, along with a photograph or measurements of your current triple tree spacing and hub width, so we can verify if this custom girder spring fork matches your geometry. Let us know if you need a sample for fitment confirmation before committing to your final build requirements. We will review your stem diameter and axle spacing needs to ensure the links stay parallel.
Frequently Asked Questions
Q: How do I measure the correct length for a custom springer fork on my build?
A: Measure the distance from the bottom of your lower triple tree to the center of the axle position. This custom girder spring fork has a 36-inch length in this specific area. Compare your frame measurement to this specification to ensure the front-end profile and ride height match your design goals.
Q: What axle dimensions and spacing are required for this specific girder fork?
A: You must use a 7-3/4-inch axle with a 3/4-inch diameter. The axle spacing is fixed at 6-3/16-inch outside to outside and 5-3/16-inch inside to inside. Verify these exact measurements against your front hub width to ensure the wheel seats correctly between the fork legs.
Q: How should the stem and triple trees be spaced to ensure the links stay parallel?
A: The stem must be spaced for your specific neck length, and the triple trees must be spaced correctly. A large spacer is included for under the top tree, but additional spacers may be required on the 1-inch outer diameter stem. Proper spacing keeps the fork links parallel for correct taper spring function.
Q: Can I order a single springer fork unit for a one-off custom project?
A: Yes, we support a minimum order from one piece. You can order a single custom girder spring fork for a one-off custom project without meeting bulk quantity requirements. We also offer sample supply for fitment confirmation before you proceed with larger orders.
Q: Are additional spacers included, or do I need to source them for my specific neck length?
A: A large spacer is included for under the top tree. However, additional spacers may be required on the 1-inch outer diameter stem depending on your specific neck length. You will need to verify your steering neck dimensions to determine if extra spacers must be sourced locally.