Chrome Girder Spring Fork 8.5″ Spacing – Fits Custom
In-house front-end production — Direct manufacturing of springer assemblies and chassis hardware ensures exact dimension control for custom builds.
Product Specification
Part Type | Girder Spring Fork Assembly
| Parameter | Value |
|---|---|
| Finish | Chrome |
| Construction | One-piece design, two halves with integrated handlebars |
| Lower tree to axle hole | 5/8″ |
| Top nut size | 7/8″ |
| Top stem thread | 7/8″-24 |
| Distance between mount holes | 8.5″ |
| Stem length between trees | 1″ |
| Under tree thread | 1″ x 24 |
Fitment
| Platform | Year Range | Notes |
|---|---|---|
| Custom motorcycles and custom builds | Confirm with model and year | Based on 1970’s girder spring fork design; verify frame mounting points. |
Independent aftermarket part. Not manufactured, sold or endorsed by any motorcycle manufacturer. Model names and OEM numbers are used for fitment reference only.
Why Critical Dimensions Dictate Girder Spring Fork Assembly Fitment
Missing stem thread and mount spacing data forces custom builders to guess frame compatibility.
When sourcing a girder spring fork assembly, buyers frequently encounter listings that omit the distance between top and bottom tree mount holes or the exact stem thread pitch. This forces shops to assume the triple tree spacing will match their frame. I have seen custom builds stalled for weeks because the 8.5-inch mount hole distance clashed with a frame designed for a wider or narrower spread. Without verifying the 7/8″-24 top stem thread and the 1″ x 24 under tree thread beforehand, the fork arrives and simply cannot be secured to the steering neck. [NEED_CITE: frame geometry variations across custom chopper builds]
Verifying Triple Tree Spacing for Custom Frames
Before ordering this girder spring fork assembly, you must measure the exact distance between the top and bottom tree mount holes on your frame. The 8.5-inch spacing on this unit is fixed due to the one-piece two-half construction. If your frame requires a different spread, the fork legs will not align, preventing the rockers from remaining parallel to the ground. Always cross-check this 8.5-inch measurement against your frame jig to avoid structural misalignment during the mock-up phase.
Confirming Stem Thread and Under Tree Pitch
The steering stem interface requires precise thread matching to secure the trees properly. This assembly features a 7/8″-24 top stem thread and a 1″ x 24 under tree thread. The 1-inch stem length between the triple trees dictates how much spacer material is needed to take up extra space in the neck. If your neck bearings or dust covers differ in thickness, the under tree lock nut will not engage correctly. Always confirm these thread pitches match your existing steering stem hardware before finalizing the order. [NEED_CITE: steering stem thread standards for custom front ends]
Understanding the Integrated Handlebar Construction
Unlike traditional springers that accept separate handlebars, this girder spring fork assembly is constructed of two halves with handlebars built in one length only. This one-piece design means the bar width, rise, and pullback are fixed and cannot be adjusted after assembly. The 5/8″ lower tree to axle hole dimension remains standard, but the integrated bars dictate your riding position. Buyers must verify that the built-in bar geometry suits their custom build ergonomics, as swapping to a different bar is not possible without replacing the entire front end.
The Hidden Cost of Unverified Mounting Dimensions
Ordering a front end without confirming the 8.5-inch mount hole distance often leads to expensive frame modifications. If the spacing is off by even a fraction of an inch, the fork legs bind, and the internal springs cannot function, leaving the rockers unable to stay parallel. Shops then face the choice of welding new mounts or returning the part. Furthermore, if the 7/8″-24 top stem thread does not match your neck, you cannot simply tap it; the entire stem must be re-machined or replaced. These fitment failures turn a straightforward installation into a major fabrication project. [NEED_CITE: fabrication costs associated with incorrect triple tree spacing]
Sourcing Directly from the Front-End Specialist
We manufacture this girder spring fork assembly in our own facility, allowing us to control the chrome finish consistency and the 8.5-inch mount spacing directly. Our front-end depth means you get a complete assembly with integrated handlebars, rather than piecing together separate components. We offer a single piece minimum order, so custom builders can purchase one unit for a specific project without meeting high volume quotas. Every unit is checked against the 7/8″-24 top stem thread and 1″ x 24 under tree thread specifications before dispatch.
Documentation Provided with Your Shipment
- Fitment sheet listing custom platforms and confirming the 8.5-inch mount spacing.
- Key dimensions sheet detailing the 7/8″-24 top stem thread and 1″ x 24 under tree thread.
- Chrome finish specification and quality inspection record for the integrated handlebars.
- Cross-reference sheet for steering stem hardware marked reference only.
- Packing photographs showing the one-piece two-half construction and 5/8″ axle hole.
Receiving and Pre-Installation Checks
- Measure the 8.5-inch distance between top and bottom tree mount holes against your frame.
- Verify the 7/8″-24 top stem thread and 1″ x 24 under tree thread match your neck.
- Check the 5/8″ lower tree to axle hole dimension for axle and wheel compatibility.
- Inspect the chrome finish on the one-piece two-half construction for shipping damage.
- Ensure the integrated handlebars are straight and the 1-inch stem length is unobstructed.
- Store the assembly in a dry environment to protect the chrome and internal springs.
Requesting a Fitment Check Before Ordering
Send us your frame model, year, and a photograph of your current triple tree spacing to verify if the 8.5-inch mount hole distance matches your build. If you are unsure about the steering stem requirements, provide the top stem thread and under tree thread pitch from your existing hardware. We can also supply a sample unit for fitment confirmation before you commit to a bulk order for your shop. Let us check the dimensions to ensure this girder spring fork assembly drops straight into your custom project.
Frequently Asked Questions
Q: How do I measure the distance between the top and bottom tree mount holes?
A: Measure the center-to-center distance from the top mounting hole to the bottom mounting hole on your frame’s triple tree area. Compare this directly to the 8.5-inch spacing of this girder spring fork assembly. If your frame spacing differs, the fork legs will not align, and the rockers will not remain parallel to the ground during suspension travel.
Q: What stem thread sizes must I check before ordering this fork?
A: You must verify both the top stem thread and the under tree thread. This assembly requires a 7/8″-24 top stem thread and a 1″ x 24 under tree thread. The under tree lock nut installs on top of the bearing dust cover, so ensure your dust cover thickness works with the 1-inch stem length between the triple trees.
Q: How do I determine the correct spacer length needed for the stem?
A: Installation requires adding spacers to the stem to take up extra space in the steering neck. Measure the total length of the steering neck and subtract the 1-inch stem length between the triple trees, plus the thickness of your bearing dust cover and lock nut. This calculation gives the exact spacer length needed to secure the assembly without binding.
Q: Are the acorn top nut and bearing dust cover included in the fork assembly?
A: The acorn top nut is available separately and is not included in the base fork assembly. The under tree lock nut installs on top of the bearing dust cover, which is also sourced separately. You must ensure your existing dust cover and lock nut match the 1″ x 24 under tree thread before finalizing your steering neck hardware setup.
Q: Can I place a single piece order for a custom build project?
A: Yes, we support a single piece minimum order for custom builders and shops. You do not need to meet high volume quotas to purchase this girder spring fork assembly. We provide a fitment sheet and key dimensions documentation even for single-unit orders to ensure the 8.5-inch mount spacing and stem threads match your specific frame before dispatch.