Girder Spring Fork Assembly for Custom Motorcycles – Single Piece Order
One-Piece Minimum Order — We supply this girder spring fork assembly for custom motorcycles as a single unit, allowing shops building one bike to order exactly what they need without bulk commitments.
Product Specification
| Parameter | Value |
|---|---|
| Part Type | Girder Spring Fork Assembly |
| Finish | Chrome |
| Lower tree to axle hole | 5/8″ |
| Top nut | 7/8″ |
| Top stem thread | 7/8″-24 |
| Under tree thread | 1″ x 24 |
| Stem length between triple trees | 1″ |
| Distance between top and bottom tree mount holes | 8.5″ |
| Design | One-piece design, constructed of two halves with handlebars built in one length |
Fitment
| Platform | Year Range | Notes |
|---|---|---|
| Custom motorcycles and chopper builds | Confirm with model and year | Verify frame neck spacing matches the 8.5″ mount hole distance. |
Independent aftermarket part. Not manufactured, sold or endorsed by any motorcycle manufacturer. Model names and OEM numbers are used for fitment reference only.
Verifying Triple Tree Spacing for a Girder Spring Fork Assembly for Custom Motorcycles
Always measure the top and bottom tree mount holes and stem length before confirming fitment.
Custom springer and girder forks often lack clear statements on overall length, tree mount spacing, and stem dimensions, making it difficult to judge ride height and steering geometry before purchase. When the 8.5″ distance between top and bottom tree mount holes does not match the frame neck, the fork binds or wobbles. I once saw a builder order a custom springer fork for a 1970s style build without checking the triple tree spacing. The 8.5-inch mount hole distance and 1-inch stem spacing did not match his trees, forcing him to machine spacers just to make it fit [NEED_CITE: frame neck geometry variations across custom chopper builds].
Checking the 8.5-Inch Mount Hole Distance
When evaluating a girder spring fork assembly for custom motorcycles, the 8.5″ distance between top and bottom tree mount holes dictates whether the fork will seat correctly in your frame neck. If the frame neck is narrower, the trees will pinch the steering stem; if wider, the steering head bearings will lack preload. You must measure your frame neck directly rather than relying on generic chopper specifications [NEED_CITE: steering head neck width tolerances in aftermarket frames].
Matching Stem Threads and Lengths
The top stem thread (7/8″-24) and under tree thread (1″ x 24) must align perfectly with your triple trees and steering stem. Furthermore, the 1″ stem length between triple trees often requires adding spacers to take up extra space in the steering head. The trees must remain parallel as determined by the mounting on the fork legs to ensure smooth steering action [NEED_CITE: steering stem thread pitch standards for custom front ends].
The Hidden Cost of Incorrect Fork Dimensions
Ordering a front end without verifying the 8.5″ tree mount spacing or the 1″ stem length means the bike sits on the lift while you figure out a workaround. Shops end up machining custom spacers, re-tapping threads, or returning the part, which delays the build and adds unexpected machine shop costs. A mismatched girder spring fork assembly for custom motorcycles turns a straightforward installation into a fabrication project.
Sourcing Front Ends with Fitment Certainty
We confirm the 8.5″ distance between top and bottom tree mount holes and the 1″ stem length against your frame specifications before quotation. This girder spring fork assembly for custom motorcycles is produced with consistent chrome plating across batches, ensuring the two halves match visually when assembled. You can order a single piece to confirm the fitment on your jig before committing to a larger batch for your shop.
Documentation Provided
- Fitment sheet stating the custom motorcycle platforms and year ranges checked
- Key dimensions sheet listing the 8.5″ tree mount spacing and stem threads
- Finish specification detailing the chrome plating process and thickness
- Quality inspection record verifying the one-piece design and handlebar alignment
- Packing photographs showing the fork assembly secured for transit
Receiving and Pre-Installation Checks
- Measure the 8.5″ distance between top and bottom tree mount holes upon arrival to verify shipping accuracy.
- Check the 7/8″-24 top stem thread and 1″ x 24 under tree thread for any transit damage.
- Inspect the chrome finish on both halves of the one-piece design for consistency and plating defects.
- Verify the 5/8″ lower tree to axle hole and 7/8″ top nut dimensions match your hardware.
- Have a qualified technician inspect the internal spring suspension and rocker parallelism before mounting.
- Store the assembly in a dry environment to protect the chrome finish and internal components.
Requesting a Fitment Check
Send your frame neck measurements, specifically the 8.5″ tree mount spacing requirement, along with your triple tree stem thread specs. Provide photos of your current steering head or old fork if the dimensions are unknown. Let us know if you need a single unit or a sample to confirm the fitment on your custom build before placing a bulk order.
Frequently Asked Questions
Q: How do I measure the triple tree mount spacing for this fork?
A: Measure the exact distance between the center of the top mounting hole and the center of the bottom mounting hole on your frame neck. This measurement must match the 8.5″ distance between top and bottom tree mount holes on the fork to ensure the trees sit parallel and the steering stem is not pinched or left loose.
Q: What should I do about the 1-inch stem length between triple trees?
A: The 1″ stem length between triple trees is designed to accommodate frames with specific steering head heights. If your frame neck is taller, you will need to add spacers to the stem to take up the extra space. The under tree lock nut then installs on top of the bearing dust cover to secure the assembly.
Q: Can I order a single fork assembly for a one-off custom build?
A: Yes, we support a one-piece minimum order. This allows custom builders and chopper shops to purchase a single girder spring fork assembly for custom motorcycles without meeting high bulk thresholds. You can also request a sample to confirm the 8.5″ spacing and chrome finish on your jig before ordering more.
Q: How is the chrome finish consistency maintained across batches?
A: Our front-end lines undergo strict quality control to ensure the chrome finish remains consistent between batches. When you order this one-piece design constructed of two halves, both halves are processed together, preventing visible color or plating differences once the fork is fitted side by side on the bike.