To measure a trailer axle correctly, here are the key steps and measurements you should take:
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Measure Hub Face to Hub Face : This is the distance from the outside edge of one hub to the outside edge of the hub on the opposite side of the axle. This measurement is one of the most important and determines the overall length of the axle.
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Measure Spring Centers : Measure from the center of the spring seat on one side of the axle to the center of the spring seat on the other side. This ensures the new axle aligns properly with the trailer frame and suspension.
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If Hubs Are Missing : Measure from brake flange to brake flange, which are the flanges at the end of each axle where the hubs usually sit. Measure from the outside face of one flange to the outside face on the opposite side.
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Spring Center + Overhang Method : If the axle is bent or missing hubs, measure the distance between the centers of the two spring mounts (spring centers). Then measure the overhang from the spring center to the end of the axle where the hub mounts on one side. Calculate total hub face with this formula:
Spring Center + (Overhang × 2) = Hub Face Measurement -
Additional Space for Hub Based on Axle Capacity : Depending on the axle's weight capacity, you may need to add space for the hub:
- 2,000 lb axles: add 7 inches
- 3,500 lb axles: add 6 inches
- 6,000 to 8,000 lb axles: add 9 to 10 inches
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Measure Axle Beam Diameter : This helps determine axle weight capacity. For example, 3,500 lb axles use a 2 3/8 inch diameter tube, while heavier axles have larger diameters.
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Measure Bolt Pattern : Important for wheel compatibility. Common patterns vary by axle weight capacity and number of lug nuts.
To summarize, the two most critical measurements are the hub face length (outside edge to outside edge of the hubs or equivalent flange) and the spring center length (center of spring seats). These ensure you get an axle that fits correctly and supports the load safely. If you have bent or missing parts, alternative measurements like flange to flange or spring center plus overhang help estimate the right size accurately.
