Replacement Trailer Suspension Components


Hello, I am looking to replace rusted U bolts on my springs and also possibly replace the springs at the same time. #SP-038275 seems to be the matching size, style and capacity. However, my axle is attached below the springs, with some kind of angled bracket that holds the axle in place. I cant tell for sure but this seems to be welded to the under convex side of the bottom spring leaf. I have attached a couple pictures. Is this a separate piece or some kind of a specialty spring?


Expert Reply:

In a typical leaf spring trailer suspension a spring seat like # TRSS300 is welded to the axle but the u-bolt plate is not. The u-bolt plates are bolted around the axle and leaf spring and these hold the spring in place on the spring seat and to the axle, as noted on your photo. You can also refer to the linked article on slipper spring suspensions for more on the details of how these parts work together and on how to measure.

You'll want to completely remove one spring from the suspension to measure it. It is hard to get this dimension when the spring is still installed. New springs should be selected based on both size and on the axle weight rating. Note that springs tend to elongate when they are well worn so the correct new spring may measure slightly shorter than the one you remove. The linked article will help you. The slipper type spring # SP-038275 that you referenced is rated for 1800-lb axles and measure 30-inches form the center of the eye to the end of the spring.

U-bolt and plate kits appear on the linked page, such as kit # APUBR-10 which fits round axles that are 1-3/4-inches in diameter.

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expert reply by:
Adam R

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