Difference Between 3-Leaf and 4-Leaf Leaf Springs

Question

Question:

My boat trailer currently is using 3 leaf springs and I’m replacing them with your 4 leaf springs. What difference will I notice? I’ve broken a few 3 leaf in the past

asked by: John C

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Expert Reply:

The only real difference between your current 3-leaf springs and the 4-Leaf Double-Eye Spring for 3,500-lb Trailer Axles - 27" Long # SP-210275 will be the thickness of the leaf spring stack. This will be 3/8" thicker when compared to what you have now. It may be possible that with the additional material and thickness they will hold up a little better and last longer. Overall though, they have the same capacity regardless of the number of leaves.

expert reply by: Robin H

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Answer 1

You need to use square U-Bolts with having a square axle tube. Trying to use round U-Bolts you risk damaging both the bolts and the axle as it creates pressure points rather than distributing the load across the surface. We have a few different…

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Answer 2

The varying heights of the hangers is all designed so that you end up with the leaf springs as level as possible and still end up a desired distance away from the trailer frame. It may seem odd, but the center hanger will stick down further because…

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Answer 3

Front and rear suspension hangers are not often the same height like this but they can be. If you have the hanger spacing right then what will happen is the center of the spring will be offset a little between the two hangers to compensate some for…

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Answer 4

Ff the springs you are installing are 25-1/4 inches, you would need to place the hangers between 24-3/4 and 25 inches apart. The shackle should be angled as the drawing shows in the attached helpful article, which should be toward the rear of the…

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Answer 5

Since your axle is mounted on top of the leaf spring you will want between 2 and 2-1/2 inches between the top of the axle and the trailer frame. You will also want 3 inches of clearance between the top of the tire and the fender. Check out the FAQ…

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Answer 6

The trailer will have a plate or sticker on it that will list the VIN number. The weight rating of the axle should be listed on that same plate or sticker. Also, the axle could have a tag or plate on it that will list the weight capacity. You can…

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Answer 7

Often an axle's weight rating will appear on a sticker or plate on the axle beam itself, or sometimes the trailer's main identification sticker will include axle ratings. This is helpful unless of course the axles have been replaced during…

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Answer 8

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 9

To find the load capacity for your axle you should look on the trailer VIN plate or sticker that lists the VIN number. The weight rating of the axle should be listed on that same plate or sticker. Also, the axle could have a tag or plate on it that…

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Answer 10

Thank you for providing the specs for the suspension components that you already have. Correct hanger spacing really depends on the components being used such as springs, hangers and equalizers. Most of the hanger spacing dimensions that we have are…

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Answer 11

For a single axle trailer, you want the shackle strap to be able to move so that you have the spring deflection needed for your suspension. Angled like the photo or even almost vertical is fine you just don't want the shackle strap to bind and…

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Answer 12

The difference between an load range C and load range D tire in the same size is the capacity and psi rating. The two tires will still have the same dimensions and fit on the same wheel. The D rated tire has a higher capacity. For a ST175/80D13 like…

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