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Replacing Inverted Leaf Spring Suspension on Old Utility Trailer

Question:

I am trying to refurbish a utility trailer my grandfather had. I believe it used to be a boat trailer he converted. The only stamped information I can find on the entire trailer is on the hubs. They are HADCO 394. The axle is 1 3/4inch square solid steel and appears to be 57inch long. The springs that are on there now are something Ive never seen. They are inverted half springs that bolt onto brackets that are welded to the axle. I have attached pictures. Im hoping you have a solution that will allow me to use a more traditional leaf spring. I know next to nothing about any of this stuff so any help you can provide would be much appreciated.

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Expert Reply:

The first thing you will want to do is to remove the current springs from the frame and the axle. You can still use your axle if it is in good working order, but you will also want to remove any hardware welded to the axle.

To install leaf springs, you will first want a hanger kit. For your single axle trailer, I recommend Redline's Single-Axle Trailer Hanger Kit for Double-Eye Springs # APS1. This hanger kit will have a 1-1/2 inch drop for the front hanger, and a 7/8 inch drop for the rear. The hangers are welded to the frame of the trailer.

The weight capacity of your trailer is determined by your axle, hub, suspension, tires and wheels weight capacity. I have two leaf spring recommendations of different weight capacities for you, but you will still be limited to the weight capacity of your axle. Unfortunately, I have no way of knowing for certain the weight capacity of your axle. If you do not know the axle capacity, then the only way you can be sure of the weight capacity would be to replace the axle. From what I could find, it looks like the 390 series hubs from HADCO could have a weight capacity anywhere between 1,500 and 2,500 pounds.

The 3-Leaf Double-Eye Spring # SP-169275 is rated for 2,000 pound axles. This part number includes only one spring, so you will want to make sure you order two of them. These springs measure 20-3/8 inches long. Since hangers should be lightly shorter than the length of the springs, you will want to mount the hangers 20 inches apart.

The 3-Leaf Double Eye Spring # SP-219275 is rated for a 2,500 pound axle. Again, you will want to make sure that you order two springs with this part number. The length of these springs measures 25-1/8 inches long. The distance you would mount your hangers for these springs is 25 inches.

To attach the axle and the springs, you will need square U-bolt # 175130 and U-bolt plate # 116308. You will want 4 U-bolts total and 2 U-bolt plates. These will fit around your 1-3/4 inch axle and your leaf springs.

You may also need to drill a hole in your axle to accommodate the spring bolt in the center of the leaf spring.

I have attached a diagram on aligning the axle. Before you make any welds, it is best to mock up the layout of the suspension by using clamps to temporarily place your hangers. You want to make sure that your hangers are located correctly so that your axle is still aligned properly.

I have also attached an article on double-eye trailer suspension for you.

click to enlarge
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Victoria B

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