Are Shackles Necessary For A Single Axle Utility Trailer?

Question

Question:

Are shackles necessary for a utility trailer? I resently restored an older single axle trailer with new leaf springs and axle. I did install shackles but they completely flatten to the frame with my own weight as I jump on the trailer.

asked by: Greg

0

Expert Reply:

Hello Greg. Generally, yes, shackles are required for any single axle utility trailer. The diagram below will show you the components of a typical single axle setup. You will have shackles on the rear hangers only. This is because as your axle hits bumps in the road it not only gets pushed up, but also back. With the shackle in the back you will have the best ride quality and suspension travel. Without shackles the suspension would likely be quite rough.

The shackles should not be flattening out like that though. This makes me wonder if perhaps the new springs are too long, or the shackles are not the correct size. When you replaced these components, did you make sure the new parts were identical in size to the stock parts? If the parts are not sized correctly, it can throw off the suspension and cause the kind of issue you are describing. The trailer being out of level, or the springs being overloaded could also cause this kind of issue, although it doesn't sound like overloading is the issue.

expert reply by: Jesse M

0

Single Axle Trailer Suspension Components
(click to enlarge)

Sean

7/3/2024

Hey Jesse, My utility trailer (former double with snowmobile trailer) doesn’t have shackles. It was like that when I bought it used. Based on your comments above, I assume you’d recommend I add them? Thanks, S

Jesse M.

7/3/2024

@Sean How is the ride quality? There are trailers out there that don't use shackles, but the standard for single axle suspension is to use shackles on the rear hanger. The shackles allow the suspension to articulate the way it was intended. If you are unhappy with the current ride quality, then yes, I do recommend that you add them.

John V.

4/30/2025

@Sean wit out the shackles the spring is no different than a solid steel bar the sprinflattens out as it absorbs the bumps in the road and as it does it makes the spring longer if mounted solid it can't flatten out and lengthen so it just acts as a solid mount.

Jesse M.

5/1/2025

@JohnV Yep you are absolutely right. Thanks for sharing!

Answer 1

To slightly lower your trailer that has had an "axle flip" kit installed you would want to use slightly shorter shackle straps, not longer ones. Shorter shackles will let the axle rest closer to the trailer frame, which lowers the trailer…

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Answer 2

The 19575-14 and 205/75-14 tire sizes are close enough that you won't have any issues with this transition. The tire I recommend picking up is the Karrier ST205/75R14 Radial Trailer Tire #AM10234 because it's very reliable, has a load range C…

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Answer 3

As long as the weight capacity is inline with your trailer/axle rating and the measurements match your current springs, the number of leaves in a spring pack does not matter. The difference between a 3 and 4 leaf spring pack within the same weight…

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Answer 4

Assuming you are using 1/2" diameter U-bolts like #APUBR-1 for your 4-Leaf Double-Eye Spring #e54SR, you will want to torque the nuts down somewhere between 45 and 70 foot pounds. The shackle bolts at the end of the springs don't require a…

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Answer 5

For all of our springs we list the unloaded length measured center eye to center eye straight across. Leaf springs can extend up to 1" when flexed. If you are looking to replace old leaf springs, you will want to jack up the trailer so that the…

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Answer 6

Bushings do not always have to be used. Springs typically have bushings or they will use wet bolts depending on which part of the suspension system it is but not always. The bushings limit the wear on the suspension components. There are just…

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Answer 7

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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Answer 8

When replacing shackle straps they should be the same length as the ones that were previously on your tandem axle trailer (if possible); replacing them with longer straps will result in additional play in your trailer suspension which could lead to…

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Answer 9

Hello Dan. Our rule of thumb is that you want at least 3" between the tire and the fender, and at least 1" between the inside of the tire and the frame of the trailer. If you need additional clearance there are ways to do this, but using…

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Answer 10

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 11

The #84 spindle is just a common way to identify the spindle dimensions typically used for 3,500 lb axles. So instead of listing out the parts, people can just say they have #84 spindles and it's easier to know what fits it. The CE Smith Trailer…

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Answer 12

The Never Fail upgrade kits like the #LC281285 have two really distinct advantages. One of them is what you mentioned and is that they don't require greasing or any maintenance. The other is that they last about twice as long as any other heavy…

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Are Shackles Necessary For A Single Axle Utility Trailer?

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