Why Did My Shackle Flip On My Tandem Axle Utility Trailer?

Published 08/13/2021

Products Featured in This Question

Straight Equalizer for 1-3/4" Wide Double-Eye Springs - 8" Long - 3/4" Center Hole

(117)

$39.67

SumoSprings Trailer Helper Springs w/ Line Relocation Bracket - Single Axle - 3K to 5K - Underslung

(65)

$299.99

SumoSprings Trailer Helper Springs w/ Line Relocation Bracket - Single Axle - 3K to 5K - Overslung

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$267.99

Question:

I had one pair of shackles flip on my tandem axle utility trailer. I recently installed new nylon bushings on all suspension points 14 total but retained the springs and equalizer. I measured everything and it all seems precise 35inch c-c axle spacing. The trailer was unloaded 7k, 7x16foot car carrier style, the road was dirt and bumpy, and my speed was about 25-35mph. So why did this happen and how can I prevent it from happening again? My though is that a triangular equalizer causes a forward/backward rocking that allows the shackle point to shift away from the spring eye and the shackle simply rotates around the point and flip up. The flat equalizer would not allow this to happen. Is the flat equalizer less durable or reliable?

asked by: Carl H

Expert Reply:

What most likely occurred when you were driving on the bumpy road with no weight on your utility trailer is the trailer bounced enough to upset the suspension and after it landed it caused the shackle to flip. This tends to happen a lot with trailers that carry a large amount of weight as their suspension is very ridged and the trailer bounces more than absorbs shock when it is empty.

Since you just recently changed out all your nylon bushings your suspension is more prone to articulate through its full range and that is why you have most likely not had it happen previously as the suspension may have been more bound up causing less articulation.

A flat equalizer will not be less durable or reliable from your triangular equalizer, but it will have an effect on your suspension height and may cause parts of your suspension to contact the frame when it is moving through its travel.

I have linked an article below that covers trailer suspension systems and the different components. Also if you would like to send me pictures with measurements of all your components this may help to determine that everything in your suspension is what it should be and in proper working order. If everything looks good and you do not see any parts that are broken or worn heavily you should be alright as things like this can happen. If it starts to become a reoccurring issue then you will want to dive deeper into the suspension components.

The SumoSprings Trailer Helper Springs # TSS-107-40 or # TSS-106-40 can also be added to help absorb the shock in your suspension. These progressive springs help to dampen shock and will also provide support to your leaf springs. These may also prevent the suspension from compressing so far that it causes the shackles to flip. Of course first you want to make sure that your trailers suspension is correct first.

expert reply by: Bud M