Dimensions of Hangers and Equalizers on Tandem Axle Suspension on 16-Ft Trailer

Updated 09/23/2015 | Published 09/22/2015

Question:

Im rebuilding my trailer and I think who ever built it had no idea what they were doing when it came to mounting all the suspension. Was wondering if you could help me choose the right equalizer and shackle? Using your tandem axle picture for measurements: A- 30 1/4 front hanger to center B- 29 7/8 Center to rear hanger C- 36 D- 6 1/2 Front and rear hangers are 1 3/8 tall Center hanger is 3 1/4 tall axle is 2 3/8 round 3500lbs leaf springs are 25 1/2 long, 1 3/4 wide double eye with 4 leaves Now the equalizer that is in there is 2 7/8 tall, 7 3/4 long with 9/16 dia. on center hole and the shackles are 2 3/4 long What I found to be strange is the A and B measurements, the height combination of the hangers, the shackle lengths and they had the shackles facing down towards the ground instead of up towards the frame. Does this sound ok? Thanks

asked by: Marc W

Expert Reply:

Front and rear springs hangers should be equally spaced around the center hanger and spring equalizer. It may be that your trailer was modified (if not originally built) with a different height center hanger and that might be how the spacing became how it is. Also, it may be that at some point the shackle straps were changed to a different length - we offer three different lengths: 2-1/4-inch, 2-5/8-inch and 3-1/8-inch. On a tandem axle trailer the 2-5/8-inch length is most common.

It is not unusual for shackle straps to flip around when the trailer is not under load. The face-up position for the strap will usually return once you load the trailer with some weight and pull it to actuate the suspension. This in itself is not a problem. But shackle straps are also the most likely part of the system to wear out from use. They carry the weight of the trailer and also have to deal with constant movement. A worn strap may develop oval holes from the wear and this can change the alignment of the rest of the system. I suggest you check your shackle straps for wear and replace as needed.

You may also care to review the linked article for more on trailer suspensions.

expert reply by: Adam R