Vintage Trailer Suspension Replacement Recommendations
Published 08/26/2014
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Question:
I have a 1956 Silver Streak Rocket Trailer. Its a 27foot trailer with tandem axles. The axles are old square Hadco Engineering axles, and are in pretty good shape. The fixed hangers are in good condition, holes dont seem to be oblonged or worn. They are spaced 63.50inch on center, and are 1.5inch from the surface theyre attached. The center hanger is in the middle, and is 4.75inch from the surface. This hole is a little oblonged. The equalizer is currently 5.5inch on center, and isnt offset. The springs when measured are 28inch eye to eye. The shackles are 2.75inch if I recall. Trailer rated weight is 4000#. Would it be reasonable to go with two 27inch springs, a 7.5inch or 7-3/4inch equalizer with offset? I could then drill out a hole a distance up equal to the offset. I realize this would give me 2 3000# axles, or 6000lbs. Would this be pretty hard on my setup? Currently the springs are 9-leaf which seems like they may be pretty heavy. Also - Id like to mount the axle below the springs, to increase the ride-height and ground clearance. Im an engineer, so I have access to CAD to draw things up. Just not a lot of time to research the finer points. I know I need ot make sure my shackles wont bottom out on the frame. Should the shackles be sitting vertical when on the ground? Theyre at an angle now, and Im worried a shackle may reverse, leaving the ride awkward.
asked by: Clint L
Helpful Expert Reply:
Going to a higher rated spring will not give you higher rated axles. The axles themselves have their own rating independent of the springs. So going to a higher rated spring would only increase your trailer capacity if they were the weakest link prior to replacement.
That being said, your current springs are 28 inches long so you will want to pick out a spring that is slightly shorter than that as springs tend to stretch over time. The part # SP-210275 would be the best candidate as it is 27 inches long. The closest equalizer we have to what you have is the part # TREQ356. This is 2-1/2 inches tall and 6-1/8 inches long. I wouldn't recommend modifying this equalizer either.
Without knowing the dimensions of your square axles all I can do is show you the link I attached to the right that has all of the u-bolts and u-bolt plates we offer for you to check out and pick the right parts.
For shackle straps you would want the part # TRSL275. The angle of the shackles should be about what you have in your picture. You wouldn't need to worry about one of them reversing. Since the equalizer I recommended is shorter in height you could also go with a shorter shackle strap to make up for the difference. For that you would want a 2 inch shackle part # TRSL200.
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