6k Trailer Axle Leaf Spring and Tandem Axle Hanger Kit Recommendation

Question:

Hello, I may need some help in beefing up a trailer I recently bought. It is currently a 14 ft. trailer that I want to haul 16 ft. logs on. This trailer looks well designed – not unlike the new deck-over trailers and weighs similarly at 2780 lbs. empty, but w/sideboards installed. I need to haul some 16 ft. logs from my property to finish paying off our house so my wife can retire by age 70, I am age 73. Our access road has too tight of switch-back to hire the logs hauled. The trailer has a main frame from channel that is 5” x 1.875” flange x .325 web. The lumber bed support cross-members are from channel that is 3” x 1.5 x .258 web, except above the wheels where there is 3” channel lined up vertical over the frame, effectively making the main frame 8” deep over the axle support system. The axles are manufactured/mobile home axles with 3” tube and a 1” outer nut restraining the roller wheel bearings. I suspect each of these axles is designed for about 6000 lbs. The tandem axes are suspended by standard U bolt system w/3 leaf springs approx. 26” long hung from homemade spring hangers, 3 ¼” front and rear, with 6 ¼” center hangers. These hangers are welded to 3” x 3” x ¼” angle iron that the main frame channel sets in and is bolted to w/seven 5/8” bolts. The equalizer is straight, with 5 ½” outer bolt centers and the shackle straps 2 3/8” centers. This makes the axles moveable under the trailer frame, towards the front or rear, depending on desired load balance. The springs sit on top of the 3” axle tube. Currently, bed level height is 34” with 5” tire clearance which should be enough. The distance between the axle tube spring seat and the bottom of the main frame 3” angle iron is 8 ¾”. The 3 leaf spring pack is 1 ½” deep. Your 5 leaf spring pack, e34SR does not say how deep the spring pack is but the two extra leaves will raise the trailer a bit. The ½” U bolts are 7 inches long. The APUBR-9 “U” bolts should work, they are 9/16” but with new plates that shouldn’t matter. My questions: 1. Are 4 e34SR springs suitable for up 12 K GROSS trailer load or should I go w/2” springs? 2. Do you recommend shorter or longer than 5 ½” equalizers, straight or angled, and why? 3. What are the advantages of shorter or longer, and straight vs. triangle equalizers? 4. Which equalizers and shackles do you recommend? 5. What are the science differences shear between regular and re-lube or wetinch spring bolts? 6. Please discuss the differences between nylon and bronze bushings. Recommendations are appreciated regarding those things I mentioned and whatever I did not mention. Thanks,

asked by: Lloyd

Helpful Expert Reply:

The leaf spring part # e34SR is designed for 6k axles. On a tandem axle trailer with these springs you would end up with a 12k capacity. If your axles really are 6k rated these would be the ideal springs to use.

The recommended hanger kit to use with this spring is the # APT5 because all of the hangers are the same size and you end up with great tire clearance. The equalizers that come with this are 7-3/4 inches.

The distance between the axles will end up being 33-1/2 inches and the distance between all of the hangers will be 29-1/2 inches. This would be measured from front to center and then center to back.

The different shape equalizers are available to accommodate replacement parts on trailer that use the different shapes/style. There's no real advantage to one or the other as long as you end up with a level leaf spring.

We bolts have a zerk fitting that allow them to be easily lubed. This will help the suspension last as long as possible since it will prevent undue premature wear.

Nylon and bronze bushings surprisingly have about the same longevity. It would come down to personal preference. You would think that nylon would wear out much quicker than bronze, but since nylon dissipates heat so much better than bronze it actually doesn't take as much abuse as the bronze.