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Will a 4000-LB Leaf Spring Fit on a 3500-LB Axle


Hey guys, I am the second owner of a 2016 KZ Spree Escape 200S Travel Trailer. GVWR is 3500#, single axle. Left hand side springs are flat and trailer has bottomed out breaking the brake line wires, which I have repaired. Right hand side springs are not far behind already. Trailer is equipped with 205/75R-14 tire /wheel set. I would like to give it a mild lift to fit 225/75R-15 tire /wheel set with +1 higher load rating. These are +2.18inch taller, so a 1inch gain in fender clearance is needed for the radius. Also, I would like to upgrade the spring set to 4000# to prevent a premature spring sage and for boondocking excursions. Additionally I would like to add heavier duty shackle straps. I do not know if the frame can exceed 3500# so I will maintain that rating. Are there 4000# springs that will cover all the bases or do I have to go a different route? I feel a spring over conversion will be way more than I need and adversely effect towing. RH spring measures 26.5inch loaded 1.75inch wide 0.25inch thick. I will measure frame mounted Bracket - Bracket if you need it. Thank you in advance,


Helpful Expert Reply:

Yes the 4,000-lb leaf spring is compatible with a 3,500-lb axle. There are a couple of important measurements.

Spacing from eye to eye on the spring when unloaded with no weight on the axle.
Inner eye diameter of the spring roll
Spring width from outer edge to outer edge

Based on your measurements I recommend the 3-Leaf Double-Eye Spring for 4,000-lb Trailer Axles - 25-1/4" Long Item # SP-220275 and Dexter Heavy Duty Suspension Upgrade Kit for Single Axle Trailers - Double Eye Springs Item # K71-358-00. This kit is designed for 3500-lb to 7000-lb single axle trailers. Upgrading to wet bolts allows you to grease the inner portion of the spring roll to minimize friction between the two metal surfaces of the bolt and the bushing.

The easiest way to gain any height is to move to an axle less kit. I recommend Timbren Heavy-Duty Axle-Less Trailer Suspension - 2" Lift Spindle - Standard Tires - 3,500 lbs Item # TASR35HDS07

Keep in mind installing any of these components does not provide more carrying capacity. You do not want to exceed you trailer's GVWR

Be sure when measuring the spring length that there is no weight on it.

helpful expert reply by:
Shane H

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