Acceptable Deflection of Torsion Axle Spindle on Homemade 4 x 8 Trailer

Updated 09/07/2017 | Published 09/05/2017

Question:

I have a new homebuilt trailer 4x8 for hauling fire wood with a new torsion suspension 3500 lb .IF i carry 2500 lb on bumpy road .do you think i will have problems. fully loaded it comes down .75 inch

asked by: GILLES R

Expert Reply:

Since your trailer's torsion axle is rated for 3500-lbs, and since a 4 x 8-foot trailer frame is unlikely to weigh more than a few hundred pounds, you should still be well within the axle capacity even when you have 2500-lbs of firewood loaded.

Since the trailer is homemade there is the question of the weight capacity for the frame itself. In any trailer, the actual weight rating depends on each of the component parts (frame, suspension, axle, wheels and tires) and the lowest-rated among them determine the trailer's overall capacity. This is the classic "weakest link in the chain" scenario.

If the wood weight alone causes a frame height drop of 3/4-inch this is not excessive. The spindles on torsion axles can deflect as much as 4-inches between the unloaded and loaded conditions so 3/4-inch height drop again suggests you are well within the axle capacity.

Just the same, when transporting any heavy load (2500-lbs of firewood certainly qualifies!) you should keep your speed within a safe limit suited to the road conditions, not only to avoid damage to the trailer axle but also to avoid loss of any of that firewood...if you're like me you split by hand and every bit of that effort is precious!

expert reply by: Adam R