Parts Needed to Convert a Tandem Axle Trailer to a Triple Axle Trailer

Question:

I have a 38’ trailer frame that has 2 5200 lb axles. I need to add a third axle … but would like a little more load capacity. Can I add a 6000 lb axle to it rather than another 5200 lb? I would prefer a 6000 lb 6 lug with same bolt pattern as the 5200 lb hubs take also. If acceptable, should the 6000 lb axle go in the center?

asked by: Daniel

Expert Reply:

Daniel, you can add a third axle but you're going to want to keep all of your axles the same size. So if you wanted 6K axles instead of 5.2K then you'd want to swap the other two as well.

With that said, to add your third axle you're going to need the U-Bolt Kit for Mounting 5,200-lb to 7,000-lb, Round Trailer Axles # APUBR-8, the Triple-Axle Trailer Hanger Kit for Double-Eye Springs # APTT5, and the 6-Leaf Double-Eye Spring for 5,300-lb Trailer Axles # e76SR.

For the axle itself, let me know what the hub face center to center and the spring seat center to center measurements are and I'd be happy to get that part for you.

expert reply by: Bryce D

Dan

2/27/2024

Thanks for the info. The current acord are AL-KO. From what I have researched, I should be able to upgrade the axles to 6000 lb by upgrading the hubs with the bigger outside bearing (15123 I believe). Does that sound accurate? I figure I will also need to upgrade the leaf springs. Oddly, the hangers are about 29.5” apart and are 4 leaf’s…which don’t seem to match any springs thst should be rated for 5200 lb axles. The tag indicates they are Rockwell. I didn’t see the part number though. My assumption is a 29.5” hanger separation is for 30” springs. I will be replacing the u bolts as well.

Bryce D.

2/29/2024

@Dan Yes that does sound right, you're going to need to upgrade your trailers suspension, hubs, wheels, and tires if you were to swap your axle size.

Daniel

2/29/2024

@BryceD I plan to pull the tires off soon to accurately measure distance to hub face and verify my leaf spring distance (center-to-center). I also will take off one of the hubs to confirm #42 spindle and try to confirm leaf spring part number. My plan: Keep current (2) 5200 lb axles and confirm if I can upsize the hubs and outer bearings to 6000 lb. Buy a third 6000 lb axle kit. Upsize current leaf springs for 6000lb. axles. With current springs eyelets at approx 29.5” apart…may have to relocate hangers). I will stay with 15” tires….i found that there are F and G load range 15” trailer tires out there. So if this works out, I will need: (1) 6000 lb axle setup (with electric brakes) (4) hubs (for 6000 lb axle) - may have 2 of these invludd brakes (4) outer bearings (should be 15123s) (2) hanger/unbolt axle kits (2) sets of leaf springs for 6000 lb axles. Not sure if length yet (will probably have to move hangers) Anything else