Converting single axle to tandem axle - The Hull Truth

Agitator · 02-11-2009, 10:47 AM

Anyone have any experience in converting a single axle aluminum trailer to a tandem axle?

rwidman · 02-11-2009, 12:55 PM

I'm sure someone does, but why?

You're not going to increase the trailer's capacity unless you replace the frame rails and possibly the coupler.

Want to do it anyway?

Do you have a torsion axle? Get another axle just like the one you already have. Mark the position of the axle on both sides of the frame. Now remove the original axle, figure out how far apart the axles need to be to avoid the tires hitting each other (under all conditions), divide that distance in two, and install each axle equidistant from the original axle position (one forward, one rear).

You may need different brake lines for the repositioned axle and you'll need another set of brakes and brake line adapter and lines for the new axle.

Leaf springs? Someone else will have to chime in here unless you want to buy two new torsion axles.

And, you'll need new fenders. And tires. And wheels. Bleed the brakes when you're finished.

1Mainiac · 02-11-2009, 01:52 PM

Pretty good explaination Ron and also applies to leaf springs if the trailer is properly setup to begin with the leaf spring procedure would be as follows mark the center line of the current axle on the frame verify by measurement to the center of the hitch ball that it will be in alignment and use this to attach the equalizer mounts. Then based on the requirement of the springs and axle selected you should have a measurement as to spacing the other spring mounts forward and rear of the Equalizer mount also making sure they are in alignment with the hitch so it will pull straight. Is pretty simple and straight forward just mark where it used to be remove everything and start over if you get it right it will even follow you down the road not in the next lane. However the DOT tag on the trailer won't change so it won't legally carry one more pound for all this work in some states you can remove the tag and call the trailer homemade but then you assume all liabilty for its failure if it occurs. Also your insurance may enjoy the loophole of not having to pay the claim due to your modification which if I were the adjuster would happen. But I am not a insurance adjuster I just have to deal with them from time to time doing the repairs.

rwidman · 02-11-2009, 02:10 PM

The way I aligned the axles on my trailer when I moved them to balance the weight was to make spacers from 2X4 lumber to place between the axle and a frame crossmember. This allowed me to make locate the axle parallel to the frame. Then I cut the spacers to the distance between the axles so they would be parallel with each other.

autobaun70 · 02-11-2009, 06:56 PM

if you trailer is in decent shape, I would at least check into the option of trading it. Check out your various local dealers, as well as any marinas that may be around. You will problably end up with a better end product this way, with way less work, and about the same or possibly less $.

rwidman · 02-12-2009, 08:10 AM

Quote:

autobaun70 - 2/11/2009 8:56 PM

if you trailer is in decent shape, I would at least check into the option of trading it. Check out your various local dealers, as well as any marinas that may be around. You will problably end up with a better end product this way, with way less work, and about the same or possibly less $.

And if it's not in decent shape, why waste money on it?

Rascalsdad · 03-08-2009, 05:29 PM

I have a steel trailer that underwent this operation. I just hired it out at a local trailer manufacturer. Ran $550 including new wheels and tires.

Although the weight of my boat doesn't justify a tandem axle I did it for safety reasons. I pulled it from AZ to central FL twice (4400 miles roundtrip) and wanted an extra set of wheels under me. I've noticed that it is easier to maneuver and doesn't require such wide turns to clear a corner. For the price it was well worth it.