Tandem axle fix and upgrade.

[Stumpalump]

The typical tandem axle suspension like this takes a real beating.



The triangle thing holding the shackles is called the equilizer. The nylon bushings are gone in as little as 6000 miles and then the hole on top of the equilizer elongates. The shackle holes elongate as well and break between 15k and 30k miles so you have to maintain them. Look at the grooves worn into the bolts. This is typical.



When packing the wheel bearings and checking brakes, the weight is off of the trailer. This is a good time to wiggle the parts and see how much slop is in the parts.

Dexter is the main source for good axle parts and they make all sorts of kits to maintain trailer axles. I used the EZ Flex kit because it has brass bushings, greasable "wet bolts" and the equilizer is hinged with a huge rubber shock absorber. Basically it comes with everything except grease. They make all sorts of claims about the new regulator but the RV camper crowd loves them and mine was worn out. This shows one side but both sides come in the kit.




You can see how much better the new stuff is.



The install is straightforward. Clean up the spring eyes and press or tap in the brass bushings. Mount the outside fixed end of the springs first, then raise or lower the axles to line up the shackle holes. It's just grunt work but plan time to do it right and use the torque specs.



Now every pivot can be kept greased! The EZ Flex is supposed to stop that "push me pull you" feeling called chucking and cushions the ride. I noticed that I can't hear or feel the trailer back there. Now every time I hit a bump, I look back to see if the trailer is still there.

 

[verdesardog]

Good job! One of the reasons I chose a single axle trailer is to minimize the moving parts .... I did rebuild my springs set up with all new grease able pins, heavier shackles and new springs

 

[Stumpalump]

Good job! One of the reasons I chose a single axle trailer is to minimize the moving parts .... I did rebuild my springs set up with all new grease able pins, heavier shackles and new springs

It's complex but better than two independent axles like torsion. As one tire is forced up it forces the spring on the other axle down. That force evens the load when you hit a bump on to both axels. They pull nice when loaded because of the way it balances the load between tires. Torsion axles don't do that. If you swap from two 3500lbs spring axles to torsion you would need two much higher rated torsion axels to handle the hard hits and heavier rated tires. That's why torsion trailers break, the wheel falls off and they eat tires. On the spring set up if something breaks the spring or axle hits the frame and you can ease on down the road. Here is a pic stolen from the web that shows one tire up and the other spring being forced down.



Here is one of my walled out equilizers proving it moves constantly.



I think torsion has its place it's just that in my opinion you would need a 10,000 lbs tandem torsion trailer with bigger tires to do what the 7000 lbs spring axle will do. A single heavy axle pulls the best by far especially for the typical application on this site. I have two single axle trailers and love them. Drawbacks to single compaired to tandem are they bounce and sway a little more. The weight distribution is way more criticle and safty during a blowout. I use the tandem to haul the buggy and Jeep so it's a lot of weight up high and needs the extra stability.

 

[Mark Harley]

The new hardware looks robust compared to the original.
I guess they want the originals to wear so they can sell more parts to rebuild.

I bought an enclosed box trailer that was beat to hell and the original owner wondered why it ate tires and crab walked down the road.
I replaced everything and it rolls straight and true.

Nice write up. Thank You!