Can a 2,500 Pound Drop Axle Be Upgraded to 3,500 Pound Straight Axle

Updated 01/11/2016 | Published 01/09/2016

Products Featured in This Question

Trailer Axle w/ Electric Brakes - Easy Grease - 5 on 4-1/2 Bolt Pattern - 89" Long - 3,500 lbs

(252)

$521.99

U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts

(2141)

$80.93

Question:

I have a 1988 Wilderness travel trailer that developed a bent axle. OEM is tandem 2500# axles not sure if 4inch or 6. I would like to replace both axles with 3500# assemblies with e-brakes. Is that feasible/advisable? Can I change to a straight axle versus a drop? This will increase ground clearance but also raise the center of gravity. I have never before had an instability problem with this trailer.

asked by: John C

Helpful Expert Reply:

You can certainly replace your existing 2,500 pound axles with 3,500 pound axles. If your trailer is not already wired for electric brakes and you want to add them, you will need to wire the trailer for electric brakes. I have attached a help article on adding electric brakes to a trailer for you.

You can change your axle to a straight axle from a drop axle. As you mentioned it will move the center of gravity up. This is important to keep in mind while driving and when making turns. If you are using a weight distribution system without sway control, adding sway control can help keep the trailer straight when driving down the road.

To replace the axles on your trailer, you will want to find axles that have the same hub face measurement and spring center measurement as your existing axles. The hub face is the length of the axle measured from the base of one wheel stud to the base of the wheel stud on the opposite side of the axle. The spring center is the approximate width of the trailer, measured from the center of the spring seat on one side of the axle to the center of the spring seat on the other side. I have attached a photo showing where to take these measurements for you.

The 3,500 pound axle you referenced has a hub face measurement of 89 inches and a spring center measurement of 74 inchese43SR will work well for you.

If these measurement don't match your trailer, feel free to let me know and I will be happy to see if we have an axle that will work for you.

For a U-bolt kit for 3,500 pound axles, you can use # APUBR-1. This kit includes U-bolts, nuts, and U-bolt plates to mount 1 axle. You will want 2 kits for a tandem axle trailer.

When you increase the weight capacity of your axle, you will also want to increase the capacity of the leaf springs. If the leaf springs used are not rated for 3,500 pounds, they will limit the weight capacity of your trailer. I have attached a link to all of our leaf springs rated for 3,500 pounds. You will want to match the center of eye to center of eye measurement, the height from the top-center of spring to center of eye, and length from the center of eye to center of spring when choosing new leaf springs. If you would like to let me know the measurements of the springs on your trailer, I will be happy to recommend 3,500 pound springs for you.