Ordering a replacement axle goes smoothly when you show up with the right numbers. An axle that’s an inch too wide won’t line up with your springs, and one rated for less weight isn’t safe to tow on. Here’s what to measure, in what order, and what to bring to the store.
What you’ll need
You don’t need special tools. A tape measure and a phone camera cover almost everything.
A tape measure (a 25 ft tape is plenty)
Your phone, to photograph tags, hubs and spring seats
A notepad, or the notes app on your phone
Wheel chocks and jack stands if you plan to take the wheels off
Safety first
Park on level ground, chock the wheels and never work under a trailer that’s held up by a jack alone. Use jack stands under the frame.
Step 1: Find the axle tag
Most axle makers put a sticker or a metal tag on the axle tube, usually near the middle. It lists the capacity and often a model or serial number. Write it down and take a photo.
If the tag is gone, check the VIN plate near the tongue. It lists the gross axle weight rating (GAWR) for each axle, which tells you the capacity the trailer was built for.
Step 2: Measure hub face to hub face
This is the overall width of the axle, and it decides where your tires sit under the fenders. Measure from the flat face where the wheel bolts on at one end to the same face at the other end.
It’s most accurate with the wheels off. If you have to leave them on, measure from the center of one tire tread to the center of the other and tell us that’s how you measured, so we can allow for it.
Step 3: Measure spring center to spring center
Measure from the center of one leaf spring to the center of the other. The center bolt or the middle of the U-bolts marks the spot. This number has to match your trailer frame, or the spring seats on the new axle won’t line up with your hangers.
On a torsion axle there are no leaf springs. Measure across the mounting brackets instead, outside edge to outside edge, and note how the brackets bolt to the frame.
Step 4: Note the capacity and tube size
Capacity is the most important number on the list. Never go lower than what you have now. The table shows common pairings, so you can sanity-check what you find.
Axle capacity | Common tube | Common brake size |
|---|---|---|
3,500 lb | 2-3/8″ round | 10″ x 2-1/4″ |
5,200 lb | 3″ round | 12″ x 2″ |
7,000 lb | 3″ round | 12″ x 2″ |
Good to know
These are common sizes, not rules. Always go by your tag or your old parts. We work on axles up to about 10,000 lb.
Step 5: Check the spring seats and drop
Look at how the axle sits on the springs. If the axle tube is above the springs it’s an underslung setup; if it sits below them it’s overslung. Also check whether the axle is straight or a drop axle, which bends down at the ends to lower the trailer, usually by about 4 inches.
Note the width of the spring seats too. They have to match the width of your leaf springs.
Step 6: Lug pattern and brakes
Count the wheel studs and measure the bolt circle. Our guide on how to match a trailer hub shows the method. Then check the brakes: electric, hydraulic or none. If you’re not sure, see electric vs hydraulic brakes. Brake size is usually stamped on the backing plate.
Your checklist
Bring these to the counter and we can match the axle in a few minutes.
Capacity, from the tag or VIN plate
Hub face to hub face width
Spring center to spring center width
Straight or drop axle, and spring seats over or under
Lug count and bolt circle
Brake type and size
Photos of the tag, the hubs and the spring seats
Repair or replace?
A bent axle often shows up as uneven tire wear, wheels that lean in or out at the top, or a trailer that doesn’t track straight behind the truck. It usually happens after hitting a curb or a deep pothole. If you see those signs, have the axle checked before you order. Sometimes the problem is a bearing or a spring, not the axle itself.
Get the part or the repair
Shop online for local pickup, or bring the old part to our Port St. Lucie store at 496 SW Voltair Terrace and we’ll help you match it. Not comfortable doing the job yourself? Request a repair and we’ll take care of it, or call us on 772-924-7299.
Guides are general advice. Trailers vary, so check your trailer’s labels and manuals, or ask us before you order.
