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How to Measure for a Custom-Built Dexter Trailer Axle
A custom built Dexter axle beam from Southwest Wheel is made to the numbers you enter on the order form. Once the order is placed, the axle cannot be altered, changed, cancelled, or returned for any reason, so do the measuring before you order. This guide covers every measurement the form asks for, in order.
The Custom Built Dexter Trailer Axles category has standard spring beams from 2,000 to 8,000 lb., in straight and drop styles, each with a 45" to 95" hub face.
Key takeaway
- Hub face: Every custom beam takes 45" to 95". Do not guess this number.
- Spring center: Enter it only if you want the seats welded.
- Overhang: Total overhang (hub face minus spring center) must fall inside the range for your beam.
- Built to order: A custom axle cannot be altered, changed, cancelled, or returned once the order is placed.
Start with the axle label
If the old axle still has its label, start there. The label is usually on the center of the axle tube, on the back side of the beam, under the trailer frame. It carries the axle description number.
If the label is missing, measure the hub face, the spring center and the brake size. Match the capacity printed on the label, or the capacity you know you need. Do not estimate capacity from the size of the axle tube.
Every beam in the custom line is a standard spring (leaf spring) axle. If your trailer rides on a torsion axle, see Torsion Axles instead; this guide does not apply.
Measure the hub face
Hub face is the measurement from the wheel mount on one hub to the same point on the other hub: the outside of one hub mounting face to the outside of the other.
Every custom beam takes a hub face from 45" to 95". 95" is the maximum. Do not guess this number. If you cannot get a clean measurement, call 1-800-866-3336 before you order.
Measure the spring center (welded seats only)
Spring center is the distance from the center of one spring seat to the center of the other spring seat.
On the order form, spring center is optional. Enter it only if you want the seats welded. Leave it blank and the seats ship loose.
Check your overhang
Overhang can be stated two ways. The order form wants the total.
Total overhang
Total overhang, as entered on the order form, is the hub face minus the spring center:
Total overhang = Hub face - Spring center
Example: a 95" hub face and an 80" spring center is 95 - 80 = 15" of total overhang.
Per-side overhang
Per-side overhang is the distance from the spring center to the hub face on one side. It is the total divided by 2:
Per-side overhang = (Hub face - Spring center) ÷ 2
In the same example, 15 ÷ 2 = 7.5" on each side.
Overhang range by beam
If you are having the seats welded, your total overhang has to fall inside the range printed on the form for your beam:
| Beam | Straight | 4" drop | 6" drop |
|---|---|---|---|
| 2,000 lb. | 11.50" to 15.24" | 15.24" to 18.00" | Not offered |
| 3,500 lb., 2-3/8" tube | 11.25" to 18.00" | 14.00" to 18.00" | 15.74" to 18.00" |
| 3,500 lb., 3" tube | 11.25" to 23.00" | 14.00" to 23.00" | 14.00" to 23.00" |
| 4,400 lb. | 12.00" to 19.00" | Not offered | Not offered |
| 5,200 lb. | 12.75" to 19.00" | 15.74" to 19.00" | Not offered |
| 6,000 lb. | 12.75" to 20.00" | 15.74" to 20.00" | Not offered |
| 7,000 lb. | 13.26" to 18.00" | 15.74" to 18.00" | Not offered |
| 7,200 lb. | 14.00" to 18.00" | 15.74" to 18.00" | Not offered |
| 8,000 lb. | 16.00" to 19.00" | 18.00" to 19.00" | Not offered |
| 8,000 lb. narrow overhang | 14.00" to 15.95" | Not offered | Not offered |
Some forms print a different range when the axle has disc brakes. If yours does, use this range instead:
| Beam | Style | Range with disc brakes |
|---|---|---|
| 3,500 lb., 2-3/8" tube | 4" drop | 15.00" to 18.00" |
| 3,500 lb., 3" tube | Straight, 4" drop and 6" drop | 15.00" to 23.00" |
| 5,200 lb. | Straight | 18.00" to 19.00" |
| 6,000 lb. | Straight | 18.00" to 21.50" |
| 7,000 lb. | Straight and 4" drop, Dexter disc brakes | 18.00" to 20.00" |
| 7,000 lb. | Straight and 4" drop, zinc or aluminum disc brakes | 16.00" to 20.00" |
These ranges are total overhang, so compare your total (hub face minus spring center) to them. A drop beam has its own range, which is not the same as the straight beam of the same capacity, so use the range for your capacity, style and tube. If your build is close to a limit, call 1-800-866-3336 before you order.
Each range is printed on the beam's order form:
- 2,000 lb.: 2,000 lb. straight beam, 2,000 lb. 4" drop beam
- 3,500 lb.: 3,500 lb. straight beam, 3,500 lb. 4" drop beam, 3,500 lb. 6" drop beam
- 4,400 lb.: 4,400 lb. straight beam
- 5,200 lb.: 5,200 lb. straight beam, 5,200 lb. 4" drop beam
- 6,000 lb.: 6,000 lb. straight beam, 6,000 lb. 4" drop beam
- 7,000 lb.: 7,000 lb. straight beam, 7,000 lb. 4" drop beam
- 7,200 lb.: 7,200 lb. straight beam, 7,200 lb. 4" drop beam
- 8,000 lb.: 8,000 lb. straight beam, 8,000 lb. 4" drop beam, 8,000 lb. narrow overhang beam
Choose straight or drop, camber and seats
Straight or drop
On a straight axle the spindle center is in line with the axle tube. On a drop axle the spindle center sits below the tube. Drop spindles lower the trailer floor.
Overslung or underslung
Overslung puts the spring seat on top of the axle tube; underslung puts it under the tube. Underslung springs lower the frame, and overslung springs raise it.
Camber
Camber is a slight arch in the axle tube so the tires stand more upright when the trailer is loaded.
The five seat choices on the form
- Straight, seats ship loose
- Straight, seats welded on
- Cambered, seats welded over the axle (overslung)
- Cambered, seats welded under the axle (underslung)
- Cambered, seats ship loose
Pick the remaining options
- Tube: The 3,500, 7,000 and 8,000 lb. forms offer more than one tube, and the heavier tubes are an added cost. On the 3,500 lb. beam the default is a 2-3/8" tube with a 3/16" wall, and the 3" light wall (.188") and 3" medium wall (.250") tubes are the upgrades. The 3" tube also allows a wider overhang (see the table above).
- E-Z Lube: No or yes. Yes is an added cost.
- Brake flange: Offered on the 2,000 lb. form. The 3,500, 5,200, 7,000 and 8,000 lb. forms do not offer one.
- Pre-wire: No or yes.
Confirm the capacity
Axle capacity is the gross vehicle weight minus the hitch load. If the load sits off to one side, that side must not exceed half the axle rating.
The axle's rating at the tires is limited by its lowest rated part, including the springs, wheels and tires. Match your Trailer Wheels, Tires, and Assemblies to the axle capacity.
What the beam does not include
Custom listings are the beam only. Hubs, springs, hangers and U-bolts are not included. Plan to add:
- Hubs: Two hubs from Trailer Hubs with Parts. On the 2,000 lb. beam, idler hubs are 4 on 4" or 5 on 4.5".
- Springs, hangers and U-bolts: As a kit from Single Trailer Axle Suspension Kits or Suspension Kits, Springs, Hangers and U-bolts, or separately from Trailer Leaf Springs, Hanger Shackle Kits and U-Bolt Kits.
- Wheels and tires: From Trailer Wheels, Tires, and Assemblies.
Hubs ship without grease or oil. The bearings must be packed or filled before use.
Need a stock size instead? Pre-Configured Dexter Trailer Axles are listed separately.
Lead time, returns and shipping
- Lead time: Delivery is 2-3 weeks after the order.
- Returns: Each axle is built to order. Once the order is placed it cannot be altered, changed, cancelled, or returned for any reason.
- Shipping: Shipping is one charge for the entire order.
Custom axle measuring checklist
- Capacity, from the label or your trailer's needs
- Straight or drop
- Hub face, 45" to 95"
- Seats loose or welded; if welded, over or under, straight or cambered
- Spring center, only for welded seats
- Total overhang (hub face minus spring center), inside your beam's range; per side is half that
- Tube, E-Z Lube, brake flange (2,000 lb. only) and pre-wire
- Hubs, springs, hangers, U-bolts, wheels and tires
Questions about a custom Dexter axle beam? Call 1-800-866-3336.
Frequently asked questions
What is hub face?
The measurement from the wheel mount on one hub to the same point on the other hub. Custom beams take 45" to 95".
Do I need a spring center?
Only if you want the seats welded. Leave it blank and the seats ship loose.
How do I work out overhang?
Subtract the spring center from the hub face. That total is what the order form wants, and it must fall inside the range on your beam's page. Divide it by 2 for the overhang on one side.
Are hubs, springs, hangers or U-bolts included?
No. Custom listings are the beam only.
How long does a custom axle take?
Delivery is 2-3 weeks after the order.
Can I change or return a custom axle?
No. Once the order is placed it cannot be altered, changed, cancelled, or returned.
Who can help me measure?
Call 1-800-866-3336.
Deciding between a straight or drop beam? See Drop Axle vs Straight Axle: Deck Height Guide.
Not sure which capacity to order? Read how to pick the right trailer axle capacity.
Got your measurements? Check them against the stocked sizes in Custom Built vs Pre-Configured Dexter Axles: Which to Order.
After the beam, see how to build a complete Dexter trailer axle with matching hubs, brakes and suspension.
Placing the hangers on the frame? See trailer spring hanger spacing for single and tandem axles.
Ready to build your custom Dexter axle?
Shop Custom Built Dexter Trailer Axles
Or call Southwest Wheel at 1-800-866-3336.
Southwest Wheel - Your Trailers Best Friend Since 1919.
References
- Trailer Axle Terminology, page 1 (Hub face, Spring center, Overhang), page 3 (Straight axle, Drop axle, Overslung and underslung), page 4 (Camber).
- LIT-008-00, Dexter Axle applications guide, page 3 (Definition of Terms, GAWR), page 8 (Wheels And Tires), page 9 (Axle Types), page 10 (Specifying Axles).
- FAQs About How to ID Your Trailer Axle, page 1, sections 1, 2 and 7.
