Hanger Spacing for Single and Tandem Leaf Spring Axles

Hanger spacing is the distance between the spring hangers welded to the trailer frame. It is set by the length and type of leaf spring you run, so a single axle with 25-1/4" double eye springs, a tandem with slipper springs and a triple axle all use different numbers.

This guide gives the trailer spring hanger spacing for single and tandem leaf spring axles, by spring, with the hanger kits that match. It covers the suspension only. To pick the hubs, brakes, wheels and tires that finish the axle, see Build a Complete Dexter Trailer Axle.

Key takeaway

• The spring sets the spacing: Measure the spring and note whether it is a double eye or slipper spring before you lay out a single hanger.
• Single axle, 25-1/4" double eye springs: Set the hangers at 24-3/4".
• Tandem axle, 25-1/4" double eye springs: 29-1/2" from the front hanger to the center hanger, 29-1/2" from the center hanger to the rear hanger, and 33-1/2" axle spacing.
• Slipper springs use their own numbers: A double eye chart does not apply to a slipper spring, and the 26-1/2" E5226 slipper does not use the same chart as the 6-leaf 28" slipper.
• Never mix charts: Do not use single axle spacing on a tandem, or tandem spacing on a triple.

Terms you need

• Hanger spacing: The distance between hangers along the frame. The Dexter catalog labels it A on a single axle and B and E on tandem and triple axles.
• Axle spacing: The distance from one axle to the next on a tandem or triple. Dexter labels it C.
• Double eye spring: A leaf spring with an eye at each end.
• Slipper spring: A leaf spring with an eye at the front and an open slipper end at the rear. It does not use the same hanger as a double eye spring.
• Equalizer: The part at the center hanger of a tandem or triple that connects the springs of one axle to the next and helps transfer load from one axle to the other.
• Overslung and underslung: Overslung puts the spring seat on top of the axle tube. Underslung puts the spring seat under the axle tube.

Measure your springs first

Measure a double eye spring from the center of one eye to the center of the opposite eye. Measure a slipper spring from the center of the eye to the center of the hanger position at the slipper end. Then match the spring to the charts below.

25-1/4" double eye springs are the most common size, so most trailers use the 25-1/4" numbers below. 26" double eye springs are less common. Measure before you use a 26" figure.

Springs are rated per spring, and a pair carries one axle. A single axle uses two springs, a tandem four and a triple six. Shop all sizes in Trailer Leaf Springs.

Single axle hanger spacing

A single axle has a front hanger and a rear hanger on each side of the frame. Start with the 25-1/4" double eye row, the common case. The 26" row is for the less common 26" spring.

The 25.75" Dexter figure is for a 26" spring. It is not the spacing for a 25-1/4" spring. Use 24-3/4" for 25-1/4" double eye springs.

Single axle hanger kits

• Double eye springs: APS1BX, with 1-3/8" front hangers and 1-1/8" rear hangers. The wet-bolt version is WBAPS1BX.
• 2" slipper springs: APS188SEBX, with heavy-duty front and rear slipper hangers.

A hanger kit does not include springs. If you need the springs, hangers and U-bolts together, a single axle suspension kit covers all of them, such as the 3500-KIT-SINGLE for a 3,500 lb. axle. See Single Trailer Axle Suspension Kits.

Tandem axle hanger spacing

A tandem has three hangers on each side: front, center and rear. The center hanger carries the equalizer that links the two springs. You need two numbers: the hanger spacing from the front hanger to the center hanger and from the center hanger to the rear hanger, and the axle spacing that results.

The Dexter catalog also lists a 36" axle spacing for 2" slipper springs, with 30.4" hanger spacing. Use it only if you want 36" between the axles. For the standard layout with E5226 springs, use 28.8" and 33.5".

Tandem axle hanger kits

• Double eye springs, 3,500 lb. axles: APT3BX, with 2.5" center hangers, 1-3/8" front and rear hangers and two EQ-E1 equalizers. Greaseable: WBAPT3BX. With Dexter E-Z Flex equalizers: APT3BX-EZ.
• Double eye springs, 5,200 to 7,000 lb. axles: APT5BX, with 4.25" center hangers, 2.5" front and rear hangers and two EQ-E1 equalizers. Greaseable: WBAPT5BX. With Dexter E-Z Flex equalizers: APT5BX-EZ.
• 2" slipper springs, 5,200 to 8,000 lb. axles: APT288SEBX, with two 12" EQ-4541 equalizers.

At 5,200 lb., both double eye and slipper springs are offered, so pick the spring first and then the kit that matches it. Not every equalizer and hanger combination works together, so order the hanger kit made for your spring type and axle capacity. Complete tandem kits with springs, hangers, equalizers and U-bolts include the 3500-KIT-TANDEM, 5200-TANDEM, 7000-KIT (double eye), 7000-KIT-TANDEM (slipper) and 8000-KIT-TANDEM (slipper). Replacement equalizers are in Trailer Equalizers.

Triple axle hanger spacing

Triple axles use the Dexter catalog, not the single or tandem charts. A triple has four hangers on each side. B is the spacing at each outer end, from the front hanger to the first center hanger and from the last center hanger to the rear hanger. E is the spacing between the two center hangers.

The Dexter catalog lists triple axle double eye spacing for 26" springs, not 25-1/4" springs. For a triple with the more common 25-1/4" double eye springs, call before you lay out the hangers.

Triple hanger kits: APTT3BX (double eye, 3,500 lb.), APTT5BX (double eye, 5,200 lb.) and APT388SEBX (2" slipper). Each triple kit has four equalizers.

Hanger height and ride height

Spacing sets where the hangers go along the frame. Hanger height and how the springs mount to the axle set how high the frame rides.

• Overslung or underslung: Underslung springs lower the frame and overslung springs raise it. On a straight axle it does not matter which side of the tube you weld the seats on for fit, but overslung and underslung give different ride heights.
• Hangers too short: The axle can contact the frame as the suspension moves, which can overload the axle.
• Hangers too long: Too much travel can damage the springs under heavy loads. Use bump stops to prevent over travel.
• Equalizer hangers too short: On a tandem, the spring eye can contact the frame as the suspension moves and overload the spring.

The hanger kits above use matched hanger lengths. To replace a single hanger, loose hangers are sold by length in Spring Hangers, including the HG-112, HG-144, HG-246 and HG-425. If you are working out deck height, see Drop Axle vs Straight Axle: Deck Height Guide.

Lay out and install the hangers

• The axle must be square to the trailer centerline within 1/2 degree. On a tandem or triple, each axle must be parallel to the others within 1/16", measured at the wheel centers.
• Do not measure from a cross member unless you have checked that it is square to the centerline.
• Dexter axles are directional. Install each axle with the front facing forward and the top facing up.
• On a stock beam, the spring seats ship loose. Southwest Wheel does not weld spring seats on stock beams. You weld them at your spring center before the springs go on.
• Spring eyes and equalizers must be free to rotate. Per the Dexter service manual, 9/16" shackle bolts, spring eye bolts and equalizer bolts without a shoulder are a snug fit only.
• For a shoulder type shackle bolt with 7/16" threads, drive the bolt into the hanger so the serrations grip. Do not pull it in with the nut. Torque the nut to 30-50 ft. lbs. A shackle bolt that can spin will wear out the hanger.
• Inspect the suspension every 6,000 miles.

Hanger spacing checklist

1. Identify the spring: double eye or slipper, and its length.
2. Decide single, tandem or triple.
3. Find the hanger spacing, and the axle spacing for a tandem or triple, in the matching chart above.
4. Choose the hanger kit made for your spring type and axle capacity, or a complete suspension kit.
5. Decide overslung or underslung for the ride height you want.
6. Lay out the hangers, then check that the axles will be square and parallel.
7. On a stock beam, weld the loose seats at your spring center.
8. Install the springs with the eyes and equalizers free to rotate.

Verify fitment before ordering or contact Southwest Wheel for assistance. Call 1-800-866-3336.

Frequently asked questions

What is the hanger spacing for a 3,500 lb. axle?

With 25-1/4" double eye springs such as the SW4B, a single 3,500 lb. axle uses 24-3/4" hanger spacing. A 3,500 lb. tandem uses 29-1/2" from the front hanger to the center hanger and 29-1/2" from the center hanger to the rear hanger, with 33-1/2" axle spacing.

Can I use single axle spacing on a tandem?

No. A tandem uses its own hanger spacing and axle spacing. Do not use the 24-3/4" single axle number on a tandem.

Is slipper spring spacing the same as double eye spacing?

No. A slipper spring does not use the same hanger as a double eye spring, and its spacing is different. A single axle with 6-leaf 28" slipper springs uses 28" hanger spacing.

Does the E5226 use the same spacing as the E5115?

No. The E5226 is a 26-1/2" slipper and uses the Dexter slipper chart: 24.0" on a single axle, and 28.8" hanger spacing with 33.5" axle spacing on a tandem.

Why does the Dexter catalog show 25.75" for a single axle?

That figure is for a 26" double eye spring. A 25-1/4" double eye spring uses 24-3/4".

Does a hanger kit include the springs?

No. A hanger kit includes the hangers and their bolts and nuts, with shackle links on the double eye kits and equalizers on the tandem and triple kits. A suspension kit includes the springs, hangers and U-bolts together.

Does Southwest Wheel weld the spring seats?

Not on stock beams. The seats ship loose, and you weld them at your spring center. Pre-configured beams have the seats pre-welded, and a custom beam has welded or loose seats, chosen on the order form.

Ordering a new axle for your hangers? See How to Measure for a Custom Dexter Trailer Axle and Custom Built vs Pre-Configured Dexter Axles: Which to Order.

Matching springs to your load? Read How to Measure for a Custom Dexter Trailer Axle.

Southwest Wheel - Your Trailers Best Friend Since 1919.

References

• Southwest Wheel spacing charts: Single axle double eye using 25 1/4 inch springs; Tandem axle double eye using 25 1/4 inch springs; Single axle slipper using 6 leaf T2E5115 (E5115); Tandem axle slipper using 6 leaf T2E5115 (E5115).
• Dexter Light Duty Catalog, 600-8,000 lbs. axle capacity (2020.05), page 25 (Leaf Spring Application Information: Double Eye Springs), page 26 (Leaf Spring Application Information: Slipper Springs).
• LIT-008-00, Dexter Axle applications guide, page 9 (Running Gear Systems: Leaf spring, Axle Attachment Systems), page 10 (Specifying Axles), page 12 (Installation Suggestions), page 13 (Installation Suggestions: shackle bolts), page 19 (Axle Alignment).
• Trailer Axle Terminology, page 3 (Overslung and underslung), page 4 (Double eye, Slipper).
• Dexter Trailer Axle Service Manual, 2,000 to 8,000 lb., page 66 (Suspension Fastener Torque Values).