Leaf Spring Replacement for Flat Trailer with 3.5K Axle

Updated 07/09/2026 | Published 06/27/2026

Products Featured in This Question

4-Leaf Double-Eye Spring for 4,000-lb Trailer Axles - 26" Long

(2447)

$73.28

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

(2265)

$79.34

Question:

Hey there. I have a flat trailer used for hauling my raft. I am needing to replace the leaf springs. Can you provide intel on best needs. Best I can tell, axle is rated for 3500lb based on 2-3/8” dia and quick google search from tag on axle. I measured CL to CL of bolts and it is approx 26-1/4. What’s throwing me off is the height of approx 6-3/4” that is usually spec’d as dimension “D”. Most seem to be in ballpark of 4-1/4”. Thanks for your help!

asked by: Rick O

Expert Reply:

Hi Rick,

Thanks for your question!

The "D" dimension is measured from the center of the spring eye down to the top of the leaf spring pack. It's a little difficult to tell from the photos, but it looks like yours is right around 4 inches, which is pretty typical.

While the "D" dimension is worth considering, the most important factors when replacing leaf springs are matching the spring length and weight capacity.

Based on the "D35" shown on your axle tag and the 2-3/8-inch axle tube diameter, I would agree you have a 3,500-lb axle. We don't currently offer a 3,500-lb leaf spring with the 26-1/4-inch eye-to-eye measurement you provided. However, the 4-Leaf Double-Eye Spring for 4,000-lb Trailer Axles - 26" Long # e22YR would be a potential replacement option. Of note, these springs are likely rated for a higher weight capacity than what you would be replacing. This can sometimes lead to noticeable difference in ride quality especially when the trailer is empty.

Before ordering, I'd recommend removing one of the existing leaf springs and measuring it directly. You can either measure the eye-to-eye length (if the spring is unloaded) or the flat length if it's off the trailer. I've included a photo that shows how to take both measurements so we can be certain you're getting the correct replacement.

Since it sounds like you're replacing the springs on a single axle, you'll want to replace both leaf springs at the same time. It's also a good idea to install new U-bolts whenever replacing leaf springs. I recommend the U-Bolt Kit for Mounting 3,500-lb Round Trailer Axles - 5-1/2" Long U-Bolts (#APUBR-1).

If you find that you need any other suspension components while you're working on the trailer, just let me know—I'd be happy to help.

By the way, what other rafting gear do you usually bring along on your trips?

expert reply by: Christopher H

Leaf Spring Dimensions
(click to enlarge)

Measuring Leaf Springs
(click to enlarge)

Rick O.

7/6/2026

Ok I will pull a spring off and measure. I was indeed planning to replace all hardware as well while I’m at it and definitely both springs. I typically travel with my raft loaded with cooler and camping gear for multi day floats so I can be ready as soon as I get to the put in. I don’t know weight fully loaded but I’d estimate at around 2000lb. This of course also entails travel along bumpy gravel roads etc.

Rick O.

7/8/2026

I measured both eye to eye and flat. Eye to eye shows 26”. Flat I got 13-3/4” one side and 14” ( maybe 13-7/8”-ish) the other.

Christopher H.

7/9/2026

@RickO I would recommend going with two of # e22YR and one of # APUBR-1. This will give you what you need to replace the springs on the single axle. If you run into any other hardware you need to replace while doing this, just let me know.