Replacement Leaf Spring for a Nitro Z-18 Boat Trailer

Updated 05/21/2025 | Published 05/15/2025

Question:

Good afternoon. I need new double eye leaf springs on my Nitro Z-18 single axle bass boat trailer. The axle is a 3,500lb axle. My hanger bolts are exactly 25.5 inches apart horizontally. Of course, one bolt toward the front is lower than the bolt in the back with the shackles. I have 4 5/8in shackles 3-1/8in distance between both center bolt holes. How long should my leaf springs be, would 25.25-25.5 inches work? My current leaf springs seem a bit long as seen in picture as they are around 26-26.25 inches eye to eye and are single leaf. Can you please recommend a product? Should I go three leaf or four leaf? Is it beneficial to jump up to a 4,000lb leaf spring for peace of mind, such as e93SR?

asked by: Tom H

Nitro Z-18
(click to enlarge)

Expert Reply:

Hey Tom, thanks for the picture and all the information! The 25-1/4" Long etrailer Rust-Resistant 3-Leaf Double Eye Spring item # e93SR, you were looking at will probably work just fine but I still recommend measuring to confirm.

Leaf springs tend to stretch out quite a bit over time the more you use them. The best way to get an accurate measurement for a replacement is to jack one side of your trailer up to get the weight off of the suspension. Once you do this you can just measure from the eye hole to the eye hole of the leaf spring and go off of this to pick out a replacement.

You can definitely jump up to a 4,000 lbs capacity spring. Any additional leafs are going to offer more support. You'll notice a slight adjustment in rise height due to the extra leafs compared to your current set up.

If you have any additional questions, go ahead and throw them into the comment box below and I'll be happy to help you.

expert reply by: Jerred H

Thomas H.

5/20/2025

Hi Jerred. Thanks for the response! I went ahead and purchase and installed #e93sr leaf springs along with the Dexter wet bolt kit. I am unable to post another pic through this portal, but I’ll try and articulate this. When the trailer is unloaded, the shackles lean slightly forward to the front of the trailer, and when the trailer is loaded, they flex and lean slightly toward the rear. Just wanted to get your expert opinion on if this install will work and not cause issue as the leaf eyes are about 1/4 inch shorter than my hanger bolts. My previous leafs were measured and were 26 inches unloaded and removed from the trailer. I want to avoid having to go 26 inches as it looks like all my options would have a fourth leaf and raise my ride height even more. Thanks!

Jerred H.

5/21/2025

@ThomasH You're welcome! That sounds like it's set up and working normally. How does it feel when you're driving around?

Thomas H.

5/21/2025

@JerredH thanks for confirming that this is within normal range of motion for the shackles. Ride is a bit stiffer due to the multiple leafs and the jump up from 3,500 to 4,000, but seems within reason. No pulling on one side or the other, etc. Seems like a good fit from my perspective. Thanks for your help!