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Suspension Enhancement to Lengthen the Life of My Leaf Springs  

Updated 01/07/2026 | Published 01/05/2026



Question:

I have a tandem axle RV travel trailer that has 3500 lb axles. The current leaf springs DEXTER Vendor Part 072-042-00 are now flat and need replacement. I would like to upgrade them to heavier weight rating leaf springs in hopes to prevent flattening in the near future understadnign that heavier leaf springs will not increase the RV GVWR. Is there a products thats recommended as replacements?

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Expert Reply:

Hey Juan,

I recommend getting the Dexter 4-Leaf Double-Eye Spring # DX23CR like you currently have but adding SumoSprings Trailer Helper Springs - Overslung # TSS-107-40 to your system. Install is easy and they don't require any tubing or air pressure management. Adding leaf springs rated for higher than your axle capacity is going to give you a stiff ride, while the SumoSprings will make your whole suspension system last longer and give you a smoother ride.

If your leaf springs are underslung, then you'll want the SumoSprings Trailer Helper Springs - Underslung # TSS-106-40.

To determine which setup you have: overslung means the axle is mounted below the leaf springs, underslung means the axle is mounted above the leaf springs.

Do you need to replace your U-bolts as well?

expert reply by:
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Josh B
Juan P. profile picture

Juan P.

1/7/2026

Thanks for the input. Regarding the u bolts, are they recommended to be replaced (along with any other suspension components) when replacing leaf springs? Said differently, are any components 1 time use after being torqued?

Josh B. profile picture
Etrailer Expert

Josh B.

1/7/2026

@JuanP I would recommend replacing your existing u-bolts because the nuts are designed to mis-align the threads as they are torqued down to prevent the u-bolts from coming loose. Finding the right replacements will be based on the diameter and shape of your axle, so once you have that info you can plug it into the filters of the u-bolt page from the link I attached. As far as the rest of the suspension parts, it's always good to check them for excessive wear and tear or corrosion when you're already replacing the leaf springs. You can skip the pain of having to jack up the trailer and pull it apart again if there's something that clearly could use a replacement now.

Helpful Links

dept-pg-trailer_suspension_parts-sf-u~bolts.aspx

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