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It's Always Spring-Time at Donovan Spring!

Your One-Stop Spring & Suspension Specialists

Donovan Spring Co., Inc.
6 Enterprise Drive
Londonderry, NH 03053
(603) 627-9800



Extra Leaf

WHAT is an Add-A-Leaf?

An Add-A-Leaf is an extra leaf added to a leaf spring pack. Added leaves are installed to increase vehicle carrying capacity or to reduce sway by creating a firmer ride. They can also be used to increase the ride height of your vehicle. The number or leaves added and the thickness of the leaves directly determine the percentage of ride quality/height change. Adding a leaf to your leaf spring is very similar to simply upgrading your springs. You are essentially adding another level of support to your spring which is making the spring capacity greater.

The Stanley Plus XL and TXL Series are a complete line of tapered extra leaves for virtually all light, medium and heavy duty full taper front and rear spring applications. Every XL and TXL leaf is rated to make adding extra leaves easy. These leaves improve the carrying capacity on applications where factory springs won’t do the job.

The Stanley Plus SXL Series of extra leaves are designed specifically for pickups with a rear spring utilizing the new dual centering system. Every SXL leaf is designed to make adding extra leaves easy. Stanley SXL leaves add the carrying capacity to provide additional stability and strength.

About our Add a Leaf Kits

Our extra leaf kits are for light duty trucks, vans, utility vehicles, and motorhomes and come equipped with extra leaves for the front or rear of your vehicle. All Dayton Add a Leaf kits are packaged complete with all necessary hardware and U-bolts for installation. Our Add a Leafs will come with a center pin and will either utilize factory u-bolts or require u-bolts to be purchased separately. Many of the add a leaf kits we sell will bring the spring capacity to the exact level of an HD spring for that very vehicle.

Warning: DO NOT attempt to “build up” a tapered spring unless using an extra taper leaf specifically designed for that purpose. If you have any questions regarding these add a leaf kits please contact us.


Add-A-Leaf vs Helper Springs

What is the difference between an Add-A-Leaf Kit and Helper Springs? Both will give you lift while supplying load support. Some Add-A-Leaf kits will mount between the leaf springs and the rebound leaf whereas all helper spring will mount onto the springs. The one main difference between add-a-leafs and helper springs is an add-a-leaf will give you a constant rate while helper springs will give you constant and progressive. What is progressive rate? The progressive rate means that your truck must be loaded and the leaf spring compressed in order to activate the helper spring. When the load in your truck increases the helper spring will progressively increase its resistance to the load.


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