One of our most repetitive, albeit – rare, tech calls here at Carli relates to “Squeaky” leaf springs. Contrary to popular belief, leaf springs themselves don’t squeak; the bushings do. Looking at the Carli Deaver’s, its easy to scapegoat the springs as the culprit – after all, the layers of spring steel that comprise the leaf springs appear to be in constant contact with each other. Truth is, there’s a small gap formed between each layer by the slider on the outer edge of each spring BUT the coating bridges much of this space.

The majority of the steel on steel contact is at the center of the pack where the center-pin is located. This portion of the pack is static; it doesn’t grow, shrink or shift during travel relative to the outer extremity of the spring. Additionally, the contact at the end of each leaf spring is again, where you’ll find the plastic sliders minimizing friction and thereby, the noise and bind during spring operation. In many of our newer spring packs, you’ll find a thin (barely visible) spacer between each leaf spring in the pack to separate the springs and further reduce friction. Again, tiny and hid by the leaf spring coating but extremely effective, none-the-less.

Years of experience led to the discovery that leaf springs don’t squeak, bushings do. Many customers have come through the shop pointing to their squeaky leaf springs; a few hours of labor later and they’re on their way with a quiet truck after we drop the hanger bolts one at a time, disassemble the bushings and coat the leaf spring eye, factory bracket, bushings and crush sleeves with a heavy synthetic chassis grease.

Want to test at home? Grab a can of penetrating lubricant. Soak one bushing assembly and drive the truck, repeat this until you’ve hit all bushing assemblies or, until the squeak is gone and you’ve found your culprit. With the culprit found, drop and grease that assembly (the penetrating lube is ONLY diagnostic). If the squeak persists, soak one leaf pack at a time with the penetrating lubricant until you’ve isolated your cause. If it’s in the pack and they’re more than a couple years old, droop the rear end, pressure wash and hit them with some dry-lube. If everything the packs and bushings are all greased and you’re still getting a squeak, you know it’s not in the springs.

Leaf springs don’t have zerk fittings and they’re a pain to service once installed – properly greasing the bushings on initial installation is the best way to ensure silent operation as long as possible.

Let’s start with the installation of your Carli Leaf springs as the process by which you’ll service existing springs is the same except you’re removing bolts and pulling bushings apart to reach the same end result.

Some Carli springs come with vulcanized bushings in one eyelet or both; these vulcanized bushings are non-serviceable; ignore these.

With your Carli Leaf spring pair, you’ll receive a box – this box contains your bushing kit; in the bushing kit, you’ll get 2 bushings and 1 crush sleeve per spring eye and some small tubes of grease. For this spring (L70 – Matches 4.5″-5.5″ Carli Systems for 2017 Super Duty), the bushing kit contains (4) Front Bushings, (4) Rear Bushings, (2) Front Crush Sleeves, (2) Rear Crush Sleeves and a bag with 6 small tubes of heavy, synthetic grease.

The Bushing kit comes with everything assembled as they are when installed in the spring for easy reference and packaging; these will need to be completely disassembled to properly grease the assemblies.


Cut the tops off all the grease packs and get some gloves on – you’re about to make a mess. The old saying, “A little bit goes a long way” – ignore that. Over-grease these bushings as you won’t hurt anything. You may waste some here but all excess grease will be pushed out when you drive the sleeves into the bushings. I’d rather go to my local parts store and pony up the $15 it costs for a good tube of grease and cake it on as it’s cheap insurance against noise vs. being stingy with the grease and needing to pull it apart in a month when the bushing start squeaking. In the shop, we use Castrol Pyroplex Blue 2. I use the better part of 1/3rd of a tube on a single leaf spring install. The grease tubes we provide are fantastic as well and convenient if you don’t have access to a local parts store; that said, I always prefer working with a full tube of grease.

With the bushings and crush sleeves coated (ALL SURFACES), pay special attention to the grease flutes. Our bushings are custom designed to hold more grease and better migrate the packed grease thanks to these engineered channels. Ensuring they’re full of grease on install will pay peaceful dividends in the coming months/years.

With the bushings packed, you can begin assembling into the leaf springs. The Carli leaf springs are designed with a military wrap. This double-wrap ensures the leaf spring eyelet has a fail-safe should the spring with the bushing eye fail. This double-wrap is the FRONT of the spring. Where applicable, this will house the larger of the bushings/crush sleeves as the front hanger bolt is larger than the rear on all but a few (older Ram) platforms. The rear eye is a single wrap as there’s limited space to install into the shackle.

Step One? You guessed it. Stand the spring up and coat the inside of the spring eye and outside surfaces (anything that will touch bushing material) with the provided grease. Once greased, install the pre-greased bushings by pushing them into the eye, one on each side. I was easily able to push the Red bushings into the front eye of the spring, by hand, with a bit of force. If your spring wrap is a bit tighter, you can use a dead-blow to assist in driving the bushings in.

With the bushings in, GREASE and slide the crush sleeve in. This is where the dead-blow comes in. We use the dead-blow hammer to drive the sleeves in. This process may slightly unseat the bushing on the opposite side; repeat the hammering on that side until the assembly is flush on both sides. Some prefer to use a c-clamp and 2 plates and it’s a bit more gentle but we’ve never damaged a bushing using this method.

As you can see, I dipped into my tube of Castrol.

The process is the same for the rear with the smaller bushings and crush sleeves.

With the bushings installed and flush, grab a rag and clean the spring wraps of grease on the outside of the wrap; it’ll attract dust/dirt. One more quick greasing of the bushing faces and crush sleeve and the springs are ready to install.

When installing the springs, put a layer of grease on the inside of the factory spring hanger (bracket) and on the shank of the bolt; don’t grease the threads of the bolt!

There you go, a quiet-leaf spring recipe pulled from the cookbook of Sage Carli’s Great, Great Grandmother. Happy Trails, all!