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.