Securing all parts that rotate or move at a high rate of speed may seem like common sense when putting an engine together, but do you know what kind of hardware to actually use? Harmonic balancers fall into the category of parts that spin really fast since they’re attached to the crankshaft, and if they aren’t bolted down properly there is going to be trouble. Nick Orefice and Aaron Neyman from Fluidampr provided us some solid tips on how to make sure a harmonic balancer is secured properly.
There are three main ways that a harmonic balancer is secured to an engine; press fit, slip fit, and flange mount methods. Each of these are used with different engine applications and have different requirements for how they need to be mounted to an engine.
The bore of the balancer for a press-fit application is smaller than the crank snout; this type of balancer needs to be aligned properly and installed or removed with the right tools to prevent damage. These balancers need to be secured to the crank via keyways or being pinned in higher horsepower applications. A slip fit balancer can be removed by hand since it doesn’t have a diametrical press fit; these aren’t the best to use in a drag racing application where there’s a lot of horsepower in play. The most robust way to attach a balancer is the flange mount method; this is seen in diesel applications and requires high strength bolts and a torque plate to provide the most clamping surface possible.
After you’ve figured out what kind of balancer fits your needs and are ready to install it, how do you decide on what kind of hardware to use? Orefice explains that using the right bolts and high-quality bolts is important to a successful installation.
“New OEM or better quality bolts are always recommended. Fluidampr offers specially developed bolt kits and mounting hardware for high-power Cummins and Duramax diesel drag racing engines. Installing new hardware is especially important if a torque-to-yield bolt(s) are used. A torque-to-yield (TTY) bolt achieves its precise clamping force by permanently stretching the shaft. Once that is achieved it will not provide the proper clamping force on re-use. You can identify a TTY bolt by the step down non-threaded shield area on the shank.”
Now, when it comes time to start buttoning up your harmonic balancer installation, paying attention to the torque specs is critical. Besides the torque specs, Neyman tells us what you need to do to prepare your fasteners for installation.
“Follow the recommended torque spec provided by the OEM or high-quality aftermarket bolt kit manufacturer. It is good practice to completely clean, deburr and inspect the threads of the crank and bolt. Note if the recommendation is for dry torque or wet torque. Apply high-torque fastener lube if recommended. Too little torque will allow the bolts to back out and the damper to slip. Too much torque will result in stripping the threads or snapping the bolt. Always use a quality, calibrated torque wrench. An impact driver is not recommended to install the bolt(s).”
Drag racing and high horsepower applications will push parts like your harmonic balancer to their limits so installing them properly is important. By making sure your balancer is bolted down properly you will get the maximum performance your engine offers while preventing any major damage.