Installing Fluidampr’s Harmonic Damper In A 5.9-Liter Cummins


Vibration is a natural part of any engine, but just like anything else, too much or too little of it is a potential debacle. Where it concerns diesel motors, the happy medium is affected directly by the harmonic balancer at the end of the crankshaft.

Over at Fluidampr, harmonic balancers are the company’s forte. Decades of research and development have led Fluidampr to create some of the best balancers on the market, surpassing elastomer offerings from OEMs and giving diesel drivers a more safe and secure driving experience.

We recently received a harmonic balancer (PN 920301) to install in our 2006 Dodge Ram 2500 and improve its lifespan. Prior to installing it, however, we took the opportunity to talk with Fluidampr’s Brian LeBarron, who helped to shed some light on what the harmonic balancer will do, how to tell when one is going bad, and how Fluidampr tests its products.

Background Of A Harmonic Balancer


Simple though it may appear, the Fluidampr harmonic balancer is an improved design over OEM elastomer harmonic balancers.

Engines go through three types of vibration: torsional, axial, and rotational. Where it concerns harmonic balancers, torsional vibration is the order of the day (axial and rotational vibration are addressed by thrust washers and balancing the rotating assembly, respectively.)

“Torsional vibration is the end-to-end twisting and rebounding of the crankshaft, and is caused by internal combustion,” explained LeBarron. “With a properly designed performance harmonic balancer, you can increase overall durability, as well as unleash lost torque and horsepower through greater efficiency.”

Wear on the stock harmonic balancer can sound rather vague. LeBarron explained what this meant in greater detail. “Most passenger car and light-truck OEMs use a tuned elastomer style harmonic balancer,” he said. “They are inexpensive to mass-produce. In these designs, a rubber-based ring is bonded to an inner hub and outer inertia ring. Engineers will ‘tune’ it to control peak torsional vibration frequency only in a narrow, pre-determined range. They are adequate for daily driving under stock conditions and become an area of concern once performance engine parts are added.”

For the sake of curiosity, we wondered: what if a harmonic balancer is removed entirely? LeBarron said, "Uncontrolled torsional vibration can lead to accelerated bearing wear, inefficient timing, and failures of the oil pump and crankshaft."

For the sake of curiosity, we wondered: what if a harmonic balancer is removed entirely? LeBarron said, “Uncontrolled torsional vibration can lead to accelerated bearing wear, inefficient timing, and failures of the oil pump and crankshaft.”

LeBarron elaborated: “Installing performance parts that increase torque can overwork an elastomer harmonic balancer. Overworking generates excessive heat within the balancer, and that rubber-based ring is susceptible to this heat. Age and exposure to chemicals add to the wear.”

How Can I Tell If My Harmonic Balancer Is Going Bad?


There are many ways that you can tell if your harmonic balancer is going bad. Fluidampr’s Brian LeBarron listed the following methods:

  • Inspect for cracked, bulging or missing rubber
  • Timing marks out of place
  • The outer ring wobbles
  • Accessory drive belt(s) slapping
  • Excessive engine vibration

LeBarron added that “changes to the rotating assembly can shift where peak torsional vibrations occur. This causes the elastomer harmonic balancer to go ‘out of tune,’ and no longer protect the engine when it needs protection the most.”

A diesel owner worth his salt will always have an eye on his truck’s internals, checking exhaust gas temperatures, oil levels, engine codes, and other areas. However, diagnosing the harmonic balancer isn’t something done with a dipstick or code reader. LeBarron offered some insight on how to do it on one’s own.

“There are ways to identify signs or symptoms of a worn elastomer harmonic balancer include,” he said. “You can inspect for cracked, bulging or missing rubber; timing marks out of place; wobbling of the outer ring; accessory drive belt(s) slapping; and excessive engine vibration. If these signs or symptoms are found, it is recommended to look at upgrading your damper.”


Moving to Fluidampr is indeed an upgrade: gone is the problematic rubber, and in its place is a proprietary silicone blend that does the job a whole lot better. “Compared with elastomer, silicone is an excellent dissipater of heat, and will maintain its damping stability across a wider temperature range,” said LeBarron. “It can handle temperatures as low as -40 degrees Fahrenheit, and up to 300 degrees Fahrenheit.”

LeBarron added: “Fluidampr performance dampers control torsional vibration by an inertia ring that shears through a thin layer of viscous silicone inside a sealed housing. The shearing action converts torsional vibration into heat. The heat then radiates through the outer housing.”

Our harmonic balancer works across the entire rpm range and is built to stand up to abuse. This means you can maintain optimum protection when increasing power and modifying the engine. – Brian LeBarron, Fluidampr

Some might wonder why Fluidampr’s harmonic balancer weighs a noticeable amount more than the stock balancer – 23.25 pounds versus 15.25 pounds. LeBarron had this to say: “The housing cavity is where we have a heavy inertia ring, because proper mass is required to control torsional vibration. This is why our balancer will generally weigh more than stock. The advantage we have on stock is with the rotating weight: since the inner inertia ring is non-bonded and freely rotates in a thin layer of silicone – about the thickness of two business cards – its full weight is not resting on the crank once it begins spinning at rpm.”

“This makes it so our damper’s actual rotating weight is only two-thirds of the damper’s static weight,” continued LeBarron. “This allows the added mass of the inertia ring to provide torsional vibration control, but at a rotating weight close to stock.” For the record, that difference in weight is only .3 pounds – 15.2 for stock, compared with 15.5 for Fluidampr.

The integrity of Fluidampr’s harmonic balancer is achieved with laser welds to the outer housing, which provides an “accurate and consistent cavity-free weld to prevent any outside contamination,” as LeBarron stated. He affirmed that a leakdown test is performed afterwards to make sure the damper is completely hermetically sealed.

This Fluidampr harmonic balancer weighed in at 23 pounds, eight more than stock. Read on to learn why this was actually a good thing.

Testing on the dampers is done using Vibratech TVD’s (the OEM supplier of heavy-duty diesel engine manufacturers) strict ISO 9001:2008 Design and Development criteria. “We test with computer-assisted engineering, modeling, and live engine validation,” said LeBarron. “We also do finite element analysis, 3-D printed prototyping, accelerated lifecycle testing, thermal imaging, and much more.”

Of course, Fluidampr enjoys feedback from customers, and seeks to always meet their needs when asked. “We have championship engine builders who have relied on our dampers for over 30 years,” said LeBarron.



To begin, we took off the negative terminal from the battery to prevent accidental electrical discharges while working in the engine bay. Our 2500 had an aftermarket air intake kit from Banks Power, which we removed to allow for access to the fan shroud brackets. Once the brackets were gone, the fan was removed as well.

Next, we removed the accessory belt by loosening the tensioner and carefully working it over all of the pulleys – power steering, A/C, alternator, and so forth. Now we had a good deal of space to work in to get access to the harmonic balancer.

Left to right: we removed the negative terminal from the battery to prevent accidental discharge during the installation; the air intake was removed to allow us more access; the fan shroud and fan were removed.

The balancer was held in place with four 15mm bolts. Thankfully, they came off without much difficulty; we’ve seen others use “cheater bars” to get theirs off!

We didn't have to, but if you have a 1992-98 Cummins, you will need to check the gap between the magnetic pickup and the damper.

We didn’t have to, but if you have a 1992-98 Cummins, you will need to check the gap between the magnetic pickup and the damper.

We eventually got the bolts out and were able to slide the balancer off of the crankshaft’s snout. At this point, Fluidampr recommended that we check to make sure the snout was free and clear of any burrs, chips, or other defects that could negatively affect the new balancer’s operation.

We compared both balancers. The stock one was lighter and smaller than the Fluidampr one, but the extra weight was actually an advantage. This was because the Fluidampr balancer had a heavy inertia ring that was non-bonded and rotated freely in a layer of silicone. At speed, its rotating weight would be right in line with that of the stock balancer, while also being stronger and better at dissipating heat.

We took the chance to compare both of the dampers and recognized some key differences right away. First off, the rubber ring that LeBarron had spoken about was right there, chewed up and chipping away. The stock damper as a whole seemed in acceptable shape, but we were glad all the same to have our brand new Fluidampr ready to go in and keep the truck running smoothly.

LeBarron commented, “As rubber hardens and chips away, it stops providing the elasticity needed to leverage the outer inertia ring and thus loses the ability to effectively reduce torsional vibration. Eventually, the elastomer will fail and the outer ring can go flying into the engine bay. This is why race organizations require teams to run harmonic balancers that meet SFI specifications.”

Now, we took the new balancer and slid it onto the crankshaft snout with the help of some moly grease coating the contact areas. In went the four 15mm bolts, and we tightened them as much as the freely moving crankshaft would allow. We then put on the accessory drive belt, which helped limit the crankshaft’s movement, and tightened the balancer’s bolts to their proper specification – 92 ft-lb. Fluidampr recommends using new bolts with a new balancer, but ours showed no signs of extreme wear and abuse, so we decided to use them again.

The Fluidampr harmonic balancer was installed onto the motor and torqued to its proper specification of 92 ft-lbs.

We put back everything in its place in reverse order, starting with the fan, then the fan shroud, then its mounting brackets, and finally the air intake. Our installation was finished.



At the time of this writing, the Fluidampr harmonic balancer has been in the Dodge Ram for several weeks. The owner, Lloyd Hunt, has experienced firsthand what a difference the damper has made in the driving experience.

“To me, there has been a reduction in noise, and less vibration in the 2,000-3,000 RPM range,” he said. “Also, the idle is much smoother. I am enjoying the new damper, and now I am able to focus more on getting my truck ready for the next level.”

With less noise and vibration, the 2500's 5.9-liter Cummins motor is running driving like new, and will for a long time to come.

With less noise and vibration, the 2500’s 5.9-liter Cummins motor is running like new, and will for a long time to come.

Getting one’s engine dialed in and taken care of is a great feeling, and everyone should ride around with the utmost confidence in their machine. Fluidampr’s products are part and parcel of that feeling, and with offerings for all Big Three diesel applications, there is something for almost every diesel owner out there. Head over to Fluidampr’s website and Facebook page for more information and announcements.

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About the author

David Chick

David Chick comes to us ready for adventure. With passions that span clean and fast Corvettes all the way to down and dirty off-road vehicles (just ask him about his dream Jurassic Park Explorer), David's eclectic tastes lend well to his multiple automotive writing passions.
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