TCI’s Rattler Balancer: Tech Review

According to my mom, and just about everyone else, a car’s “powerplant” rests serenely in the engine bay. Of course, there’s a whole lotta shakin’ going on beyond what the eye can see — certainly enough to impress any high school physics teacher. The energy released during combustion and transformed into rotary motion requires a damper to minimize the vibrations that can lead to automotive ruin. The traditional solution for this is the harmonic balancer.

We recently hooked up with Mississippi-based TCI Automotive to learn more about balancers and why they see their new Rattler torsional vibration absorber as an option for people building engines for both street and strip applications. powerTV is currently building two engines for different applications — read on to see how each one was built and how they both benefited from TCI Automotive’s technology.

Types of Balancers:

The traditional balancer that we’re all familiar with is the damper-type that attaches to the nose of the crankshaft (most often in cooperation with the front pulley) and reduces torsional vibration through a number of methods.

Viscous dampers use a viscous fluid and an inertia ring to dissipate the torsional vibration as heat energy.

Contrast this with polymer dampers, which also use an inertia ring but are paired with a spring element (usually rubber or other polymer) that is tuned to counter-act the first natural frequency of the crankshaft when torque is applied at a respective engine speed.

According to TCI, there are three potential problems with both of these types of dampers:

• They could wear out due to a combination of elements such as energy, age, and exposure to various temperatures and chemicals.
• They tend to be tuned to only one RPM range.
• They generally merely dampen, not absorb, energy.

pendulum absorber is a balancer that is relatively new to the automotive aftermarket.

This balancer absorbs — not merely dampens — vibration through a set of counter-weights whose natural frequencies are directly proportional to the rotating speed of the crankshaft. This alternative to the traditional damper-type balancer have now begun to trickle down to those of us on the street and the strip.

The Rotating Pendulum Vibration Absorber aka the TCI Rattler

“Not only is the Rattler an alternative to traditional balancers, but it’s also an advancement because it puts engineering creativity from the aviation industry right in your hands,” claims Chris Douglas of TCI. “This theory of controlling harmonics has been used by the aviation industry in small engine aircraft for years by hanging weight from the crankshaft.”

Rotating pendulum vibration absorbers were introduced way back in 1936 on the Series G Wright Cyclone radial engine; engineers observed noticeable reductions in engine wear plus higher take-off speeds, yet there was a reduction of “airscrew” stress due to reduced torsional vibration.


The motion of the absorber mass, under the action of the vibration transmitted from the crankshaft, resembled the motion of a pendulum. Also, worthy of note was that the absorbers had the benefit of not needing to be tuned to an exact resonance due to close manufacturing tolerances. Chris continues, “It had never been used in a balancer form until TCI Automotive and its consultants developed the Rattler.”

With over 60 years of proven research and reliability behind it, TCI now offers the Rattler torsional vibration absorber to us grunts on the ground. Looking like a traditional balancer, the Rattler’s magic is due to the centrifugal force of the rollers that ride on the outside wall of the absorber’s body. The rollers sit there until detonation in a cylinder slows or twists the crank. At that exact moment, the momentum of the centrifugal force moves the rollers in the opposite direction of the force to cancel out the vibrations.

“The biggest difficulty in developing the Rattler was learning which engines had which specific vibrations,” Chris points out. “After a couple of years of testing with Roush Industries, we found out that the harmonics ran the same in all engines with one discrepancy—harmonics changed based on the number of cylinders the engine had, i.e. the most detrimental order of vibration in a 6-cylinder was the 3rd & 6th orders, while V-8 engines were the 2nd & 4th order of vibration.”

What the Rattler Will Do For You

The Rattler is notable because according to TCI, it is effective throughout an engine’s entire RPM range. “It works better because it attacks the specific order of vibration an engines has,” Chris says. “It’s design allows for the elimination of detrimental harmonics in an engine. The roller is held to the outside of the hole they ride in by centrifugal force. The momentum of the engine’s RPM hold them there. There is no movement in the roller until the crank begins to see a force opposite of its revolution. At that point in time, the roller counteracts that force.”

The Rattler’s design has been claimed to yield a smoother-running engine, maintain increased valvetrain stability, offer more accurate ignition timing, and ensure more overall power and extended engine life. It has the advantage of being lighter than traditional dampers, and it’s CNC-machined for precision tolerances. Racers have the additional assurance that the Rattler has earned SFI 18.1 certification, making it legal in just about any racing series around the country. TCI Automotive also offers a complete selection of timing pointers designed to be used in conjunction with the Rattler or other dampers of similar dimensions.

Our Projects That Use TCI Rattlers

Project Riced Rat Rod: 400ci Dart-SHP SBC

If you’ve been keeping up with Project Riced Rat Rod, you know it’s being built as a hybrid of sorts—a RWD Japanese car with good ol’ American iron-block ingenuity! The small block Chevy sits in the engine bay of one 1991 Nissan 240SX. However, this East/West hot rod will basically serve as a budget weekend warrior.

Handling the building and dyno chores is Steve Brule of Westech. A Dart SHP 400 CI short block was chosen for the features that make Dart race blocks so attractive: excellent oil provisions, siamese bores, blind bolts, and ductile iron main caps with splayed bolts (you can say we’re in love!). Since Project Riced Rat Rod will be huffing laughing gas on occasion, it was decided that forged pistons and H-beam rods should be used in conjunction with a forged steel 4340 crank. We chose the Dart Pro 1 Aluminum top end kit, especially because it comes with stainless valves, springs, and retainers. Matching the 72 cc heads to the above gave a 10:1 compression ratio—perfect for a car that will mainly see street duty. Comp Cams 1.52 Pro Magnum steel roller rockers (made from 8650 chrome moly steel) with beefier 7/16th studs were paired with the Magnum-series one-piece chrome moly steel pushrods and spider-style lifters.

When it was time to decide on the all-important cam, Steve reasoned that the Comp Cams 12-443-8 would be best suited for a car in Southern California with a 5-speed and power brakes. A Zex Perimeter Plate nitrous kit was installed under our Holley 830 CFM 4150 HP carburetor. Finally, chosen for its microprocessor’s ability to adapt dwell time, was the Pertronix Flame-Thrower Plug ‘N Play distributor.

Of course, to reduce torsional vibration, we went with TCI Automotive’s Rattler. Hear that rattle? Not only is it virtually maintenance-free, but installation is the same as traditional dampers too. With about 2,000 miles on the engine, not counting the dyno or track runs, the revs are quick and smooth, plus it’s been utterly reliable.

All told, hooking everything up to the dyno produced 523 horsepower on 91 octane. An impressive 668 horsepower was accomplished with a 950 psi shot of nitrous; upping the shot to 1050 psi netted an even more amazing 702 horsepower!

Project 666: Pro Power 427ci Windsor

For this project, the goal was to make 675+ horsepower while still staying intact under consistent redline runs at the strip. Achieving this power and reliability with our Ford Windsor small block means you need the right balance among displacement, RPM range, longevity, and the right horsepower and torque. Pro Power was called to help achieve this goal.

Dart’s Virgin 355-T61 aluminum block was selected, being able to be bored and stroked up to 450 cid. It is also available in several deck heights and bore applications. We went with 9.500” and 4.125”, respectively, to add cubic inches and take advantage of the breathing offered by the Trick Flow heads. A 4340 steel alloy Lunati Pro Series crank was chosen because it’s designed to be internally balanced. With four different stroke sizes to choose from, Pro Power went with the largest—a four-incher—for its ability to fit pistons with reasonable compression height. The light weight and tough construction of Lunati’s 4340 Superlight I-Beam 6.125” forged rods made them an easy choice.

With all the tailoring on this project, we knew that only custom pistons would do. JE Pistons offers them in any dome, dish, or valve relief configuration. The current specs of the engine and the desire to achieve 13.5:1 compression demanded us to use their custom forged 2618 pistons. This combination ends up being 427 cubic inches, which is a number that’s close to the hearts of Ford guys around the world (although the classic 427 was of the FE big block design).

Ronnie Wilson of Specialties Machining was chosen to put it all together, including honing the sleeves to 4.125”. A mechanical roller was designed on a computer to allow revs up to 7,500 RPM and maximize usable horsepower and torque; consideration was given to the amount of lift needed to get air into the engine without losing cylinder pressure. Comp Cams provided a bumpstick for us.

After degreeing the cam, Ronnie installed TCI Automotive’s Rattler torsional vibration absorber to keep crankshaft twist and vibrations to a minimum. And with the Trick Flow heads now installed, the next step is to dyno the combination!

What’s Next?

The premise of the torsional vibration absorber is extremely clever, and it will be interesting to see how motorheads embrace balancers like the Rattler. So, if this really is 60 year-old technology, what can we expect for next evolution of the Rattler?

Chris hints, “It would be a ‘bending damper’. It would control not only the most detrimental vibrations but also all orders of vibration.” With the technology benefiting our 400 and 427 engine builds, we can expect more safety, durability, and efficiency with more horsepower like never before.

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About the author

Kevin Shaw

Kevin Shaw is a self-proclaimed "muscle car purist," preferring solid-lifter camshafts and mechanical double-pumpers over computer-controlled fuel injection and force-feeding power-adders. If you like dirt-under-your-fingernails tech and real street driven content, this is your guy.
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