The Rattler Frequently Asked Questions
TCI RATTLER®” Tortional Vibration Absorber.
Most Frequently Asked Rattler® Questions
- Why do you need an absorber or damper?
Engine speed slightly increases during power strokes and decreases during compression strokes. This is what causes twisting vibration of the crankshaft. In some instances, since the crankshaft drives the cam, crank vibrations can also cause instability in the valve train. The dampers and absorbers are designed to reduce these vibrations.
- What is crankshaft torsional vibration?
Answer: Due to their mechanical design, all internal combustion engines will display crankshaft torsional vibration. This is due to the fact that torque cannot be applied to crankshafts from firing cylinders with steady pressure. It varies with the position of the crankshaft in relationship to each cylinder. As the piston rises and falls, so does cylinder pressure. The changing pressure, acting on the piston, results in forces transmitted along the connecting rod and applied to the crankshaft journal. In the operation of the crankshaft assembly, the forces reverse back and forth. The crankshaft reacts and transmits these forces that are indicative of crankshaft torsional vibration.
- What is resonance frequency?
Answer: We have all seen the old Memorex commercial of a glass being shattered by the sound of a singer’s voice. What you were actually seeing was the point at which the glass was exposed to its own natural frequency and at that moment it shattered. This is a common example of resonance. Inside the engine the torque spikes from the firing cylinders excite the crankshaft at certain critical speeds to its own natural frequency. It is not uncommon for these conditions to cause failures in crankshafts, front end accessory belts, gear train, and valve timing problems
- What does resonance have to do with selecting an engine damper/absorber?
Answer: Remember, resonance occurs when the exciting frequency is equal or close to the natural frequency of your crankshaft assembly. Resonance can be controlled either by dissipating the energy causing the crankshaft to twist or by absorbing that energy. Energy dissipation, common to the elastomer and viscous type dampers, convert mechanical energy into heat energy through friction. Energy absorption, common to the Rattler®, provides torsional control by providing counteracting forces to the forces that actually cause torsional vibration. Through research and testing, detrimental engine harmonics have been identified. The absorber is designed to eliminate those specific harmonics which can cause failure. In other words, the absorber concentrates on eliminating the cause as opposed to reducing the effect of torsional vibration.
- Does just the crankshaft have a resonance frequency?
Answer: No, all objects have a natural or resonance frequency. Through research and testing, we can identify where resonance frequency is most harmful to an engine. Piston firing, by far, is the force that causes major damage to an engine.
- What is the Rattler®?
Answer: It is a torsional vibration absorber that controls twisting (torsional) vibration of the crankshaft. Engineers call it a pendulum type of absorber.
- What is the difference between dampers and absorbers?
Answer: There are fluid type and stock type or elastomer dampers. Newest to the market is the Rattler® absorber. The first two units have been readily available to the automotive market for many years and in fact were the only types available. The fluid type and elastomer type devices are dampers and tend to reduce vibration by using friction to dissipate energy. The Rattler®, an absorber, is a device that absorbs and controls vibration by using internal rollers that automatically offsets the twisting forces that cause vibration.
- How does the Rattler® work?
Answer: Inside the Rattler® are steel rollers that fit loosely into a specific number of holes. By using an exact mathematical relationship, the rollers will roll forward during compression strokes and roll backward during the power stroke to keep the engine speed variations and vibration, to a minimum.
- Is this new technology?
Answer: The concept is not new. In fact it has and is currently being used in airplane engines where cost is not an important consideration. What is new is that TCI® was able to apply this technology to the internal combustion engine and obtain aU.S. patent for the design of the Rattler®. This design and concept permits the unit to be produced at a competitive price for the automotive industry.
- What is the main advantage of the Rattler®?
Answer: The Rattler® is tuned to the number of cylinders and is effective at all engine speeds. It is important to remember that maximum efficiency is achieved at all engine speeds. In order for the elastomer type to be effective, it must be carefully matched to each specific engine combination. It can be effective on stock engines since many of the OE and industry engineers spend a great deal of time tuning for a specific engine. No engine builder can do testing to match a modified engine to a damper’s characteristics. Because of the design, the Rattler® is tied primarily to the number of cylinders. It can easily be produced to match the specific needs of the enthusiast.
- What are some of the other advantages and differences the Rattler® has over other units on the market?
Answer: The torque capability of the Rattler® to control vibration is huge. For example, the centrifugal force of one roller (the Rattler® has a total of 9) at 7000 RPM creates 2407 pounds of force which is available as needed to control vibration. In other words, the rollers move as needed to control vibration.
- What about horsepower? A lot of claims have been made regarding increase in horsepower.
Answer: In high performance motors where crankshaft vibration can be excessive, it can provide increased power by providing a stable and vibration free driving force for the camshaft and valve train.
- So what are you saying?
Answer: We have data that show horsepower gains but according to engine builders and results from dyno information, on an average performance engine you actually are not going to see a tremendous amount of horsepower gain unless something is wrong with the engine to begin with. The Rattler® has shown horsepower gains on the dyno but its primary function is extended durability due to reduced twist and fatigue.
- Can an engine dyno show torsional vibration twist?
Answer: No. To test torsional vibration twist you need monitoring equipment that you will not find at your average engine builder/dyno facility. TCI® initially contracted a highly specialized facility to do testing in their torsional vibration testing labs. In fact, we also did actual on track testing with a variety of race cars to see if in-house dyno cell results and on-track testing were consistent with the mathematical theory that was patented. This is a very costly type of testing and very few units sold in the aftermarket have ever been exposed to this type of testing.
- The Rattler® makes noise. Does it have to make noise to work?
Answer: The only time you may hear the Rattler® is when starting and stopping the engine. When you hear the slight “click” you know the Rattler® is ready to work. The slight noise could have been eliminated but TCI® decided to keep it as a distinguishing trademark.
- Do you have to have special tools to install the Rattler®?
Answer: You use the same tools and procedure that you would when installing a balancer.
- Can you balance a crankshaft with a Rattler® installed on the assembly?
Answer: Unlike some units, the Rattler® can be installed when balancing an engine assembly. The rotation of the crankshaft is sufficient to push the pucks inside the Rattler® into position. Some aftermarket brands recommend using a stock balancer when using an external unit to balance the assembly, some recommend removing part of their damper before balancing the crankshaft due to certain elements not being properly centred.
- What is the life of the Rattler?
Answer: To ensure that the Rattler® was safe to operate at the high rpms associated with the performance industry, several measures were taken. Extensive finite element analysis was performed to ensure that the design could withstand extremely high rotational speeds without failure. TCI® has run durability, SFI 18.1, and destruction tests and the unit just keeps on going. Test Rattlers® have surpassed the 100-million cycle mark with very little wear. Steel pucks roll, not slide, very small amounts inside steel holes to absorb torsional vibration. Rattler® is unaffected by temperature. Fluid and elastomer dampers do require replacement in time.
- In the past, stock type units have been known to have had timing marks that have slipped relative to the crankshaft. Can the Rattler® have the same problem?
Answer: No. The timing marks are integral to the body itself and cannot move relative to the crankshaft.