How YOU can help US

So your pulley, balancer or damper needs repair or modification; a new rubber; needs the timing realigning; must be modified so you can put that awesome supercharger on your engine for terrific performance.
To help us get the remanufacturing work done faster and your damper back to you in a brand new state, there's a few things you can do before you send it.

• Clean it - in the wash tank or sand blaster.
• Take photographs of the front, back and edge and email them to us.
• Wrap it up well and put it in a box to send it to us. Label it as 'Fragile' - cast iron can break like a tea cup if dropped.
• Include the position of the timing mark by marking the hub or sending a photo or diagram.
• Do include your name, address, contact phone no and the year, make, model and capacity of the engine the damper belongs to.
• Email us to let us know the parcel is on it's way.

We will call or email you to let you know it has arrived safely.

We have an eftpos machine and can process your credit or debit card once the damper is repaired to our satisfaction.

Perished rubber on a harmonic damper

Harmonic Damper History - Who invented crank pulley balancers and why?

The inventor of the harmonic damper was Dr Frank Lanchester. He and two of his eight brothers started the Lanchester Engine Company in 1900. They had high standards for their engines and Dr Lanchester would tinker with each motor that went out the door to make it more perfect than the last one. He invented the Torsional Crankshaft Damper [harmonic damper] and the harmonic balancer to cut vibrations in the Lanchester 38 hp six which was introduced in 1907. In 1910 he invented the single and double counter-rotating balance shafts. The patents for which were purchased in the 1970s and used by Mitsubishi and licensed to other manufacturers to the present day. He also invented the steering wheel, amongst many other things.

Luke Brennan has corrected our account with more recent information: You may wish to refer to him as Frederick W. Lanchester. Fred, not his brothers Frank or George.

His damper patent was 12th September 1910. He licenced this to Daimler shortly thereafter. Not Frank – Fred.

Also you may also wish to read the superb “Royce and the Vibration Damper” by Tom C. Clarke, which casts strong doubt on the primacy (though not the brilliance) of Lanchester.

It would now appear that Henry Royce had developed a friction-based harmonic damper for his 30HP engines in 1906 but had failed to patent it.

Royce then developed an extremely effective spring-drive/viscous damper that was used on all RR vehicles until the 1950’s. 

Thanks Luke, as you can see, the inventors of things can be mis-reported or debated, they are long dead so who knows who really did what and when?

Harmonic dampers are called by a wide range of varied names. In truth they are all torsional vibration dampers. Terms like crank pulleys, balancers, power pulley etc are to varying degrees erroneous. The term harmonic balancer comes from some manufacturers using the hub as a convenient location for external mass balance weights. The reason for this is that it made fine tuning of engine vibration simply done by adding or removing weight from the mass balance.
Though it is common belief that large steel parts such as crankshafts are rigid and inflexible this is not true, when a force acts on a crankshaft it bends, flexes and twists just as a rubber band would. While this elastic deformation is often very small it can have a significant impact on how an engine functions.
All objects have a natural frequency that they resonate or vibrate at when struck. An everyday example of this is a tuning fork. The sound that a particular fork makes is directly related to the frequency that it is vibrating at. This is it's natural frequency which is dictated by the size, shape and material of the fork. A crankshaft is a series of tuning forks in a line, it has a natural frequency that it vibrates at. When an object like a crankshaft is exposed to a heavily amplified order of it's own natural frequency it will begin to resonate with increasing vigor until it vibrates itself to pieces. This is called fatigue failure.
Crankshafts twist back and forth a small amount every time a cylinder has a power stroke. This motion is complicated because the amplitude of the vibration varies along the shaft. The crankshaft will experience torsional vibrations of the greatest amplitude at the point furtherest from the flywheel or load.
Engines have major and minor critical rpms and are different due to the fact that some harmonics assist one another producing large vibrations whereas other harmonics cancel each other out. Major critical rpms have harmonics that build on one another to amplify the torsional motion of the crankshaft. Conversely, minor criticals are at rpm that tend to cancel and damp the oscillations of the crankshaft. If the rpm remains at one of the Major criticals for any length of time fatigue failure of the crankshaft will result. These major critical rpms are dangerous and must be avoided or properly damped.
The oscillation of an undamped crankshaft at a major critical speed will commonly shear the front crank pulley and/or the flywheel from the crankshaft. I have seen hub keys sheared, flywheels loose, and pressure plates coming apart. These failures have often required crankshaft and or gearbox replacement and in extreme cases the diff.
Technically, 'the primary purpose of a harmonic damper is to cancel out third harmonic distortion by using intermodulation between the second harmonic and the fundamental in the space charge regions of the triodes.'
Put simply the harmonic damper works by relaying resonance and torsion energy out of the crankshaft and dissipating it as heat by flexing a heavy metal inertia ring which is mounted on a vulcanized rubber cushion. Essentially the damper is a simple spring of rubber plus a vibration and heat absorbing mass - the hub and inertia ring.
Harmonic dampers are made of cast iron for the primary reason that cast iron has the ability to absorb and dissipate large amounts of energy because of it's high specific gravity. The damper on each engine is designed for the specific range of vibrations that a particular engine produces. Keeping the damper cool is also of primary importance.
The key weakness of the harmonic damper is the rubber. Next blog we will cover signs your harmonic damper or crank balancer is dying or dead - it's serious engine damage ahead if you keep driving it vibrating like that folks.

Ford Thunderbird repaired ready for painting.

Porsche 944 damper alteration to run a supercharger.

The Job:- to drive the supercharger faster. To provide more boost pressure to the engine requires a larger diameter pulley than the standard Porsche 944 3 litre four cylinder engine damper.

The solution John found: He machined a new steel belt drive pulley ring for the supercharger which runs over the existing damper on the same belt drive line as the original but on a larger diameter belt drive line.
The damper itself was bonded, re-rubbered and strengthened with a custom made hub turned up from a special grade of  aircraft aluminium which was positioned in the centre of the damper hub to provide additional support to the hub because the original is only a thin steel pressing.
As the original inertia ring could not be altered because of its design the new pulley was attached to the hub of the damper via the new aluminium hub. The whole was bolted together, balanced and polished
Today Graeme, the owner of the Porsche 944 called to say that the modification is successful and that he has raced his machine successfully in two races.

This modification is not cheap but it is an effective solution for a racing car with limited space for modifications. If you seek an innovative solution to a supercharger issue like this give Damperdude a call or drop us an email damperdude . at . gmail. com.