The most common items over looked during assembly and installation of a rebuilt motor, are the motor mounts, transmission mounts, and the harmonic damper (balancer). Motor mounts are commonly bonded together using a rubber compound, while most OEM dampers utilize an elastomer (rubber) inertia ring, which is inserted or pressed into place. Over the years these rubber compounds dry out and become brittle, eventually resulting in product failure. In most cases, these failures lead to un-necessary and costly repairs, and can be dangerous, even life threatening, if they occur at the wrong moment. Therefore it is essential to thoroughly clean and inspect these parts prior to reuse. If the rubber, or metal parts, show signs of cracking, small fractures, excessive wear, or have small pieces missing, they need to be replaced.

To select the proper damper, one first needs to understand it's purpose. A harmonic damper is often referred to as a balancer, which seems to suggest that the unit “balances” the engine. However it's actual function is to dampen torsional vibrations which occur in the crankshaft. These vibrations are the result of the combustion process, or more accurately the sudden reversal of load on the pistons, connecting rods, and the crankshaft. The subsequent relaxation of the load, following the combustion event, causes a deflection or flexing of the crankshaft. At certain rpm ranges these oscillations come into phase with each other, which generates potentially harmful and damaging torsional peaks within the crankshaft. This oscillating vibration, which results from the reciprocating load changes, will remain in force until it is dissipated by internal friction and/or damping. Unless the amplitude of these torsional vibrations is controlled, major damage can occur to engine components, such as rapid wear of the timing gears, stretching or breakage of the timing chain, pitting or cupping of the camshaft and lifters, broken valve springs and valve train failure, and reduced service life of crankshaft bearings. In extreme situations, uncontrolled torsional vibrations can lead to a loose flywheel or a broken crankshaft with serious safety consequences.

As we stated earlier, most OEM and/or rebuilt dampers utilize an elastomer (rubber) inertia ring, which is inserted or pressed into place. While this is adequate for low revving engines, it won't handle the higher torque and revolutions of a performance motor. Using an old worn out damper, or an inadequate damper for the application, usually results in the spinning of the inertia ring, which in turn results in the loss of timing accuracy and eventual component separation. Even some of the more costly steel or alloy performance dampers use a similar rubber insert, which will break down over time, in the same way as standard damper.

Classic Inlines offers three different harmonic dampers, Stock Rebuilt, Street Performance, and Race (SFI Certified). All of our dampers are bonded, offering superior strength and durability over your stock OEM damper. Which one you use depends on the application and the performance level of your motor. The Rebuilt OEM damper is great for stock or mild performance engines which normally operate under 5000 rpm. Our Street Performance dampers are designed for performance inlines, that spin up to 6500 rpm, which will suit most all street/strip applications. The Race dampers, which are SFI Certified, are good for 12,500 rpm, which in most cases are only required for an all out race application. However, you should check with your sanctioning body to see if an SFI Certified damper is required for your class.

Our Stock Rebuilt dampers are disassembled, cleaned, and inspected for defects. Including stripped bolt holes, worn or cracked keyways, cracked center webbing, and there overall condition. Once they pass inspection they prepared for assembly, which includes resetting the timing marks using a superior laser aligning process. The dampers are then injected with a high-temperature, high-strength silicone rubber that is then platinum cured for a extremely strong hold.  This new silicone rubber compound is capable of withstanding temperatures in excess of 450 degrees, and will hold up to pressures as high as 770 psi. All Stock Rebuilt dampers carry the manufacturers "Three Year Limited Warranty".

The limiting factor with a rebuilt damper, is that they still use the stock gray cast iron, which can crack in the keyway and/or center webbing. While the bonding process is far superior to new OEM dampers, the gray cast iron limits the revolutions to 5000 rpm. Our Street Performance dampers solve this problem by using new metal components, which are made from high strength SG (nodular) iron. Next, a state of art bonding process utilized, which uses extreme heat and pressure to positively bond the dampening compound to the new metal components. By using SG nodular iron and the superior bonding process, the common failures which are associated with stock and rebuilt dampers is eliminated, thus increasing the performance capabilities to 6500 rpm.  All Street Performance dampers carry the manufacturers "Limited Warranty".

Classic Inline's Race dampers go one step further, by using new metal components which are precision CNC machined from 1045 steel. Finally, the dampers are balanced to precise tolerances and tested to verify each damper complies with SFI specifications.

1)  Remove the damper carefully using a Professional damper removal tool.

2)  Clean the crank snout with very fine abrasive paper to ensure no burrs exist.

3)  Check the bore of the damper to ensure there is no paint residue, if required clean
the area with very fine abrasive paper.

4)  Re-check the sizes, particularly the height of the crankshaft key, as some aftermarket keys do not meet OEM specs.

5)  Prior to installation heat the damper in boiling water for 15 minutes, or place it in a preheated oven at a low temperature (max 250 deg F or 120 deg C) for 15 minutes.

6) Coat the crankshaft snout and inside diameter of the damper with an anti-seize compound or moly grease to prevent galling during installation.

7) Remove from oven using insulated heatproof gloves, oil the crank snout and promptly install using a professional damper installation tool.

Note: If you don't have a damper install tool, stop by your local hardware store and pick up a 4-5" long bolt, a fender washer, and a nut which are the same diameter and thread as your original dapmer bolt. Spin the nut all the way on to the long bolt, then slip on the fender washer, and finally your original damper washer. Once the heated damper is fitted onto the crank snout as far as possible (without hammering) thread the bolt assembly into the crank. Make sure it goes into the crank atleast an inch to prevent the threads from stripping (it takes a lot of force to install the damper). Spin the nut until the washer is snugged up to the balancer, then tighten with a box wrench until the damper is fully seated, remove the bolt assembly and install the original bolt and washers, and torque to the proper spec. NEVER hammer the balancer into place, as this can easily damage the crankshaft thrust bearings and seals.

All Classic Inlines balancers include a core charge in the purchase price, which may be refundable. Please remember to send in your core once you receive your new or rebuilt damper. Not only is it required for a core refund, we need them so we can keep the process going. Without cores, we have nothing to rebuilt for our future customers. Thanks.

For more information, please read our Core Charge Refund policy.