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for Aluminum and/or Steel flywheels


1)    DO NOT USE LOCK WASHERS OF ANY TYPE ON CRANK BOLTS!!  A Bellville (wave or spring) washer may be used in place of a flat washer when additional bolt retention is desired.  A chemical locking agent (such as Loctite) may be used sparingly on the bolts, however it must be kept away from the crank flange area.  Use only the highest quality fasteners available.


2)    Always test fit a new flywheel.  Check the flywheel carefully after removal for evidence of improper fit.  No galling or burrs should be present on either the crankshaft flange or the flywheel.  Aluminum flywheels can be heated slightly to install, but the interference should be no more than .001".  A small amount of heat should also be used to remove a flywheel installed this way.


3)    Due to manufacturing tolerances in both the crankshaft and the flywheel, fit may vary form a slip to a slight interference.  Be sure the flywheel rests tightly against the crankshaft flange when the bolts are torqued to manufacturer's specifications.


4)    If excessive interference is present, use a three cornered scrapper to remove material from the register diameter of the flywheel.


5)    With the flywheel installed on the crankshaft, check for axial runout using a dial test indicator.  Total Indicated Runout (TIR) should not exceed .004" or .100mm (7-1/4" racing clutch)  or .003" or .075mm (5-1/2" racing clutch) at the clutch register (step or pot) diameter.  TIR at the ring  gear should not exceed .01" or  .25mm.


To maintain the performance and reliability of the flywheel, it should be inspected whenever possible.  Watch for fatigue cracks in the following areas, 1) crankshaft register diameter, 2) between the flywheel bolt holes, and 3) between the weight reduction holes (if applicable).  To maintain optimum clutch performance, use a straight edge and feeler gauge to check the friction surface for flatness.  For most racing clutches, this surface should be flat within .008" or .2mm.


Aluminum flywheels use a steel insert (heat shield) for the friction surface.  This insert is heat treated and should not  be resurfaced.  Inserts are easily replaced and should not affect the balance of the flywheel.  Steel ring gears on aluminum flywheels should also be checked periodically for cracking or loosening, especially if the flywheel has been hot.  Replace any flywheel or heat shield that shows signs of excessive heat (extreme discoloration or bluing) or is warped beyond the above specifications.


All DP racing flywheels are zero balanced unless noted. However, the balance should be checked with the clutch cover to be used installed.  This will help avoid balance issues arising from clutch manufacturing tolerances.

Because of the extreme stresses that racing/high performance street parts are subjected to, and because DP Racing has no control over how these parts are used or installed, no warranty is expressed or implied for any DP Racing flywheel.


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