VTwin Flywheel Truing Tips
Here are some things that make the final truing better than factory specs.
* - Install the sprocket shaft and the pinion shaft in the flywheel halves. Torque them to
only half their specified value.
* - As my lathe is in the same area as my truing stand, I use it with dead centers. Mount a
flywheel half, with a slight amount of oil on the lathe centers. Take up the slack, then back
off ever so slightly.
* - Set up a dial indicator to make contact with an outermost side edge. Find the high and
low spots, and zero to your liking. Note: you may have to draw file the inside edge, to clean
up the surface from previous generations of truing. Some mighty hard smacking has occurred
on older wheels.
* - Use soapstone to mark the wheel, so that you will know where to adjust the shaft.
* - Remove the wheel and lay it on the bench. Use a piece of hardwood, teflon, or thick
plastic as a buffer and a plastic head/leather head hammer to slightly strike the shaft. Never
at the end. Midway to near the wheel. Note: be easy here. You only want to move it in tens of
thousands. Be light with the strike. Only practice will let you know how much is just right.
* - Mount the wheel half back on the centers, and check the side runout. The goal is zero. If
the indicator moves, it is amplified in the combined wheels. Use your own judgement as to what
you need. You can split hairs all day. There are no perfect wheels. But, learn to read it.
* - Once both are as close as you can get to zero, torque them to their full value, and lock
the nuts in place. You can check them if you like. No more striking, though. Very doubtful
that you will move them. But, it is guaranteed that you can fracture these brittle shafts.
That's why the half torque, for alignment.
* - Install the crankpin on the keyed wheel. Mount on torque fixture and pull to full torque.
Lock the nut. Install the rod assembly, and the other flywheel half.
* - Lock the wheels together with a clamp, to keep them from rotating, when torquing, and pull
to half torque.
* - Mount on truing stand and follow the procedures in the manual. NOTE: REMOVE FROM FIXTURE
TO STRIKE. Use the same mallet and buffer to strike the wheels. They are softer than the
shafts, and dent easily. H-D shows striking on the stand, in their older manuals. They removed
this step in later manuals. You will cause major damage to your truing fixture/lathe. The
runout goal, again, is always zero. The book specs are 0.002". Less than 0.001" is easy.
0.0005" or less is obtainable. But, only if a runout alignment is performed on the sprocket
and pinion shafts.
* - When you are satisfied with this runout, you get to do it, again. Mount the assembly on
the torque fixture, and clamp to prevent rotation.
* - Torque the crankpin nut to it's full value, and lock the nut down. No more wrenches. You
are doing your finish work.
* - Mount on truing stand and do it all over again. It will have moved.
* - Remove and correct.
* - When you are done with truing, handle the assembly with care. No bumping. Put it
completely away from all other work, if you don't plan to install it right away. Wrap it up in
a clean trash bag. Dust is the enemy.
It ain't fast. Take your time. Hours, if needed. Walk away from it, if it doesn't come right
in. Frustration makes for damage.
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