Came across this info and thought it was interesting.

S&S® 4-1/8" Stroke Flywheel Assembly For S&S®V111 Engines For 1984-'99 HD® Big Twins

Product Description:

This 4-1/8" stroke 8-1/2" diameter flywheel assembly replaces the original flywheels in S&S® 111" V111 engines for 1984-99 HD® big twins. Flywheel assembly is three piece design. Pinion and sprocket shafts are forged as part of the flywheel. The only joints in the assembly are where the 1.671" diameter connecting rod crankpin is pressed into the flywheels. Flywheels are CNC machined from heat-treated, closed die, steel forgings, which are 114% stronger than late style stock steel flywheels. Fully assembled with premium quality S&S® heavy duty 7.667" connecting rods, with full width wrist pin ends, and dynamically balanced. Assembly is trued to less than .0005" runout on pinion and sprocket shaft bearing surfaces, making them capable of higher rpm.

 

Interesting! I have an S&S V107T, predecessor of their 111", which has a longer stroke of 4.25". In my service manual S&S say the smaller engines have five-piece cranks, but don't specifically say that mine is three-piece (simply imply that). It involves a lot of expense to make a three-piece crank (I was a production engineer in a previous life!), which leaves me wondering if they use the flywheel blanks (with integral shaft) across their engine range, to even out the manufacturing costs. It will certainly fit the 124s, as they have the same stroke as the 111", may even be possible to machine the blanks to fit the 143". S&S seem to have changed their philosophy from using a standard bore of 4", to using standard stroke of 4.125", which certainly makes sense. They have reduced the variety of sizes they now make.

 

They must of ran out of old stock 5 piece flywheels, maybe a 3 piece is cheaper to manufacture or know a potential weakness is present in the bigger cube. We just recently debated this topic on another thread when some opinions wasn't accepted too well.

 

Believe me, it is more expensive to make a three-piece! It involves forging to produce the shaft, then machining the shaft is more difficult with the flywheel attached.

 

Write up say's it's 114% stronger. Dynamically balanced and Assembly is true to less than .ooo5 run out. Don't sound cheaper to me. Sounds like the best around.

 

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