Harley 4-Speed Mainshaft and Countershaft Differences
Throughout it's 50 years of use on EL, FL, and FX Big-Twins, the Harley 4-speed transmission saw several different mainshafts and countershafts.
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Mainshafts
Style One - Late 1937 through 1964 Big-Twin models, OE #35040-50, 11.75" length.
Pictured: Andrews #208500 for L1937-1964 Harley Big Twin
Style Two - 1965-1969 Shovelheads (generator motor), OE # 35039-65, 12" length.
Pictured: Andrews #208650 for 1965-1969 Shovelhead
Style Three - 1970 to Early 1984 models (alternator motor), OE # 35039-70A, 12.5" length. These are longer than previous mainshafts and require an outside bearing support.
Pictured: Andrews #208600 for 1970-1984 Shovelhead
NOTE: Although mainshaft lengths are different for generator motor and alternator motor, they can be swapped.
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Countershafts
Style One - 1941 to Early 1976 Big-Twins, OE #35614-65, has threads on one end and grooves in the other.
Pictured: Andrews #207650 For 1941-1976 Harley Big-Twin
Style Two - Late 1976 to 1979 Shovelheads, OE #35614-76, has grooves on both ends and threads on one end.
Pictured: Andrews #207770 For 1976-1979 Shovelhead
Style Three - 1980 to 1985 Shovelheads, OE #35614-80, has two grooves and no threads.
Pictured: Andrews #207800 For 1980-1985 Shovelhead
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Checking Shafts for Straightness
Before reassembly, both shafts should be checked for straightness. Anything past .003" run-out is questionable.
The picture above shows straightness being checked on a homemade flywheel truing stand.
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Harley 4-Speed Rebuild Kit
Shop: Harley 4 Speed Transmission Overhaul Kits
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