Classic Motorcycle Build

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.

Harley Shovelhead transmission

For article on Harley 4-Speed Transmission Differences click here.

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Mainshafts

Style One - Late 1937 through 1964 Big-Twin models, OE #35040-50, 11.75" length.

Harley 4 speed mainshaft lengths

Pictured: Andrews #208500 for L1937-1964 Harley Big Twin

Style Two - 1965-1969 Shovelheads (generator motor), OE # 35039-65, 12" length.

Shovelhead transmission mainshaft differences

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.

Harley 4 speed mainshaft lengths

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.

Harley 4 speed transmission countershaft differences

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.

Harley Big Twin transmission parts and interchange

Pictured: Andrews #207770 For 1976-1979 Shovelhead

Style Three - 1980 to 1985 Shovelheads, OE #35614-80, has two grooves and no threads.

Harley 4 speed transmission countershaft

Pictured: Andrews #207800 For 1980-1985 Shovelhead

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Check For Straightness

Before reassembly, both shafts should be checked for straightness. Anything past .003" run-out is questionable.

how to check mainshaft run out

The picture above shows straightness being checked on a homemade flywheel truing stand.

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4-Speed Gear Set

Andrews stock ratio 4-speed gear set for Harley big twin 1936-1977

Andrews 4-Speed Gear Set, Made In USA

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Harley 4-Speed Rebuild Kit

Harley 4 speed overhaul kit

Jims Harley 4 Speed Transmission Overhaul Kit

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