"THE CURE" MAIN DRIVE GEAR SEAL KIT FOR 4-SPEED BIG TWIN

Fits 1937 thru early 1977 4-speed Big Twin

'Every Harley 4-speed Big Twin rider knows "The Leak": the ever-present oil leak from the main drive gear. "The Cure", is a seal kit that will stop this oil leak! The stable and reliable Harley-Davidson 4-speed transmission has been built for half a century, but the oil leak has always been present. The reason is that Harley designed the main drive gear spacer without a seal. This state of the art hardened two piece stainless steel spacer features an additional Viton O-ring that permanently prevents oil coming out between the spacer and the main drive gear.

It can be installed easily without disassembly of the transmission as it is located just behind the main shaft oil seal. Kits replace the OEM 35171-37 spacers from 1937 thru early 1977, OEM 35070-77 from late 1977 thru 1979, OEM 35070-80 from 1980 thru 1981 and 35079-82A from 1982 thru 1985. They include the spacer washer, spacer sleeve, Viton O-ring and detailed installation instructions. 

1.) Loose and remove the sprocket nut, take off the sprocket nut lock washer and drive pinion gear.

2.) Remove the transmission main shaft oil seal and spacer.

3.) Grease spacer washer from the backside, and push it –the notch facing towards the front- over the 4th gear wheel as far at it will go.

4.) Hammer the greased transmission main shaft oil seal evenly in, until it sits approx. .08" (2mm) under the outer edge of the transmission case.

5.) Insert the greased Viton O-ring seal onto the 4th gear wheel right up to the spacer washer.

6.) Insert the greased spacer bush –the notch facing towards the rear- with a rotating movement (to avoid damaging of the main shaft oil seal) onto the 4th gear wheel as far as it will go.

7.) Tighten the drive pinion gear and the sprocket nut with a new lock washer. (190-210 Nm)