I'm working on a 78 FLH1200 with "the leak". A pretty hefty leak.
The spacer has no key and the bearing is one piece. It had a supernut, double lip big seal and tight mainshaft bushing. Seals were not old and sprocket was tight and vent is clear. only thing missing was small seal inside main drive gear but the supernut should have covered for that.
This setup is different than my 71 trans with loose rollers etc. I never had a leak with nice DL seal, small seal and supernut. I don't know what i may be missing.
The 78 spacer may need replace? my plan is to get a new spacer, big & little seal and new supernut seal or whole new supernut.
1977 to 1981 then 1982 to 1985 used caged bearing 4th gears different bearings and different seals your 1978 was the problem years No sprocket drive key was used look at the back of the sprocket spacer (running up against the case) if its worn we have a case repair for those years to address damaged sprocket spacers.Call us and I'll be glad to explain what we machine into the case to cure 4th gear oil leaks on 1977 and up 4 speeds should not leak
I'll chime in and make mention of the fact that a ton of those have also lost the fitment on the main drive gear babbited bushing, to mainshaft.
Once you open it up you'll find more...............
Scott
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"If a street Harley doesn't have torque, how much horsepower it makes, simply does not matter."
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Had the same problems on my '79 FLH.
The CURE is the Andrews main drive gear.
It has a grove for an O-Ring that helps to take oil "inside" the transmission!!!
I think that same late style 4 speed main drive gears had the same grove.
the 4 speed main drive leak ...
Linear Mode
