The HD 4 speed transmission is essentially the same from 1936 to 1979 with the exception of mainshaft length and countershaft bearing configuration. It's constant-mesh straight cut gears / sliding shift clutches, mixture of roller bearings and bronze bushings.
Factory has always recommended motor oil for that tranny.
In 1980 they went to a different shifter mechanism, by 1981/82 they had it working OK, but early efforts were awful. There was a recall on the early 1980 models, I did a lot of those.
I have an early '80 in the shop right now that looks like the recall may have been done, I didn't see any of the obviously defective parts. But it still shifts really hard, I probably should have polished the tracks on the shifter cam while it was apart.
Some of you may see where this is going.
Is there any harm in adding any of the teflon products or even something like STP to the oil?
[edit for typo]
Factory has always recommended motor oil for that tranny.
In 1980 they went to a different shifter mechanism, by 1981/82 they had it working OK, but early efforts were awful. There was a recall on the early 1980 models, I did a lot of those.
I have an early '80 in the shop right now that looks like the recall may have been done, I didn't see any of the obviously defective parts. But it still shifts really hard, I probably should have polished the tracks on the shifter cam while it was apart.
Some of you may see where this is going.
Is there any harm in adding any of the teflon products or even something like STP to the oil?
[edit for typo]
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