1939 knuckle tranny vented or not vented?

[Robert Luland]

Flat the vent never had a washer under it or thats what it appears to be in the photo. It also looks like theres a boss under it. The vent boss on the case did not apper until 1940 and up. I'm not a tranny expert by no means. Just learned alot about this particular 39.5 one. Bob L

[flat-happy]

yeah man i'm still learning too---the is no washer under the vent on anything i have but it does appear that way in the photo---it is actually just a machined flat surface

[Robert Luland]

Flat in that case thats the boss. 40 up. Thats how I ended up with the 39 in the first place. Saw J8 and the vent and never paid it any mind. In my head it was a 48. Wrong! If you look carefully at the picture I posted above you will see that theres is no boss under the vent. Bob L

[Chris Haynes]

Granted it is hard to see but if you look right behind the kicker return spring you can see the breather in the kicker cover in this 12/10/1938 photo of a mid 1939 model.

[flat-happy]

that's what i thought---so just weld the hole shut because i don't think they had a vent without a boss---well maybe not quite yet. i'd sure like to know what chris and carl olsen have to say about this

[48hdbob1]

I've had three of these cases in my hands, one remaining. All had -9 dates. I know of another other than the one Bob Luland had and it too had a -8 date. The three I have seen the spot done with an end mill were identical in location, depth and diameter so I don't think it was a dealer thing. The one remaining in my possesion was on an early '40 EL and will go back on that bike.

[flat-happy]

thank you for that pic---it is definitely different from mine isn't it?

[knuckjunky]

Interesting. I think I'm best off finding a non vented later 38 case in order to be "correct" for a 39 knuckle. However, it seems to show that some of these part transition periods (such as unvented to vented transmissions) are still pretty murky waters. Thanks for all of your input.

[koanes]

Thanks Flat Happy for the look at the kick cover you have. Certainly more of a curiousity than an important restoration detail, but I have been curious about the change to the 39 style throwout bearing. I have an undated cover, without the extra reinforcement boss between the clutch release shaft and the fill plug, that has been factory machined. I have a cover dated F-8 that does have the reinforcement boss and has been machined as well. The 3rd cover I have is G-8 and has relief as cast. Is it possible that some 38s had the improved bearing? The 3rd picture is of the 37-38 cover for the small bearing.

[Chris Haynes]

Here is one that few have seen

No boss for the breather in the kicker cover. Early 1936.

[Robert Luland]

My take on this whole 38-39 thing was plain and simple. The factory being the factory? Once they had those new kicker covers. They took anything they had left over. No matter what it was dated and drilled, tapped and vented them. If I was the manufacture, that’s what I would have done. Just a theory guys. Bob L

[flat-happy]

and i think a very good one and probably spot on. the problem lies with which judge is looking at which bike on which day