Transmission Vent Screw

Transmission, clutch, chains and belts
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jarhead
Posts: 152
Joined: Sun Oct 17, 2004 11:56 pm
Location: Lisbon, Connecticut

Transmission Vent Screw

#1

Post by jarhead » Fri Jun 11, 2010 10:53 am

In my research, the picture below shows where the vent screw is placed on two different ratchet top lids. Correct? The reason I have some doubt is in my transmission case there is a small hole inside that corresponds to where I thought the vent screw goes. It would be the bolt hole on the other side of the dowel pin on the same side as pictured where the arrows are pointing. What is that small hole? The small hole is about two inches down, parallel with that bolt hole inside the case. All input would be appreciated...
Tranny-tops-1.jpg
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Robert Luland
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Re: Transmission Vent Screw

#2

Post by Robert Luland » Fri Jun 11, 2010 11:16 am

Jar head it sounds like you have a 54 and down tranny case with a 52 and up ratchet top on it. Is the box out of the frame? Can you provide a picture of the top of the case ?
Last edited by Robert Luland on Fri Jun 11, 2010 12:45 pm, edited 1 time in total.

Ohio-Rider
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Re: Transmission Vent Screw

#3

Post by Ohio-Rider » Fri Jun 11, 2010 12:03 pm

Wouldn't the vent screw be in the housing? What years where vents in the ratchet top?

jarhead
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Re: Transmission Vent Screw

#4

Post by jarhead » Fri Jun 11, 2010 12:22 pm

Here is a few pictures...In the 3rd picture, which you probably can't see , near the cam follower retainer are the numbers A4662 if that helps...
Efrenspictures053.jpg
Efrenspictures055.jpg
Efrenspictures054.jpg
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Robert Luland
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Re: Transmission Vent Screw

#5

Post by Robert Luland » Fri Jun 11, 2010 12:46 pm

Well thats a 55 and up case. Rule out the first idea.

Dave_R
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2001 Heritage
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Re: Transmission Vent Screw

#6

Post by Dave_R » Fri Jun 11, 2010 6:27 pm

The vent screw should go exactly where your arrows point. On earlier cases, the vent was in the case like Ohio-Rides has shown, and there were no vent-screws (All normal screws for the lid).

Later, the hole was not drilled and tapped in the case, and a vent screw was used. It is in the through-hole that vents on the kicker-side of the case casting, not in the main gear case casting area. If you put the vent screw in one of the through-holes that goes in the main gear area, it blows oil all over (Tried it once and learned).

Not sure what little hole your looking at.......unless you are looking at the hole that is for the retaining screw for the countershaft. That one gets covered by the ratchet lid.

-Dave

jarhead
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Location: Lisbon, Connecticut

Re: Transmission Vent Screw

#7

Post by jarhead » Sat Jun 12, 2010 1:48 am

Ok , appreciate the clarification and information. I'll now put my vent screw now in the correct location...

Speeding Big Twin
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Re: Transmission Vent Screw

#8

Post by Speeding Big Twin » Sat Jun 12, 2010 3:55 pm

jarhead, my vent screw is in the same place as that indicated by the red arrows in your first post. According to my 1959–69 H-D SM, transmission section 4D: ‘The short cover screw with vent hole is inserted in hole nearest locating dowel pin on right side of gear case.’

The five characters stamped on your trans case are sometimes known as additional original component identifying numbers or anti-theft numbers and the first Big Twins they appeared on were the 1962 models. The letter A apparently indicates either a 1962 or 1963 model component. H-D also used similar, but usually non-matching, sets of characters on the Big Twin lower triple clamp and the left side of the frame steering head, again beginning with 1962 models.

On the underside of your trans case you may find casting number 121 35. And you may also find a casting date code to indicate the month and year the case was cast—for example, 11 61 would indicate November 1961 casting. Eric

Speeding Big Twin
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Re: Transmission Vent Screw

#9

Post by Speeding Big Twin » Sat Jun 12, 2010 4:06 pm

Steve, according to Palmer the vent screw was in the BT trans case for 1940–55 models and was first located in the top cover for 1956 models. He says the blank (undrilled) boss remained through 1964 to make the case a suitable replacement for earlier cases on parts orders. Palmer also mentions 1965-later trans cases and includes the following comment: ‘Also, the later cases no longer have the boss for the vent plug ...’

However, the photo below obviously shows a 1965 or later case and it appears to have a vent screw boss. Eric
Transcase.jpg
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jarhead
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Re: Transmission Vent Screw

#10

Post by jarhead » Mon Jun 14, 2010 12:16 pm

To Speeding Big Twin, thanks for the additional info...Looks like my transmission is original to my motor. I have a 62...

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