Straight leg frame

Identification information of frames and transmissions
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Straight leg frame


Post by Wilbe29 » Sun Sep 13, 2015 10:04 pm

Is there any way to tell what year a frame there is # s on the back of front motor mount 47664 -4805

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Re: Straight leg frame


Post by RUBONE » Sun Sep 13, 2015 10:47 pm

All Panhead straight leg frames had a date code stamped in the right side of the top motor mount bracket. They are easily dated if unmodified. Knuckle straight leg frames need hallmark codes and features to date them.

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Re: Straight leg frame


Post by Bigincher » Sun Sep 13, 2015 11:20 pm

I'm not sure I understand the question. Is it panhead frame that's missing the top motor mount? That frame was used from mid-'54 through '57 and was unchanged during that period.
Or are you trying to determine if it's a knuckle straightleg frame vs. panhead frame? Panhead will have a steering head lock.

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Re: Straight leg frame


Post by Speeding Big Twin » Mon Sep 14, 2015 7:32 am

Wilbe29 wrote:Is there any way to tell what year a frame there is # s on the back of front motor mount 47664 -4805
Welcome to the forum. I don't think that number is exactly as you read it and it sounds like it’s from a swingarm frame. Is it a swingarm frame? Forging number 47664-48 first appeared for 1958 models and it was used for a long time. However, I don’t think the next character is 0; instead it may be a forging hallmark consisting of a circle with the letters M and F inside. The hallmark indicates the piece was made by Modern Drop Forge. I think the 5 is a die number and I have an example of it in use for April 1962 although the picture is not the best. I do not know when die number 5 was first used or last used.

I also have examples of other die numbers and the picture below is one of the clearest. It shows forging number 47664-48 followed by the hallmark and then die number 7. This frame was made in May 1967. Notice M above F inside the circle:


Stamped on the right-hand side of your frame top engine mount there may be a date code consisting of a letter and a number, although not necessarily in that order. The letter indicates month—for example, A indicates January. The number indicates the year the frame, or at least the top mount, was made.

There is more info available but can you please first confirm the style of frame: is it swingarm or rigid? And let us know what the date code is. Photos of the entire frame would help, as would pictures of any other markings you find.

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Re: Straight leg frame


Post by 58flh » Mon Sep 14, 2015 11:42 am

Try Posting some pics. in the areas mentioned!----Respectfully---Richie

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