1972 frame

[tgarcia]

I have a 1972 fx frame that has a disc brake swing arm. Did they have disc brakes in 72 or could this be a late model frame technically 73 model year or maybe swapped out. Don't know much about fx models.

[joe fxs fxr]

Most likely someone changed the swing arm to the later style. Does VIN end in H2? If so it's a 72 model year frame.

[tgarcia]

Yes it's H2, it's a shame that it got replaced because the frame is mint.

[Speeding Big Twin]

I agree someone may have changed the round swingarm to the disc brake style swingarm. But just because the VIN ends with H2 doesn’t necessarily mean it’s a 72 frame. What do the VIN characters look like? Are they consistent with factory stamping for a 72 frame? For example are the C and H a certain width? Any 4s, 6s/9s? If so what types? If you’re not sure what a 72 FX frame VIN normally looks like you could post a partial photo. For example 2C123++H2.

Also check the frame date code and the numbers on both lower rear forgings. Photos?
Eric

[tgarcia]

PXL_20230529_194107057~2.jpg
here it is,I don't really have any love for this frame just trying to figure it out since it's sitting around the garage. Probably pass it on to someone who could use a good frame.

[Speeding Big Twin]

Thanks for the photo but the VIN boss is longer than I’d expect. Here’s what it normally looked like for 72.







As of 1981 models the amount of characters in the frame VIN increased from nine to seventeen although the VIN boss didn’t increase in length until about mid-81. Your VIN boss looks like the longer style.

Can you post photos of both sides of the entire frame please.
And look for a date code on the left side of the top engine mount. Photo?
Also look for numbers on both lower rear forgings. Photos? Thanks.
Eric

[dukekleman]

Speeding Big Twin,
I agree, my 1971 frame numbers are like you showed in your photo. I wonder if Tgarcia's frame wasn't a factory replacement frame due to damage occured from an accident in its years of service???

[tgarcia]

It's up in the garage rafters so it's a huge pain to get down to take pictures of in its entirety.i can probably get pictures of the forgings and motor mount when I get home.

[Speeding Big Twin]

Speeding Big Twin,
I agree, my 1971 frame numbers are like you showed in your photo. I wonder if Tgarcia's frame wasn't a factory replacement frame due to damage occured from an accident in its years of service???

I agree a replacement frame is a possibility. I have photos of some other 1970s VINs on frames with the longer boss. Some look like fake stampings but others may be authentic and some of those are even on 83–84/85 style frames.

Notice in my example the C and H are what I call narrow and the H appears to have its crossbar higher than halfway while on the other frame the C and H appear wider and the H looks to have its crossbar in the centre. But in this instance I don’t think those differences necessarily indicate something untoward. If it’s a replacement frame it may even be on record at the factory.
Eric

[tgarcia]

Here is the numbers you were asking about

[joe fxs fxr]

The -78 and -83 casting numbers should answer your question. Most likely a replacement frame.

[tgarcia]

Don't know anything about 70s frames so the casting numbers didn't mean anything to me,looks like part numbers. I did see the E3 on the motor mount so I'm guessing that is a model year stamp.

[joe fxs fxr]

Casting numbers are like part numbers, the dash indicates first year of use. So the frame is 83 or newer based upon the -83 casting number. I don't remember how to decode the date stamp, but I'm sure Eric or someone will respond with the correct answers.

[tgarcia]

Ok I see,that makes sense. So sound like the most likely of scenario is it was a replacement. I guess that makes it a good candidate for a rigid back half install.

[Speeding Big Twin]

On H-D frames the letter in the date code represents month with A for January and B for February etc. The number indicates year depending on the type of frame. On your frame E3 indicates manufacture in May 1983. This would be consistent with the long VIN boss which first appeared about mid-81 as I mentioned above.

Date code E3 is also consistent with the type of lower left rear forging.

The lower R-H rear forging has me intrigued. Its number is 47652-73 which was introduced about mid-73 but I’m not certain how long it was used for. For the first couple of years the forging had no provision for a passenger footpeg but that situation was addressed with a single-hole block welded to the back of the forging from about mid-75 thru 76. The two-hole block welded to the back of your R-H forging was introduced for 77 models along with that bracket for a footpeg.
But was the factory still using that type of R-H forging on frames produced in May 83? Or would the R-H forging have been the type shown below which is similar to what you have on the left. This R-H forging number appears to be 47646-83. Also notice the gusset plate welded to the back of the downtube and forging.







Further investigation may be required. I can’t see any forging ID on your steering head but are there any markings on the other side of it? Perhaps in the webbing?
Any forging ID on the front engine mount and rear engine mount?
Near the front engine mount is there a thin plate between the downtubes?
Any forging ID on top of the seat post area? Or maybe a stamped number? Or is there a plate across that area?

Can you post a photo of the left side of the seat post where the coil would normally be fitted.
Photo of the front mount for the oil tank?

Both upper rear forgings may have 47645-65-Y but do they have any other markings? Thanks.
Eric