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Forged frame lugs #588770
03/05/15 11:38 pm
03/05/15 11:38 pm
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Magnetoman Offline OP

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Thanks to Boomer (Boomer, thanks) we've been able to nail down certain identifying features on early Gold Stars. One of the features of interest are the forged engine mounting lugs on the downtubes (replacing welded stubs in the upper location) that appeared sometime after frame number CB32.275 and prior to .2880.

It would be great to narrow this down further, so if any of you have a 1954-56 Gold Star with a frame number within the above range, please post whether all four of its lugs are welded, or if the upper two are forged. Don't post your actual frame number but round it up to the nearest 5 or 10 (e.g. if it's 1906 post 1910).

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Re: Forged frame lugs [Re: Magnetoman] #588776
03/06/15 2:17 am
03/06/15 2:17 am
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SC
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jimm Offline
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My frame, number 1755, has the upper forged lugs.

Jim

Re: Forged frame lugs [Re: jimm] #588848
03/06/15 11:00 am
03/06/15 11:00 am
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Magnetoman Offline OP

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Originally Posted By jimm
My frame, number 1755, has the upper forged lugs.
Thanks very much for this. Ever such post helps narrow the range of possibilities where this change to forged lugs occurred. By the way, the goal of this exercise isn't rivet counting, it's to help separate the Gold from the Pyrite when considering a bike for purchase.

Re: Forged frame lugs [Re: Magnetoman] #588900
03/06/15 3:28 pm
03/06/15 3:28 pm
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Luton Bedfordshire UK
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Seamus Offline
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Am I mistaken, as I thought the forged lugs were available as the originals broke under stress and could have been used as repairs on earlier bikes. They were then fitted to production bikes a bit later. Believe late 1954 if I recall a conversation with Ian Jackson correctly.

Re: Forged frame lugs [Re: Seamus] #588979
03/06/15 11:01 pm
03/06/15 11:01 pm
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Magnetoman Offline OP

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Originally Posted By Seamus
Am I mistaken, as I thought the forged lugs were available as the originals broke under stress and could have been used as repairs on earlier bikes.
Yes, I suppose it's possible some people have frames that originally had welded stubs that long ago were replaced with forged lugs. But if enough people reply to my question we should be able to determine approximately when this improvement entered production at the factory.

Re: Forged frame lugs [Re: Magnetoman] #588990
03/07/15 12:35 am
03/07/15 12:35 am
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Kansas City
RGSDave Offline
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So, how did they repair the frames with the forged lugs? Did they actually cut them apart and put forged lugs on them, or did they just replace the whole front frame section?

Re: Forged frame lugs [Re: Magnetoman] #589008
03/07/15 4:06 am
03/07/15 4:06 am
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Kerry W Offline
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Ian Jackson, Machine registrar in the UKGSOC, did a piece in a similar vein a little while ago. I'll see if I can find his data.


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Forged frame lugs [Re: Kerry W] #589072
03/07/15 1:02 pm
03/07/15 1:02 pm
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Magnetoman Offline OP

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Originally Posted By Kerry W
Ian Jackson,...
Thanks for mentioning this. I just sent now sent Ian an email and will report what he tells me.

Re: Forged frame lugs [Re: Magnetoman] #589113
03/07/15 5:26 pm
03/07/15 5:26 pm
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newcastle australia
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As an aside, the CA7 frame had the forged lugs fitted some time during 1955 production.

Re: Forged frame lugs [Re: trevinoz] #589162
03/08/15 12:40 am
03/08/15 12:40 am
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Magnetoman Offline OP

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Originally Posted By trevinoz
As an aside, the CA7 frame had the forged lugs fitted some time during 1955 production.
It's a very interesting 'aside'. I wonder if all frames got the lugs at the same time.

Re: Forged frame lugs [Re: Magnetoman] #589173
03/08/15 5:50 am
03/08/15 5:50 am
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Luton Bedfordshire UK
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Seamus Offline
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Did the B31 frames also get the lugs?

Re: Forged frame lugs [Re: Magnetoman] #589222
03/08/15 12:28 pm
03/08/15 12:28 pm
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Middle East,
Kerry W Offline
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Good question. None of the ones I have experience of - all pre '56 (pre Ariel hubs) had forged lugs.


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Forged frame lugs [Re: Kerry W] #589226
03/08/15 12:48 pm
03/08/15 12:48 pm
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Magnetoman Offline OP

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Unless I've forgotten something -- in which case please fill in the missing information -- following are the variations I can think of in the evolution of the Gold Star's swinging arm frame:

Initial (1953) swinging arm frame
1954 frame with welded engine mounts
c1955-56 with forged upper mounts
Catalina without rear passenger loops
Catalina with right loop for mounting silencer
c1960 with full height headstock brace
c1962-63 with forged upper and lower mounts

In addition to identifying anything missing from this list, it would be interesting to correlate some of these variations with what was going on with similar frames of other models, i.e. B31/33, B32/34, and A7/10.

Re: Forged frame lugs [Re: Magnetoman] #589241
03/08/15 1:45 pm
03/08/15 1:45 pm
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Scotland
kommando Online content
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Are these lugs actually forgings, aren't they more likely to be malleable cast iron due to the low volumes and its use for footpegs etc ?

Vincent's use malleable cast iron

http://www.voc.uk.com/net/docs/1.3/1.3-633-23.pdf

Last edited by kommando; 03/08/15 1:47 pm.
Re: Forged frame lugs [Re: Magnetoman] #589246
03/08/15 2:02 pm
03/08/15 2:02 pm
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Kerry W Offline
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BSA did have what was considered to be the best forging operation in the industry at the time.


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Forged frame lugs [Re: kommando] #589251
03/08/15 2:31 pm
03/08/15 2:31 pm
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Magnetoman Offline OP

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Originally Posted By kommando
Are these lugs actually forgings,
That's a good question, and I admit I have just been using "forged" because that's what most people write, without having actually determined whether this is the case. Here's a composite of the, um, "forged" upper engine mounting lug on a late DBD and the "forged" mudguard bracket on the fork leg of an unknown Gold Star (or B34?):



At least in the case of the mudguard bracket it would have been cheaper to stamp/forge it into the rounded shape than to machine it. As Kerry wrote, BSA is well documented to have had the forging technology in house.

I have access to a butchered A7 frame from which I could cut one of the mounting lugs, section it, etch it, and examine in my metallurgical microscope. The grain structure would reveal whether it had been forged or cast. Although I'm interested in this, and it's now on my to-do list, realistically it isn't going to make it to the top of that list anytime soon.

Re: Forged frame lugs [Re: Magnetoman] #589271
03/08/15 4:12 pm
03/08/15 4:12 pm
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Winona, MN
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Originally Posted By Magnetoman
Unless I've forgotten something -- in which case please fill in the missing information -- following are the variations I can think of in the evolution of the Gold Star's swinging arm frame:

c1962-63 with forged upper and lower mounts


FWIW here is my 1962 BSA Gold Star frame CB32 1102X after media blasting:




1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
Re: Forged frame lugs [Re: Swan] #589301
03/08/15 8:37 pm
03/08/15 8:37 pm
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Magnetoman Offline OP

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Originally Posted By Swan
FWIW here is my 1962 BSA Gold Star frame CB32 1102X after media blasting:
It's worth a lot. This narrows things down considerably. Along with my own frame, it means the "forged" lower mounts were added sometime in the next 700 produced after yours, i.e. after 1102x and before 1172x.

Re: Forged frame lugs [Re: Magnetoman] #589474
03/09/15 6:30 pm
03/09/15 6:30 pm
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Luton Bedfordshire UK
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Seamus Offline
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More mud in the water,
Looking closely at the top lug on my frame reveals a stamp of 42-4320 BSA. Can take a photo if required

Re: Forged frame lugs [Re: Seamus] #589504
03/09/15 10:02 pm
03/09/15 10:02 pm
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Magnetoman Offline OP

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Originally Posted By Seamus
Looking closely at the top lug on my frame reveals a stamp of 42-4320 BSA. Can take a photo if required
Can you clarify where this stamp is (or is it a raised forging number)? I just spent a few minutes crawling around my '63 DBD and can't see a number on the top of any of the engine mounting lugs. What year is yours?

Re: Forged frame lugs [Re: Magnetoman] #589506
03/09/15 10:19 pm
03/09/15 10:19 pm
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Kansas City
RGSDave Offline
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I have the same number on two 63 RGS frames,cast raised numbers on the inside of the lugs

Last edited by RGSDave; 03/09/15 10:20 pm.
Re: Forged frame lugs [Re: RGSDave] #589510
03/09/15 10:44 pm
03/09/15 10:44 pm
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Magnetoman Offline OP

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Originally Posted By RGSDave
cast raised numbers on the inside of the lugs
Ah, inside the lugs. I didn't carefully look there. But, I did check BSA's master price guide for that period and no such part no. (differing by 1 from the casting number) was available as a spare part so treat yours carefully because you won't be able to buy a replacement.

Re: Forged frame lugs [Re: Magnetoman] #589516
03/09/15 11:08 pm
03/09/15 11:08 pm
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Kerry W Offline
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Then there's the question of when BSA went to 4 forged lugs..


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Forged frame lugs [Re: Kerry W] #589521
03/09/15 11:30 pm
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Magnetoman Offline OP

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Originally Posted By Kerry W
Then there's the question of when BSA went to 4 forged lugs..
That was addressed a few posts earlier. At least, it narrowed it down to the number produced between Swan's and mine. It would be nice to narrow it down further, though.

Re: Forged frame lugs [Re: Magnetoman] #589542
03/10/15 6:58 am
03/10/15 6:58 am
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Westminster, Colorado
stubbicatt R.I.P. Offline
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Warning... thread veer...

Does the fitment of lower forgings in the last years suggest that the welded on tube lower lugs are prone to failure? Now I'm afraid to start the old girl...

Last edited by stubbicatt; 03/10/15 6:58 am.

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