petrol tank centre mount bolts for '60

[Rocket Racer]

In the absence of parts fit for purpose I ordered parts as per the parts list to mount the tank only to find they are not going to fit without something changing  .
The frame doesn't appear to have been altered but I'm missing something here, what is it? 
Both bolts supplied are bigger than the threaded ole in the frame

[Dean]

Just had to do mine.

Yours looks like someone has fitted their own centre boss with a smaller than standard hole.
Your new bolt and boss looks just like the one I fitted.

[Rocket Racer]

so in your case the lower fitting screws directly into the frame? I can modify mine, but didnt want to do that if its currently correct as it is.

[Dean]

Yes the boss threads into the frame. I'm guessing BSA planned for the threads wearing.
I was very lucky. I just tapped a small chisel into the old boss, applied a spnner and the boss came out easily. Loctited thte new one in.
But I would wonder why someone would make the mod you seem to have in your frame. It may mean the thread in the frame is buggered so you'd have to braze/weld the new boss in?

[Rocket Racer]

Dean,
 thanks for that, sounds like I have a plan: modify the frame to accept the bottom fitting.

Its very hard to tell whats right and whats been altered sometimes and after all these years anything is possible.

Tim

[terryg]

One of mine came with an M6 stud brazed into the adaptor fitting. As a consequence the adaptor was also brazed to the frame.

Fortunately the culprit was not too good at brazing and the whole was relatively easy to remove without damaging the frame boss.

Now all back to standard, happily.

[coater87]

 Funny this comes up. My frame had the tank mount shaved off at some time in the past. I have looked, but outside buying a different frame and cutting that up (not going to happen) it seems this mount cannot be found.

 I started building a new mount last night, and it will look exactly like what you have now R.R., except with a 3/8 hole. Should work fine, it is hidden, and its better then the bungie cords the coffin gas tank was held on with.

 Lee

[Butch (cb)]

Mmmmm - coffin tank. Picture?

[bsa-bill]

my last restro had both fittings removed, I purchased new saddle and adaptor but can't recall from whom, anyone got a clue

[coater87]

 You have never seen those cheesy fiberglass coffin shaped gas tanks from the early 70s? I will work on a picture for you. The metal ones are actually worth a few bucks, the fiberglass ones not-so-much.

 Is there any good reason why BSA used the arrangement they did? The boss on the frame, and threaded insert, and bolt?

 I am trying to see ahead in this, and wonder if anyone can see a problem with the same system RR shows in his pictures.

 They must have had reason to spend the extra money just to mount a gas tank that way, but I just cannot think of it.

[Topdad]

knowing bsa'S management, they had a job lot of these fittings found they could work and so used 'em ,

[KiwiGF]

It's not a lot of use Tim, but I heard a while back a guy in Aussie was making repro tank mount fittings to fit to the frame hence return it back to standard (I'll have one if you find a the source!).

The standard fitting has an threaded insert I think so there is a bit more to it than one would expect.

Someone on the forum might know who this supplier could be?

[Rocket Racer]

 Is there any good reason why BSA used the arrangement they did? The boss on the frame, and threaded insert, and bolt?

 They must have had reason to spend the extra money just to mount a gas tank that way, but I just cannot think of it.

I'd hazard a guess the lower insert acts as the rubber stop to expand the rubber block against. The later unit frames have a slot into which a bolt is located but then have miscellaneous sleeves and plates .

The earlier plunger and rigid framed bolted on tanks tended to split and the centre mounting rubber was BSA's response that lasted throughout until the last 72 Beesa's albeit slightly amended. 

[warmshed]

Looking at your picture the best option would be to turn down the threaded ends of the bolt (or a stainless one) so it fits the thread you have in the frame.  If you don't have a lathe message me and i would be pleased to make one for you, free of course.  The other option would be to drill out the boss on the frame and thread it to match the bolt. Where do you live? If you are nearby Ill pop over and do it for you or send you the taps and paste so you can do it yourself.
You wont need the large threaded boss on the bolt you have unless you wish to start hacking the frame boss off.  Dave.

[Rocket Racer]

Cheers Dave, very generous offer.
If you did ever happen to be within driving distance you would be most welcome to call in.
Some very good people on this forum 
Will sort something out with my engineer and post the results. 
Tim