1964 G12 CSR Petrol Tank Fixings.

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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owen
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1964 G12 CSR Petrol Tank Fixings.

Post by owen »

Help please, I am at the stage of rebuilding my G12 after about an 5 year rebuild, It has been slow because of health, and if a sunny day got to go out on the push button Honda cross tourer.Mid Wale's is twenty minutes away.
The biggest problem is after such a long rebuild time, I have reached the accessory and tin wear area, So nice shiny rows of reprayed bits of tin and this is where I have tripped myself up.(Age is part of it).
I have had the devils game to get the tool box cover to fit the main box, My reasoning is that if its easy to fit on a bench it may well refit at the side of the road more easily.But I am still not happy with it.
The biggest problem refitting my nice shiny zig-zag petrol tank, I have fitted new crush rubbers lowered it on and if the first stud-rubber is located the other one is approx. one and a quarter inches out, The bracket it rests on is part of the brazed up part of the frame, I have looked at all the tinwear bits hanging up and there is nothing there that seems to resolve this, Any help or photo will help.
Probably this is the first post of many.

Thanks Owen
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dave16mct
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by dave16mct »

I'm trying to get my head 'round this. Are you saying the centres of the mounting holes in the tank are 1 1/4" wider than the tank brackets on the frame?
Dave.
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owen
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by owen »

Thanks for the reply Dave, Yes I have double checked the centres, The tank centres are Six and one eighth, and the bracket off the frame is Five inches.
I thought I would of noticed this difference on the original dismantle of the bike, The only thing I can think of is the old rubbers where a heath Robinson set up a lot thinner and perhaps they splayed enough to nip up. The whole thing has got me well brassed off.

Cheers Owen.
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clive
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by clive »

You have not sent off the tank to be painted have you? Possible someone pressure tested the tank before painting to ensure there were no leaks. I have been told by a club member that he did this using an airline and the result was flexing of the tank with the outcome that the mounting holes were out of line with the frame.
clive
if it ain't broke don't fix
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owen
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by owen »

Thanks for the input Clive, The tank has been resprayed,and a fine job done, I have checked if the tank was pressure tested, and as I had said there were no leakes,no need to pressure test.
The only thing I can think of is the bottom of the tank splayed out but why, It would need some force to do so, I could understand if it had been dropped or some thing but if any thing it surely would tend to perhaps creep in not out.

Cheers Owen.
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ajscomboman
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by ajscomboman »

You really need to post a picture of the underside of the tank. I've just been out to measure my CSR tank and the bolt centres are 5" approx when inserted into the rubber sleeves and placed inside the sockets of the tank. I can't believe that a tank can splay out that much without looking obvious when mounted on the frame. Let's have a picture of the tank mounted showing the downtube/headstock area.
Reynard24
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by Reynard24 »

Like Rob I've just checked a '63 on tank and the mounting bolt centres are 5" so it looks like yours has splayed out somehow.
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owen
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by owen »

I have a really good think about this, I took the tank off,ie after unbolting same, Then a few years down the road I had done all the respraying of the frame all brackets etc. I had met this guy at a few classic bike shows,and I decided that he would do a much better job than myself, The bit that scared me was the pin stripeing. So off it went along with the tool box and oil tank and heat shield, and to be fair to him I told him no rush, I was having fun Red Kite spotting in Mid Wales. But after losing my Licence for 6 months, I had no excuse to get the Matchless finished.(Heart attack-6 Months automatic withdrawal of licence)
Any I am starting to verbally ramble The only reason I can think of the tank not fitting is perhaps air pressure had splayed the tank, although he told me he had not gone down that route. But there was a large dent at the rear or the tank,(God help the gent riding the bike his jewels must be around his ears now.)
Can I use two wooden dowels in the rubber tubes and gently pull it in over say a week, Has any one else had this problem, Will it crack the finish or the brazing holding the tank together.
I will post some photographs tomorrow.
Cheers Owen.
bob
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by bob »

Are you sure you've received back the same tank you sent .
1 1/4" movement sounds beyond the possibility of movement .
Does the 6 1/4" centres match up to a tank for a different model / year .
Stranger things have happened !!
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owen
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Re: 1964 G12 CSR Petrol Tank Fixings.

Post by owen »

P8310009.JPG
Here is a set of photos, complete with my cure I have whittled down some 1"1/4 square to fit in the tunnels and then cramped up gently in increments to 5".
.

Bugger only 1 photo Ill try again, 7-30 back in garage slacked the tank off and it pretty well sprang back to 6/14",So I have cramped it up to 4" carefully and I will leave it overnight.




centrhttp://www.jampot.com/forum/download/file.php? ... ea0bc4dfbe.
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