Flat or Round Oil Tank?

[Peter Gee]

Hi Guys I have a 56 A7 Shooting Star.Sould I have a flat oil tank or the round variety? Are they interchangeable?

ThANKS

pETER g

[Greybeard]

In my experience the rigid and plunger frames use a smaller rounder oil tank and the swinging arm frame uses the larger flatter oil tank. What frame do you have?

[morris]

Spot on GB. And not interchangeable without major surgery...

[RichardL]

Someone recently tried to tell me that some swingarm models had flat-faced oil tanks and some were more rounded. As far as I know, this is incorrect and, I believe, all swingarm oil tanks are slightly bulged out (rounded). I argued (a bit) that he may be confused because there were flat and rounded tool boxes.

Am I wrong about the oil tanks?

Richard L.

[chaterlea25]

Hi All,
There are two versions of the swingarm oil tank, same with the tool boxes
The early 54-55 have a flat outer profile, the later as pictured are more rounded
I cannot say when the change over took place???? , you would need to search the different year parts books
They are interchangable

HTH
John

[RichardL]

jOHN,

Not debating you here, but when I look at this: http://www.ebay.com/itm/OIL-TANK-OLD-BSA-B31-32-33-34-A7-10-FLAT-SIDED-GOLD-STAR-has-a-dent-repair-/201366806198?hash=item2ee2659eb6&vxp=mtr

I still see a bulging outer face, not flat like the flat tool box. It seems that the difference may be in the radii where they turn back toward the seam. I'm just not sure. Care to clarify this for me?

Editing: The more I look at this the more I am seeing it as flatter with smaller radius corners but still not seeing it as "flat".

Richard L.

[chaterlea25]

Hi Richard and All,

Remember that once they believed the Earth was flat

Lets hope that this series of pics will explain the differences between the two types
Looking at the earlier types the tool box cover  is flat flat while the early oil tank is "roundy" flat
The black oil and toolbox are from a late 54 manufactured B series
Chrome tank is from 63, red tool box is 61

Hope this helps

John

[trevinoz]

The flat sided toolbox & oil tanks were used until 1957, changed to rounded for 1958.
A further change to the oil tank was around 1961 when the short nipple was changed to a long one.
There is not much difference in profile between a flat sided oil tank and a rounded. The toolbox is much more pronounced.

[morris]

Started to wonder if I got the flatter or the rounder type on the SA but John cleared it out. Thanks.
I definitely got the rounder one.
Does look though as if the flatter one on the picture came from a bike which fell over a couple of times...

[RichardL]

John,

 Thanks for the pictures. They are very interesting . Now I've got to go look at my two tanks. Too lazy this minute.

Richard L.

[duTch]

 

Remember that once they believed the Earth was flat

  ...so now it's "roundy flat"....

 sorry

[groily]

As says Trevinoz and as illustrated by John (Those Who Know).
I have the flatter bits on my B31, whose frame is def a '56 (although a lot else isn't including the alternator engine), and the more convex bits on the A whose frame is def a '59 (although a lot else isn't). They would interchange.
I don't think I'd sulk if they were the other way round, given the mix of bits there already  . . . have to leave things for the next (and probably pickier) owners to scratch their heads over!

[bikerbob]

What could be confusing some people is that BSA kept the same part numbers for both types of tank and toolbox, I have a parts book for 1954-57 and also a later parts book which shows all the changes that were made in 1958 and later such as headlight, hubs silencers tank badges etc. also Roy Bacon's book on the twins shows the same part numbers for all years of the A7-A10. My own BSA A7 which is 1956 and is original has the rounded tanks.

[KiwiGF]

My Dec 55 (56 model year) gf has the flat tank and toolbox....I cannot be certain they are the originals but it's very likely 

[Seabee]

My 57 RR has both a flat side box and a 'flat" oil tank.