BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: RobW on 25 July, 2017, 22:21:10

Title: Spitfire Tank fitting
Post by: RobW on 25 July, 2017, 22:21:10
Hi all I am presently bringing back to UK spec a 67 Spitfire. It came from the US fitted with a Lightning tank. I have now a finished traditional 4gallon tank 👍 I think I have purchased all the additional parts required to fit it to the bike .As I have never removed one before not quite sure on the process of fitting.
Where the U shaped rubbers fit on the frame, The bar that attaches to the central part of the frame do I fit the rubber ball first ? Or does it sort of slide down through the tank ? I believe there is a clamp style bracket that fits across the underside front of the tank across a spigot on the frame ?
A step by step guide would be much appreciated 😉👍
Cheers Rob
Title: Re: Spitfire Tank fitting
Post by: Bess on 26 July, 2017, 16:00:31
Hi RobW,
             There maybe other ways, this method works for me (note tank schematic shown not 67 but fittings are the same):

U shaped rubbers, tape around frame about 2" from either end (not set in stone, move them as necessary) of the tank, large in the front small at the rear. Check the handlebars turning far right and left to ensure they do not strike the tank.

Centre tank bolt (20), fit first, then washer (5), distance tube (4), tank (28), tank o ring (21) , tank mounting ring (22), front and rear beading (6 + 27), beading holder (23), tank bolt rubber (rubber ball) (24), washer (3) and finally nut (2) tighten as required on completion push in BSA logo grommet (1) on top.

Fit rubber bush (18) to spike on the underside frame, then petrol tank bracket (15) secure with 2 x 5/16" set bolts (33). I put a rubber washer between bracket and tank and bracket and washer (32).

Things to watch out for:

 5/16" set bolts are correct length and do not puncture tank.
 Don't mix 2 gallon tanks parts with 4 gallon tank parts.
 Its fiddly, so good luck.
 Fit and adjust beading beforehand. I fit a good quality insulating tape over the tank seam before fitting beading, it protects the paintwork.

Best wishes...
Title: Re: Spitfire Tank fitting
Post by: RobW on 26 July, 2017, 21:52:12
All I need to get is the larger central bolt I think the one I purchased must have been for the Hornet as it's far to small I would struggle to reach and bolt on that rubber bung
Title: Re: Spitfire Tank fitting
Post by: Bess on 27 July, 2017, 08:59:10
    Nice bike.

To help, apologies if you have this information already - my records show - tank bolts:

68-8080 Spitfire(USA), Hornet & Wasp 5/16" 26tpi 4"
68-8045 Spitfire (For use with 68-8165 tank, the one shown in your photo) 5/16" 26tpi 2 7/8"

68-8011 All 5/16" 26tpi 3 1/2" (4 gallon)
68-8173 All 5/16" 26tpi 4" (2 gallon)

It might be you have the wrong rubbers and under tank bracket. 1967 tank details attached.

Best wishes....
Title: Re: Spitfire Tank fitting
Post by: Robspitfire on 27 July, 2017, 15:25:30
Presumably if your fitting the 4 gall tank it is the proper fiberglass one. If so the front underneath should have two bonded studs that go through the frame bracket. I'd be very wary of using bolts as a tweak to far can create a fracture. (hope your tanks red!)
Title: Re: Spitfire Tank fitting
Post by: Rob Atkinson on 30 July, 2017, 14:58:16
I am also trying to fit a Spitfire fibreglass tank after removing it to fit choke slides, (earlier post), and would benefit from the wealth of knowledge out there. I took notice of the way it was fitted as I removed it. The tank was very secure but not fitted exactly as per the manual drawings. A few things: Although my bike is a MK2 fitted with concentrics, I believe it is fitted with a 5 gallon fibreglass tank as fitted to MK3 & MK4 Spitfires. Most, but not all, specifications sheets I have read state the earlier fibreglass tanks were 4 gallon and later models had the 5 gallon version. I bought a strap or petrol tank bracket for a 4 gallon fibreglass tank from a reliable source but found the two studs that are fixed to the underside of the tank are too wide apart for the bracket. The studs appear to be original and there is no evidence of repair work on them. I am getting a local engineering workshop to adapt the bracket. The one fitted prior to me removing the tank was a straight bar as fitted the A10 etc. so the spike and rubber bush were not utilised. I have spent hours on the internet looking at photos of different models of Spitfires but the tanks look the same shape. Does anyone know if there were 4 & 5 gallon versions of the fibreglass tanks and if they had a very similar profile?
Next query or observation: the steel tanks I have experience of are all "pulled down" when the centre bolt is tightened. When I have examined the fittings on the fibreglass tank, it seems this does not happen. The spacer tube fits inside the rubber ball and doesn't seem to "space" anything. Plus the rubber ball just seems to act as a steady if this makes sense. Is this correct?
The only thing I can see that pulls the tank down onto the u shaped frame rubbers is the tank bracket on the front underside.
Apologies to Robw as I have not helped you with fitting your tank but I hope any replies to this post may assist us both.
Title: Re: Spitfire Tank fitting
Post by: JulianS on 30 July, 2017, 15:36:16
The rubber ball expands as the nut is tightened so gripping the tube into which it fits. I think it avoids putting stresses on the weaker structure (compared to steel) of the glass fibre tanks.

Photo is from the 1966 UK catalogue showing thenSpitfire Mk2 fitted with a 5 gallon tank.
Title: Re: Spitfire Tank fitting
Post by: Bess on 30 July, 2017, 16:46:10
    The A5065 workshop manual, page GD22 also states 5 gallons. I presumed RobW meant the steel tank as 4 gallons was mentioned, hence the drawings for steel.

I've had problems with the strap in the past. I now make my own using a clutch spring cup as the centre section which fits over the spike (it is uncannily similar to the OEM part).

Best wishes...