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Series A Fuel Tank-Mounting bolts

Bikerjoan

Well Known and Active Forum Website User
VOC Member
I'm currently reviving a 37 Meteor, could someone please advise the size of the four tank mounting bolts. The ones I bought are 3/8 Cycle but it now find my tank needs 7/16 BSF. :confused:

Any help appreciated.

Thanks

Jon
 

Pete Appleton

VOC Hon. Editor
VOC Member
VOC Forum Website Administrator
My '36 Comet ones are 3/8 BSCy


Peter (rapidly becoming a series A expert and much poorer at the same time)
 

Bikerjoan

Well Known and Active Forum Website User
VOC Member
Thanks Peter, I suspected as much, now I'm at this stage!

Glad there a few up & coming A experts around in the club, I can agree with you that you soon get past the point of no return.

However I'm told they are a rewarding bike to own & ride, so lets both keep at it!
 

Robert Watson

Well Known and Active Forum Website User
VOC Member
The 3/8 bsc are a pretty fine thread for holding the tank. I imagine they got damaged and they were tapped out to 7/16 and bsf is a coarser more robust thread.
 

Bikerjoan

Well Known and Active Forum Website User
VOC Member
Thanks for the reply Robert, you may well be correct.A possible way forward will be to get some studs made 7/16 to 3/8, as there's not much clearance where they sit through the frame support.

Series A machines are like nowt else Ive come across before, maybe that's part of the appeal..............
 

Robert Watson

Well Known and Active Forum Website User
VOC Member
I think if I was going to repair that I would make thread inserts that are 7/16 bsf male and 5/16 bsf female and thread them into the existing holes and give them a little loctite! Then I would make 3/8 shoulder bolts with 5/16 bsf thread. Make them just the right length to nicely tighten the tank rubbers when screwed home. If you need a little more compression use a thicker washer under the bolt head.

I just repaired a Twin tank in very much this manner, although the inserts has to sit proud a bit with a flange and got soldered into place to cure leaks around the original inserts.
 

Simon Dinsdale

VOC Machine Registrar
VOC Member
VOC Forum Website Moderator
My A tank has been tapped 7/16 BSF sometime in the past.

What I did was make some studs which are 7/16 BSF wasting down to 3/8 diameter with 3/8 BSF the other end. The 7/16 BSF part is slightly shorter than the depth of the tank mounting holes so only 3/8 diameter protrudes from the tank. I also on the 3/8 end slotted the end so a screwdriver can be used to screw the studs into the tank. The method of fitting is place the two mounting rubbers over the 3/8 part of the studs and then hold them on with a 3/8 nut and washer. The nut and stud are drilled for wirelocking and I temporary put a piece of wire throught them. Then position the tank on the frame, lift the front and slide the front studs in the slots in the frame with the rubber mounts either side of the slot bracket. Then lower the tank onto the studs screwing the studs into the tank two turns. Repeat for the rear mountings. Then with a short screwdriver tighten the studs. I don't believe the studs / bolts should be that tight and using a screwdriver I have found is tight enough. If the studs are the correct length they will nip the rubber mounting washers before the 7/16 section bottoms in the tank. Then remove the temporary wire and wirelock the two front studs / nuts together across the frame and the rear two together. It's easier than it sounds.

It is important that there is clearance between the studs and the slots in the frame otherwise you are bypassing the rubber mounting washers and vibration will be transmitted to the tank.

I found on my A it was not possible to screw the studs into the tank first and then fit the tank on the bike.

On a final note, my tank would not fit flat onto all four mounting points, so I made an extra 1/16 thick rubber washer for the offending rear mount. Then the tank sat on all 4 points and tightened down without any stress been applied. Something to look for.

Cheers,
Simon
 

Bikerjoan

Well Known and Active Forum Website User
VOC Member
Simon,
thanks for the info regarding your tank.There's a couple of interesting points I had not yet considered.

Cheers

Jon
 

Albervin

Well Known and Active Forum Website User
VOC Member
Not only were the holes in my tank taken out to 7/16 BSF but the slots in the mounting bracket were widened to accommodate them!! AAgh. I was going to have some waisted bolts with reduced size heads made up by a well known Series A "nut" by I have been sidetracked by my B. You must be very careful to have clearance between the tank and the valve springs. When I bought some "new" springs this became an almost impossible task due to the height of the springs. I ended up using some old springs that another well known "nut" gave me. Lots of good help is out there if you need it.
 

Vincent Brake

Well Known and Active Forum Website User
VOC Member
And please do wire lock the nuts as they are not firmly fixed

Indeed its a very very nice drive this bike is.

I am doing again the It motogiro with it

regards

Vincent
 
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