Fuel tank captive fixing issue

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Hi all,

I went to remove my 961 fuel tank today, as I've done several times in the past. However, I couldn't get one of the front fixing screws out due to the captive thread fixing in the tank spinning round with the screw. As I said, the tank has been off many times in the past & I'm always extremely careful when re-assembling anything. As such, I'm absolutely certain the thread is not cross threaded or was overtightened etc. I always re-fit threaded parts using finger & thumb only as far as they will go first before using a tool to nip them up & then I only tighten as far as necessary, particularly where captive fixings like these are concerned. Therefore I can only assume that, for whatever reason, the plastic around the fixing has failed. VERY FRUSTRATING.!! :mad:

So, has anyone else suffered this same issue &, if so, how did you manage to overcome it? With the rubber trim prised away, there is enough width to get a saw blade in & cut through the stepped shoulder of the screw, but I would rather not do this because it would leave me with the headache of having the cut off end of the screw left in the captive fixing. I have tried quick bursts with a cordless drill whilst tweaking the tank in various directions to see if that would get it moving but with no joy, the captive just spins with the screw every time. My hope is that if I can get this screw out I can then cut a groove around the captive fixing & reset it in place with an epoxy adhesive etc.

Any help or ideas greatly appreciated.

Cheers!
 

Voodooo

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Since you have no access to the insert to hold it while trying to unscrew the flanged bolt, my recommendation is to use a left hand drill bit to drill out the Allen key hex, and work your way up one drill bit size at a time to drill off the flange. Once the bolt flange is drilled off the tank can be removed then you can access the insert for replacement or repair.
Personally I’d replace the insert with a larger outside diameter and glue it in place.

The reason why I say to drill it and to use a left hand drill bit is, as you are drilling sometimes you get lucky and the bolt / screw will start to unscrew.
The reason I say to drill and not cut is because you have more control of the drill than a saw or cut off wheel and also don’t have the sparks or micro steel chips etching into your paint. Hot sparks or micro abrasive metal chip will destroy your paint.
The drill will allow slower but effective removal.
 

Voodooo

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Once removed perhaps you can epoxy one of these in place that has a over sized out side diameter. And then use anti seize on the bolt.
 

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Fast Eddie

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The tank does need holding down with huge force, with careful prep and a good choice of epoxy adhesive, Britfan managed to fix this problem on his tank using something like this:

 
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You have got to get the screw head off to remove the tank so drilling is needed. Are Norton still able to supply the aluminum fuel tank ? Are Norton making bikes again ? Am I having a nightmare ?
 
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The tank does need holding down with huge force, with careful prep and a good choice of epoxy adhesive, Britfan managed to fix this problem on his tank using something like this:

Cut the flanged hex bolt of with a dremel. Not much choice because its tightened down and there isn't much space. Took the tank off, ground down the bolt flat. I found the best way to align the bolts with the bracket was to drop the bolt into the bracket, place the tank on and THEN epoxy in between. It tends to move if or not be as accurate if you epoxy the stud on and then put the tank on. Its holding. I think its a better design if the had glassed a male post instead of female. At least then you can hold the excess while taking off the nut.
Goood luck. Next to go is the bracket. Sigh

What Voodoo posted would be the the proper repair. I'd have effed it up. I'm not as well equipped tool wise.
 
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Update:

Firstly, thank you all for your replies & suggestions, all very much appreciated.

In the end I managed to get the captive fixing to pull out of the tank by making a tapered fork out of a length of flat bar & driving it inbetween the flange on the screw and the saddle bracket that it goes through. Once the tank was lifted off I was able to unscrew the captive from the screw quite easily, which is worrying as it suggests that the captive fixing location in the tank had failed for some reason whilst in normal use. The only collateral damage done was a slight bending of the mounting lug on the saddle bracket, but this will be easily straightened out again.

The captive fixing itself is nothing more than a domed head four sided nut with rounded corners, certainly not what you would call a good secure anchor for sitting within a plastic moulding. So, rather than set this fixing back in the tank again & forever living in fear of a repeat episode, I will attach more secure captives of some sort instead. With the tank off it should be easy enough to use an M6 bolt with some appropriate sized washers to draw the other side out & then replace both sides with something more fit for purpose.

Thanks to you all once again... :)
 
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You have got to get the screw head off to remove the tank so drilling is needed. Are Norton still able to supply the aluminum fuel tank ? Are Norton making bikes again ? Am I having a nightmare ?
I really like the aluminum tank idea, but at this point, the bike doesn't warrant the expense. 12 bucks was a deal. 3 grand for a bike that needs constant attention is far down the road.
 

Voodooo

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Personally you’d be better off putting a new thread insert in the tank then use a long set screw and use a washer and nut or a flange nut. This would prevent the force being placed on the insert and help from this happening again. Basically the set screw is the same as a stud.
 
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Update:

Firstly, thank you all for your replies & suggestions, all very much appreciated.

In the end I managed to get the captive fixing to pull out of the tank by making a tapered fork out of a length of flat bar & driving it inbetween the flange on the screw and the saddle bracket that it goes through. Once the tank was lifted off I was able to unscrew the captive from the screw quite easily, which is worrying as it suggests that the captive fixing location in the tank had failed for some reason whilst in normal use. The only collateral damage done was a slight bending of the mounting lug on the saddle bracket, but this will be easily straightened out again.

The captive fixing itself is nothing more than a domed head four sided nut with rounded corners, certainly not what you would call a good secure anchor for sitting within a plastic moulding. So, rather than set this fixing back in the tank again & forever living in fear of a repeat episode, I will attach more secure captives of some sort instead. With the tank off it should be easy enough to use an M6 bolt with some appropriate sized washers to draw the other side out & then replace both sides with something more fit for purpose.

Thanks to you all once again... :)
Good Job ! You got it out .
 
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Personally you’d be better off putting a new thread insert in the tank then use a long set screw and use a washer and nut or a flange nut. This would prevent the force being placed on the insert and help from this happening again. Basically the set screw is the same as a stud.
Thats the best of both worlds. The only drawback which is preventable is corrosion to the threads. I use the nylon nuts to avoid the metal to metal surface and barely go tighter than finger tight.
 
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Voodooo, I'm thinking along similar lines to what you've suggested.

It would be good to know just how much material there is to play with around these captive fixings. A decent sized boss would allow for a larger & much more secure anchor point. I might get the inspection camera in there & take a look.!
 

Voodooo

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Thats the best of both worlds. The only drawback which is preventable is corrosion to the threads. I use the nylon nuts to avoid the metal to metal surface and barely go tighter than finger tight.
The thread insert is brass. The stud / set screw can be stainless. A dab of anti seize would be good.
 
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The insert that pulled out of my tank is stainless steel, but that’s not to say they were all necessaarily the same over the years? The real problem as I see it is insufficient achorage in the plastic due to the shape & size of the insert vs the job it’s being asked to do.
 

Fast Eddie

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If the insert is stainless AND the bolt too then there’s real danger of these welding themselves together. Better make sure these bolts are anti seized in some way.
 
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Agreed, stainless is prone to picking up or binding. For that reason I always use copper grease on stainless threads (& just about anything else I assemble for that matter). Unfortunately though, it still didn’t prevent this from happening...
 
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The insert that pulled out of my tank is stainless steel, but that’s not to say they were all necessaarily the same over the years? The real problem as I see it is insufficient achorage in the plastic due to the shape & size of the insert vs the job it’s being asked to do.
Could be the old ethanol expanding the tank around the anchor.
 

cliffa

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Could you replace them with studs JB welded into the tank? You can get studs with a hex key in the end so you can stop it rotating while you undo the nut.

Or failing that how about a nice Tritonesq stainless strap over the top of the tank?
 

Stephen_Spencer

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Could you replace them with studs JB welded into the tank? You can get studs with a hex key in the end so you can stop it rotating while you undo the nut.

Or failing that how about a nice Tritonesq stainless strap over the top of the tank?
Stainless or leather strap over the tank would look very cool indeed and may be functional of course! Would protect the rear of the tank also. Not sure how it would be secured or how it would interface with the modern central petrol cap, as opposed to an offset Monza/vintage cap.
 
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