Tank Fixing

[Arthur Farrow]

I'm nearly done with the "mechanicals" on my rebuild.

Is the rear of the tank fitted on bobbins like the radiator?

It was 10 years since I took her apart  and I cannot remember I know on my bike there was one up the front and its logical to assume they are on rear too but must be small diameter

HELP appreciated !!

[hendred]

Yes.  My MKII has two bobbins at the rear.  I used the same size front and rear and trimmed the rear to fit.  The bike came like that when I acquired it.  I think they are old BMC Mini exhaust bobbins.  The ones  on the instrument console are too stiff in my opinion, causing the instruments to fail from vibration.  Morini 3 1/2 style ones, very flexible , would be better.

Hope this helps.

[gilesorton]

They are indeed Mini exhaust bobbins. Interesting to hear that somebody else found that one of the rear tank bobbins had been modified- in my case I had to take a hacksaw to the replacement to trim it down to the narrower shape of the one it was replacing.

[Arthur Farrow]

Brilliant thanks folks...it was the possible need to trim them down that made me scratch my head.

[Arthur Farrow]

Ok took hacksaw to them and now fitted even if one thread in the tank let go (Ill helicoil it)

Picture here of the front mounting...not much tread showing and slim for a nut...what have you guys got here. Sorry to ask so many questions, but its all good knowledge for the future!!

[hendred]

It's a special nut with a small head and parallel "tube" which goes down into the bar piece.  I'll measure it up after lunch.

[gilesorton]

I was hoping to upload a picture of mine but computer only seems to want to show a load of text.

If this does not come out and you would still like a picture of the extended nut o my bike please send me an e mail direct. [e-mail]

[hendred]

Dome headed Hex  tube nut, 7/16 AF. Overall length 0.810 inches, length of hex part 0.237 inches, length of tube 0.400 inches, diameter of tubular part 0.435 inches.  Thread to suit bobbin.

Hope this makes sense.

[hendred]

Hopefully here is a picture!

[Arthur Farrow]

Brilliant thanks guys !

Now where the heck am I going to get that !! (B & Q is closed ...ha ha)

When I bought my bike 10 years ago as a rolling wreck it probably had something to hold down the fitting and I kept everything that came off in a box, but nothing like this. Detail being sorted now and Electrics to do but she is looking pretty promising

[hendred]

Dust off the lathe, buy a short length of 7/16 af stainless hex bar off eBay and have fun!  

P.S. B&Q is now open but don't think you will have much luck!!!!!!

[Arthur Farrow]

There was absolutely nothing like that on my bike.

Clearly you do not know my skills. I do have a nice Myford covered in dust and crap. I reckon I can make some of the worst spares in the world but that's about it. How the heck do you make a domed head.

BUT for you I will have a go. It will take all day and look crap but I will have a go.

[hendred]

You can buy a fancy turning attachment for Chronos or do a quick and dirty by turning down the hex bar to round for the height of the dome, turn a 45 degree chamfer on the end and finish off with a file.  I found turning stainless was ok as long as I kept the speed slow.  Stainless tends to work harden and forms a skin which wrecks the lathe tool.  My Myford doesn't have enough power to take deep cuts to get below the hard skin.  So nice and slow prevents the hard skin forming.  Same for drilling.

Have fun.

[gilesorton]

I can't help thinking that Silks would not have gone to all the trouble of turning these for themselves but will have raided the parts bin from somebody else to find these. Probably not off a Mini exhaust like the bobbins but they must be in a catalogue somewhere?

[hendred]

I wouldn't be surprised if  Silk did make the nut.  It is quite simple to make really and the history of Silk was manfacturing bespoke on site machine equipment.  They would have had all the equipment readily to hand.  A very innovative company, that's why Furmanite wanted to buy them.  Not for the motorcycle business , but the on site machining part.  Did a lot of work in power  stations machining large journal bearings in situ  and other specialist machining jobs.  Saved a fortune in down time and dismantling costs.

[hendred]

Alternatively, try calling Clive Worrall, he might just have one spare.

[Arthur Farrow]

I did as it happens speak to Clive about a few matters at about the time you sent the e mail! He has a bag of them and apparently they are the same as the ones that hold on the radiator on later models, but not on my Mk1

I did however order some bar before speaking to Clive...and just to clarify a typo in an earlier e mail. I make some of the worlds worst SPACERS under duress. Making spares is quite beyond me however my son enrolled me on an Axminster residential machining course in the Autumn..watch out Alan Millyard!!!

Arthur Farrow

------ Original Message ------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

To: "Arthur Farrow" <[hidden email]>

Sent: 25/04/2020 21:17:56

Subject: Re: Tank Fixing

Alternatively, try calling Clive Worrall, he might just have one spare.

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[Smokey_Paul]

Easily made I make a lot of parts

[Arthur Farrow]

The lovely clive had some so all sorted.