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Interesting post over on the Triumph Experience.     A dedicated restorer has found that his 'bonnet iron' (UKspeak - hinge tube for bonnet) is a double tube, one inside the other!   I presume for stiffness/strength.

See: https://www.triumphexp.com/forum/spitfire-and-gt6-forum.8/dissecting-a-bonnet-iron.1630259/

He was concerned about the amount of rust between the two, which had holed at one point, and appears to have largely cut off the outer tube in sections,  intending to weld it all back together (!!) when he's de-rusted it.   But is this a known feature of the bonnet tube?  Early, late?    And which cars had them, all small chassis Triumphs with the forward tilting bonnet?

John

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I suspect no one...…  certainly was new to me.

I wonder even if it's a factory feature or a historic "local repair" by someone who didn't have the right tube.  Seems like a completely bizarre construction method for production.....

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I learnt another factoid over there the other day.     1200 Heralds and early Vitesses didn't have the "volts stabiliser", and ran their guages on whatever the system was delivering in the region of 12V, not the average 10V that the stabiliser gives.   Special gauges, with narrow connectors apparently.  At the same time, Spitfires and Estates had the stabiliser!

That'll do for the Triumph pub quiz!

John

Edited by JohnD
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Back to the double tube bonnet support.

Over on the Triumph Experience, several others have looked into their tubes, at the end and seen double tubing!

This is, I think,  a new item not previously documented.  Will anyone here look into their bonnet tubes, please?     And report?    Please include the model of Triumph you have looked at.

JOhn

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Might be a US crash protection thing. (stupid I know) but US cars had differences. .Never seen it on a bonnet tube but I used o have an old SAH tubular exhaust manifold that was double tube.

Laurence

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Hello All

               I have looked at Spittys bonnet (1500 built 1980 registered 1981) and it is double tubed

I also looked at a spare new never used bonnet (believed to be a Triumph one)and that is double tubed.

Roger

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my initial thought was that a twin wall tube would resist fracture and buckling better than a single wall of same thickness, rather like when using an internal spring to bend a pipe. i dont have time to do any digging but my first hit seems to have some partial answers in that direction

alan

https://physics.stackexchange.com/questions/12913/hollow-tube-stronger-than-solid-bar-of-same-outside-diameter-o-d/12919

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