JohnD Posted July 7, 2019 Share Posted July 7, 2019 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 Link to comment Share on other sites More sharing options...
JohnD Posted July 10, 2019 Author Share Posted July 10, 2019 No one or everyone? Link to comment Share on other sites More sharing options...
Nick Jones Posted July 10, 2019 Share Posted July 10, 2019 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..... Link to comment Share on other sites More sharing options...
JohnD Posted July 10, 2019 Author Share Posted July 10, 2019 (edited) 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 July 10, 2019 by JohnD Link to comment Share on other sites More sharing options...
DeTRacted Posted July 10, 2019 Share Posted July 10, 2019 Same as the sidescreen TRs then John. The instruments are different internally, using a balanced-coil arrangement so do not need a voltage stabiliser. Link to comment Share on other sites More sharing options...
JohnD Posted July 11, 2019 Author Share Posted July 11, 2019 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 Link to comment Share on other sites More sharing options...
Gt6s Posted July 11, 2019 Share Posted July 11, 2019 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 Link to comment Share on other sites More sharing options...
rogerguzzi Posted July 12, 2019 Share Posted July 12, 2019 Hello All Some Japanese bikes had tube in tube exhaust pipes to help stop the bulging f the chrome plating Roger Link to comment Share on other sites More sharing options...
rogerguzzi Posted July 12, 2019 Share Posted July 12, 2019 5 minutes ago, rogerguzzi said: Hello All Some Japanese bikes had tube in tube exhaust pipes to help stop the bulging f the chrome plating Roger Fringing auto thing blueing Link to comment Share on other sites More sharing options...
rogerguzzi Posted July 13, 2019 Share Posted July 13, 2019 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 Link to comment Share on other sites More sharing options...
oldtuckunder Posted July 14, 2019 Share Posted July 14, 2019 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 Link to comment Share on other sites More sharing options...
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