Kev Posted August 16, 2021 Report Share Posted August 16, 2021 Hi All I have removed the 3 nuts on the downpipe (Herald 13/60) from the manifold only to have sheared the thread on one of the bolts! There is not enough remaining thread shown to refit the exhaust to the manifold. My question is, can these bolts be removed or are they part of (attached) to the manifold? If they can be removed, any ideas how and where I can get one of these from? Hopefully someone can help?? Many thanks Kev Link to comment Share on other sites More sharing options...
johny Posted August 16, 2021 Report Share Posted August 16, 2021 They are studs that can be unscrewed from the manifold but the risk is that after all this time and heat cycling they snap off leaving you with the job of drilling out the remains.... I believe the thread is 5/16 UNF and you might be able to repair the existing stud with the correct die or if too much metal has been lost rethread it with a smaller die (M8?). I dont know why Triumph used such an unnecessarily fine thread in one of the most arduous locations! Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted August 16, 2021 Report Share Posted August 16, 2021 I would agree with what Johny says but before you attempt to unscrew and remove the stud, apply plenty of heat to the joint with a blow lamp or welding torch. The last one of these that I did, (Mk1 GT6 circa 1978) I was able to use mole grips to turn the stud and it came out intact. Before replacing it with a new stud, I used a smaller diameter bolt (not a set screw) to hold the exhaust in place together with the two remaining good studs. Link to comment Share on other sites More sharing options...
NonMember Posted August 16, 2021 Report Share Posted August 16, 2021 Even if the stud does snap off, and you can't drill it out accurately enough to re-tap for a new stud, the smaller diameter bolt and nut option has worked on my Vitesse for many years. Link to comment Share on other sites More sharing options...
Andy Moss Posted August 16, 2021 Report Share Posted August 16, 2021 All good options above. Id get a nut and push that down to the bottom of the stud. Weld the nut to the stud (thereby putting lots of heat into the stud and manifold thread). Then lots of penetrating oil and maybe heat from blow lamp to free the stud. If starts to move turn it and back it off then repeat. If it comes out, tidy thread and find use similar threaded set screw cut to length to replace. If it shears off, repeat the above with another nut, or drill out. Must use centre punch first. I just shape an old drill bit into a centre punch (don’t buy one). Then drill small. If drill bits are rubbish - sharpen them on bench grinder (see YouTube). Could try an easy out (left hand thread) to wind it out, but have a tendency to snap. I’d drill to size of the appropriate tap and remake the thread. If too eccentric in drilling to hold stud, put a blob of weld on the top. Avoid this happening again by applying copper ease to stud thread. Hope that adds to the above responses in some way. Cheers. PS: if you have a spot blast gun, cleaning up what you can see of the thread with one of these things can be really helpful to free awkward studs. Works a treat on break calliper bleed nipples. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 17, 2021 Report Share Posted August 17, 2021 the simple alternative it to drill down from the top as the holes do go right through the flange and use a std bolt and brass nut to replace the failed stud Pete Link to comment Share on other sites More sharing options...
Kev Posted August 17, 2021 Author Report Share Posted August 17, 2021 Thanks everyone for your comments. Really appreciated. I purchased a good quality stud remover tool to try first before attempting to drill. The bugger is not budging... Could the stud be a left handed thread perhaps?? I am trying to turn the stud clockwise from above with the carb off the manifold. (which will be anti clockwise from below). Link to comment Share on other sites More sharing options...
Clive Posted August 18, 2021 Report Share Posted August 18, 2021 8 hours ago, Kev said: Thanks everyone for your comments. Really appreciated. I purchased a good quality stud remover tool to try first before attempting to drill. The bugger is not budging... Could the stud be a left handed thread perhaps?? I am trying to turn the stud clockwise from above with the carb off the manifold. (which will be anti clockwise from below). No, they are a normal thread. But 50 years of heat cycles, corrosion etc causes them to seize. You may have some luck if you can get it hot. Really hot. Sometimes welding a nut on the remains of the stud will do it, but not always. A blowtorch with MAPP gas might. Oxyacetylene will almost certainly do it. Plan B involves removing the manifold, and drilling the stud out, nice and centrally and then cleaning the thread up and fitting a new stud. Or as I have done in the past, drill out and use a nut/bolt. A replacement manifold will probably have similar issues unless it has been re-studded. Link to comment Share on other sites More sharing options...
Kev Posted August 19, 2021 Author Report Share Posted August 19, 2021 Hi everyone. I think we have success!! I had to drill the stud out in the end and went for a nut and bolt to clamp together. Really appreciate everyone that helped me! Regards Kev Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 19, 2021 Report Share Posted August 19, 2021 i would get a brass nut or heat and corrosion will seize the new one quite quickly and then your into cutting it off next time brass nuts cant seize might go a bit stiff but always removeable just a thought Pete Link to comment Share on other sites More sharing options...
NonMember Posted August 19, 2021 Report Share Posted August 19, 2021 As Pete says - brass nuts! I notice you have a nyloc on one of the studs that's still there. Factory fit was a brass nut for exactly the reason Pete said. Link to comment Share on other sites More sharing options...
Kev Posted August 19, 2021 Author Report Share Posted August 19, 2021 Roger that. I'll get a brass bolt and nut and will replace the nylocs. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 20, 2021 Report Share Posted August 20, 2021 no steel or gun metal bolt brass nut you need dissimilar metals or youre back to seizure so steel bolt and just brass nut is all that required and a good flat washer Pete Link to comment Share on other sites More sharing options...
PeteH Posted August 20, 2021 Report Share Posted August 20, 2021 Hi Can I just make an observation?. I note the Bolt is entered from the bottom and the nut to the top,? That does not affect the function. However in practice, should the fastener loosen and the nut be lost, the bolt will drop out, the perceived wisdom in all vertical fasteners was to enter the bolt from the top, the nut will likely cause less problems than a bolt if it drops off. The bolt could potentially jamb some other part in a lower situation. As apprentices we would get our wrists soundly slapped!!😭 (usually a "clip round the lughole"). Some of "our" Bolts where 3ft or more long and 3"+ in dia!!. Pedantry (still) rules OK!! Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 20, 2021 Report Share Posted August 20, 2021 Just to add, from recent experience - buy quality items. I bought these from eBay recently, the threads on the brass nuts vanished as if by magic on the first hint of pressure, and the studs were not much better. https://www.ebay.co.uk/itm/372782052999?hash=item56cb8ab687:g:8wIAAOSwQItT2RM5 I ended up going to a fastener company, Spalding Fasteners, and bought much better items. They also sell deeper brass nuts which I also bought and these are very good. https://www.ebay.co.uk/itm/290738985249 Link to comment Share on other sites More sharing options...
PeteH Posted August 20, 2021 Report Share Posted August 20, 2021 "Brass" per-se, is probably too soft for the particular job. I would suggest that P-B (phosphor bronze) would be a more suitable material?. Pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 20, 2021 Report Share Posted August 20, 2021 well on trucks Commer /Dodge all chassis bolts went nut inside with the coming of Renault they have all nuts outside ...easier for tooling but looks tacky and you could see it it was missing Link to comment Share on other sites More sharing options...
Kev Posted August 20, 2021 Author Report Share Posted August 20, 2021 2 hours ago, Colin Lindsay said: Just to add, from recent experience - buy quality items. I bought these from eBay recently, the threads on the brass nuts vanished as if by magic on the first hint of pressure, and the studs were not much better. https://www.ebay.co.uk/itm/372782052999?hash=item56cb8ab687:g:8wIAAOSwQItT2RM5 I ended up going to a fastener company, Spalding Fasteners, and bought much better items. They also sell deeper brass nuts which I also bought and these are very good. https://www.ebay.co.uk/itm/290738985249 Thanks Colin. Ordered from Spalding Fasteners. Thank you for the tip Link to comment Share on other sites More sharing options...
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