Did a search on here and found many examples of exhaust studs snapping but no suggestions for replacement studs manufactured of something other than low grade stainless steel. The horizontal cylinder exhaust studs probably experience the most extreme environment being in the direct line of fire of all the crap and water thrown up by the front tyre so whatever material you do use has to cope with sudden changes of temperature as well as being corrosion resistant and have a coefficient of expansion compatible with the alloy head. Any suggestions ? TIA, Andy
A stripped thread is a lot easier to deal with than a snapped stud. Might even decide to do a thread insert instead. Andy
any turbocharger studs will be a vast improvement if you can find them with correct thread and similar dimensions.
agree, stainless usually plenty good enough. Probably a bit of an eyesore on Panigale etc but often choose a st/st longer stud and then a double height brass nut.
Best option, if you could find them would be Inconel 718, these are what they use in F1 cars and most thing that get very hot.
Inconel to brittle for road use,excellent for racing where fasteners are replaced as a matter of course. Mild steel that is Berrylium coated would be perfect if it wasn't for the fact that that process is banned now.
Cadmium plating would work to but i think the only people who use this is the Aviation industry where metric is still not widely used.
I would use stainless studs A4 marine grade with stainless dome nuts with a stainless spring washer, all threads in the head and inside the dome copiously lubricated with copaslip, but not so much that you hydraulic lock the dome nut. You will need to shorten the studs a bit so the dome nut does not bottom out before clamping the spring washer and the header to the head. You might lose the odd one (dropping off/out) but in my view this is better than having the nightmare of sheared studs and/ or completely rounded and corroded nuts
^^^^ the cut end is then not plated so if it goes into the head it seizes with galvanic action which encroaches upon the whole length of the thread in the head and buggers the thread if/when you try to get it out - or if it is "to the atmosphere" it corrodes so welding itself to the exhaust clamp nut or not permitting it to pass the end of the thread. Also repeated (daily) extreme heat and quenching with cold (salty) water does not mean it will be high tensile when you come to undo it. High tensile steel is not corrosion resistant, better in my view to start with something that resists the cruddy environment and make other provision for making sure they stay where they are supposed to (stainless spring washers).
Used ARP fasteners for other things. Presently making a set of stainless nuts for the heads on my monster from stainless bolts with a 14mm flanged bi hex head as per original but without the crap plating. Basically cut head off and tap. Not cheap for the bolts though. Anyway they do stainless exhaust studs with nuts. They have a very extensive catalogue. https://arpcatalog.com/76/
