JeffR Posted January 24, 2014 Share Posted January 24, 2014 Currently getting the 110 ready for an MOT. Got a quandary, whilst somewhat inebriated I bought some new flange headed screws, unfortunately I accidentally bought stainless A2-70 (M10x25) to replace item 8 on the diag below. Now 8.8 steel screws have a shear strength of about 785nm, whilst A2-70 stainless have a shear strength of 700nm. Will the "missing" 85nm matter? Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 24, 2014 Share Posted January 24, 2014 Seat belt mounts Jeff? Personally I'd go with the 8.8 bolts instead. Wouldn't want any insurance company to start digging around and finding them. Quote Link to comment Share on other sites More sharing options...
JeffR Posted January 24, 2014 Author Share Posted January 24, 2014 gotta stop buying things when I'm half cut..... Quote Link to comment Share on other sites More sharing options...
robertspark Posted January 25, 2014 Share Posted January 25, 2014 M10 bolts! If it's the seatbelt mount / bracket I cant see anyone breaking them under accident conditions (different if it was a suspension component), and I will be VERY surprised if an MOT inspector would ever pick up on it. Come on it's an M10 bolt, and you've got 4 or them (did you change the others too??), that has got to be a fair amount of force to sheer 4 of them The problem with stainless is they are brittle (as I understand it.... nope , no expert). The steel bolts will stretch before giving up, where as stainless tend not to stretch much before shearing. 8.8 bolts have a number of copies about.... (back to the box shifter thread), so may be of questionable actual strength, unless from a traceable source (3rd link at the bottom) 10.9 bolts seem to be a better choice.... given there may be less forgeries (imitation ones) about (although that's not the consensus of some of the links below, just my opinion). 12.9 bolts i've heard / read can be a little tricky... given they rely on deformation when being torqued up in order to lock and provide their strength... in other words if you use a 12.9 bolt with a spring washer... it won't be as strong as a 12.9 bolt + flat washer being torqued up to the right torque in the same hole as the spring washer can affect it's actual bolt holding properties and resistance to release. The message on these 12.9 bolts is.... unless designed to use them, don't put them into holes / fixings that would be expected to use 8.8 or 10.9 bolts, as they will probably work loose (unless you use threadlock compound.... before someone pipe's up about crownwheel replacement bolts, but don' forget a crownwheel + diff is very good steel, and not for instance a caliper mount on an axle). http://www.volksbolts.com/faq/basics.htm http://www.landroverclub.net/Club/HTML/Schrauben1.htm http://donsnotes.com/home_garden/bolts.html http://www.vwjim.co.uk/news_6694_79160.html Quote Link to comment Share on other sites More sharing options...
western Posted January 25, 2014 Share Posted January 25, 2014 some strength info here http://www.westfieldfasteners.co.uk/Ref_Strength_Spec.html Quote Link to comment Share on other sites More sharing options...
JeffR Posted January 25, 2014 Author Share Posted January 25, 2014 Chatting to a mate in a local university and their metallurgy bod was of the impression that the 85nm was of no real consequence, but, it was how the threads were cut that would worry him. Evidently (if I was listening closely) rolled threads are significantly weaker than cut threads. But to be on the safe side, said mate has taken one of the ss ones and one of the genuine ones and they are gonna stress test em.... Don't know when... Also managed to source some traceable normal steel ones. Will use the ss ones to replace non-safety critical screws in other places. For the sake of spending and extra £16 ..... And besides, as the wife says, you can never have too many nut n bolts! Quote Link to comment Share on other sites More sharing options...
robertspark Posted January 25, 2014 Share Posted January 25, 2014 To be honest, A2 bolts are brilliant for doing things like seat boxes, panels such as the ones in the footwell etc as they don't rust + look pretty .... and there are loads of them, so the chances of a catastrophic failure is near (99.999999%) zero. But you also need to consider dis-similar metals when Aluminium panels and stainless screws / bolts are in the area (thinking door panels + said SS fixings here). ... galvanic action on a defender is bad enough without adding SS to the mix too. But would not use them to hold an axle or caliper etc on where there is only one or two bolts in play and the forces are likely to be high. Quote Link to comment Share on other sites More sharing options...
JeffR Posted January 25, 2014 Author Share Posted January 25, 2014 To be honest, A2 bolts are brilliant for doing things like seat boxes, panels such as the ones in the footwell etc as they don't rust + look pretty .... and there are loads of them, so the chances of a catastrophic failure is near (99.999999%) zero. But you also need to consider dis-similar metals when Aluminium panels and stainless screws / bolts are in the area (thinking door panels + said SS fixings here). ... galvanic action on a defender is bad enough without adding SS to the mix too. But would not use them to hold an axle or caliper etc on where there is only one or two bolts in play and the forces are likely to be high. I have a vast collection of assorted nylon/plastic washers for just such a use! Another useless tip is to use a bit of silicone tubing (aquarium stuff is cheap enough) to cover the threads of ss screws/bolts where they go thro Al panels, stops the ss touching the Al so no electrolytic corrosion where you can't see it. Works with mild steel thro Al too. Quote Link to comment Share on other sites More sharing options...
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