Russell_ds80 Posted August 9, 2011 Share Posted August 9, 2011 Hi all. Quick question. I need some bolts for my nato hitch just not sure best place to get them! Is my local bolt suppliers the best option or can i order some from someone?? Cheers Russell Quote Link to comment Share on other sites More sharing options...
landy V8 Posted August 9, 2011 Share Posted August 9, 2011 local bolt supplier.unless you want to pay for "special bolts" from someone who will rip you off by telling you they are made especially for the job,"BUL****T" springs to mind. they'll only be M10 or M12 with nyloc's. you could also make a spreader plate to mount on the inside of the crossmember to stop the bolts maybe pulling through. Quote Link to comment Share on other sites More sharing options...
western Posted August 9, 2011 Share Posted August 9, 2011 And MUST be high tensile of 8.8 rating or higher, nothing else will be safe. Quote Link to comment Share on other sites More sharing options...
Night Train Posted August 9, 2011 Share Posted August 9, 2011 I do sometimes get my 'odd' bolts from Ebay. Not always the cheapest but I can get 1 or 2 and not a box of 50. You could use M12 x 1.5 cap screws/bolts as they are 12.9 strength. Quote Link to comment Share on other sites More sharing options...
Tazz070299 Posted August 10, 2011 Share Posted August 10, 2011 And MUST be high tensile of 8.8 rating or higher, nothing else will be safe. Or A4 if going down the stainless route. I got some of my bolts from Screwfix, and the rest from Boltit.co.uk. Tazz Quote Link to comment Share on other sites More sharing options...
q-rover Posted August 10, 2011 Share Posted August 10, 2011 A4 is the material class, you also need to add the property class. A4-80 Quote Link to comment Share on other sites More sharing options...
simonr Posted August 10, 2011 Share Posted August 10, 2011 You could use M12 x 1.5 cap screws/bolts as they are 12.9 strength. You have to remember that although 12.9 have a higher tensile strength, it comes at the cost of being more brittle. 8.8 are a good compromise of strength, elasticity and resistance to fatigue. I've had situations where 12.9 bolts have snapped where 8.8 have held on, particularly when high shock loadings are applied. Si Quote Link to comment Share on other sites More sharing options...
Russell_ds80 Posted August 10, 2011 Author Share Posted August 10, 2011 Thanks for the help all. I went to my local bolt place today. Got some 8.8 M12 bolts with nuts for a couple of quid. going to go make a spreader plate and get it fitted. Cheers Russell Quote Link to comment Share on other sites More sharing options...
bishbosh Posted August 10, 2011 Share Posted August 10, 2011 You have to remember that although 12.9 have a higher tensile strength, it comes at the cost of being more brittle. 8.8 are a good compromise of strength, elasticity and resistance to fatigue. I've had situations where 12.9 bolts have snapped where 8.8 have held on, particularly when high shock loadings are applied. Si Hooray! At last a statement from a position of knowledge! Thank you Si!!! The number of times I have tried to get that point across only to be shouted down in favour of 12.9's by the "bigger is better" brigade. For a mostly tensile application like this 8.8 ( or perhaps 10.9 maybe..) is a much more appropriate choice. Quote Link to comment Share on other sites More sharing options...
Night Train Posted August 10, 2011 Share Posted August 10, 2011 You have to remember that although 12.9 have a higher tensile strength, it comes at the cost of being more brittle. 8.8 are a good compromise of strength, elasticity and resistance to fatigue. I've had situations where 12.9 bolts have snapped where 8.8 have held on, particularly when high shock loadings are applied. Si I never knew that. Cheers, I'm going to re-spec some of the fasteners on my trike project. What's the strength comparison with stainless A2, A4 and 8.8 steel bolts of the same size? I can't find any comparison data. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted August 10, 2011 Share Posted August 10, 2011 That's something I've known for years and I'm only 20 . Always amazed by the number of people who assume 12.9 is always stronger than an 8.8 in every situation. Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted August 11, 2011 Share Posted August 11, 2011 For those who come to this thread looking for the answer to "where to get bolts", I have always found that Namrick have a good range and quick delivery. Sometimes a bit expensive though... In terms of strength I don't know of any direct comparison between various grades of stainless and traditional HT bolts, but for an individual application it wouldn't be hard to get the information together (understanding it is another matter!). But I have always shied away from SS in 'heavy duty' situations, preferring as a general rule, to use 8.8 assembled with waterproof grease*. I would only use the stronger grades if some official source (LR Manual, the accessory manufacturer etc) required it (Or if some particular people who post here said it's a good idea... ) Roger * Waterproof grease (AKA "marine grease") is just that: A reasonable light-duty grease which will prevent corrosion. I was once told many years ago by somebody I trust (well I trust him in engineering terms - the person I'm not that keen on sacked me!) that most normal greases are not waterPROOF and will allow corrosion to occur beneath them, so in certain situations (chassis, running gear, some of the drive-train, body) I tend to use it on assembly rather than my once-time favourite, copper grease which, to be honest - I have never been too impressed with. Quote Link to comment Share on other sites More sharing options...
q-rover Posted August 11, 2011 Share Posted August 11, 2011 Bolts and bolting is an entire engineering subsection in itself, that can take years to understand. Like I said earlier a SS A4 only refers to the material. A4 80 would be equivalent to 8.8 steel strength wise. However you can get stronger SS bolts as well, even titanium if you want. You need to decide what spec you want, there are manufacturers that that can supply them. All depends how deep your willing to put your hand in your pocket. Then there is torquing up a bolt. Do you know the spec of the torque? Not just NM, but wet or dry? If wet which lubricant is specified. If you torque up a dry bolt using wet torque, it will probably snap. Prestretch? And so on, and so on..... Quote Link to comment Share on other sites More sharing options...
UdderlyOffroad Posted August 11, 2011 Share Posted August 11, 2011 I can only echo Q-rover and Si’s sentiments. As a Mechanical Engineer, we spend many hours at work producing calculation sheets for bolt loadings, pre-load, torque, etc to show suitability for the application. I can have a dig around in the standards at lunchtime today for e.g. the tensile strength of 8.8 bolts compared to 10.9, A4-70 and A4-80…but as Si said that’s not the only factor. It’s worth noting though that you won’t get A4-80 bolts from a stainless supplier unless you ask, and even then they will be f-expensive. In fact they’re usually A2-70! Best to stick to 8.8 from your local friendly engineering fastener place (GR Fasteners in Avonmouth in case anyone from Bristol is reading this). 10.9 if it makes you feel better… Quote Link to comment Share on other sites More sharing options...
tweetyduck Posted August 13, 2011 Share Posted August 13, 2011 This is, to be honest, O level engineering. If any one does it any more as GCSE or something else. Theres a difference between "Strength" and "Toughness" and as has been said there are situations where the correct bolt (and nut) has properties of both and situations where only one is desirable. Usually they have attributes of both but various materials which are tough are not strong, plastic for example and cast iron. Just for the ones who want a pretty picture....me included. http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-toughness/NS6Chart.html Quote Link to comment Share on other sites More sharing options...
Tazz070299 Posted August 15, 2011 Share Posted August 15, 2011 A4 is the material class, you also need to add the property class. A4-80 Apologies. In my desire to answer the question, my brain worked quicker than my fingers. Tazz Quote Link to comment Share on other sites More sharing options...
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