longlandy Posted July 17, 2011 Share Posted July 17, 2011 What do you lot think of steering bars made of 7075 aluminium, 1.250" dia solid thru ,or will being solid cause problems with arc specs, the reason I ask is the fact that I can get it cheaper than 1.250" cds, Iam also thinking the same for rose jointed rear trailing arms.Any thoughts? Quote Link to comment Share on other sites More sharing options...
Daan Posted July 17, 2011 Share Posted July 17, 2011 This is done in america quite a bit, but I have not seen it in steering. I suppose the pull out force of a balljoint in aluminium threads will be the decider. Another question is, how much weight is saved with solid aluminium vs. steel tube with a given wall thickness. Daan Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted July 17, 2011 Share Posted July 17, 2011 Is this for a road vehicle or a trialer? I suppose for a trialer it's can't do a lot of harm, but I think you will be disappointed by how long they (don't) last - it's not just about the ultimate strength of aluminium, it's also about how it behaves under repeated stress (it breaks sooner or later). If you are thinking of this for a road vehicle then you need your bumps felt. Nick. Quote Link to comment Share on other sites More sharing options...
longlandy Posted July 18, 2011 Author Share Posted July 18, 2011 I may do/get so uts testing done,to confirm calculations and give direct comparisons to oem bars, as for the fear of aluminium, nearly all high end cars have nearly all alloy suspension components and what do you think aircraft are made from, motorcycle frames etc etc. Thanks for replying Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted July 18, 2011 Share Posted July 18, 2011 Well, if you've got the equipment and knowledge to do the job properly then I'd say go for it, but you didn't make that clear in your original post, and if you think you know what you are doing then I do wonder why you bother asking here! Assuming that you will be using standard threaded ball joints, my concern is that I can't see how the threaded joints can be as strong when made in aluminium as they are in steel. I take your point about aircraft and other components but they are designed to make the most of the properties of the materials and compensate for its shortcomings, they are not just copies of steel components made in a different material. Nick. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted July 18, 2011 Share Posted July 18, 2011 I don't see the point. Solid alli bar would probably weigh as much as steel tubing and as above the threads would almost certainly be weaker than in steel. Assuming you would be drilling and tapping the middle of the bar, the fact that most of the rod is solid will be neither here nor there for strength as the weak point will be the bit in the end with the hole drilled in it which will effectively be as strong as a threaded aluminium tube, 'cos that's what it is... It looks from the original post like the object of doing it is to save money, which is not really the same ethos applied to testing aerospace components or suspension on £200k supercars. I'm happy to accept you may know something I don't and the first to admit I'm no metallurgist but on the face of it, it looks like an idea with more negatives than positives? Quote Link to comment Share on other sites More sharing options...
zim Posted July 18, 2011 Share Posted July 18, 2011 They were talking about it a bit recently on pirate : http://www.pirate4x4.com/forum/showthread.php?t=989880 Quote Link to comment Share on other sites More sharing options...
longlandy Posted July 18, 2011 Author Share Posted July 18, 2011 They were talking about it a bit recently on pirate : http://www.pirate4x4.com/forum/showthread.php?t=989880 Thanks zim for that, it confirms my idea of 7075 being the way forward. The reasoning behind my use is the fact is I have it as a stock material so I get a good price(and not 6m of cds to use up) , speed of manufacture ,not having a potential weak point of a welded bung and the main benefit of reducing unsprung weight. My concern with steering bars is the 11/16 thread diameter of rover ball joints, so these would need destructive testing and not simple over engineering to confirm a good safety factor.Bog monster by high end I meant not Ford or French! Why did I post? cos Im pretty certain there are some metallurgists and all round clever people on here! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 18, 2011 Share Posted July 18, 2011 I'm not a metallurgist (before anyone says it, I know nuffink about anyfink ) but there are some valid concerns raised here (not to discount the idea out of hand, anything is possible). I think the main cause for concern is that you're only changing one bit (the bar) and retaining the same size/thread of TRE which is engineered to work when in a steel bar, the characteristics of the same part in ali of a given grade will be very different and the loads are in the "bad" direction (pushing/pulling on the thread rather than like a fastener in shear). I'd also think twice about galvanic corrosion when used on a road vehicle, having the join between ali bar & steel TRE slowly and quietly turn to powder over a period of time could be a bit inconvenient. The Pirate4x4 crowd often live in warm dry places where they don't have to deal with mud & water in the same way that we do over here, hence why they get away with using things like heim joints more often. Yes cars & planes etc. use ali components but they're part of a complete setup that's all been designed to work that way - not beyond the wit of anyone to do but does require a bit of thinking about before jumping in with something safety-critical. Mistakes with material properties have caught out far greater minds in the past with nasty consequences. Quote Link to comment Share on other sites More sharing options...
longlandy Posted July 18, 2011 Author Share Posted July 18, 2011 Valid point about the corrosion, the thread size was always a concern on the rover balljoint though the push pull forces on said thread are nowhere near the forces when torqued up for a shear joint, that said a good locking mechanism is vital to stop movement and the material being almost eroded away by the push pull action. Quote Link to comment Share on other sites More sharing options...
Diff Posted July 18, 2011 Share Posted July 18, 2011 I am in the definately NOT category. There are a number of issues that concern me. My opinion: The material is not as resistant to impact damage as the steel used in Land Rover steering bars and suspension links. This means that the bars will be easier to damage and once damaged they could fail spectacularly. A slight bend or nick could cause a sudden failure when put under load. As stated, the thread form/size/pitch used for the ball joints will not be suitable for aluminium and will therfore be weaker than the original. There is very little advantage to be gained in terms of the amount of unsprung weight saved and its affect on improving the performance of 'standard' Land Rover designed suspension set up. Regards, Diff. Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted July 19, 2011 Share Posted July 19, 2011 Bog monster by high end I meant not Ford or French! Steady on! I used to work in RLD testing for Ford and I can tell you there aren't many brands as well tested, the amount of "high end" cars that collapse under a Ford testing regime is depressingly high. Anyway, not in favour of aluminium parts holding the wheels on, it's not just a matter of ultimate strength of the part but the failure mode of the whole system. Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted July 20, 2011 Share Posted July 20, 2011 Controversially, i think it's good idea for a trialler. I don't think corrosion would be an issue 7075 doesn't oxidise anything like birmabrite. i think the tread form would be unsuitable though, every bolt i can think of in modern ally suspension systems are metric course. An option could be helicioling the thread? or recutting the tread on the tre? I normally make my steering bars out of 30mm od en24t solid bar, and they still bend. so i think ally ones could live a short and painfull life Quote Link to comment Share on other sites More sharing options...
zoltan Posted July 20, 2011 Share Posted July 20, 2011 I don't think corrosion would be an issue 7075 doesn't oxidise anything like birmabrite. The 7 series alloys (7075 especially) are an absolute nightmare for salt corrosion on road vehicles. Given the fit and forget nature of suspension/steering type components I would not use it. Ive seen more than just a few brake calipers made from billet 7075 which have literally crumbled away from road salt corrosion Quote Link to comment Share on other sites More sharing options...
longlandy Posted July 20, 2011 Author Share Posted July 20, 2011 If I can summon the interest to do it I will some static load tests and post the data regarding thread failure. The test rig will be crude, but there again when I finished my degree and went to work for a major car makers design centre I was expecting some really serious stuff, but It was nearly all home made! As for bending I would think designing some shape into the bar instead of just parallel could help matters as the forces are not running down the centre line. Quote Link to comment Share on other sites More sharing options...
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