Cynic-al Posted May 7, 2015 Author Share Posted May 7, 2015 Went underneath to see where the transfer box was leaking from and found this. Your all a bunch of know it all! ! Box has snapped through. Going to bodge it for now with a plate wirher side and make new from scratch. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 7, 2015 Share Posted May 7, 2015 Ooops Did you not feel that in the driving? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 7, 2015 Author Share Posted May 7, 2015 Not with my ability I only use it offroad so I guess I must have just ignored any signs as being rough ground. There is a line of weld along the bottom so maybe that's made it weaker? Either that or that bracing underneath is putting all the torsion onto that point. There was one bit where I was stuck in some slop and slamming it from forwards to reverse to see if the axles would break. Maybe that was it? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 7, 2015 Share Posted May 7, 2015 It's a definite stress concentration, if it were curved it would be much better. So... how you are going to make the next ones? Cut from solid flat plate? Looks like your brake line had a lucky escape too! Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 7, 2015 Author Share Posted May 7, 2015 There are 2 airlines and a 2 core wire cable tied to the other side. Think that's what held it together Going to weld this one and brace both sides to buy me time then design something to have laser cut. Don't think I could bend tube to the radius needed. Atleast with laser cut I could do a w shape where it goes over the steering arm if required. Glad I traced it onto card now Quote Link to comment Share on other sites More sharing options...
Anderzander Posted May 7, 2015 Share Posted May 7, 2015 No wonder you were getting a lot of flex from the front :-) Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 7, 2015 Author Share Posted May 7, 2015 Super flexy bushes Quote Link to comment Share on other sites More sharing options...
aniesigh Posted May 7, 2015 Share Posted May 7, 2015 Slightly OT, but did you already have the plugs to connect into the Difflock switch (the one that tells you when its engaged) or did you buy them somewhere? Would like to wire mine up so i know when they've engaged/disengaged If you did buy them, where from? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 8, 2015 Author Share Posted May 8, 2015 I soldered a short flying lead to the switch and used some 2 pin waterproof connectors I already had. I did get the axle wiring loom with the axles so I could've cut the standard plug off and used that but I felt it was a little wasteful as it has all the motor wiring on it too (I'm odd like that!) so gave the full looms to someone who might make use of them. I guess you must be able to buy new plugs but I wouldn't like to say where from? I've been told the switch is the same as a reverse switch off one of the toyota cars but I can't remember off the top of my head which one, however that switch is supposed to be cheaper and maybe the plugs would be easier to track down? Quote Link to comment Share on other sites More sharing options...
aniesigh Posted May 8, 2015 Share Posted May 8, 2015 hmm, i might just do the same, saves time trying to track down plugs which i can imagine could be a nightmare! cheers Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 8, 2015 Author Share Posted May 8, 2015 Had a first stab at copying my card template onto solidworks then took a bit of a stab in the dark guess at the torque it might see. The design below has a pretty high safety factor but weighs 10.6kg. I want to have a stab in the dark guess at what force it will see if you drive into a rock face and try cut a bit of weight but first I want to print it 1:1 and check the geometry is ok. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 8, 2015 Share Posted May 8, 2015 I'm not sure you need the deeper part of the arm where the red arrow is, I guess this is to clear the track rod, but by going out deeper behind it, you are not going to make it stronger in my eyes, as the weakest point is forward of this, at the necked part, and this is also where force is greatest. I think you may be better off just radiusing the curve over the trackrod, and then use that thickness back, the rest of the arm does not need to be so strong as the force will decrease as you go to the rear. You can 'speed hole' it to reduce weight Other option, which may cost a little clearance, is maybe go under the bar? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 9, 2015 Author Share Posted May 9, 2015 Good point regarding the step down. That's what I traced off the MK1 and didn't think to change it, I just went thicker above the steering bar cut out as this was the point that failed. I looked into going under the steering bar on the MK1 as I figured it would protect it and you could go closer as if you go over the top you have to leave clearance to get the track rod end out, however, I found that during steering the bar goes down which gives you the clearance to get the track rod end out and means that actually you have to go really low to go under the steering bar :/ Once I've been able to print it and check the position of all the holes I will do a bit of iteration to see how light I can get it without risking breaking it... hopefully... It has to have speed holes to make it look hardcore Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 11, 2015 Author Share Posted May 11, 2015 Did a bit of cad, looks ok, do the radius arms stay on the outside of the chassis when it flexes? Wondering if they will miss the chassis if I go higher? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 13, 2015 Author Share Posted May 13, 2015 So the final design, 8.3kg each, gues it'll have to do, guess I could go thinner, that's 20mm, but I'm worried if its too thin it'll buckle if I drive into something. Guess I could estimate it based on the car hitting something at 20mph or whatever? Or go thinner but weld a web around the edge to make it an I section... but that's more work looks like I will need to get a good weld at the front Lets see what price the laser cutter comes up with? Anyone see any obvious errors? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 13, 2015 Share Posted May 13, 2015 I'm no expert but the first speed hole nearest the axle looks a bit close to the last point of failure. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 13, 2015 Author Share Posted May 13, 2015 Initially I didn't have that but it didn't seem to make a great difference to the predictions in CAD and the QT ones seem to have holes all the way around so I went for weight saving, it might pay to lose it to be on the safe side, especially with the QT ones being straighter? Quote Link to comment Share on other sites More sharing options...
elbekko Posted May 13, 2015 Share Posted May 13, 2015 Shouldn't you also be checking twisting forces? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 13, 2015 Author Share Posted May 13, 2015 I don't know, I thought about it but then i figured it's relatively free to rotate at the chassis end as it can twist in the bush? As I see it theres; -The side to side movement which is relatively controlled by the panhard so that shouldn't be a problem. -The torsion on the axle from acceleration / braking etc is the test above. - The driving into a wall which is a buckling issue but I haven't done the test yet but figured work on the energy of a 2 tonne car hitting something at maybe 20mph? - The up / down is taken by the spring so its just a case of will the stud through the bush bend / break off the laser cut bit, but it has to fit through the standard bushes so I'm a little restricted there. - Maybe some funky stress as the axle cycles up and down and twists about that I was going to rely on the bushes to deal with - The fatigue, especially on the welds, which to be honest I wasn't going to concern myself with as it's not easy to predict especially with my welding What else? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 13, 2015 Share Posted May 13, 2015 Gwyn Lewis used to have a picture of a truck up on a barrel with one front wheel, the twist in the front arm was quite noticeable, so yes you will need to allow for this in your design. For the stud end, I would be tempted to get it drilled out to size, that way you rely on the weld strength much less. I forget the size of the stud at this point, but probably around the same as your planned 20mm arm. Have you considered making them out of flat plate, like the QT arms? You would find it easier to weld, especially DIY, and you could cut them out with your grinder if you wanted to save on laser cutting costs. Something made from 6mm steel maybe? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 13, 2015 Author Share Posted May 13, 2015 The pin is about an inch diameter so I would struggle to drill down the 20mm as it would be breaking out both sides. Agree it would be better though. I remember that picture... can't find it now Was it twisting along it's length or due to the chassis end bush allowing it to rotate? The stress in the latter will only be due to the resistance to rotation caused by the bush so much lower? I guess the QT one is a thinner centre plate with a flat strip formed and welded around the edge? Would probably be ligher if more work. I'm going to draw it up and see how it compares to the solid one for strength. The price for the above profile in 350N/mm steel is £98+vat ea laser cut or £165+vat ea waterjet so it's worth spending the time to try get it right Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 13, 2015 Share Posted May 13, 2015 Interestingly, QT have done away with the holes shown in the picture you show above: http://www.qtservices.co.uk/parts/range-rover-classic/suspension-range-rover/radius-arms-range-rover-classi/r1010-ultralight-std-narrow-ra_ultralight-standard-castor-rad.html They also have their weight quote on the site -14Kg, for a PAIR, so 7Kg each. TF also don't have the holes that far down the arm: http://www.terrafirma4x4.com/product_detail.php?prod=TF508&grp=74 They weight .8Kg more though... not really much is it Notice where QT reinforce, I guess they have some experience after the failed arms from a few years back... Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted May 13, 2015 Author Share Posted May 13, 2015 That's interesting! Always easier to learn from others mistakes than to make your own! Thanks for the info! Quote Link to comment Share on other sites More sharing options...
Lewis Posted May 13, 2015 Share Posted May 13, 2015 Does anyone have the weight of a factory radius arm? I'm interested how all the figures compare Quote Link to comment Share on other sites More sharing options...
Daan Posted May 13, 2015 Share Posted May 13, 2015 So the final design, 8.3kg each, gues it'll have to do, guess I could go thinner, that's 20mm, but I'm worried if its too thin it'll buckle if I drive into something. Guess I could estimate it based on the car hitting something at 20mph or whatever? Or go thinner but weld a web around the edge to make it an I section... but that's more work looks like I will need to get a good weld at the front Lets see what price the laser cutter comes up with? Anyone see any obvious errors? What is the red arrow doing there? is that were you react the forces? it should be at the chassis end. Or am i getting it wrong? I personally would get 2 thinnish, say 5 mm plates cut and create a box section. I would also taper them towards the chassis end, like the landrover ones. at the moment it is clear where it will brake, around the speedhole nearest to the axle. From memory, the old rangerover radius arm is 10kg, the newer defender one is 10.5 kg. Daan Quote Link to comment Share on other sites More sharing options...
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