Tonk Posted September 20, 2005 Author Share Posted September 20, 2005 good point, maybe i should use a 90? Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 20, 2005 Author Share Posted September 20, 2005 02, as a temp fix i will fit a bar down the inside and weld it there, also a guide from the diff to stop it bending too far when it gets hit. long term i'm still thinkin Quote Link to comment Share on other sites More sharing options...
John_T Posted September 20, 2005 Share Posted September 20, 2005 I have Sumo Bars and seem to remember when I fiited them that they are tubes. However, they are tough as old boots. IMHO the advantage of Sumo Bars over Dan Bars is that the former do away with the time honoured problem of TREs siezing in the track rod and making tracking adjustment a nightmare. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted September 20, 2005 Share Posted September 20, 2005 One of the best ways of strengthening your track rod is to provide some restraint at midpoint to effectively halve the length over which it is bent (not precisely true for the pedants out there, but you get the idea!! ) The QT diff guard does just that and when coupled with a Sumo bar or similar provides a pretty robust solution. As stated before, solid bar is stronger than tube for the same OD and I would advocate sticking to a circular cross section to maintain strength in all directions - don't forget the track rod can take some pretty large axial loads in compression so an asymetric section will leave you open to buckling about the minor axes. Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted September 20, 2005 Share Posted September 20, 2005 That sounds like a great plan. If you want a fatter bar, but the diff gets in the way, I suppose you have 3 options to shoe-horn that extra-big track rod in: 1. Make custom steering arms (longer than standard) to space it away from the diff (adjust steering stops to suit of course) - you could raise the track bar at the same time if you did this. 2. 'Shave' the diff housing if there is some spare room inside? 3. Bend up a rod with clearance for the diff housing. I like the sound of this combined diff shield / track bar support. Al. Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 20, 2005 Author Share Posted September 20, 2005 I like the sound of this combined diff shield / track bar support. thats easy, qt style diff guards and bolt summat to the front of it, well thats wot i'm planning Quote Link to comment Share on other sites More sharing options...
02GF74 Posted September 20, 2005 Share Posted September 20, 2005 I like the sound of this combined diff shield / track bar support. thats easy, qt style diff guards and bolt summat to the front of it, well thats wot i'm planning is it that easy? Doesn't the track rod move to and fro from the diff as the wheels are turned? you obviously have a cunning plan...... Quote Link to comment Share on other sites More sharing options...
MogLite Posted September 20, 2005 Share Posted September 20, 2005 I like the sound of this combined diff shield / track bar support. thats easy, qt style diff guards and bolt summat to the front of it, well thats wot i'm planning My Camel Disco had a piece of U-shaped steel bolted to the diff. This allowed the track rod to move forwards/backwards as the wheels turned, but only let it deflect a little before the track rod protector caught it. There was a big thread on Pirate a while back on tube vs solid strength, and tube won. I think its to do with surface area on the outside and on the inside. Obviously the tube has to be of a reasonable wall thickness for this to hold true. With MogLite - reasonable is 7.5mm Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 20, 2005 Author Share Posted September 20, 2005 I like the sound of this combined diff shield / track bar support. thats easy, qt style diff guards and bolt summat to the front of it, well thats wot i'm planning is it that easy? Doesn't the track rod move to and fro from the diff as the wheels are turned? you obviously have a cunning plan...... the rod moves towards and away from diff front when steering, i wouldn't create a guide for it to run in, more of a fence that will stop it when deflected Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 20, 2005 Author Share Posted September 20, 2005 hmmm, fence not a very good word, tube/box section Quote Link to comment Share on other sites More sharing options...
Hillbilly Raider Posted September 20, 2005 Share Posted September 20, 2005 Tonk said "maybe i could use a 90?" yeh any 90 except mine!! Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 20, 2005 Author Share Posted September 20, 2005 u'd hand the keys over, dont u trust me? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted September 20, 2005 Share Posted September 20, 2005 Right. Andy - sorry mate, but that's just not correct. I guess you mean this thread: http://www.pirate4x4.com/forum/showthread....+solid+strength The reason people get confused is that as a tubes wall thickness increases, it's strength APPROACHES that of a solid bar, but it never actually reaches the same value until the wall thickness = the radius (i.e. it becomes a solid bar!). there's nothing in that thread about surface area which doesn't get straightened out in the end. Too many people talking carp though... So as I said originally, FOR A GIVEN WEIGHT a tube will be stronger, as its mass is further from the axis - this just makes it more EFFICIENT, not STRONGER. The strength of a tube is asymptotic to the value of the solid bar of the same outside diameter (I'm talking similar materials here). So yes, you can reduce mass without affecting strength too much, but not completely. Take away material, you will always reduce the strength. The equations for tube strength effectively boil down to the strength of a solid bar of the same outside diamtere MINUS the strength of the bar that would fit exactly into the tubular hole down the centre. Since you are always subtracting the strength of this missing part in the centre, it will NEVER be as strong as the equivalent solid bar. There is NO surface area factor in the equations - if there were you'd get all sorts of grooved bars and splined shafts being sold to increase this factor. It's simply not important. The stress experienced by the material is dependent on the loading and the geometry. A tube will always see higher stresses for a given loading than a solid bar. If there is still confusion on this, I can wheel out the equations, my anorak, the slide projector and an industrial size jar of anti-depressants. Tonk - some ideas? : http://bulletproofsteering.com/tubingspecs.html Hope that helps. Again: if you just want strength, use bar. End of story. If you are worried about the weight, use the largest diameter tube you can with the thickest wall you can afford (weightwise). Al. Quote Link to comment Share on other sites More sharing options...
LR90 Posted September 20, 2005 Share Posted September 20, 2005 Square bar has the advantage it's easier to straighten and the profile means you can get a lerger xsection (more strength) before it fouls the diff. Quote Link to comment Share on other sites More sharing options...
steve_a Posted September 20, 2005 Share Posted September 20, 2005 My 90 already has a bracket that bolts into the diff which stops too much flex in the track rod. I bent all the previous rods while that wasn't fitted. I didn't bend my already slightly bent rod at Bunny lane this weekend, so I am thinking that the bracket helps a lot. AFAIK the protector is a standard item, I'd look on the EPC but I'm lazy BTW glad to see it's not just me who is tight Quote Link to comment Share on other sites More sharing options...
Tonk Posted September 21, 2005 Author Share Posted September 21, 2005 cant buy them for series Quote Link to comment Share on other sites More sharing options...
reads90 Posted September 21, 2005 Share Posted September 21, 2005 cant buy them for series What you need to do it find a welder and fabricator and get some made i can give you a number of someone i know Quote Link to comment Share on other sites More sharing options...
02GF74 Posted September 21, 2005 Share Posted September 21, 2005 So as I said originally, FOR A GIVEN WEIGHT a tube will be stronger, as its mass is further from the axis - this just makes it more EFFICIENT, not STRONGER. The strength of a tube is asymptotic to the value of the solid bar of the same outside diameter (I'm talking similar materials here). So yes, you can reduce mass without affecting strength too much, but not completely. Take away material, you will always reduce the strength. What is it that determines the wall thickness/diameter for the best strength for the same weight? Starting with a solid bar, as you increase diameter, wall thickness reduces, and the now tube becomes stronger but if you continue doing it, you end up with tin foil thick tubes of very large diameter that aren't strong at all . Somewhere in between the 2 extremes is the optimum - what determines that? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted September 21, 2005 Share Posted September 21, 2005 Good question 02-whatsit! I was wondering the same thing as I wrote it. I will see if I can knock up a plot later on. Strongest in what though - bending, torsion, compression...? I guess bending for now. Watch this space. Al. Quote Link to comment Share on other sites More sharing options...
02GF74 Posted September 21, 2005 Share Posted September 21, 2005 I was thinking of bicycles tubes so I guess compression, tension and the other ones. My bianchi down tube feels so thin that a good squeeze by hand would bend it, still manages to support me ok! Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted September 21, 2005 Share Posted September 21, 2005 Well, thats it really - you're gonna get to the point where increasing the diameter (and therefore reducing the wall thickness as we are discussing a given mass) will mean it has virtually no impact resistance - it'll just crumple with a light tap. Obviously no good! I'll try to put something together with some nice colourful lines, but it's a bit hectic here at the mo... Al. Quote Link to comment Share on other sites More sharing options...
jules Posted September 21, 2005 Share Posted September 21, 2005 Tonk Sumo bars are stronger than Dan bars as I bent mine and upgraded to the sumo bars If you phone Dave marsh he may tell you what grade they are or you may be able to undercut is exiting supplier Julian Quote Link to comment Share on other sites More sharing options...
Renny Posted September 21, 2005 Share Posted September 21, 2005 If you phone Dave marsh he may tell you what grade they are or you may be able to undercut is exiting supplier Julian Sumo Bars are manufactured by Ian Sykes (of Scottish Hillrally fame). He has the rights to that name and supplies them to the links of Dave Marsh, Simmonites, Tomcat etc. You may get a better price by going to him direct, but I doubt it as they big resellers probably get a discount on their orders. One of the biggest problems of a DIY "Sumo" type bar is the tap for the left hand thread needed for one end of the bar and the locknut. Quote Link to comment Share on other sites More sharing options...
02GF74 Posted September 21, 2005 Share Posted September 21, 2005 One of the biggest problems of a DIY "Sumo" type bar is the tap for the left hand thread needed for one end of the bar and the locknut. hmmm, left hand tap - there was dicsussion about this on the old LRE - can't remember details but about £60 perhaps? I did a rough calculation on the thread pitch and reckoned that with a right hand thread at both ends, you could still be within the LR spec. for the tracking. If you wanted to get closer, then buy some more tre's; the chances are they are not threaded equally so will allow for finer tuning. Quote Link to comment Share on other sites More sharing options...
darthdicky Posted September 23, 2005 Share Posted September 23, 2005 This is all I've got on mine and touch wood I haven't bent any steering rods yet... It gives some protection and stops it bending too far if you do hit something. Richard Quote Link to comment Share on other sites More sharing options...
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