Tony Posted September 8, 2009 Report Share Posted September 8, 2009 I've been beating myself up about this for a long time.... Most if not all roll bars are floating so how the hell would adjusting the length of the drop-link change the torsional load? Fact is it does and this is why. Between the bars anchor points and the drop-link there's a bend of around 90 degrees and a length of bar that meets the drop-link. If you try to twist the bar by holding each end you would feel the torsional load. If you now move the drop-links and anchor them further down the bar and try to twist again it would take more force. The fact the bar is floating is beside the point, it's the position of the drop-link along the length of the attachment point that determines how much force is resisted. Quote Link to comment Share on other sites More sharing options...
CIH Posted September 8, 2009 Report Share Posted September 8, 2009 A lad on the US S12 site is attempting to manufacture a replacement rollbar that does away with the bends. Quote Link to comment Share on other sites More sharing options...
Tony Posted September 8, 2009 Author Report Share Posted September 8, 2009 Rear live beams on the Peugeot 206/7 already have that. Quote Link to comment Share on other sites More sharing options...
Mat Posted September 8, 2009 Report Share Posted September 8, 2009 adjustable means as in the rate of torsional twist. take for example some rear anti roll bars have several holes where the drop link can be mounted, the closer to the bar stiffens the torsional effort, and further away reduces it Quote Link to comment Share on other sites More sharing options...
Tony Posted September 8, 2009 Author Report Share Posted September 8, 2009 My point exactly... for a while now i've been poised with the fact the ARB is floating so i couldn't get my head around the tuning aspect. Quote Link to comment Share on other sites More sharing options...
Mat Posted September 8, 2009 Report Share Posted September 8, 2009 its not floating though is it. its fixed to the chassis, and each moving side of the suspension, the adjustability is the ability to increase or decrease the bars resistance to twisting, its torsional resistance Quote Link to comment Share on other sites More sharing options...
Tony Posted September 8, 2009 Author Report Share Posted September 8, 2009 Vertically floating during bump (both wheels) is a factor all bars have and that's the area i didn't understand when it comes to "tuning" the bars. Independent bump adds load and that's how the bars work but this still didn't explain the tuning. Moving the connecting point on the bars you displayed highlights how the torsional load can be tuned. I wonder what increment this would be though? Quote Link to comment Share on other sites More sharing options...
Mat Posted September 8, 2009 Report Share Posted September 8, 2009 bump on both wheels at the same time, ....i see what your saying, but under equal 0 load, there is nothing acting upon the bar, other than to move it in its static mount on the chassis, therefore..... there is no requirement for the roll bar to act, its function is to reduce body roll only, which of course you know hence why its is static on the chassis, but linked to each suspension the adjustment is determined by the manufacture of the bars....you would hope with some degree of testing some are set so it is +% of stiffness on each setting, or as with some bars, a -% std setting and a +% setting. tas stated the amount, is determined by the manufacturer of the bars for example the settings for some of the multi setting bars on the is200/300 are as follows Hotchkis 32mm Front Hollow 2 way adjustable +56%, +61% 19mm Rear Hollow 2 way adjustable +144%, +227% Largus Front 35.1mm - 140% Stiffer Rear 27.5mm - 220% Stiffer the Do-LUCK and TTE bars are 3 setting adjustable but dont have my paperwork to hand to say what the settings are the plus settings are % over the standard resistance OEM bars Quote Link to comment Share on other sites More sharing options...
Rich Posted September 8, 2009 Report Share Posted September 8, 2009 Interesting...what end of the car, front or rear, would benefit from an ARB like mat posted if you were only going to make one of them adjustable? Or is that opening a can of worms! Quote Link to comment Share on other sites More sharing options...
Mat Posted September 8, 2009 Report Share Posted September 8, 2009 the rear would benefit more from an adjustable bar, and generally, manufacturers if offering adjustable bars, offer them only for the rear. only a few offer adjustable fronts as well which bar you use and in which application, to either increase or decrease under, or oversteer, depends on many factors. some of which include is the car front/rear wheel drive and most importantly, what is the car used for!! Quote Link to comment Share on other sites More sharing options...
Tony Posted September 8, 2009 Author Report Share Posted September 8, 2009 Personally i would only be interested in tuning the front bars.... In a few cases like the 5 i would remove the rear bar and throw it away. Quote Link to comment Share on other sites More sharing options...
Mat Posted September 9, 2009 Report Share Posted September 9, 2009 Personally i would only be interested in tuning the front bars.... In a few cases like the 5 i would remove the rear bar and throw it away. really... quite the opposite id say, on a rear wheel drive car you need to give the rear some control, by removing the rear completely and relying on the front only, you would increase understeer. a soft or OEM front bar, and harder than OEM rear will increase oversteer, you need to find the balance hence the use of the bars correct for the application. for example, on my original blue car, due to the lack of outright power, i removed the front bar, and fitted a 215% rear bar, this gave me the controlled oversteer i needed on the white car, i had to increase the front bar, but decrease the rear bar, as it had a natural tendency to oversteer, i had to dial back in some control Quote Link to comment Share on other sites More sharing options...
Tony Posted September 9, 2009 Author Report Share Posted September 9, 2009 Thing is i'm talking track and your talking Drift, plus there's quite a difference in the weight distribution between the makes. Quote Link to comment Share on other sites More sharing options...
Mat Posted September 9, 2009 Report Share Posted September 9, 2009 i was using the car as an example of the same chassis two different power outputs, therefore 2 different settings with ARB's the same argument i stick to for track cars Quote Link to comment Share on other sites More sharing options...
Tony Posted September 9, 2009 Author Report Share Posted September 9, 2009 Have you seen the thickness of the rear ARB on a 5..... It's like welding wire. Quote Link to comment Share on other sites More sharing options...
CIH Posted September 28, 2009 Report Share Posted September 28, 2009 how does changing ARBs effect the under/over steer balance ? Does it impact upon dynamic camber gains ? Quote Link to comment Share on other sites More sharing options...
Tony Posted September 28, 2009 Author Report Share Posted September 28, 2009 Very much so, it's the front/ rear gains and transition of weight that allows the ARB to be used as a tuning tool. Quote Link to comment Share on other sites More sharing options...
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