CIH Posted February 27, 2009 Author Report Share Posted February 27, 2009 After it settled I had gained 1 minute.... Quote Link to comment Share on other sites More sharing options...
Tony Posted February 27, 2009 Report Share Posted February 27, 2009 After it settled I had gained 1 minute.... Â Their pants mate.... In future just assume they will need an EZ cam. Quote Link to comment Share on other sites More sharing options...
CIH Posted February 27, 2009 Author Report Share Posted February 27, 2009 I wasn't surprised but I felt it was worth a go. Â Hey do you fancy covering phunamtic slip and DI ? ie; what dictates the OEM figures ? Quote Link to comment Share on other sites More sharing options...
Tony Posted February 27, 2009 Report Share Posted February 27, 2009 I wasn't surprised but I felt it was worth a go. Hey do you fancy covering phunamtic slip and DI ? ie; what dictates the OEM figures ?  Can you define the topic?..... PS im fine with and DI but not OEM because i'm not a design engineer, historically we deal with their consequence's. Quote Link to comment Share on other sites More sharing options...
CIH Posted February 28, 2009 Author Report Share Posted February 28, 2009 I was wondering how DI and Geometry interact/define one or another ? I assume fixed things such as wheelbase, track etc mean a manufacturer has to taylor the Geo to get the desired behaviour ? Quote Link to comment Share on other sites More sharing options...
Tony Posted February 28, 2009 Report Share Posted February 28, 2009 I was wondering how DI and Geometry interact/define one or another ? I assume fixed things such as wheelbase, track etc mean a manufacturer has to taylor the Geo to get the desired behaviour ? Â You may have missed this> Â "Option one would always be to shed some weight! having a DI soo far above 1.00 can really only be caused by a mis-match in wheelbase to the mass, basically the chassis has far too much yaw inertia for the short wheelbase to influence easily. If we could take just 10% weight out of our demo car we'd have a DI of 1.39, much better! Â Unfortunately to take 10% weight out we'd have to seriously comprimise the car's very comfortable characteristics so for some (most) people this would defeat the object. Â The other option is to simply accecpt that the car will as a result of it's high DI always make poor use of it's rear axle in terms of producing lateral acceleration and then to try to work around it. Â A good example would be the Mitsubishi Lancer Evo-5, it's actually a car with a DI of 1.35 so this would make it pretty vectra/modeo'ish to drive... But Mitsubishi's chassis dynamics team have cunningly swerved this potential marketing disaster by employing an overly pointy geometry and suspension sollution giving the car the ability to change direction light a housefly, then in order for the average joe customer to be able to control and exploit this very odd and naturally quite unbalanced set-up they've been forced to add an active yaw control system in the form of an electronically controlled torque biasing center diff. This solution works so well that not only is the car acceptable to it's intended market it's actually now considered as one of the worlds best handling cars." Quote Link to comment Share on other sites More sharing options...
CIH Posted March 3, 2009 Author Report Share Posted March 3, 2009 Yeah I got that and a couple of old threads before you parted with TDi. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 3, 2009 Report Share Posted March 3, 2009 Yeah I got that and a couple of old threads before you parted with TDi. Â Good, then from this you would understand the DI can be improved but most times it's just the need to know how good the DI is so that you/we have an idea how the chassis performs. Â Our position is to "modify" the chassis in order to tune the characteristics of the DI. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 3, 2009 Author Report Share Posted March 3, 2009 Had a car on today that was a good example. '02 Audi TT with OEM target of -2'30" camber on the rear. That apeared t me to be a huge amount of camber for a modern 4x4 coupe. Presumeably the inherent chassis configuration required a fairly hefty geometry to create an acceptable DI ? Quote Link to comment Share on other sites More sharing options...
Tony Posted March 3, 2009 Report Share Posted March 3, 2009 Tuning the DI.....Look at the Evo10, it has next to no Geometry, -10' camber rear, 0 front, no toe and 3d castor, the chassis is near perfect. Other than toe there's no OEM adjusters so no future corrections are forecasted...... It a DI babe. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 4, 2009 Author Report Share Posted March 4, 2009 I don't suppose there would be much in the way of dynamic gains huh ? Quote Link to comment Share on other sites More sharing options...
Tony Posted March 4, 2009 Report Share Posted March 4, 2009 I don't suppose there would be much in the way of dynamic gains huh ? Â Near perfect dynamic gains more like.... The problem with cars like this is they are hard work to drive, the chassis is crisp and reactive. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 6, 2009 Author Report Share Posted March 6, 2009 Presumeably very little actual travel though ? That 0 front camber seems rather shallow ? Â Hey do you mind if we skip off of DI briefly and go into detail about ARBs ? We haven't discussed them much here. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 6, 2009 Report Share Posted March 6, 2009 Presumeably very little actual travel though ? That 0 front camber seems rather shallow ? Hey do you mind if we skip off of DI briefly and go into detail about ARBs ? We haven't discussed them much here.  Not at all.... Prevalent topic in view of our new links for the Mazda MX5 nc ... Fire away. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 6, 2009 Author Report Share Posted March 6, 2009 Other than combating roll I don't know so much about them TBH. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 7, 2009 Report Share Posted March 7, 2009 Other than combating roll I don't know so much about them TBH.  Some people call it as "Stabilizer bar" or "Sway bar". As its names indicate, anti-roll bar is used to reduce body roll. It is a torsion bar fixed to the body of car and is attached to the lower control arms of both right and left wheels.  Explanation  Deal with body roll due to road irregularities  When both wheels are on the same level, the anti-roll bar does not affect the suspension motion. When one wheel is riding on a hump, the anti-roll bar will be twisted and transfer the force to another wheel to push it down, so the car body will remain balanced. The thicker the bar, the more anti-roll ability it has.  Deal with body roll due to cornering force  Based on the above description, you might be surprised to find out that anti-roll bar can introduce even more roll when the car is subjected to cornering force. Nevertheless, such impression is actually incorrect.  When body roll occurs due to cornering, the outside wheels are compressed, hence the anti-roll bars will push the inside wheels away from the body. Does this action result in even more body roll ? no. Because even without the anti-roll bar, the inside wheels will also keep in contact with the ground (due to weight of the car and the expansion force from springs), thus are pushed far away from the body (don't expect them to hang in the air !). In other words, the anti-roll bar doesn't alter the natural movement of the inside wheels.  On the contrary, the twist torque of the anti-roll bar always tries to fight against the compression in outside suspension. Therefore it also reduces body roll.  The advantage of anti-roll bar is very clear - it suppresses body roll on bump or during cornering, but does not deteriorate ride comfort in straight line. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 8, 2009 Author Report Share Posted March 8, 2009 So an ARB upgrade could improve traction by combating inner wheel lift ? Â How does the drop link infulence the ARBs effect ? I know you may have covered atleast some of this in ER's thread already. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 8, 2009 Report Share Posted March 8, 2009 So an ARB upgrade could improve traction by combating inner wheel lift ? Â How does the drop link infulence the ARBs effect ? I know you may have covered atleast some of this in ER's thread already. Â The link is nothing more than a messenger transmitting load at a prescribed level oem, tuned if they are adjustable. Â One of the advantages of the arb is it allows a much lesser coil/oil package, reducing the need for crashy suspension rates trying to reduce body roll, the arb is less active allowing for a better domestic ride feel. Â The "lift" can be controlled by the arb but only within a "moment" during the inertia/ transition, this is a complicated area that encompasses the roll centres, roll couple and indeed the entire suspension configuration. Â For the domestic vehicle the arb is of little interest, once the car is lowered or other intentions are born then we need to use this tool for tuning the suspension/ geometry calibration... this is when you hit the dark art. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 9, 2009 Author Report Share Posted March 9, 2009 Would you like to hear about my Geo experiments in Forza Motorport by the way ? Quote Link to comment Share on other sites More sharing options...
Tony Posted March 9, 2009 Report Share Posted March 9, 2009 I'm all ears Quote Link to comment Share on other sites More sharing options...
CIH Posted March 9, 2009 Author Report Share Posted March 9, 2009 Well I wanted to see if I could improve lap times using Geometry alone. Starting with a stock AE86 on the Fujimi downhill point-to-point run (yes I have been watching initial D!), a kinda of B-road downhill blast. This was quite fun but the 8-6 was far too over-steery for really fast times, especially when powering out of corners. I couldn't beat the time I set with a more powerful Teg type R even though that was an indifferent run. So I set some benchmark times with the stock car and upgraded to full race suspension, necessary for any adjustment. The flatter cornering and better traction obviously improved times, using the default camber -0.5 front & rear, minimal toe-in front & rear and +5.1 caster but still too much oversteer.  By now I had Japanese Performance and nicked WIMs Mx5 fast road settings. These were better but didn't really change the car's nature. Going back to Forza default, I switched to toe-out 0.5 front and rear and it was transformed. Turn in was much the same but power-oversteer was completley tamed. I could set it up for a corner with braking and steering and could adjust the car's posture mid-turn with the same, but almost with full throttle. I'd only spin-out if I really banzai'd into a corner, or put a rear-wheel on the gravel lining the tarmac. It now responds quite well to left-"foot" (or rather hand!) braking. I could actually drift, full throttle, round some of the faster flowing bends without loosing too much speed.  Adding front camber made it little better but it would quite heavily under-steer if I missed a braking point, corner apex etc and required total comitment. Taking the camber off and putting it to the rear quelled this but didn't really help out all that much overall.  So currently running Camber; -0.5 front, -7.0 rear Castor; default +5.1 Toe; -0.2 front, -0.6 rear  with these settings I beat my previous best by 2 seconds, and that previous PB had been a real effort too. I know this is probably quite lame compaired to the real deal and I've no idea how any of this would translate to real life but it's fun. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 9, 2009 Report Share Posted March 9, 2009 Is that -7d rear. Quote Link to comment Share on other sites More sharing options...
CIH Posted March 10, 2009 Author Report Share Posted March 10, 2009 No, it's all minutes save for the castor ?? Â Oh right, I see. That's a typo. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 10, 2009 Report Share Posted March 10, 2009 No, it's all minutes save for the castor ?? Oh right, I see. That's a typo.  wouldn't work in the real world Quote Link to comment Share on other sites More sharing options...
CIH Posted March 12, 2009 Author Report Share Posted March 12, 2009 I dailled in -4 degrees front and rear (max allowable) for a giggle. It was horrible, understeer, snap oversteer, no traction or grip at all. Quote Link to comment Share on other sites More sharing options...
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