CIH Posted December 17, 2008 Author Report Share Posted December 17, 2008 Doesn't the Omega suffer from such a big camber angle ie; forward stability on the autobahns ? In what sense.... are we talking aerodynamics? No. I've always thought high camber angles had certain inherent problems such as instability under braking ? Or is that incorrect ? Quote Link to comment Share on other sites More sharing options...
Tony Posted December 17, 2008 Report Share Posted December 17, 2008 Yes it can... Really deep camber transmits huge loads on the spindle amongst other areas, keeping the castor off-set as near to the spindle as possible normally means you can have a deep camber without braking abnormalities. Most times when the camber position is measured the concern is "will" this cause tyre wear or will this make the car pull.... Another way of looking at the camber is "how" will this position effect the roll centre and how much camber should i use? For the domestic market this has pretty much been Math for us, but when the modified car appears's there's another catalogue of considerations to master. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 18, 2008 Author Report Share Posted December 18, 2008 roll centre ? Quote Link to comment Share on other sites More sharing options...
Tony Posted December 18, 2008 Report Share Posted December 18, 2008 roll centre ? The main implication of the roll centre locations are that they are used to calculate diagonal weight transfer, which in turn can be used to derive suspension deflection and individual tyre loads (which in turn influence understeer/oversteer balance. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 18, 2008 Author Report Share Posted December 18, 2008 So what is it about the Omega that dicatates such deep OEM camber ? Is it the combination of soft suspension, indifferent chassis and the fact it's such a heavy old tank ? Quote Link to comment Share on other sites More sharing options...
Tony Posted December 18, 2008 Report Share Posted December 18, 2008 So what is it about the Omega that dicatates such deep OEM camber ? Is it the combination of soft suspension, indifferent chassis and the fact it's such a heavy old tank ? The suspension articulation, the roll centre and the geometric gains command a deep static geometric position..... Well that's all fine until the coil's sag!.... Now the roll centre's gone so the car corners like a boat, plus the geometric gains are to pot hence the understeer and the tyre wear. The Omega has a poor dynamic index for all the reasons above... Areas like SR, SAI, weight transfer explores the fact the Omega has a desperate geometric compensation so that the tyres saturation limits are expanded.... But not without consequence. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 26, 2008 Author Report Share Posted December 26, 2008 So what is it about the Omega that dicatates such deep OEM camber ? Is it the combination of soft suspension, indifferent chassis and the fact it's such a heavy old tank ? The suspension articulation, the roll centre and the geometric gains command a deep static geometric position..... Well that's all fine until the coil's sag!.... Now the roll centre's gone so the car corners like a boat, plus the geometric gains are to pot hence the understeer and the tyre wear. The Omega has a poor dynamic index for all the reasons above... Areas like SR, SAI, weight transfer explores the fact the Omega has a desperate geometric compensation so that the tyres saturation limits are expanded.... But not without consequence. Odd plod use them/ued them don't you think ? Can we explore how positive camber could be desireable in my Silvia ? Seems contradictory to everything I've seen. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 26, 2008 Report Share Posted December 26, 2008 Let's do it....... 1: Is the steering and suspension stock 2: What's you intentions for the car 3: You need to check the camber/ toe tendancies 4: What's your flavor over/ under steer. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 26, 2008 Author Report Share Posted December 26, 2008 Doesn't have to be an S12 specifically I was just curious about positive camber generally. Only other car I can think of with posi. camber were obscure early eighties Mitsi Colt Galants..... Quote Link to comment Share on other sites More sharing options...
Tony Posted December 27, 2008 Report Share Posted December 27, 2008 Doesn't have to be an S12 specifically I was just curious about positive camber generally. Only other car I can think of with posi. camber were obscure early eighties Mitsi Colt Galants..... Camber theory in wim-web> http://www.wheels-inmotion.co.uk/tech-cambertheory.php is entirely based on positive camber in order to keep the explanation simple. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 27, 2008 Author Report Share Posted December 27, 2008 So does the car see dynamic camber gains in the same way as negative camber ? I'll have to get it back on the hunter and see how it reacts to pitch, yaw etc. Anyway, in the meantime and keeping it hyperthetical shall we explore what you had inmind ? 1) Stock for now 2) Fast road, track possible but unlikely. Will be doing the Jap shows. 3) (Will do) 4) Neutral to mild progressive oversteer. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 27, 2008 Report Share Posted December 27, 2008 So does the car see dynamic camber gains in the same way as negative camber ? I'll have to get it back on the hunter and see how it reacts to pitch, yaw etc. Anyway, in the meantime and keeping it hyperthetical shall we explore what you had inmind ? 1) Stock for now 2) Fast road, track possible but unlikely. Will be doing the Jap shows. 3) (Will do) 4) Neutral to mild progressive oversteer. Image camber in a particular way "Articulation".... camber is a passenger of the suspension with the intention to maintain the tyres contact patch during the "articulation", our position is to decide the radii and influance the saturation levels/ grip limits. 1: How adjustable is the car? 2: Same as 1 really unless we use stupid amounts of toe. 3: Tiss a must... more so the castor during a "live sweep" 4: Over is very posible even on a FWD. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 27, 2008 Author Report Share Posted December 27, 2008 1) Toe front and rear only. And the N/S/R is damaged/worn as it makes very little difference either on or off cam. So not much then. Well I did say I wanted to explore "bilding in" adjustment via aftermarket parts! Probably be a while before I have the money to do so. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 28, 2008 Report Share Posted December 28, 2008 Let's experiment...... What do you feel the result will be if you toe the rear out one degree total? Quote Link to comment Share on other sites More sharing options...
CIH Posted December 29, 2008 Author Report Share Posted December 29, 2008 when i did that (by accidnt) in Forza with an MX5 it was super-oversteery. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 29, 2008 Report Share Posted December 29, 2008 Good, so with the adjusters available you can experiment with the front/ rear toe and customize it to how you want the car to perform. Quote Link to comment Share on other sites More sharing options...
CIH Posted December 29, 2008 Author Report Share Posted December 29, 2008 N/S/R appears to have issues as it made little difference wether on or off cam. Can we explore what's actually happening with the extra toe ? Especially why wether or not it's a driven wheel is relevant ? Quote Link to comment Share on other sites More sharing options...
Tony Posted December 30, 2008 Report Share Posted December 30, 2008 The type of drive is mainly relevant to the front wheels since these are either being pulled or pushed, the idyllic position for the front dynamically is zero toe. On a RWD (depending on suspension type) most times under acceleration the torque produced tends to pull the wheels toward the suspensions pivot points generating toe-in. This is intended since toe-out during acceleration is not something most would enjoy. Saying that though some rear toe-out on a FWD could reduce the inherent under-steer. Outside of the oem box you should consider toe as a turning tool since it's effect on the tyres contact patch is lateral, add a snippet of weight transfer then it's quite a powerful tool. Quote Link to comment Share on other sites More sharing options...
CIH Posted January 8, 2009 Author Report Share Posted January 8, 2009 What kind of range would I be looking it ? That is, how much toe would you normally be looking to dial in ? Quote Link to comment Share on other sites More sharing options...
Tony Posted January 8, 2009 Report Share Posted January 8, 2009 What kind of range would I be looking it ? That is, how much toe would you normally be looking to dial in ? It would need to be something noticeable, i would go for -30' per side. Quote Link to comment Share on other sites More sharing options...
CIH Posted January 9, 2009 Author Report Share Posted January 9, 2009 eek! how much ?? Quote Link to comment Share on other sites More sharing options...
Tony Posted January 9, 2009 Report Share Posted January 9, 2009 eek! how much ?? Put it this way, if i am training someone in the centre they need to feel how the angles work so 30'ps is enough fore them to detect. Try and let go a little from the margins you normally work with domestically and evolve specific handling qualities you desire. Get a feel of the oversteer and tune it down from there. Quote Link to comment Share on other sites More sharing options...
CIH Posted January 23, 2009 Author Report Share Posted January 23, 2009 Off topic, I'm really getting peeved off with work at the moment. Twice today I was told not to "mess about" Once with a rear beam shunt on a Passat and again with that wee allen head bolt on a late 3 series strut top. I'm beginning to wonder if I'm wasting my time. If my secret little portfolio is full of non-adjustments it's goning to look rubbish Back on, something that puzzles me somewhat is how a larger Camber angle can promote understeer on something like an MX5 but promotes traction on something like our barge Omega and thus fight understeer ? Quote Link to comment Share on other sites More sharing options...
Tony Posted January 23, 2009 Report Share Posted January 23, 2009 Off topic, I'm really getting peeved off with work at the moment. Twice today I was told not to "mess about" Once with a rear beam shunt on a Passat and again with that wee allen head bolt on a late 3 series strut top.I'm beginning to wonder if I'm wasting my time. If my secret little portfolio is full of non-adjustments it's goning to look rubbish Back on, something that puzzles me somewhat is how a larger Camber angle can promote understeer on something like an MX5 but promotes traction on something like our barge Omega and thus fight understeer ? You do know that allen bolt undoes anti-clockwise? Be patient at work, remember they don't understand what you are doing.... Maybe talk to the AM and explain you are studying chassis dynamics in your own time to better the company and gain additional (paying) adjustments from cars that don't have adjustments in these areas, this is actually "tuning the chassis". I am a qualified instructor within the realm of chassis dynamics so i can grade you on the intuitive questions/ answers within this thread, "retroactive interaction". As for your last question...."Polar moment of inertia" Definition: The resistance of an object to rotational acceleration. When the mass of an object is distributed far from its axis of rotation, the object is said to have a high polar moment of inertia. When the mass distribution is close to the axis of rotation, it has a low polar moment of inertia. A mid-engined car has most of its mass within its wheelbase, contributing to a low polar moment of inertia, which, in turn, improves cornering turn-in. Quote Link to comment Share on other sites More sharing options...
CIH Posted January 23, 2009 Author Report Share Posted January 23, 2009 As for your last question...."Polar moment of inertia" Definition: The resistance of an object to rotational acceleration. When the mass of an object is distributed far from its axis of rotation, the object is said to have a high polar moment of inertia. When the mass distribution is close to the axis of rotation, it has a low polar moment of inertia. A mid-engined car has most of its mass within its wheelbase, contributing to a low polar moment of inertia, which, in turn, improves cornering turn-in. I would have thought a higher camber angle would have exagerated the phenominum ? Quote Link to comment Share on other sites More sharing options...
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