GP2: Packers

Hello all... I've been trying to figure out how to set the packers, and while the description in the manual makes sense to me, it doesn't seem to match the behavior I've observed. Maybe one of you experts could give a short summary on their effect? I understood that they limit the travel on the suspension by the set amount. So if ride heigth is, say, 40mm and packers 20mm, the suspension would only be able to travel 20mm and then stop at the bumps. So the lowest the car could get is 40-20=20mm. This is clearly not the way it works though, since at a setting like this the plank can still rub, and checking the ride height graph shows it was indeed going way below that. Even more confusing is being able to set the packers at a higher value than ride height! Clearly, I'm visualizing the packers as something other than they are, but I haven't been able to find any logical pattern to their effect (would be nice for the manual to have diagrams showing what these are!). Thanks for any possible enlightenment! -- Jyri J. Virkki - Linux: Choice of a GNU Generation - http://intac.com/~jyri

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> Hello all... > I've been trying to figure out how to set the packers, and while the > description in the manual makes sense to me, it doesn't seem to match > the behavior I've observed. Maybe one of you experts could give a > short summary on their effect? > I understood that they limit the travel on the suspension by the set > amount. So if ride heigth is, say, 40mm and packers 20mm, the > suspension would only be able to travel 20mm and then stop at the > bumps. So the lowest the car could get is 40-20=20mm. This is > clearly not the way it works though, since at a setting like this the > plank can still rub, and checking the ride height graph shows it was > indeed going way below that. Even more confusing is being able to set > the packers at a higher value than ride height! Clearly, I'm > visualizing the packers as something other than they are, but I > haven't been able to find any logical pattern to their effect (would > be nice for the manual to have diagrams showing what these are!). > Thanks for any possible enlightenment!

Ride height is the height of the vehicle above the ground when stationary. At this point there will be some element of load on the spring (not that much), giving the potential for movement of the car vertically, in both directions (up and down). Our particular interest is in the down direction. If we consider the car moving at speed, there will be additional load on the springs from the downforce, causing them to compress and generally lowering the ride height. Softer springs will compress to a greater degree for a given load and hence a soft car with a low initial ride height will start scraping the plank before a stiffer car would. There comes a point when the there is no more movement available in the suspension, either the spings are fully compressed (unlikley) or some other method has been employed to limit the travel, in F1 cars there still has to be some give, so the additional load goes onto the bump ***s. The ammount of compression on the spring can be further limited by the introducion of packers. Packers effectivly transfer load onto the bump ***s, rather than having any elastic properties themselves. Ok, weak visualisation: Imagine you have a spring infront of you, standing upright, and fixed to the desk. You can put your hand on it and press down, compressing the spring, let go and the spring, well it springs (that's the technical terminology btw). You don't like to fully compress the spring so you break up a pencil and put a length inside the spring. Now you hurt your hand on the pencil before the spring is fully compressed. Your not keen on that so you use a bit of sculpted ***/eraser/whatsit under the pencil. You still hurt your hand, though not so bad. Finally you decide that perhaps you should visualise a nice cup of tea instead. Ahem, so spring=spring, pencil=packer, and conviniently enough ***=***/eraser/whasit. Great! Err, maybe. If your plank is getting worn, there are several things you can try, Lower the wing, stiffen the Springs, put in the packers or raise the static ride height. Any one or combination of these may solve the probem, and quite possibly introduce new ones. Lucky for us, we can examine the ride heigh and suspension travel at any and all points of a track. Use the Graphs Luke. To get an idea of when the bump ***s will come into play you need to look at suspension travel and ride height. Usually you can see what you would need to hit the bump ***s by looking at the remanding travel on the fastest part of the course, or in detail anytime the ride height goes below 10mm. Put in packers, and do another lap, look at the graph and lo and behold, the available travel will be reduced. -- Suck The Goat

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> Hello all... > I've been trying to figure out how to set the packers, and while the > description in the manual makes sense to me, it doesn't seem to match > the behavior I've observed. Maybe one of you experts could give a > short summary on their effect? > I understood that they limit the travel on the suspension by the set > amount. So if ride heigth is, say, 40mm and packers 20mm, the > suspension would only be able to travel 20mm and then stop at the > bumps. So the lowest the car could get is 40-20=20mm. This is > clearly not the way it works though, since at a setting like this the > plank can still rub, and checking the ride height graph shows it was > indeed going way below that. Even more confusing is being able to set > the packers at a higher value than ride height! Clearly, I'm > visualizing the packers as something other than they are, but I > haven't been able to find any logical pattern to their effect (would > be nice for the manual to have diagrams showing what these are!). > Thanks for any possible enlightenment! > -- > Jyri J. Virkki - Linux: Choice of a GNU Generation - http://intac.com/~jyri

Packers limit the downward motion of the vehicle. Obviously, the more packers you have the more the downward motion is limited. The objective is to stop the plank flashing yellow at any point around the circuit. I do this by continuosly lowering the suspension ride height with zero packers until the yellow starts flashing. Then, by increasing the packers on different corners getting the optimum ride height on each wheel. There's no point in adding more packers as an excess of packers will prevent the car from achieving the optimum ride height. On some courses, there's an argument for allowing the yellow to flash in a controlled manner. For example, at Spa in Belgium as you reach the bottom of Eau Rouge and suddenly start going up the hill again your car will bottom out. As I tend to run three stops, that allows me 15 laps of plank wear until the car is forcibly powered down. Finally. The circuits are bumpy. You will notice at Hockenheim that towards the first chicane as you hit 200+ mph your plank will rub intermittently. This is due to bumps on the circuit. This is ok, again as long as the rub is not too much over your inter-pit period. The plank becomes an issue when your downforce is forcing the plank on to the ground at high speed continously. Then it wil take les than a lap to wear it way and then you get power loss. Mike