suspension modifcation talk

[nthfinity]

ive heard about it, but never thought a lot about it. id think with toe out over steer may be a result, becoming unstable at speed. however toe in may result in higher exit speeds.
but like the sergeon general, im basing this off guess work, and no real evidence.
i do remember my brothers taurus SHO had pretty bad toe out, but only noticable above 90mph while taking turns; and over 110 it became an annoying viberation.

[graywolf624]

". id think with toe out over steer may be a result, becoming unstable at speed. however toe in may result in higher exit speeds.
"

For the most part race cars go with 0 rear toe. Most of the reason for rear toe in is the force of moving can make it toe out on a road car. Toe out tends to cause oversteer on a specific side when the weight transfers there.
In terms of passive steering I am not sure what you mean. Some racers do minor toe out in the front to make for quicker response for turn into a turn. Also in circle track you would want to setup toe to make steering around the track easier.

[hotgemini]

nthfinity: No, additional toe-in at the heavily laden outside rear would reduce the turn in. Again taking the example of peugeots, they DO oversteer when the rear is loaded up, but as the rear starts to slide the load reduces and thus the toe decreases. etc etc etc.

graywolf: A number of manufacturers peugeot being the best example use suspension designs which by design allow geometry change under load, allowing all sorts of weird and wonderful effects to be dialed in.

[graywolf624]

A number of manufacturers peugeot being the best example use suspension designs which by design allow geometry change under load, allowing all sorts of weird and wonderful effects to be dialed in.

I wouldn't know. They don't sell peugots here. This also is far beyond the scope of what you can do to your own car. Thanks for the info though.

they DO oversteer when the rear is loaded up, but as the rear starts to slide the load reduces and thus the toe decreases. etc etc etc.

Are they going for drift or something? Sounds like a good setup for a drifting challenge but not necessarily road racing. Or is it something to do with safety in slides for their customers?

I'll admit it. If it doesn't help me for the race track I know about as much about it as your typical ricer.

[hotgemini]

No, the idea is to give a car which in normal use handles and behaves like any other shopping trolley, but when pushed handles more neutrally rather than being a pig-understeerer.

[graywolf624]

ut when pushed handles more neutrally rather than being a pig-understeerer.

Not sure I completely understand your statement here. You said the car oversteer pushes the car to slide then recovers to work normal. That toe was set to out stock.

Toe out causes over steer under load from the rear of the car causing a slide. It will slide further out under weak materials.

That isn't what you want in a road racing car. You want neuturality. Are you saying their front setup is so poor that they must compensate with major oversteer? Why not design the car to be neutural. Providing bigger roll bars would have done the same thing much more inteligently. The bigger roll bars only have an effect under load anyway. In other words this all seems like putting a bandaid on a amputated limb.

[nthfinity]

intriuging; bing that peugeot is a major rally competitor/manufacturer, perhaps this is where the rear wheel toe helps on non dry tarmac conditions, and they are bringing the racing technology to the road?

they DO oversteer when the rear is loaded up, but as the rear starts to slide the load reduces and thus the toe decreases. etc etc etc.

does this mean the rear toe response active being actuated by computers, or possibly passive through hydrolics under lateral loads so it is self correcting once the limit is pushed?

[hotgemini]

graywolf: The system works fantastically well, I'm no proponent of it, nor privy to the design documents that accompany it.

nthfinity: I very much doubt they use this technology in their racecars. The passive rear steer is entirely by the deflection of rubber bushes by the load applied in cornering, no computers or hydraulics. What you've described is active rear steering, as used by nissan, mazda etc etc.

[deth]

BTW when i was talking about the passive rear steer it was actually thinking about the volvo 850 series. supposedly as the bushings were out its gets quite severe and feels like the rear is completely washing out

[graywolf624]

You definitly don't want to just let them wear down to see if it will do that. You'll prolly just get bind.

[deth]

nono....thats just what i heard..supposedly when that happens they;'re still within manufacturers specs

[yin_cheong]

This is getting a little tough on me... heh heh..... what other models have this passive rear steering?