Passive rear steer revisited
Ok after messing with this online game called "live for speed" more specific the rear toe settings on the car I came up with what seems to be a brilliant idea (Mabye).
when tunning the rear of a car to rotate we generally sacrifice the independent suspension by upping the stiffness of the rear bar or reducing the front bar. then mabye some tire pressure. Why not play onto the rear steering of our car? Its been overlooked as far as I know.
- Going straight rear tires point foward for most part.
- turn left and the suspension rolls right and rear right tire toes out and I think rear left toes in causing the rear steer.
- this could be tuned by replacing the arm or what ever it is that bends, flexes, or acts lever.
- more turn in could be had.
- better rotation could be had (rear will track aroujnd the turn vice drag ala large swaybar)
- as you let off the turn the body will start to go back to center as will the toe I think this may alow for you to get on the gas sooner as the rear is actually not breaking traction and you dont have to wait for traction to catch up.
- A non passive rear steer car with alot of rear toe out will be really tail happy and less effective as both tires are pointed outward and your scrubbing speed and eating tire even when going straight.
-Passive rear stear guides the rear based on whatever bends, flexes, or acts as a lever and by the body roll.
- make for a much better slip angle when tuned with your current suspension, almost feel like your drifting the corner but actualy are turning around the turn but have enuf stiffness to set you center quickly in transitions.
- on a stiff track car I assume you loose a good bit of (PRS) since your roll is reduced you can up the effect on whatever bends, flexes, or acts lever to regain some of this.
** heres an analogy for over clockers of the AMD type all others skip this:
Body roll = MGHZ (bus speed)
bends, flexes, or acts lever suspension part = CPU multiplier
CPU mghz = amount or rear steer
if you lower your mghz you can up the multiplier to regain some cpu power.
if you reduce body roll you can up the part that bends, flexes, or acts lever to get more (PRS)
***end of wierd analogy ***
to summarize I really think this is a part of our suspension we have really been over looking.
Don't forget, some of the PRS works through bushing deflection as well. If one can engineer a different piece that could change its charactistics, its worth exploring then.
Re: Passive rear steer revisited
"on a stiff track car I assume you loose a good bit of (PRS) since your roll is reduced you can up the effect on whatever bends, flexes, or acts lever to regain some of this."
PRS is immobilized on cars that have it when raced. Drivers prefer to be able to induce oversteer when necessary. Example, early Mitsubishi Galant 4wd turbos had PRS and the first thing people did whether it was for rally or the track was to disable the system.
Same with some of the 300z turbos. A friend of mine bought one a few years back to build up, and I honestly thought it felt ALOT better with the PRS disabled. The car was more predictable in the turns, but maybe thats just me.
Rear steer, both active and passive, was a bit of a fad in the 90's, especially with the Japanese. Most racers who use those cars now actually buy kits that defeat them, as they are unpredictable and unreliable in nearly every incarnation that has been tried yet. The only one I know of that was really good and still used in the racers is the Porsche 928's "Weissach Axle."
i believe the 3000GT, Dodge stealth R/T and the 94 (i think) Mitsu galant VR4 are the only ones i can think that had any kind of rear steer.
honda prelude, nissan 240sx, and probably a few other too my bmx'r
Other cars with rear steer
Nissan 300ZX, Skyline, Micra
Honda Prelude SH
Mazda RX-7 (FC3S), MX-6
SAAB 9-3 (ReAxs Equipped)
2006 G35, M45
Rolls Royce Phantom
Several non-us cars (EDM, JDM, ROW cars)
Toyota Aristo (Lexus GS here I believe, not equipped so in US)
GM trucks (QuadraSteer)
And probably many others. Even the Focus's Control Blade suspension offers a bit of passive rear-steer.
Duplicate threads merged.
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