16 replies to this topic

[FW11B]

Probably and old topic, but why ban four wheel steering, Surely this is the sort of developement that can be passed to road cars!

[Damop]

Four-wheel steering has been all but abandoned on raod cars too due to complexities required and marginal increases in performance, but it will be returning on GM's full-size SUVs next year to improve manoeuverability. Even so, there is still four-wheel steering of sorts on many road cars and probably F1 cars - it's passive steering built into the suspension where the toe changes depending on loading to provide some passive steering. I deally for stability and higher cornering speeds you want the rear wheels to deflect in the same direction as the front wheels.

There were a number of cars in the 80's that provided counter-steer at the rear wheels for tighter turning at large steering wheel angles and in-phase steering at small steering wheel angles to improve stability. I drove a Prelude equipped with such a system, as well as the SuperHICAS 240SX and didn't care much for either, but that is a personal thing.

[FW11B]

Damop, Thank you for the reply, very informative, just what I like...

[desmo]

Is any one else as tired of hearing drivers whine about not being able to get the balance right as the reason they are not competitive in qualifying or race trim? I say let's give them more tools to correct imbalances, like rear steer- either through an actual rear steering system or through using a differential that can impart a turning moment. I see no real downside. The more promising course- 4WS through toque splitting, would be a relatively simple matter of changing the chassis ecu's software. It may well be cheaper than the present constant search for balance, so I think saying it would cost more is off base. I'd at least like to hear some fresh excuses from the drivers, I wonder what they'd come up with.

[Ray Bell]

Perhaps off topic, but in keeping with the earlier comment on road cars... 4WS introduced more maintenance, which when the cars are old might mean more unreliability. And unreliability in the steering department means Thud!
Not a nice thought for when the tenth owner with no knowledge of anything gets one!
F1 rules should be free enough to allow this kind of experimentation, I agree.

[tak]

Rear wheel steer on a racing car is a great idea in theory. But on a formula car where the difference between maximum grip and sliding is 1 or 2 degrees of tire slip angle, rear wheel steer mostly confused the drivers. The feeling of rear wheel steering was similar to a tire exceeding the it's optimum slip angle. Drivers backed off, and went slower, or turned inconsistent times. It's probably just a seat time issue, but who's going to invest in all the seat time?

Now in rally where fast IS sliding, I believe 4ws is on several cars. I'm not a rally fan so I don't know any details. Anyone else?

[desmo]

If the rear-steer was implemented through the diff, I think it would be possible to make it mimic the "feel" of a conventional system. I could even see a cockpit mounted dial that would, in effect adjust the handling balance, or better yet software that would sense the yaw angle and automatically correct in real time. Anything to stop the constant complaining about not being able to find the right balance. If that excuse was removed from the driver's list, would they have to admit that they or the car is simply not up to the task? Or am I not giving them sufficient credit for creativity?

[green-blood]

I am not so sure as to how many top Rally cars use active rear sterring, but most have an element of passive steering, In France the "Ice racing" series uses very specialized vehicles which all use 4WS, for the same reason - sliding is everything. You should see them guys slide the car for basically the whole lap, crabbing the whole time!!!!!! It is also a popular addition to rallycross cars. In F1 today grip is all and hence sliding is bad, the drivers need the tires to be hooked up to get on the power early, rear steering would in this case be of negligable advantage.

Give them back a clutch, the lazy gits.

[goGoGene]

My stock Subaru RS has passive rear steering. The inner rear wheel, during a turn, will deflect in, amazingly sharp, fast, precice turning. Haven't driven a car that can compare, and certainly not in it's price range.

If I not mistaken this is in all Subaru's.

ggg

[Darren]

Desmo, I think you are right - you're not giving the due credit for creativity. Although it's not really creative any more. It's become the standard shorthand for "couldn't get it to go quickly" and when mutliplied by journalist shorthand ("explained that" = "complained") you get the litany we've witnessed this year. I've noted that Benetton are regular plaintiffs in the balance case; Williams lodge complaints when their qualifying results aren't up to the "doing suprisingly well" standard we've come to judge them by.

[desmo]

Ironically the Minardi drivers are the only ones in the field to consistently praise the "balance" of their cars. Apparently the secret to getting the balance nailed is to go very slow!

[Powersteer]

First, F1 drivers do slide the car, maybe not in full speed corners. Tape a race and see it again in slow motion and you will notice they slide the car a little. Maybe 3-4 degree sideways but they do it. Thats what balance is all about.Balance is not simply for minimising slip which we might led to believe.



Thats why 4 wheel steering would benefit in F1. Don't be surprised if they ban passive steering and the F1 teams would come out with steer-by-wire? that is if they life the ban on 4WS. Also 4WS can benefit in reducing understeer and oversteer. When a wheel is turned it either goes forwards a little and backwards from center and from this they can take advantage.


But the biggest advantage is quick correction and quick responce. This all adds up to very good tyre degridation. I can turn into a corner with the slightest front wheel movement, taking full advantage of racing line. Oversteering correction can be done much quicker with both front wheels and rear wheels reacting.


you know how it is when you turn your cars steering that the car tilts to one side. Here too is another scope to look at into the advantages of 4WS. Passive steering would surely be considered as driver aid but active steering-by-wire?? which connected to every sensor in the car management, including heart beat?you figure it out, as for me, i want to see it in F1,ciao

[Powersteer]

Another advantage is high speed corners. The rear wheels if they toe in slightly would narrow the rear turning circle and widened the front. So this would make the rear move slower and the front faster yet keeping overall speed. As you know oversteer is a porblem in highspeed corners so here is a huge advantage. Just look at the CART cars on a straight line, the don't travel straight, very noticable during thier pit entry/exit this is ofcourse on an oval. It'll be too huge a compromise for F1 track with this radical set-up so here 4ws will come out tops.

[rainern]

Mitsubishi used fourwheel-steer successfully on their Galant VR4 Group A car in the late 1980s and early 1990s.
It won the Finnish Rally and also the British RAC Rally in 1989. It stayed competitive until the end of 1991.

The successor (Lancer) was more conventional and ultimately also even more successful.

Rainer

[desmo]

It seems that 4WS was a bit of a fad in retrospect. It makes more sense to me to just write new software for the diff.

[Yelnats]

Couldn't aggre more Desmo. Inspite of all the claims made for 4 wheel steering, it never made it in the marketplace because no-one could really tell if it was doing anything. Racing is another matter and rallying a whole separate world apparently entirely divorced from the needs of the road motorist but I've have'nt hear of 4ws on a major winning marque and it's apparently a low priority item compared to Anti-lock braking, active suspension and traction control.

[goGoGene]

Can't agree less, my Impreza's passive rear steering is quite impressive, and very effective. Gives the car a kind of poise while cornering that I don't find in other cars.

ggg