Why no Rear wheel steering?

[PoorManQ45]

I've been wondering this for a while. I think it belongs in this section because it's about engineering, I think.

Why do car manufactures always make the front wheels the main steering wheels? Why don't they make the back wheels turn instead of the front?

Most heavy machinery and monster trucks steer with the rear wheels, and they can literally turn on a dime.

So, how hard would it be to impliment complete rear wheel steering. I don't mean just partial steering?

Now, if the rear wheels were used to turn the car, would that eliminate most of the problems that FWD cars have?

[Red coupe]

Now, if the rear wheels were used to turn the car, would that eliminate most of the problems that FWD cars have?

the front tires would still unload under acceleration and the engin and transaxle would still be crammed in the front making it nose heavy like alot of fwd cars, although the weight of the stearing rack would be moved backward...I think it would solve the problem of spreading the work more evenly though the tires(are far as stearing and acceleration) but would most likely cause stability problems that I dont know enough to predict but im sure some one will put a little more science to it for yah...

[stfuad]

Wow the concept makes my brain hurt.

pulling with the front tires and having the back end move...

I try to imagine it in my head but all I can see is a car going around in circles. I'm not an engineering student or anything but I like to think about these things...

I just don't think it wold be practicle for street use. Maybe in tight quarters.

Wow... my brain locked up... I wish I had some sort of program which I could build a working model or something...

[PoorManQ45]

Does anybody else have anything to add?

Dennis, can you give us/me a little insight as to why car manufacturers use the front wheels as the main steering wheels?

[PalmerWMD]

I think its a lot more intuitive for human being to control a car via fronts especially since the swing out of the car in RWS would occur in the back, a place we dont naturally monitor as we have eyes only in front.( Not being sarcastic, just trying to explain why I feel its more intuitive the FWS way)

Fred..

[navysnail]

my thoughts, but with rws, those machines can turn on a dime relative to the front of the vhehicle, but the rear swings like hell. next time your at the grocery store, push a cart around backwards and observe what happenes, it is very hard to control

[PoorManQ45]

I have driven Front End Loaders and "Back Hoes" that have RWS. It is a little awkward at first. Like Fred said, we're are used to the front end of the vehicle turning, not the rear. But after about 15 minutes of driving those to vehicles, I found it extremely easy to manuver them. They can literally turn on a dime.

Now, to prevent the the massive oversteer that RWS causes, some sort of stability management could be used. Also, the rear tires could be limited to turning aproximately ~10 degrees each way. This would them to turn very easily and still maintain control.

Q45Tech Have you read this thread? If so, could you please give us your thoughts/findings on RWS?

[s13sr20chris]

ouch, imagine romping on the brakes and unloading the rear wheels. if you need to turn at this time it will be rough! i dont thing there is any cure for the natural stability issues with rear wheel steering. i dont think it is possible to turn any tighter. most front loaders and such turn very tight because they turn the wheels a very high degree. that would not work on a car. if you want to turn tighter you need four wheel steering and that still has its own issues.

[navysnail]

its not that they turn tighter, its just that the front moves a shoter distance forward and the back swings so they can menuver better, but they also move very slow

[madbouncy]

If the car steered with the rear wheels, then wouldn't your back end go into the other lane when you turn? I can't really explain it, but if you steer with the front wheels, then the back of the car tries to follow the front. But if you steered with the back, you would need a wider area because like you've said, your rear end swings out. I knwo at work the jacks steered with the rear, it was annoying as hell in tight spaces because to make the tight turn at low speeds, your front barely moves forward but your backend has to swing way out, which always ended up hitting stuff.

[drewufs137]

The shopping cart test is good....but why not just put 'er in reverse and go. You'll see just as well how hard it is to control. Even at slow speeds.

[Red coupe]

yeah but that is partialy because of the suspention tuning being aimed at going forwards...

[madbouncy]

Also has to do with the fact that you're turned around trying to steer opposed to sitting strait...

I'm sure if you dulled the steering down a bit, so it wasn't as sharp, you could do it. I don't think it would really gain anything. Because you'd either have to be able to turn the wheel a lot, or if you turned it a tiny bit you'd spin out at high speeds. I suppose you could make it more aggressive as you turn the wheel though. I still think too many people would hit things because it's hard to know exactly how long your car is and if bring the rear end out that far will hit something or not. Trial and error is great, but not when you're paying for it.

[vvaffle]

If you could place the driver very close to the rear wheels it wouldn't be too hard to know where the car is going. However as stated previously, trying to turn after or during hard breaking would not have very good results. As far as I know, it's possible that AWD 4WS cars will someday be the best thing out there, but I doubt that will be any time soon.

[AmoebAssassin]

Steering with the rear wheels would cause horrible oversteering issues. The car would always want to snap around in turns, and as mentioned turning under heavy brakeing would be a nightmare. This would be really bad for emergency maneuvering for the general public because the human reaction when in an emergency driving situation is to slam the brakes and simultaneously steer out of the way. ABS was invented to increase stability in such a maneuver. It's easy to see RWS making an emergency avoidance impossible due to inherent weight shifts involved with braking.

[cnickk]

HICAS?

[AmoebAssassin]

HICAS?

HICAS, at least on 240sx's, only engages above a certain speed, mostly eliminating the danger of RWS in a forward weight shift under braking. Additionally, HICAS is more of an active toe-in and toe-out adjustment in the rear than full, wide-angle rear wheel steering. In a sense, HICAS is like directional toe-out on demand, it makes the car more willing to rotate around turns at speed and under other conditons, but doesnt really have any significant turning influnce. That is to say, you would be unable to turn a car quickly using the rear (HICAS) rack only as compared to using the front steering.

[bware113]

I personally think that this would be kinda difficult to implement. If we were to sit the driver over the rear wheels it would still be an awkward feeling not to mention the steering would most likely be kinda unpredictable. And, the vehicle as mentioned before would swing outward. Holy Lane Change Batman!! In short think about driving your car in reverse @ like 10 mph and slightly turning. Even in a 50/50 car the turn would still be very sharp. Now, apply that to a majority of the drivers today and 25 mph. You are surely looking a a disaster. I don't even wanna think about what would happen durring inclement weather.

[ADDirishboy]

IF THE REAR WHEELS TURN, HOW WILL WE DRIFT!

[Dattebayo]

This thread is from 2005. Thanks for that.

[flyingbrick]

sarcastic rant!

Thats right. you are smarter than every automobile steering and suspension engineer in the whole wide world because you have invented REAR WHEEL STEERING. Its going to be a huge breakthrough in vehicle design! You better patent this idea before Mr nissan steals it... or worse yet- sends out hitmen to ensure you can't reap this amazing ideas fruits.

WOW i just can not believe that over 100 years of steering from the front could have been done so much more efficiently if done from the rear.

OH MY GOD SO MANY SMART PEOPLE HERE.

[Red coupe]

I know I am included in this group... but pretty much EVERYONE in this thread missed the real issue.

I am guessing many people here have not had much experience with rear steer stuff, or else you would realize that it just wouldn't work with the way we use our cars.

To turn, one end of the car has to swing out and actually turn the car.
Front steer works well for this, because the car swings in the direction you are trying to go.
Rear steer is the opposite. The rear end of the car has to swing in the direction you are steering away from.

Pull up rear steer only RIGHT next to a curb, then try and pull away. To turn back out into the street you need your rear tires to turn into the curb they are right against, then start moving forward. If you are too close to the curb, you wont be able to turn back out with out making a lot of moves.

Rear steer is maneuverable as hell, but otherwise a pain in the a**.

[flyingbrick]

I think you are forgetting the most important thing here. Airplanes fly faster than cars and their direction is controlled by rudders and elevators which are at the rear of the airplane. Also, tail dragging aircraft have three wheels and the rear wheel steers.

Therefore everyone designing cars is stupid and we should talk some more about how feasible rear-wheel steering is.

And dont give me that you'll hit the curb BS. Obviously you need to reverse out of those car parks to avoid curbing your wheels.

Also i think worth considering is a diamond wheel configuration. One wheel at the front, one wheel at the back and two in the middle. But rather than having the front or rear wheels steering this car we can have the MIDDLE wheels steer it!

ITs got the pro's of both front and rear wheel steering surely.

PLEASE HELP ME MAKE THIS IDEA COME TRUE.

[nofatchicks0073]

ok i feel the need to chime in here even though this thread was started so long ago first off flyingbrick i hope your kidding comparing the way an airplane steers and the way a car steers im really assuming that was a joke and you guys are mistakin about a few things for one a front end loader does not steer with the front or the back wheels actually the wheels dont turn at all and this goes for many pieces of equipment the machine actually articulates meaning that the chasis is hinged in the middle and the whole machine bends forceing the wheels to turn because the the whole machine bends witch is great for working on a job site because you can cut corners very easily but if you ever have the privilage of taking one of these things on the road to move it to another job like i have (i ran heavy equipment for five or six years) than you know thats its definatley not built for any kind of speed and it becomes difficult just to keep it on the road but thats not really what you guys were meaning to say the closests thing would be more like o fork lift the kind with large wheels up front and small wheels in the back they turn from the rear and turn on a dime but are very dangerous because they turn so quickly as would anything you would try to steer from the back and monster trucks though they dont articulate they do have four wheel steering and never get up to any major speed but how many times have you seen them flip over just making a turn ive seen it plenty the point im making here is that rear wheel steering is not in any way a good idea on any vehicle or machine that travels at any kind of speed and if you dont belive me hop in your car and see how long you can drive in reverse at thirty miles an hour turning back and forth between reflectors on the road just dont send me the bill when you end up in the ditch hahahaha

[flyingbrick]

I was being entirely sarcastic the whole time :-).

It just bugs me how some people think they can reinvent the wheel.

And cars can drive at motorway speeds in reverse! I saw it on 2f2f !!!!

[eugen923]

Nice post !!