I feel this is one of the more under-rated aspects of automobile performance. Sure, it will not affect the acceleration or autocross times, but it can make a huge difference in some of the things you can do in your car. If you think about it, in normal daily driving, most people make a minimum radius turn way more often than they do full out acceleration blasts or top speed runs. At least I do. Only a couple of times a day is what I am doing in my car limited by the cars capabilities, and that is usually only blasting up to a fast speed during the commute and then backing off so I can keep my license. The most common occurrence of maxing out your vehicles capabilities is trying to make tight, low-speed turns.

I often ask my car to turn as tightly as it can to throw it into parking spaces, whip around U-turns, etc. As a matter of fact, a minimum radius turn is part of my daily routine when I drop my son off I my way to work. I pull out of my parallel space in an instant low speed U-turn. I can get it all the way around with a foot or two to spare before the other curb. If my car couldn’t make that turn, I would have to drive all the way around the block, which would take a while in that school zone. I know there is no way all of the minivans around there could even dream of doing that. Those of you who live in bigger cities and more congested areas than me probably could use a small turning circle even more.

I started thinking about this after I read a magazine review of the new Mini S. From the looks of that little supercharged roller skate you would think it would be the ultimate point-to-point car in a heavily urban area. I can just imagine that little thing zipping around in parking lots and squeezing into places other cars can go. That is until I read that the Mini has a larger turning circle than a Honda CRV sport utility vehicle. How useless is that!!!??? That really defeats the whole purpose of having a small car like that.

I speak from experience on how big a pain it is if your car can’t make tight turns. We used to have a Jaguar XJ-S. It needed about as much space to turn around as the Queen Mary. Talk about a frustrating car to drive in a city! It wasn’t that long, just engineered poorly. It was like trying to park a dump truck. Every time I make a tight turn, I’m thankful I don’t have that anymore.

Here is to hoping that Mazda considers real world driving enough to put a little extra range of motion into the steering wheel and a little extra space between the hard stops of the steering rack. We will appreciate it daily.
:)

I agree with you, We have a Mazda 626 and it has a horrible turning circle, same with the protege i rented, FWD cars from my experience dont have good turning circles (based on the FWD cars ive driven). A tight turning circle makes it easier to manuver in a parkinglot and easier to park. Making tight U-turns instead of having to do quick 3-piont turns is really convenient.

I will nod to this as well.

About a year ago I had a lineup of cars of which I was wondering which to buy, which included the RSX Type-S... until I found out it has a nearly 40 foot turning circle. (Like the CL Type-S) Now one of my criteria was that I needed a smaller car so that it was easy to park in the city. This was not.

I liked almost everything about the car, except for the turning radius--and it was enough to drop it. In fact it was enough of an issue for me to spend over 10k more and a jump into the low end luxury class where I ended up with a BMW 325i.

Is a larger turning radius a by-product of front wheel drive? It sure seems like that may be the case. Obviously, a longer wheel base vehicle is going to have a wider turning radius, but the biggest variable is the range of motion of the front wheels. The further a vehicles front wheels can turn, the turning radius will be reduced. But front wheel drive cars may be hampered by drive shafts, CV joints, and suspension all contributing to a decreased range of motion.

Thats my best guess here. I know several maunfacturers dabbled with 4 wheel steering (Honda, Mitsubushi, Nissan), and there is a new GMC truck that now has it available. We'll have to wait and see if other manufacturers jump back into that technology. I would guess though, that the turning radius will be in the neighborhood of 35-37 feet, this assumption is based approximate wheel base length, and average for similar sized cars. That stat for the MINI Cooper and Acura RSX surprises me. The turning circle on my 99 Mitsu Montero Sport is 40.7 ft, and the Montero Sport is much bigger than those other two cars.

Originally posted by red_base 95
Is a larger turning radius a by-product of front wheel drive?

Not necessarily. My Focus actually has a very tight circle. Conversely, I have seen RWD's that seem to have a much larger turning circle than they should.

For any car in the size class of the RX8, I want to be able to pull from the curb directly into a U-turn (which the Focus does)! Turning circle is one of the specs I pay a lot of attention to when evaluating a car. Even if the car handles par excellance, if the turning circle is too wide, I dismiss it.

Ditto, this is very important anywhere ther is more than one car on the road!

It appears that we would all like to have a tight turning circle; does anyone recall if the 8’s turning circle is published? I for one do not recall seeing it. :confused:

Besides, without a nice small turning circle, I can't just fly out and do donuts :D!

I know, I wreck my cars, but that's why I'm leasing :)

I think FWD limits the wheels movement enough on some cars that it can do that to their turning circle.

I had a old 76 dodge cargo van ( the longest version you could buy with a 389 V8 and it had rusty old suspension) It was a peice of crap. Not the van itself just the condition it was in rust everywhere and didn't run all that good ( the point is coming up)

I also had a 88 plymoth ( can't spell) horizon. Small hatch back car with a short wheel base and little or no weight.

The point is (you guessed it) that old cargo Van would outturn that little horizon by like 10 or 12 feet!! and we had just put new wheel barings on it! I think alot of it is FWD.

the last 2 cars ive had were honda's i almost forgot how much fun there is to be had doing donuts in a RWD car.
and of course i mean that a tighter turning circle would help me in parking lots and turning around on the street in front of my apt. i don't want to give the impression that i would just like it for the donuts..,:cool: really i mean that

I agree RWD is fun, spinning some donuts and hitting the turns at 60 mph to powerslide it really brings out the adrenaline, but thats how i wrecked my benz and my insurance shot up but thats not going to stop me when it comes back:) i do agree with styjan i believe FWD limits their turning.

My friend owns a late 80's Ford Bronco that that thing has a tight turning radius, i was very amazed, it could turn on a dime, i seriosuly think it has less than a 30Ft. turning radius.

Hehe, I just find an empty lot and uhm.. 'practice' :D

Yeah, over here we have these 2 big courts in the business district area, at night there is nothing there and me and my friends started doing our stuff there the street that leads to it is a wide road with a smooth left turn followed by a right turn, a snake:) its a great spot the road is actually in front of our police station but the buildings block out the sound:)

Originally posted by red_base 95
Is a larger turning radius a by-product of front wheel drive?

Not necessarily. My current Civic has a 32 ft turn radius, which I think is pretty short.

Its certaintly more tricky to engineer a FWD car to have a tight turning circle (because of those pesky drive axles being on the wrong wheels...) but not impossible. Its just easier to make a RWD car have a tighter circle.

Oh yah, putting grippier/wider tires on a car will decrease the turning radius as well, so keep that in mind.

A big factor moreso than FWD is the length of the A-arms and their shape since the motor and trans are mounted transverse in a FWD car the engineers are limited to what they can do with the suspension but since the RENESIS is mounted behind the front axles the double wishbone suspension should have long arms and that should allow plenty of clearance to crank the wheels for you boys to do your donuts:D

Originally posted by fuz
Oh yah, putting grippier/wider tires on a car will decrease the turning radius as well, so keep that in mind.

Huh?

Originally posted by Rich


Huh?
Think about it.. if the wheels/tires are very wide then the wheelwells would have to be designed around those limitations to create a small turning circle. The angle can only be so big before the tires rub the wheel well.

No to mention that a car's wheels each follow an individual path when turning. However all four tires are attached so that they are forced into one path. When a four wheeled vehicle turns, at least two of the wheels drag, which is why cars lose so much speed when turning, unlike a bicycle. Turning tighter forces the tires to drag even harder. If you increase the drag in the tires by getting grippier tires, then the ability to turn will be reduced. Make sense? :p

Ok, maybe wider might make a difference, but I still don't buy the grippier part. I've replaced tires on my cars before and I've never noticed the turning radius change based on how grippy the tires are. I don't see how it could. You turn the steering wheel and you turn to where the tires are aimed.
I know people put wider tires on their cars also and don't change their turning radius either. I am willing to accept that the engineers do tune the maximum angle the tires can turn to their width and the wheel wells, although I haven't really thought about it.

fuz, if your wheels are dragging on your car, its time to check your differential... :D

It's a simple geometry problem. Made a quick sktech in illustrator and a compass. Don't have ACAD on my system.

http://www.rabidpineapple.com/site/misc/turn.jpg

The green line is the front tires, the green line representing the path the tires want to take.

The red line is the rear tires, the red line representing the path the tires want to take.

Going around the corner, and measuring from the apex, the pencil lines represent the path each tire must take to go around the corner. You can actually align the front tires a little better to the line, but each of the two tires is vying for their own path. What you can't really see in this diagram is that the distance between the tires also shrinks, the more the tires turn. (Sorry coudn't get enough detail in) This amplifies the different paths the tires want to take, increasing friction, and making it harder to turn. Add more grip, and the tires just fight against each other that much more.

In any case, you can see very clearly that the rear tires do not want to take the path they need to go in a circle, so they constantly fight with the front tires to take the path that they want. By giving them more grip, they pull harder on their direction making it harder to turn. Thankfully a car is elongated and can make use of leverage to minimize this effect. A car that is too long will actually find that the length itself outweighs the benefits, as it needs more space to turn.

It's complicated, but it does have a measurable effect on turning radius. It is however small and not too much concern. Just be aware that it exists.

BTW--this is only a quick overview. I left out a lot of other vectors that come into play. ;)

uh, don't most modern cars (that are worth what you pay for, i'm not talking about some of the leaf-sprung-solid-rear-axle setups) have adaptable rear suspension, which in cornering would allow the rear tyres to slightly realign themselves with the orientation of the front ones, thereby negating thier resistance?? oh, and if grip on ALL FOUR tyres was exactly the same amount, why would it matter if it was big or little?? (the forces overcoming one another would still be in the same proportion, just bigger or smaller, wouldn't they??)
it's obvious what would happen if there were grip disparities one way or the other...

Ok, just for theory:

Take a car and grease all it's wheels and turn. Easy. Leave it the same, harder.

The extra grip magnifies the tendency of the wheels to stay to their intended path through the increase in friction. Tires with a wide contact patch will magnify this even more, as the larger horizontal area resists turning even more.

according to this recent spec list the G35 has a tuning circle of 18.7 feet!!!
check out

specs (http://www.infiniti.com/ms/future/g35c/G35C_Specs/)

Originally posted by fuz

Take a car and grease all it's wheels and turn.

Kids, do NOT try this at home! :D :D

fuz,

The inner front wheel is cranked over at a higher angle to compensate for the smaller radius. This is known as Ackerman geometry and is designed into every car on the road.

I too like a tight turning radius and this is one of the many reasons I prefer smaller cars. However, to do a u-turn smaller than the turning radius all us RWD/LSD drivers need to do is blip throttle just enough to swing the tail around.

I don't know if this would help you armchair engineers but here is what I know:
Wheelbase: 106.3"
Track, Front: 58.7"
Track, Rear: 59.1"
Overall Length: 170.3"
Width: 70.1"
Height: 52.4"

Go figure:confused: :confused: :confused:

wait, fuz, i just thought of this...
in race cars which can generate large amounts of downforce, that increased normal force would effectively have the same effect as a softer compound, yes?? (if i'm wrong on that, none of this will make sence).
now, i'm aware that the wheel itself is more difficult to turn, because it's like turning a heavier car (to accelerate sideways) yes?? uh, but all this increase in grip, if BALANCED will (as far as my limited knowledge goes, i've never driven a full blooded racecar) not affect the turning radius, and only increase the grip the car has, thus enhancing its maximum velocity and capability to accelerate horizontally around that circle, yes??
just thoughts...

At high speeds, the turning circle really has very little to do with how tight you can turn since you'll almost always run out of lateral grip before taxing the car's ability to turn using its mechanics. I really would not suggest trying to make a a 30 foot turn at 100mph. It might be bad, ya know. :p

Well think about this. If there was no drag problem with the rear wheels, four wheel steering would do nothing to help a car turn tighter. We obviously know that that is not true, so what we really want to know is how optimized can we get it, and can we reallistically expect to get it on the RX-8, with all the other compromises that must be made.

Although I really must admit to being an amateur engineer, so I really don’t know just how evolved current suspension systems are, nor do I know of their capabilities.

true bro, true. :D

glad to swap ideas there!! ahahaha!! ya, 100mph in a 30ft circle, i didn't think of that.
well, us amateur engineers are only amateurs for a reason, right?? ;)

well, you've converted me, i see the light.
oh, check out the "New to the Forum" thread in the Lounge, i've got a thing there on the 5+6 ports i'd like some feedback on, if you don't mind fuzzy... ;)

-Andrew

most mazda cars have a very small turning radius...i had a 94-929 and even it could make some nice U-turns

The factors that determine the turning radius[circle] are wheelbase, track width, and the steering wheels turning angle.

Most front wheel drive cars use CAV [constant angular velocity] joints. It is not a good idea to turn these more than 30 degrees while applying torque. That is why manufactures put the 'hard stops' of the steering at about 30 degrees. Some companies like Chrysler do not, for example the LH cars [intrepid concorde 300M] can turn around in about 37.5 feet, That is impressive considering the wheelbase is 113" and the track widths are 62.4" F 62.0"R
All in all, the wheels turn about 35 degrees.

The leading champion is the GM trailblazer, They allow the wheels to turn up to 40 degrees (not sure if they use CAV or universal joints.)

So a rear wheel drive car could in theory go up to 45 degrees and turn around in about 30 feet

wooo man thats too much info for my brain to handle...anyways how do you know this?..i mean how did you come about this info?

The champ for the angle the front wheels would turn has to be Volvo on their products from the 80's. I swear the wheel would turn almost 60°.

MikeW duuuuuuuuude!! alright!! another tech-head...
PLEEEEEASE be more active on this forum!! that was fantastic!!
:eek: :eek: :eek:

Mazda says that the production rx-8 turning circle (curb-to-curb) is 5.3 M (17'5"). This can't be the diameter so must either be the radius or the typo by Mazda. 3.0 turns lock-lock.

34'10" turning radius isn't too bad eh...

buger where are you getting this extra stuff like turning circles and final gearing etc?:confused: :confused:

Originally posted by zoom44
buger where are you getting this extra stuff like turning circles and final gearing etc?:confused: :confused: Don't question it, accept it as fact :)

oh i do i do but i have scoured every press release and spec sheet i could find and none of them go into the deteails he finds. you'd think he was an insider like boo.... or maybe he is boo in disguise! ;) :eek:

i mean this is incredible have you seen these other two things he has posted( pardon me for hijacking this thread i'll move on now)
http://www.rx8forum.com/attachment.php?s=&postid=19333
http://www.rx8forum.com/attachment.php?s=&postid=19343