How does the 911 have such "responsive" steering?

[sugarwood]

The steering of the 3.2 911 is amazingly responsive, unlike any other car I've driven. Even on the highway, it's like you're on rails. You have to actively steer the car at all times. I feel like if you get distracted reaching for a bite of your food, you can veer right out of your lane! What makes the 911 steering like this? What would make the wheels respond so much with such slight steering movement? It's the rack and pinion system, correct? But do all cars with R&P steering behave this way? Or does the 911 have an aggressive steering ratio? Is this accomplished with larger rack/pinion teeth? That way, for a given amount of turn of the steering wheel/pinion gear, there will be more rack displacement?

Why aren't all cars like this? Is there a downside? Who doesn't want more responsive steering? Costs? The technology is old, so it’s not R&D costs. Materials? I’d think it can’t be more expensive. The pinion gear size should not have any effect on cost to manufacture, either. Also, if rack/pinion is so good, why do they not use it anymore? Is this a cost issue? Convenience and comfort issue related to power steering?

[oldE]

It is indeed rack and pinion and many other cars have a comparable system, from a point of view of specifications.
The light weight of the 911 front end means the cars may get by with no power assist. I think this is the single biggest factor. A lot of feel is lost when you add boost to the system.
I'm sure a dozen or so engineers will chime in shortly.

Best
Les

[Rusty Heap]

front end is light in weight when you get it corner balanced.

rear engine = pendulum = bad if you lift on the throttle in apex of corner, yay for oversteer and you steer with the right foot.


front engine cars push in corners and understeer = tree Tree TREE.


mid enginer cars like GT40 or Acura NSX = happy medium?


if thus, then why don't we see more mid engine cars?

[masraum]

I think the biggest factor is the light weight of the front end. If you don't understand why, imagine holding a hammer by the end of the handle and then try to swing the heavy end back and forth quickly. Because of the weight of the head of the hammer, you can't get the end to change direction very quickly. Now hold the hammer by the head/heavy end and then try shaking the other end back and forth quickly. Because you are holding the heavy end, you can get the other end to change direction very quickly.

Besides that, you have the fairly quick ratio rack and pinion. The quick ratio makes another quick difference. That's why a seemingly small adjustment on the steering wheel can make a fairly large difference. Most cars have much slower ratios.

[rusnak]

You might have a tad steep castor angle on the 911. It shouldn't feel THAT sharp. In other words, it should have a self-centering feel so that you can use a light touch on the wheel and not feel like you're going to end up in the weeds.

[porwolf]

All my rear engine cars, VW's and Porsches had very responsive steering and and that direct feeling with the road because the cars did not need power steering but were easy to turn even at parctically stand-still.

[Por_sha911]

Originally Posted by sugarwood

if you get distracted reaching for a bite of your food

Eating in your 911? Being distracted? BLASPHEMY!
If all you've ever driven is FWD econo-boxes and huge sedans, the 911 seems to have unearthly abilities. The reason? Its a sports car designed to handle well. Form follows function. Aside from the 917, Porsche's are not usually the fastest because of sheer power. They have more reliability and they handle and brake better.

[wdfifteen]

Originally Posted by masraum

I think the biggest factor is the light weight of the front end. If you don't understand why, imagine holding a hammer by the end of the handle and then try to swing the heavy end back and forth quickly. Because of the weight of the head of the hammer, you can't get the end to change direction very quickly. Now hold the hammer by the head/heavy end and then try shaking the other end back and forth quickly. Because you are holding the heavy end, you can get the other end to change direction very quickly.

Besides that, you have the fairly quick ratio rack and pinion. The quick ratio makes another quick difference. That's why a seemingly small adjustment on the steering wheel can make a fairly large difference. Most cars have much slower ratios.

Great explanation for the laymen. 356s have quick steering too but no rack and pinion. It's a two edged sword. Fun to go quick in a Porsche but challenging to go fast.

[Chocaholic]

Originally Posted by Rusty Heap

if thus, then why don't we see more mid engine cars?

Because most cars have a back seat where the engine goes .

[masraum]

Originally Posted by Rusty Heap

front end is light in weight when you get it corner balanced.

rear engine = pendulum = bad if you lift on the throttle in apex of corner, yay for oversteer and you steer with the right foot.


front engine cars push in corners and understeer = tree Tree TREE.


mid enginer cars like GT40 or Acura NSX = happy medium?


if thus, then why don't we see more mid engine cars?

Rear engined cars push/understeer in corners too.

We don't see many mid engined cars because they are much less practical than other designs. Cars are a compromise to fill many roles and usually practicality and cost win out. That means mid engined cars are rare.

Mid engined cars are also much more active. Because the weight is near the center of the car, when it starts to rotate, it may rotate very quickly making it hard to control.

I think the happy medium cars would have the layout of the 944 and modern corvettes with the engine in the front and the transaxle in the rear making the car more stable and slow to rotate.

[jyl]

Could be OP's 911 is toed-out too.

[sugarwood]

The discussion has really focused on engine placement.
Is rear engine really the main reason 911's have such tight steering?

Are there any front engine performance cars which also claim to have super responsive steering?
I was hoping to learn a little more about rack/pinion vs. recirc. ball.

[masraum]

Originally Posted by sugarwood

The discussion has really focused on engine placement.
Is rear engine really the main reason 911's have such tight steering?

Are there any front engine performance cars which also claim to have super responsive steering?
I was hoping to learn a little more about rack/pinion vs. recirc. ball.

I do think the biggest factor is the lack of mass over the front wheels. Mass has momentum and changing the momentum takes force. The tires have to apply that force, and they can only apply so much force before they start sliding.

Mid-rear and rear engined cars will, if similarly setup should both steer more lively than a front or mid-front engined car.

[greglepore]

"Overly" responsive steering is often the result of a zero toe or toe out setup.

[GG Allin]

Is the ratio in the rack the same from the early cars up through the 993's?

[aschen]

Originally Posted by Rusty Heap

if thus, then why don't we see more mid engine cars?

Because it is a huge PITA to build and maintain a mid and/or rear engined modern car.


I am reminded of this every time I work on my exige. Coolant lines, oil lines, refrigerant lines, they all run the length of the car.

Front drive transverse is approximately 1 billion times easier to work on.


This is all compounded by the fact that it isn't too hard to get the engine entirely inside the wheel base on modern front mid engine cars. Look under the hood of an s2000 or a vette.


If cost and packaging wasn't an issue every pure sportscar would probably have the engine behind the driver.

[masraum]

Originally Posted by aschen

Because it is a huge PITA to build and maintain a mid and/or rear engined modern car.

Front drive transverse is approximately 1 billion times easier to work on.

I believe you, but fwd cars suck to work on compared to front engine - rear drive, at least to me. I thought the 911 was pretty easy to work on, at least compared to a fwd vehicle. I think the big difference for me is the way a fwd transaxle is laid out.