Does electric power steering enhance the moth effect?

I've often wished there was some sort of resistance with the EPS. It makes it seem as though you're not exerting enough force to move the wheel compared to the typical PS, belt driven variety. I'm sure it's an adjusting phase, and that in 18 more years with it, you'll adjust to it just the same as you did the past 20 years.

Or, as you say, it could just be you. I haven't noticed that it happens to me, but maybe I just haven't noticed it at all. It could be night vision getting worse, who knows. I'm sure it's not an easy correlation, though.

 

funny i have the opposite effect
i guess the electric steering keeps a electronic centre point to provide more relaxed driving

 

I've always thought that the steering in this car is overly twitchy.
Whenever I get back into Goofy after leaving him for more than a couple of days, I have to get used to the steering again.

OK. I know that the members of "Prius PRIDE!" will say that we unwashed philistines just grew up with bad steering.
To be fair, the Prius pretty much goes where you point it, and mine does not drift about too badly---unless the wind is above 'calm breeze'...or there are other cars on the road...or the road surface is irregular...etc....
There's just not a lot of feedback from the road, and I personally find the steering to be overly light, which could translate into the "moth effect" for us old fogies that grew up in the days before video game steering.

You get used to it.
As Kermit the Frog would say: "It ain't easy being green!"

 

constant ratio steering in the Prius versus variable ratio in many other cars will also amplify your steering movement.

 

Actually, I've had several cars with better steering. My problem with Prius steering isn't that it's too light, there is too little feedback.

I can live with it.

 

Little feedback, also known as "road feel", and zero dead band. Most steering has a little slop around the center point, where you can wiggle the wheel a bit and not have the wheels turn. With the Prius, every twitch is translated into a steering movement. It makes it easy to steer, but it also means you have to steer all of the time. I find a very light touch helps.

Tom

 

I find the Prius steering is very precise, which by some measures this could be called "twitchy". This is more a mechanical issue and nothing to do with EPS. One experiment you can perform is to unplug the EPS and drive to see how it feels. It is possible to modify the EPS to have less boost.

To disconnect the EPS for testing, it's easiest to pull the connector at the EPS ECU located above the steering column under the dash.


Personally I find the steering feel very good, with a very European feel. Not quite as good as my old Peugeot 505 used to be, but definitely acceptable.

Centering force is caused by the caster angle set in the suspension geometry. I don't know if this is adjustable on a Prius, but if it is, it could be something to check into.

 

I'm going to go with no, it's not the electric power steering and no, it's not just you.

I've had my new 2010 Prius for less than a week and I've noticed the same thing... I definitely tend to wander a bit more than I do with other cars when I look down for a second.

However, I feel reasonably confident saying that it's not the electric power steering because the car I traded in for the Prius was a 2007 Chevy Cobalt which also has electric power steering and I didn't have this problem in that car. I suppose it's possible that I had just gotten used to the Cobalt, but I don't remember having this issue when I first got that car either.

Maybe it's just a Prius thing. I've got less than 200 miles on it now, but I imagine that eventually we'll get used to it.

Brett

 

My guess is it's not the steering, but rather the front end alignment geometry. To increase MPG, you need to have a more neutral setting, whereas some cars have a more "self-centering" alignment.

 

Welcome Aboard Brett! :welcome:

My daughter has a Cobalt, and yes...I wish Toyota would have stolen its electric steering for the G3.
Don't worry though. I've got 4300 miles on mine. You'll get used to the steering, and you'll get really used to only paying 25 bucks for a fill-up!!!

Good Luck with the car!!!

 

Thanks, I really like the car so far. I definitely like the time between fill ups... In fact, I haven't even had to fill it yet. I bought it Thursday evening and by the time we worked everything out it was too late for the dealer to fill up the tank, so they told me just to take it as is (with three pips on the gas gauge) and drive it for a bit and when it was low to come back and they would fill it for me. I figured that wouldn't take too long, but 24 hours later after a bit of driving I still had three pips on the gas gauge... It took me until Sunday afternoon to empty the tank... But that definitely made me happy. At this rate I still have better than a week before I'll have to fill it myself for the first time.

Brett

 

Hi All,

I am having difficulty relating to this, having driven a Prius for 4 years now. But, I know its an issue for people new to a Prius, having recently watched a newbie drive a Prius, and he was constantly twitching the steering all over the place.

The Prius steering does not have a dead zone. And its very low friction. In reality the friction is the same, its just the effect of the electric power steering to eliminate the effect of the friction in the system. So, a very small input, results in a very small change in direction. Versus, hydraulic steering, where a very small input usually does nothing.

One has to learn to be calm with the steering hands. And to accurately find the true on-center steering wheel position. Once, one finds that true on-center position, then one needs to avoid sub-conciously making small steering inputs. As these then just have to be recompensated for.

 

The "self centering" feel comes the amount of castor angle designed into the suspension and from the amount of toe-in. For toe-in, the tie-rod connecting to the left and right steering arms is adjusted so both tires are turned in slightly when going down the road for the self centering feel.

Maybe some people like it, but I think its a waste.. you are flexing and as the tires wear down, scrubbing rubber off the tires for the benefit of the "self centering" feel. There needs to be a very small amount of toe-in only to overcome the flexing of the rubber bushings in the suspension which allows the front wheels at speed to toe back out ever so slightly..

On all of my vehicles I've always tweaked the toe-in just to the point where there only enough left to overcome the bushing allowed toe-out.. The vehicle steering will feel and is more responsive at this setting but will have a tendency to wander a bit more.

Perhaps Toyota has come to the same conclusion in the interest of fuel efficiency and runs with minimum toe-in.. Toe-in is a form of rolling drag on the vehicle..

So far as wandering due to distractions such as looking down at your cellphone, a more responsive steering will amplify YOUR steering errors... Put the cell phone down!

 

I find I always veer into the middle anyway, doh.

Anyway, I love precise steering. If you want sloppy steering I was driving a corolla a few years ago you had to turn the wheel a half dozen times just to get it to react it was sloppy as all get out, just makes for an awful driving experience.

 

Yes, the Caster angle determines self-centering, however excessive Toe in will REDUCE the self centering by increasing steering force. Ideal Toe-in (for efficiency) will produce the most accurate and responsive steering. If it is too far in or out, not only will it wear the tires, but it will reduce efficiency and produce a heavy and less accurate steering response.

No, This is incorrect!

The reason there is Toe in specified is not solely due to "bushing slop", but mainly due to tire contact patch float. The other factors including bushing slop are minimal compared to what the tires contribute. The contact patch on the tire actually tends to hit the road splaying slightly out from the plane of the wheel due to the fact that the sidewall is flexible. Of course this varies by specific tire brand and type, as well as with speed and sidewall temperature. The Slight toe in is set up to compensate for this, so that you have reduced friction and more precise steering.

If you change to lower profile and/or high-performance tires, they will have less contact patch float, so thus need less toe in to compensate. Likewise, if you tend to do more high speed driving and in hotter climates this will also be affected. Toyota's specs are probably set to the average derived for the OEM tires they specify, with average temps and driving speeds. With many upgrade tires you will need less toe. Problem is determining this is near impossible with a standard alignment rack, you need special instrumentation on the car while driving at speed so the aerodynamic and road forces acting on the contact patch can be accurately profiled.

LRR tires typically have stiffer sidewalls as that is where a lot of energy is wasted, so you will see all these newer vehicles that come with OEM LRR tires have less default toe-in specified. The rolling resistance mainly comes from the contact patch flattening out on the bottom where it contacts the road, but also from the anti-paralleling effect that causes the contact patch to splay out. This is also why increasing tire pressure yields less rolling resistance at the expense of traction and ride quality.

 

Try driving a 09+ Corolla. The steering is EXTREMELY light, difficult to keep on center and no steering feel at all. People complained so much that a TSB was issued to replace steering motor and flash the ECU.

 

At lead the Prius doesn't do this when you take your eyes off the road, now that would be BAD!