PRIUS OUT-OF-CONTROL IN HEAVY WIND !!

Lots of people with this problem have gotten the BT Brace and find that it helps with the high winds. It replaces the thin brace under the car with a stronger aluminum one.

 

<div class='quotetop'>QUOTE(FloridaWen @ May 22 2007, 07:09 PM) [snapback]447663[/snapback]</div>

With all due respect sir, has the alignment been checked? There is a spirited thread here about a Prius blown into the next lane. The concensus was that this was pretty much impossible. Perhaps the circumstances are different or my memory is not 100%.

 

The Prius is certainly lighter than an Acura MDX, so you are going to notice some lateral movement due to the wind or passing vehicles. I know that I noticed a difference between the Prius and the Audi A4 I traded in on it in this regard. However, I don't think the Prius is all that unmanageable or at all unsafe.

 

I use 42/40 on stock Integrity tires and don't have the same problem. First, I'd get the alignment checked, and then I'd order a BT brace.

 

<div class='quotetop'>QUOTE(Swanny1172 @ May 22 2007, 05:40 PM) [snapback]447682[/snapback]</div>

I don't know that lightness is necessarily predictive of susceptibility to being buffeted by cross-winds. If that were the circumstance, my MINI (2,700 lbs.) would be all over the road in cross winds. I would echo the suggestion to check the alignment (in particular the Toe setting). If it is not slightly "in", you could have your answer. Separately, if the Toe was/is set to factory specifications, then you are probably looking at a wider tire. I have had 205/60-15 (Michelin Pilot Exalto A/S) tires on my Touring edition from day 1. I have driven the car in cross winds approaching 50 mph with no wandering. Slight body roll when the winds were hitting the car, but no wandering around the roadway (and this was at a road speed of 65-70 mph indicated). You might try the BT Tech rear brace as a first step (since it costs less than wider wheels and tires), but don't be surprised if the problem continues (there is a very contentious thread in the Modifications subforum where both sides of the claim of handling improvement are argued) absent wider wheels and tires

 

<div class='quotetop'>QUOTE(apriusfan @ May 22 2007, 08:55 PM) [snapback]447696[/snapback]</div>

Good point, but I think the lightness of the vehicle combined with the high side profile can lead to it catching the wind. The Prius is a very aerodynamic vehicle from the front, but the design results in the car being somewhat wedge shaped. So from the side, there is a lot of surface area for the wind to catch. Many have complained about being buffeted by the winds from large trucks passing.

 

<div class='quotetop'>QUOTE(Swanny1172 @ May 22 2007, 06:02 PM) [snapback]447704[/snapback]</div>

And the side profile may be more predictive than lightness in susceptibility to buffeting. My personal experience makes me think the solution will be found in wider tires.

 

<div class='quotetop'>QUOTE(apriusfan @ May 22 2007, 09:06 PM) [snapback]447707[/snapback]</div>

Of course wider tires will also lower the MPG because you have more rolling mass and more tire in contact with the road. I don't know. I am running my tires at 42/40 and have never had an issue with the car being blown into another lane. Sure, I've had to make some corrections due to wind gusts and passing trucks, but not to the point where I would say I was out of control.

 

I've driven through some pretty serious crosswinds on stock 15" tires, no magic brace, no mods...and I've never been close to "out of control." Definitely some buffeting, maybe a little drift to one side or the other, but all easily corrected by a little bit of steering input. I think JimN's suggestion of an alignment check should be your first order of business because that kind of instability just isn't normal.

 

Compared with a 2005 Camry 4-cycl LE,
a Prius is 3" narrower in width, same height, much larger side area (due to hatch back style),
and 200lb lighter. There is no doubt that a Prius is less stable under heavy side wind situation.
Note: An Acura MDX is 10" wider and 1600lb heavier.

I certainly hope that the next Prius is at least 3" wider than what it is now.

 

<div class='quotetop'>QUOTE(Swanny1172 @ May 22 2007, 06:11 PM) [snapback]447710[/snapback]</div>

Or, you can go with lighter wider wheels that offset the added weight of the wider tires (I am hitting 52 mpg in predominantly highway driving (65-70 mph) at 1,300 miles (still in break-in territory)).

But, given the concern about control-ability, if the alignment is at spec, I think a fuel economy penalty (from wider tires) will be a small price to pay for peace of mind.

 

I agree that the prius is a bit more unstable than a heavier vehicle or one with significantly wider tires. It also seems that the steering wheel is more responsive to slight touches. But I haven't felt out of control up to 77mph with some wind.

Perhaps it really depends on the direction of the gust?

 

After we bought our '04 Prius in Fresno, CA, I drove it back to the SF Bay area over the Altamont pass (home of the windmills). We had driven to Fresno as a family, but had to return in separate cars. Upon returning home, my wife said that she had had a rough time controlling her Passat wagon in the high and gusty winds. I had no trouble at all in the Prius, even though the car was completely new to me. I had to slow down when I saw her falling behind. The winds must have been fierce, since only on rare occasions have I noticed a problem in the Passat.

Priuses (sp?) are well known to be extremely sensitive to alignment -- even small differences w/in spec can be noticeable.

 

Yea . . . what THEY said . . . Alignment & Brace.

 

I just took mine in for the 5k service (oil change and rotation). I told the service writer that I would like to get the alignment checked for the above issue. They couldn't do it today, but told me to make an appointment next week to have it checked.

I have noticed that the problem was very apparent at first, I noticed it the first week when I took it on the freeway, but seems less apparent now. It was windy here today, and the car moves a little bit when hit with a crosswind, but I don't get the same feeling that the back tires are tracking different than the fronts. Maybe I'm adapting or maybe the tires are getting better with more miles on them. I'm running 39/37 psi.

 

<div class='quotetop'>QUOTE(ystasino @ May 22 2007, 07:09 PM) [snapback]447766[/snapback]</div>

I prefer that now, but it was a problem at first. I was in the habit of moving the steering wheel back and forth in a big car to compensate for 'play' in the steering. Once I realised the wandering in the Prius was my own damn fault, it went away. There's not alot of steering 'feel', as in vibration from the road, but it definitely responds to input.

 

<div class='quotetop'>QUOTE(FloridaWen @ May 23 2007, 02:09 AM) [snapback]447663[/snapback]</div>

I had several cars in the past with similar weight and shape to Prius. From your report I get impression that it was really STRONG wind. I can tell you that in such situations I always had to slow down to about 50 MPH regardless of the car. I just felt it was too risky to go with 65+ MPH speed.

- Piotr

 

Did you read any of the reviews on the BT Tech Chassis Stiffening Plate before you ordered it? From what I have read, I am not convinced that it makes enough of a difference to warrant purchase.

Darell's review at http://www.evnut.com:

"The difference is nothing I'd call profound; about the same difference I noticed when I went from 38psi to 44psi in the tires. If forced to come up with a specific change in handling, I think that the car now seems to want to follow pavement irregularities more. What I'd call a slight dead-spot wander that I don't think used to exist.

The Prius handled reasonably well and felt good with the factory brace. It handles reasonably well and feels pretty good after installing the new brace. I guess I'm not as big a believer as some of the other more outspoken PriusChat members who claim that the new brace now allows them to safely double their speed on familiar roads ??? It looks good, and certainly doesn't make the ride any worse!"