PRIUS OUT-OF-CONTROL IN HEAVY WIND !!

I am firmly in the skeptical camp on the benefits of the BT Brace. I can see how it could help control some body sway and improve handling in turns by stiffening the chassis, but can't see where it would help with buffeting from the wind. I'll be interested to hear your results.

 

I also would recommend the alignment check. We've driven our Prius a couple times from Chicago down to central Kansas and encountered some good winds on the highway. But never any buffeting noticebly different from that I have experienced driving other cars under similar conditions (Subaru Outback, Chevy Cavalier). We certainly never felt unsafe, and we were passed numerous times by semis.

 

I realize that you say that you are "desparate", but it seems like you are rushing to judgement on the cause and solution to your problem. I can see the benefits of installing the BT Plate to stiffen the chassis and improve handling, but I don't see where this is going to help with wind buffeting. All you are doing is stiffening the chassis in an attempt to limit torsional flex. This really doesn't seem to have much to do with the wind.

Also, I think you need to figure out what is causing the problem first -- then work on solving it. You are talking about changing tire pressure, adding chassis stiffening plates and having the car realigned. Any one of those things could solve your problem, but if you do them all at the same time, you will never know which one really did. I just hate to think of you throwing good money after bad in an attempt to solve a problem that may be something as minor as poor alignment from the factory.

 

I'd recommend the simplest solution first: Try getting used to the car.

I noticed at first what I thought was some unstable handling at high speed with crosswinds. At first, like you, I felt a little concerned. I compared to my other car though and realized I was OVER-STEERING because my Prius' steering seems to be very responsive in contrast with what I'm used to.

I didn't change a thing except my own response to the car's tighter steering, and I haven't had a single "scary" moment since that first week or two of getting used to the car.

 

Yes, the BT Plate will stiffen the chassis. The suspension is totally a separate system from the chassis, but both work together and ultimately impact handling.

In terms of my Prius, it is not a touring model and I am running 42/20 on the factory Goodyear tires.

I really think most of your problem is your wife adapting to a new car. If she was used to driving an SUV, the Prius is going to seem much more responsive, because it is a much smaller and lighter vehicle. She was driving in heavy winds and she probably had to add more steering input that she was used to in the SUV to counteract the car being buffeted from the side. I would bet that when she gets some more time in the seat and becomes more comfortable with the vehicle, all of this will become a moot point.

 

FloridaWen, can you quantify how heavy the "heavy wind" was that caused all of these problems? 20 MPH? 50 MPH? 100 MPH? If the car was literally "swerving from lane to lane" in these winds and, as you said, your wife is not prone to exaggerate, then it must either be either ridiculously strong winds (100 MPH+) or there is something seriously wrong with the car. I've driven in moderately strong cross winds (40-50 MPH) at relatively high speed (~65-70 MPH) with our "stock" '05 Prius (no fancy alignment; no BT plate, the stock tires) and never had any problems. Do I notice buffeting? Absolutely. Do I have to adjust steering a bit to compensate? Definitely. However, at most I move around in the lane a bit and have never felt that I was in danger of swerving into an adjacent lane.

 

I'd describe it more like this:

Any vehicle will be pushed by the wind, and you naturally tend to steer into the wind a little to compensate for being pushed. If you're pushed exactly the same amount in your Prius as in your other car, and you compensate in your steering by exactly the same amount, you'll be over-compensating in the Prius and end up correcting... probably over-correcting, so you feel like you're fishtailing.

I believe the alignment check is free for a short period, so you should still do that anyway. Meanwhile, be gentle on the car during break-in. Drive the speed limit and be cautious until you feel like you're really in touch with the car. You'll find that you don't really take much longer to get anywhere, your blood pressure will go down, and your fuel economy will go up!

 

<div class='quotetop'>QUOTE(Ichabod @ May 23 2007, 09:07 AM) [snapback]448073[/snapback]</div>

Same for me!!!

<div class='quotetop'>QUOTE(Swanny1172 @ May 23 2007, 09:12 AM) [snapback]448076[/snapback]</div>

42/40 right????? NOT 42/20?!?

<div class='quotetop'>QUOTE(FloridaWen @ May 23 2007, 09:02 AM) [snapback]448069[/snapback]</div>

I also changed out the stock good year incrapities with michellin pilot exalto A/S, pressure 42/40 and wow, HUGE difference in handling and stability.

4 new tire for sale ... anyone? ... anyone? (tap tap tap) is this thing on?

 

Maybe this is yet another built-in safety device of the Prius: in inclement weather, slow down for safe travel. Plus as others have stated, blood pressure lowers and MPG rises. Win-win-win!

I do think many people just overdrive conditions. It ain't a perfect driving world out there (as EPA testing is!), so adjust accordingly. After 3 years in a Prius, I feel safer (and more at ease) than any other car I owned. That's an old Rabbit, a CJ Jeep, a Harley low rider, and a Pathfinder. Try the crosswinds on a motorcycle...that'll tighten your grip.

 

I work in the Mojave Desert here in So Cal, where winds routinely peak 60+MPH, and every year there are enough super windy days (up to 80MPH) to blow over at least a dozen tractor-trailers. The only effects I've noticed from this wind is that it kills the MPG very fast, and when you drive into the 'dead zone' behind a windblock (in the form of a crossover berm or a big-rig itself), get ready for a bit of a drag towards it. I've never been blown out of my lane, and I would say the Prius performs 75% of how my old Outback did in the wind. And, not starting a debate, but that's without the BT Stiffening Plate, which I still may install.
As long as you're a competent driver, a correctly adjusted Prius is 100% driveable in high wind conditions.

 

When I got mine, I thought it handled terribly in even slight wind on the Interstate. I felt like I spent all my energy trying to get it to stay in the lane in a semi-straight fashion. Now, with over 2,000 miles on it, something is different.

Either I have learned to drive it better or the breaking-in interval has gotten things settled down. I'm having no trouble at all.

I did not change anything. Haven't even checked the tire pressure. It's just fine now.

Better than fine. It's great! I don't notice the wind as much as I did in my Passat.

(It is probably a learning curve thing.)

 

Hi FloridaWEN,

The debate over the plate has been ongoing for years. The approximate votes for the plate is about 90%. But that does not mean you do not have an alignement problem.

Steady state cross winds, like in a desert, are not going to cause steering problems. Nor drving through a wind-shadow which lasts for what 1/4 of a second is going to be similar to gusty conditions. Its the gusty conditions, that go from nothing to 40 in less than a second that are when things get dicey.

When I first got my Prius I was lucky (? has not happened this year) to have two identical days with those gusy condtions mentioned above, seperated by about a month. The first day I had no plate. But being an engineer, and wanting to see if the problem was PIO (Pilot Induced Oscillation) or not, I held the wheel perfectly steady, and let the wind take the car while drving at 65 mph. This is called the Step Response in control theory. The result was about 1/2 of a lane of movement, or about 10 feet with dramatic roll and yaw. After that I ordered the BT Tech plate and installed it. No change in tire pressure - at the time I was running the door-panel values, on the 15 inch tires. After installing the plate, I repeated that test at the same section of roadway. There was no yaw observable, but the car moved about 3 inches in the lane. There was still dramatic roll when the gust hit, and it takes some nerve to hold the wheel steady with that much roll. The Prius does have very little steering dead zone, and the electric steering is quite quick. With the plate, one can easily counter steer in synchrony with the wind and hold a straight line. Without the plate, one needs to not only consider the wind, but what phase the car is in, during its vibration.

I believe the BT Tech plate stiffens the chassis, such that the rear end ringine response vibration frequency and duration is dramatically reduced. After you put the plate on, you wont feel your rear end shaking all over in a Prius. The response I experienced in the first wind storm without the plate was about 1 second period, which lasted for several cycles. With the plate, the period was down around 1/10 of a second, and decayed the way in well less than 1/2 of a second. Kinda like a buzz at the time of wind impact and then quickly gone.

I now run my tires at 42/40, but again, that is with the 15 inch tires. The only comments I have seen on here about the 16 inches, is that 42/40 makes the car squirmier. And indeed a test at 45/43 on my car and it became much more squirmy. At 42/40 one can just begin to detect the onset of the squirmness, with the BT Tech plate. Squirmy being defined as understear due to some kinda front end phenomenah, not neccassarily wheels skidding.

 

Hey,

The Prius is not inherntly stable in big crosswinds.
It has a high prifile given its width, so it will be affected by crosswinds, alot.

What I have noticed (on the drive up th e15 between Vegas and LA, VERY serious winds, I see a flipped over big rig a week!) is that "overcorrection" is more of a problem than the wind. The wind is bad but lasts for but a second. I've learned to just let the wind have its way, and just guide the car, instead of trying to maintain the exact same line.

 

When we first got our Prius the effect of cross winds was very noticeable when driving on the highways here in Oklahoma. After owning the car for about a month, I ordered the BT plate. After installing it the car was much more stable in highway driving, including driving with cross winds. It is really worth the money. I don't even think about them any more. It didn't make me drive any faster or agressively. I usually drive near the speed limit and rarely exceed it. Our car is not a touring model. I think you will like what the BT plate does for you.

 

Well, the Prius is a bit skittish in crosswinds, no doubt about it. One look at its bluff side profile had me wondering, even before I bought it. Those teensy tires, too.

I installed the TRD suspension and the BT brace on my Prius before she even had 1,000 miles on her...and haven't regretted it since (even when she scrapes on driveway entrances!)

Do you think the difference in feel vs. the Acura is due to the electric power steering in the Prius? I like the stiffness, actually, but it's dead as a doornail, feel-wise...this may be something she's reacting to and doesn't even realize it yet. I don't know if it's a variable ratio setup, but maybe maybe the ratio changes more than her Acura, too, making the Prius more 'touchy' as speed increases(?)

Alignment can help a LOT. From what I've read here the front end is align-able, but the back isn't really without using these shims that really aren't readily available. Even so, having the front end within specs can be quite helpful.

You don't think this is all because she misses the Acura, do you...?