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Discussion Starter · #1 ·
Has anybody seen the posts on priuschat.com concerning instability at speed? I have noticed that my 05 does tend to drift around a bit at speeds over 65 or so, (depending on the surface). I recently changed to Goodyear Comfortreads, and that helps some, as well as giving a softer ride. Haven't had them on long enough to notice any mileage hit. Any way, one guy said to move the front spoilers forward, and gives instruction on how to do this. He's an engineer and a race car driver, and others say that it works. Something about not letting too much air build up under the car, thereby creating "lift" at speed and very light steering. I did it, (only takes about 5 minutes) but haven't had it out on the highway yet. Any thoughts?

Tom
 

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Don't know about dams, but did you get the alignment checked? Also, if you're not at the tire pressure posted on your doorframe, try it there.
 

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It's been said that an alignment with slight toe-in makes it more stable. Specs allow some toe-in as well as toe-out.
 

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:::singing:::

I am a happy wanderer
I wander and I roam...

:) or...

I wonder as I wander, out under the sky...

___
Is it you, or the road? There's one stretch of road near me that drags me all over the place. I have no idea why, but it's a quarter mile stretch that is just dreadful. It's like one of those amusement park rides with the little cars on a track. Just a thought.
 

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Comforttreads

Not to highjack the thread, but how do you like the Comforttreads? Are they much quieter than the OEM tires?
Thanks,
luis
 

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Mine isn't the wanderin' sort, though as Sanny points out, some areas of pavement are funky. There was an extensive thread under Q&A or Technical a while ago and my recollection is that the consensus was cars often come off the dealer's lot poorly aligned and a misaligned Prius tends to wander...
 

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Wandering and High Winds

I've driven the Prius through three hurricanes down here in Florida, and it drove just fine, with no more buffeting than my previous car (Audi TT) or my other car (92 Miata). In fact, the Miata gets whipped around pretty good due to its light weight.
 

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Wandering on some stretches of road

Note to Sanny:

Check out the roadway surface.

I was in Denver a couple of years ago, and they prep the roadway (prior to resurfacing with asphalt) by cutting grooves parallel to the direction of travel, spaced one or two inches apart. Unfortunately, whoever drove the machine that cut the grooves steered like he had a couple of six-packs before coming to work.

Anyway, for a couple of miles, I had to slow to 45, because our 2002 Prius wouldn't stay in the driving lane at higher speeds, no matter how much manhandling I did to the steering wheel.

In Phoenix, they also cut shallower, but similar, grooves; I think, for water channeling during our monsoon rains. But, it appears the machine operator was sober when he was down here, as the lines are straighter. These stretches also feel a little skitterish, but the car stays in the lane.
 

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Discussion Starter · #9 ·
wander

ryecatcher; I do believe that the Comfortreads are quiter than the Integrity tires, although I don't have enough time in the car yet to make a statement that would influence anyone to scrap their originals. I also think that the ride is somewhat softer. Look under the "care and maintance section, pg. 6, on priuschat.com and refer to poster "200volts" remarks about the aerodynamics of the Prius. I did move the air dams in front of the wheels forward, but, again, haven't had it out on the highway to check results. I now know that the alignment can be off from the factory, as noted in many discussions. My car tracks straight with no pulling, it just seems as if it will sometimes " jump over " to the left or right for no reason. 200volts says that this is an aerodynamic problem caused by too much air being trapped under the car, thereby causing "lift" at higher speed, and that moving the air dams forward will direct the air to the outside of the front wheels before it can get under the front end. Hmmmm, I wonder, or do I wander? I know that I ramble.

Good luck to everybody,
Tom
 

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Wandering....

I've been noticing this for years on my 2003 Prius....

I see it mostly on roads that have really wavy cuts in them for drainage....
not all of the roads with cuts, just ones where (I guess) they did a really
poor job of it.

I can't remember what they call those grooves cut in to drain the water
away....

The 134 Freeway in LA in the Glendale area is especially bad. First
time I noticed the wandering I thought I had a flat and pulled over.

I've noticed these on the original and my replacement tires.

But once I hit a newer patch of freeway or an asphalt part, I'm fine....

-cid.
 

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Re: Wandering....

cid404 said:
The 134 Freeway in LA in the Glendale area is especially bad. First
time I noticed the wandering I thought I had a flat and pulled over

-cid.
:lol: This is a bit off topic, but the first time I came to Pasadena to interview for my current job, I flew into Burbank and rented a car. I really thought it had a flat on this stretch of road. I was driving all bug-eyed anyway, being used to a much mellower flavor of freeway traffic. Good thing it wasn't an LAX flight! Got better.

My Prius, however, to get back on topic, doesn't seem to have a particular problem here. But maybe I just tune it out anymore...
 

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My new Prius (1100 miles) has to be steered to go straight. It is always veering slightly left or right & never goes straight too long. I ran it up to 100 mph recently & it was truly scary. I will try the various suggestions on this post starting with alignment (toe in). I think the car is somewhat "undertired" for its size. I don't think that the battery pack in the rear of the car is helping stability either.
 

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I left a big Acura 4 door when I bought my 04 Prius. At high speeds the Acura tracked like it was on rails. The Prius does not. My Prius was delivered with around 45 psi in all tires. The freeway trip home was interesting as it wandered around at 65 mph. I dropped the tire pressure to factory specs and then spent some time getting to know the car. It certainly rides better with 32/35 in the tires and I've learned how to NOT oversteer the car. The steering ratio is a little "quick" at high speeds but I've adapted to it after a year. Tire pressures over 40 psi may give a few extra mpg but the ride and tracking suffer. (My opinion)
 

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Re: wander

tomandbecky said:
My car tracks straight with no pulling, it just seems as if it will sometimes " jump over " to the left or right for no reason. 200volts says that this is an aerodynamic problem caused by too much air being trapped under the car, thereby causing "lift" at higher speed, and that moving the air dams forward will direct the air to the outside of the front wheels before it can get under the front end. Hmmmm, I wonder, or do I wander? I know that I ramble.

Good luck to everybody,
Tom
Tom,

Do you have any new comments regarding this mod? I assume you've had it out on the highway by now. What does it feel like with the dams moved forward?


DGStan
 

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When I first picked up my car from the dealer, I noticed a pull to the left. The service manager suggested to drive 1000 miles to see if it would correct itself but of course it did not. I took it back and had it aligned and shortly thereafter went on an 1000 mile trip to South Florida right in the middle of hurricane Dennis. I did notice some wandering but not that unusual given the gusts of wind that were buffeting the car. All in all the ride was enjoyable. The down side was a significant tie up on I-75 caused by a multiple car accident which included an 04/05 Prius. Fortunately I don't believe anyone was seriously hurt.
 

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Discussion Starter · #17 ·
highway wander

I just returned from a trip to El Paso (135 miles each way), and I did notice a difference from moving the air dams forward. We were in very heavy wind and rain on the way down and the car tracked straight with very little help from me. At times the wind would be straight at us, at other times it would come from the side. I was still running at 75mph. I should also mention that I changed to Comfortreads before this trip, so I believe that they come into play as well. I know that they are much more comfortable and quieter than the Integrity, and go through standing water at speed with no hint of turning loose. I am running 36 front and 34 rear. I also noted no buffeting when following big trucks, as this had been fairly severe before. I know that many issues come into play when discussing aerodynamics and wind flow, and I'm no engineer, but this 5 minute air dam change did seem to make a positive difference.

Tom
 

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I would assume higher air pressure would reduce the problem since the tires would be less "squishy". I also thought going to a +1 wheel/tire combo (16"wheel 185/55 tire vs 15" wheel 185/65 tire) might help as it would reduce sidewall flex. A wider tire (195 or 205) might help stabilize it too, at the cost of some mpg. I am skeptical of the air flow under the car thing, but will try it first since it is simple/cheap. It doesnt seem like it could be that significant and I would assume Toyota carefully "tuned" the airflow for mpg gains. My sense is the big problem is the dense/heavy battery pack sitting toward the back of the car.
 

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tomandbecky said:
Any way, one guy said to move the front spoilers forward, and gives instruction on how to do this. He's an engineer and a race car driver, and others say that it works. Something about not letting too much air build up under the car, thereby creating "lift" at speed and very light steering.
Can you please pass those instructions along? Searching didn't work out...
 

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Re Moving "air dams" or spoilers in front
************************
I looked at the Toyota factory page where you can rotate the car around and zoom in close with the mouse. (Neat IT job by Toyota)
I see a vertical piece in front of each wheel. It looks like a wheel splash guard. Is that what you're referring to...?
 
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