Instability at hwy speeds

I feel your pain.
I swiched from Minicooper clubman S to Prius V, and my other car is X5. I bought Prius last month and I have about 1500 mile on it ,I have hard time driving straight on free way, I notice a lot when I change lanes car give you extra movement like old Cadillac. I was thinking suspension is too soft so I am planing to put low down spring (should be around 10% stiffer) see what happen.

 

It depends on what the 'issue' is.

Believe me....I'm not a fan of the Priuses 'X-Box 360' steering, but if your tires are properly inflated then the vehicle is not "unstable" at freeway speeds, in high winds, going H2H on 2-lane blacktops, etc....
I think I read where you only have about 1500 miles in type. You may just not be used to the steering in this car as opposed to whatever you were driving before.

I've only got about 8500 miles in this car, and it's a company car...so I won't regale you with stories of my punching large holes in it's safe operating envelope....

If you're underwhelmed in the handling capabilities of this car, then you're in good company...it's not a sports car.
Not even close....
However (comma!) I don't find it to be the least bit unstable.

 

the issue i have with this logic is that i've never owned or driven a car, be it a honda, volvo, bmw, what-have-you where it requires *perfect* tire inflation to have noticeable stability gains. if i have to worry about a couple psi difference to maintain stability now, i'd hate to see what happens when tire gets really low after picking up a screw or something...that sounds scary.

i'm pretty sure i'm used to the steering, but again why would Toyota make a car that requires someone to "get used to the steering"?

for the record, i think the steering is poor at best and agree with your "xbox 360" comment--haha

don't get me started on the handling. while i didn't expect it to compete with the handling prowess of a bmw, i did expect it to keep up with other commuter cars and it simply does not.

don't get me wrong. the car is great and does everything i expected it to do and does it well. i guess i just didn't expect these other things to be "issues" as i assumed all cars were up to a certain spec in these terms. however, despite all of this, i won't be getting rid of mine anytime soon

 

The steering is twitchy to be sure, but I wouldn't characterize it as unstable. You gotta remember that the Aichi Iron Works had to sacrifice more than a a few things at the altar of economy and environmentalism to bring this car to the market within a predetermined budget.
Handling is on that long list, along with a few other things like interior appointments, and body styling---although I find the car to be rather well styled given its primary mission and governed by the same---and that's purely subjective. I mean...It could have wound up looking like a Pontiac Aztech... It's refreshinig that Toyota didn't put this thing to market looking like it was designed by the same 16-year-old bubblegum chewer that designs the majority of jelly-bean shaped cars that you see on the roads these days. They actually put some thought in the lines of the G3.....like it or not.

I always advise P3's (Prospective Prius Purchasers) to drive (rent)one for a weekend before pulling the trigger on a new G3. As I've said more than once, there are certain items in the Prius ownership experience that should be fully explored before you stick one in your driveway....and a 10-minute test flight with some sniveling sales associate bolted to the copilot seat doesn't usually cut it.

Unstable?
Naaaaah. It's a slab-sided front-wheel drive sedan that sits on skinny tires, and you may experience a little wind buffeting at speed, and the electro-lux steering doesn't inspire much in the way communicating what's going on down on the road. You'll experience more than a little body roll and understeer if you try to fling this car around on a parking lot or back country road somewhere, but the dimuitive thrust-to-weight ratio means that there's not much torque-steer to worry about!!
Like you said....this ain't no BMW.
But then....a BMW ain't no Prius either!!

 

I drive daily on the highway...at least 70 miles. We have rain and wind here in TX. I have Prius V/Five. NO issues with it. I find it relaxing on the highway, like my wife's TSX or my Sienna minivan. Now, my old SUV (G-wagen) can get pushed a bit due to its tall boxy design. Sure, my old BMW M3 was stable on the highway, but that is a different animal. Not sure if the V/Five's faster ratio steering or 17" rims has anything to do with it, but i like how my Prius performs on the highway. The Prius V/Five also has unique shocks and springs...so, not sure if that has anything to do with it either. No float with my Prius.

 

Please elaborate - you had it custom changed, or do they really sell it there with this "feature" compared to other versions of the Prius?

To my knowledge the shocks/springs are all the same across the Prius options offering.

 

Not true, at least here in US. Actually, you can help me. Call your Toyota dealership over there and ask them about parts number for springs and shocks. Ask them if Prius with 17" rims have different shocks and springs, based on parts number.

Here in the USA, Prius with 17" rims have different parts number for shocks AND springs. This is not aftermarket. I am only talking about stock suspensions.

 

I will ask my dealer but it will take some time - bear with me.

 

Yes, unstable in crosswinds. Gen 3 is much better than Gen 2. Tested at WGI Saturday in 50mph gusts on wet concrete. Worse when you have a full load in back on top of battery pack. When weight is on top/or behind rear axle front will drift when hit with cross winds. This is due to big side profile of car to cross winds and weight of battery pack in back. This condition will casue over steer conditions which feels unstable and can cause any sudden movement of the steering wheel to make the car react badly.

 

Torque at low speeds are at max..

Back to the OP, it sounds like the 15 vs 17 tires make a huge difference in instability.

 

Really?

-Brad

 

70 or 80 should be a cake walk for this car...and it's not!

 

Huh?

 

My English Grandfather used to say

"'Tis a poor craftsman wot blames 'is tools"

 

? with 15" rims - likely.
With the 17" stock rims with 215/45 tires I see absolutely no issue. And I have driven it up to 190km/h and for extended period of times at 150km/h. Even with 16" 195/55 winter tires is not bad.

Sure, the Prius is no Ferrari, but it is not a boat at all. The Gen2 instead... when I test drove it I took a couple of bends "happily" (i.e. with higher speed than normal) and it felt like a boat - that was the other reason I had decided not to buy it and to wait for the Gen3.

So - I see no issue compared to other similar cars in its category and type of vehicle (again, not a Ferrari) at 70 or 80mph. Really. I have seen and driven much worse.

 

Sounds like a wise and talented man.

I concur. The GenII is rather like a boat with the 15" wheels but slap a set of 17"s or larger wheel on it and it really does transform the car. I'm not kidding when I say the difference is night and day. Even with mushy stock suspension with 132,000 miles on it, I can sling around corners well over double the speed recommended. You just have to get used to "setting" the car up for the curve. Start the turn and let the car body shift into position then pour on the speed.

 

Great Quote. I agree.

If you consider the Prius (G3...I don't have any stick time in a G2) to be unstable, then you may need to consider public transportation. It's not a sports car to be sure, but I've found it to be very drivable on the interstate, and on 2-lane blacktops.

 

So to improve stability in All Pris: 1. Use good rubber (Bridgestone Ecopias or Potenzas), Inflate it to 42f/40r, Put any heavy luggage in rear or front seats, not on top or behind rear axle. Slow down in high cross winds conditions. Car is still only 3000lbs and almost all small light cars get blown around in high cross winds.

 

They are an unnecessary expense.

 

Just had 2nd Dealer maintenance visit and first alignment check @ 10K. Tire wear normal, LH front out .02 on one setting, missing clip RH front wheel well (both corrected), tire wear normal, pressures bumped to 42F/40R and all else normal.

My Prius did float at highway speeds. I believe this is the combination of the electric steering, body style, weight and tires. Minor alignment correction was not enough to make any real difference. The increase in tire pressures however all but eliminated the discussed floating, resulting in a "reasonably" stable ride. It's hard to say if there will be any real increase in MPG...Oh wait...it's +3.14 right?

Anyway, FWIW...Thanks to all that passed on the PSI recommedation here on PC. :rockon: