Braking, ABS and slippery feel

Hi mdiguy, welcome to PriusChat. Sorry your first post has to be about a problem.

What you describe does not sound normal. Particularly that <div class=\'quotetop\'>QUOTE</div><div class=\'quotemain\'>the ABS will come on hot days on dry pavement (high 80's) also some times at stop signs or traffic lights.[/b][/quote]
The Goodyear Integrity tires are not the world's grippyest, but you shouldn't see the ABS when stopped or in light traffic. I sometimes have spun my tires on the big white stop-line stripe at lights, when I dropped the hammer and tried to take off fast, but the computer just killed the speed on the slipping tire.

I'm glad you're taking it in to the dealer. I really like the Vehicle Stability Control, which corrects your line of motion when the front or back wants to go its own way. While some dislike the Traction Control, which kicked in when I spun my tire, it is essential for the safety of the Hybrid Synergy Drive. Just don't get in any bad situations on slick roads thi winter where you want to power out, you might not be able to.

Have you tried to activate the ABS where it is supposed to work, a very hard brake from traveling speed? Actually, don't try, just take it to the dealer.

You may also want to search for "accumulator" here on PC. There have been a very few brake problems reported where the brake pressure accumulator or one of its components was bad.

 

I came from a Mini Cooper s with sport package and perreli performance tires. What a big change at first, I often felt that the car had little or no traction and handled poorly. Then I was trying to take turns a little to fast for this type of car, a sports car it aint. It takes some getting used to and you may want to get some different tires if it bugs you that much.

 

Sounds like the traction control. Sometimes it seems to be super sensitive on rough road surfaces. Steel construction plates on the street in the rain seem to trigger it every time. I could be coasting to a stop with my foot lightly on the brake, but once I drive over a steel plate I will feel like the brakes were disengaged for a second before things are under control again. I am accustomed to it now, so it doesn't bother me.

I had to make a fast stop once on a road with a lot of gravel and I had a moment of panic thinking that the no brakes/skidding feel wouldn't stop me in time. After the skidding feeling, the car ended up stopping me a lot sooner than I expected and I'm convinced that my old car would have just slid on the gravel and went into the car in front of me.

I guess the important thing is how it makes you feel, so if the feeling scares you then it might be unsafe. Upgrades like better tires or possibly the bt stiffening plate might lessen the occurence but I'm not sure that the dealer will be able to cure it. All I can suggest is to scout out some road construction on a rainy day to help demonstrate it to the dealer.

 

Just thought I'd add that I've had the same experience multiple times, and I have a 2006 package 3 (no traction control). When I hit any significant bump while braking slightly hard (esp downhill), the car seems to let up on the brakes completely for a second. Most of the time the slip indicator light comes on, but sometimes not. My guess is the OEM tires slip so easily that they trigger a switch to ABS that shouldn't be needed.


Also see this thread, which has links to others: http://priuschat.com/index.php?showtopic=23889

 

We live and drive mostly in Maine. We see it all for driving conditions and live on a gravel road, up a steep hill, to boot.

The first spring snow storm I got into with the Prius convinced me we'd need dedicated snow tires for the winter.

We put a set of Dunlop Graspic DS2s on it. Went through last winter with them. I've been told there are better snows than the Graspics, but I wouldn't know how to know if they were better. The DS2s are sort of phenominal on the Prius. We had no problem on black ice, pebbly ice, wet and dry snow, slush, it handled it all. That isn't to say one can drive with ones head up ones patoot. I write that the car handled everything it encountered, but that's with normal winter driving skills in place. Just be sure you know how much torque the Prius has at low speeds and be aware that it has a tendency to spin tires, activating the Traction Control. When that happens you CAN'T continue with the same power level, you must reduce throttle. Not a problem, as in any other car with the same power going to the wheels you'd be spinning anyway and a spinning tire has no traction and you go no where. If your foot has throttle control the Prius with proper snow tires will go pretty much where a 4WD will go, just not in snow as deep. W/O a throttle controlled foot we'll be reading of your unhappiness with the Prius' traction control.

For someone who drives in Maine it shouldn't be a problem. Heck, even my wife, who by her own admission can't drive on snow and ice has no problem.

One negative to the Graspics... If you are constantly correcting the steering, that is, moving the steering wheel from side to side, you'll find the tires will be squirrely. They have a ultra flexible sidewall that gives a unique motion to the car if you're so inclined to handle the wheel in the manner described. Choose a line and hold it and they perform as expected. The same sidewall makes them a low rolling resistence tire. That translates to a few per cent better mileage when we need it most.

FWIW, if you are applying throttle and hit a bump or washboard TC can activate as the tires are unweighted. If that's the case the light will come on and immediately go off as the tires again get weighted. Same thing can happen when braking as another post says. Is that what's happening? It can also easily activate on loose gravel. If it's gravel that is the culprit, just activate your throttle control foot or start braking sooner and feather the brake somewhat (no pumping).

Another thing to check is tire pressure. Most folks on this forum run higher than reccommended pressures. If your pressure is too low you may not be getting proper contact with the road. Just stay within the max tire pressure rating when the tire is cold and maintain the 2 psi differential reccommended. Personnally, I run 43/41 all year round. It'll give better mileage too. Be sure to check pressures frequently. At least every month, more frequently is better especially if the ambient temperature is changing day to day. It can be a hassle, but it's best. To help with this go to Wal-Mart or a similar store and get a rechargeable air pump, also a quality pressure gauge; a quality gauge is hard to find. I had to order one, but there is better to found online.

 

To the OP:

It sounds like your car needs to go in to the dealer. How can any of the car's control features come on at a stop sign? Unless you are refering to the well-known oversensitivity to sand on the road:

When accelerating from a stop, if the road is slippery, the traction control will reduce power at the same time as it engages selective braking on the wheel that's spinning. The result is that starting from a stop while on ice, the car will get going faster than it otherwise would. If the ice is very slippery, it will get started when other cars just spin their wheels and cannot move at all.

But it is so sensitive that a fine layer of sand, which also causes a wheel to slip a bit, will engage the same mechanism. In this case you'd rather let the wheel slip because in a moment it would clear away the sand and have traction on the pavement. The result is that you feel you have no power, and the car is very slow to get going, which can be dangerous as it can cause you to under-estimate the time it will take you to get across an intersection.

(Some folks have speculated that this sensitivity is needed to protect motor-generator 1. Others just think that Toyota goofed in making TC too sensitive.)

None of this has anything to do with ABS, which does pulse when it engages.


<div class='quotetop'>QUOTE(tbullock @ Oct 4 2006, 06:51 PM) [snapback]328241[/snapback]</div>

All Prius have traction control standard, as well as ABS. It's the VSC (vehicle stability control) that is an option.

 

My 2008 Prius has a very loose brake on rough road. Even if it's slightly rough, it feels like there is no brake at all. ABS light flashes at that time. So I always leave plenty of space in front and slow down long before I think front car will stop. Never had this issue with any other car.