Instability and wandering on freeway solved FINALLY

After reaading your story and the other posts, so many good driving Pri and your white knuckle disaster, I wonder if it could be like a Chevy pickup I once owned ??
The pickup like your Prius was a white knuckle disaster that would leave the driver tired and frustrated after a 100 mile drive. Impossible to go down the center of a lane without constant correction.
I spent a small fortune on new front end parts, new tires and several front alighn jobs with no improvement.

I just lived with the foul handling thing for years, until a rear suspension componant fell apart. That lead to a close inspection of the REAR suspension componants. We found bad / broken parts on both side that allowed the rear axle to move around and Steer the pickup. I replaced the rear suspension parts( usually bulletproof, dead reliable leaf soring suspension) and instantly cured the foul steering piece of crap.

Spent a lot of time and money working on the wrong end of the machine. I wonder if defective REAR suspension might have been the problem with your Prius ???

 

All the things that the OP tried on the drifting issue however I didn't see any mention of new (not larger) tires but many alignments. Since the only thing contacting the road is the tires, that to me would be something I would change after an alignment. Many tires would get rounded on the edges and that will cause the car to not track properly. If your tire pressure is also not correctly set, that can also cause the car to go off track. Many times going to a larger tire would make the car less stable.

I had an experience that I thought was a bad alignment. My steering wheel seemed off centered and the car would go off track. Had my tires rotated left to right and the car was doing the opposite. To the naked eye the tire was fine but the end result was to just change out the 2 tires where they both matched perfectly and the problem went away.

 

I have brand new Michelins so I've already done that to eliminate the tire question.

SCH-I545 ?

 

Any improvement after the tire change? I noticed you have a new GenIII and the issue you experience seems very unusual as the GenIII steering feels much more heavier and shouldn't have any steering issues.

As for the original OP, I'm wondering if the steering feels loose in any way? There was a intermediate extension shaft recall done on GenII cars and if the extension shaft was replaced improperly, that can cause it to have symptoms of not driving properly.

 

None. Just had second alignment. Still bad.

SCH-I545 ?

 

What are you experiencing that's bad? Loose feeling and it's drifting in different directions? The roads are ok too?

 

Yes. Exactly as you describe. At first I thought it was the wind. Then the road. Then the tires, Then the alignment. Then the tire pressures. Then the weight distribution. --to be continued--

I'm planning on have the caster set to max spec next. I keep playing with tire pressures but nothing seems to make a difference. I want to keep this car forever but I don't think I can live with this for highway travel.

 

Did Toyota ever take a look at your complaints? Bad struts?

 

Not sure. The Toyota dealer did the alignments though and the service manager is personally assising me to try and solve this so, I suspect they have.

SCH-I545 ?

 

Yes this bothers me too. You really notice it if you bounce between different cars. Same feeling the car tracks every little line in the highway & you have to be constantly engaged with the steering can't relax and just let the car roll down the road. Twitchy. 3 sets of new tires. Bt plate. Aligned to perfection.

Looks like the Gen III rides better though.

Most important thing to do when the Gen2 feels like this is to hyper inflate the tires. The lower the tire air pressure the more it twitches. But then the car rides like crap and hits hard. In fact its my air gauge. When I feel it really twitching yep low on air. Otherwise very very good car so far 7 years later.

This car is not for everyone.

 

I am happy to report that after I installed the TRD Rear Sway Bar, my problem is solved! The car drives fantastic now. I suspect that the 150lbs I must carry in the cargo area and wimpy springs in the rear were the culprit. The sway bar has eliminated the wandering in the lane. I do NOT know if this would have solved any Gen II similar problems but for $220, it should be one of the first solutions to try. I'm a very happy Prius owner now.

 

Thanks for sharing what worked. That sounds like an inexpensive and easy to install fix for the stock Prius suspension.

 

150 lbs is alot of weight. You never mentioned that.

I could see how that would make the car squat a little in the back but doubt that's going to address the more commonplace tracking issue that myself and other posters on this thread experience.

Because how does an anti sway bar in the back no less cause a driving issue when your going straight down the road? Its completely unloaded.

 

edthefox5

Another thread had the details. I think the side to side of the rear suspension due to road undulations and crosswinds caused the direction changes. The sway bar eliminated side to side hence the direction changes.

SCH-I545 ?

 

Right after I posted above I went and looked around to locate that sway bar for my car. Having trouble locating it. Gonna scrub some threads and see if I can find out where they got it. I will definitely try it.

The car is annoying on the highway but its mainly the wife's car so she's used to it. If I can fix this issue I will be happy with the car. Have new tires...tire pressure experiments...bt brace and no joy really.

 

I bought it on Amazon. I have Prime and it was 228 with free shipping.

SCH-I545 ?

 

Was there a rear sway bar offered for the Gen II?

Remember they are different cars.

 

I do not know.

SCH-I545 ?

 

Which Michelins did you get?

 

What most people use is a 24mm bar that was used on the 2002-2006 Matrix