Side to side rocking/pulling

[Wret]

I've been observing a rocking motion as the car drives over slight irregularities in the road surface, such as seams in the asphault. I'm not sure if it's getting worse or I'm just more attuned to it. It's especially evident when driving over sections of road where the lines have been ground out. This feels like I am oscilating the steering wheel half an inch or so and at the right speed the car rocks dramatically.

Otherwise, there does not seem to be any looseness in the steering as might indicate worn tie rod ends or ball joints. The car does not randomly take off in one direction; rather it moves, then comes back. The motion does not pull on the steering wheel.

Anyone familiar with these symptoms?

[saaber]

Originally Posted by Wret

I've been observing a rocking motion as the car drives over slight irregularities in the road surface, such as seams in the asphault. I'm not sure if it's getting worse or I'm just more attuned to it. It's especially evident when driving over sections of road where the lines have been ground out. This feels like I am oscilating the steering wheel half an inch or so and at the right speed the car rocks dramatically.

Otherwise, there does not seem to be any looseness in the steering as might indicate worn tie rod ends or ball joints. The car does not randomly take off in one direction; rather it moves, then comes back. The motion does not pull on the steering wheel.

Anyone familiar with these symptoms?

If you are referring to the "grooves" in the road where truck tires normally are (2 groves in each lane), it is normal for the groves to pull you to one side or the other (and/or rock back and forth). The road feel in the boxster is so pronounced that it amplifies these grooves whereas with "slushy" cars you won't feel them at all.

Try roads where you can definately see the groves and then compare to a new section of road or one where there are no groves. There will be big difference. Also the boxster transmits to the steering wheel rough pebble road surfaces differently than smooth road surfaces and any imperfections are amplified. That has been my experience anyway.

I wonder if any car transmits road feel better? Maybe a lotus elise/exige?

[roadracer311]

I know what you're talking about. I feel it too. Higher speed turns with pavement seams in them (concrete slabs) give me this same feeling, like the car is steering by itself as it goes over bumps. I would describe it the same way, as if I'm turning the steering wheel in the middle of the corner. I've had several very responsive sports cars before, and I love the handling of the Boxster, but this sort of feeling is unsettling.

I've ordered one of Pedro's Technobraces, with hopes that this will reduce the feeling of the car steering itself as it goes over bumps. I'll report back once it's installed.

I've replaced my tires and also had the car re-aligned (not to address this problem, but just because it was time to do it), and neither had any impact on this feeling.

[CJ_Boxster]

Well i do know that the rear ends tend to get squirly on uneven road surfaces when your rear tires are worn to the point where they would need to be replaced in the next 1000 miles.

How do your tires look... still new or getting close to replacement time?

[Wret]

My tires are getting a little low on tread. Maybe that's why it seems to be getting worse. I'm also going to check the alignment.

[Wret]

New tires a couple days ago fixed the problem. I've never seen handling so dramatically affected by worn tires. Glad to be rid of those P-Zero Rossos.

[CJ_Boxster]

Good deal! What tires did you get now?

[Wret]

Got a set of Sumitomo HTRZs. Not my first choice but I found a deal I couldn't resist; less than $400 delivered.

Actually I am pleased with them so far. Smooth and quiet. All the noise and vibration is gone (I was half convinced I needed wheel bearings. Have put them through any hard cornering but they actually weren't too bad in the three inches of snow we got yesterday.

[roadracer311]

I'm surprised that changing your tires fixed this problem. The problem with bump-oversteer on my car remained when I switched from the stock Dunlops to Michelin PS2's.

I installed a lower suspension brace and now my 2003 S behaves itself much better when cornering over bumps.