Very wobbly at high speeds

[260zCaliCar]

We seem to have a common thread here. My specific symptom with these new tires is that the z wants to exaggerate my steering, as if it grabs the "rain grooves" in the freeway, then suddenly breaks loose of the groove. This didn't exist with my old tires, and now it does. I haven't tried putting the fronts on the back and vise-versa, but it's certainly an interesting idea.

Just out of curiosity, if you take the car out on a regular street (not the freeway), do you still have to battle the steering? My steering issues are much less on streets (I had assumed it was because there are no grooves in the streets)

Misturmoneybags, you would be doing a huge favor if you let us know the outcome of your visit to the mechanic.

[psdenno]

Did we rule out the steering rack bushings?

Dennis

[misturmoneybags]

260zCaliCar -- on side streets and low speeds the car doesn't wobble at all. Only when it hits speeds higher than 60+ mph. I'll definitely let you guys know the verdict after I come from the Z shop.

[Montezuma]

Did we rule out the steering rack bushings?

Dennis

after tires and wheels not in round...then I think it is the steering rack bushings. Replacing the old rubber set is not a hard job at all.

[=Enigma=]

Wider tires will always be more prone to wander and hunt lines and grooves in the road and can be exagerated by specific tread patterns. The steering on my 2002 BMW 525i is very tight but I still feel this effect on grooved roads or lines in the pavement from repairs. As interesting as this is, it is not the same as a wobble.

[240znz]

I changed from some directional tyres to normal once and the car became very light at over 65mph. I put the old tyres back on and problem when away. Just the tyre choice I made and yes they were cheap.

[hls30.com]

If the above don't work, I have two suggestions.

1) Get Gasoline with a lower ethanol content. You are using Too high a proof for the car to toe a straight line!

2) Quit testing after a Z club meeting at a BAR! maybe the "testing equipment is the source of the wobble!

Seriously,

Two suggestions from personal experience.

1) Verify the nuts at the top of you strut are tight, a wobbling shock absorber(gland nut and/or the strut shaft nut) can do this and so can a wobbling strut assy(3 nuts at the top of the strut towers)-it only happens at speed when the front end lift floats enough weight off the contact areas to let them slide around, and occasionally in spirited direction change when the friction of the contact patch is overcome by the forces of inertia.

2) Verify that the tires are actually round-After adding a front spoiler my car improved seriously, but still had this issue, I had the tires trued, and never had such great tracking and ride.

Will

[rxsleeper]

A little late here but I think Carl said it best. Check the bushings and alignment. Tires can accentuate what is going on but generally bushings and alignment will cause "tram-lining."

My RX8 is set at 0" toe both front and rear along with significant negative camber in front. It will "wander" a bit depending on the road surface and is "twitchy" at speed. Just the way I like it.

Will, thanks again for your help this past Feb. Tom is hoping to be on track soon at RA. I race in two weeks at Nashville and will be testing an entirely new suspension set up.

Paul

[260zCaliCar]

RXsleeper, I think you hit the nail on the head. Your term "tramlining" did it. I googled the word and sure enough, it's a combination of tires and/or alignment. Given that both misturmoneybags and I live in Los Angeles, I found this comment on an Infinity board funny:

"The worst case I ever had was while living in LA - the tires I had installed had their tread grooves at EXACTLY the same width as the rain grooves that SoCal DOT placed in on the freeways. My car would track on those and my car would swerve back and forth in the lane. I got stopped for suspected DUI within a day. I took them back and replaced them with a different brand of tire."

Alignment was at the top of the list of other items that cause this. I suspect the reason I didn't see bushings as a potential source on the other boards is our cars are old enough for bushings to be a potential problem.

Personally, since my bushings only have a few thousand miles on them, and my tires are brand new... It's alignment time. I'll let you know what happens.

[New-to-240z]

Check your bearings and make sure they are set properly. 240Z's have to have the front bearings set just right, or you will experience a shimmy.

I think this is what's wrong with my car right now. I get a slight wobble left to right in my streering wheel when driving on the freeway. I had new rotors and pads put on a while ago and ever since then it has been happening. It may just be because of the rotors somehow warping, but I want to check out the bearings. How can I check to see if they are set right?

[misturmoneybags]

I think this is what's wrong with my car right now. I get a slight wobble left to right in my streering wheel when driving on the freeway. I had new rotors and pads put on a while ago and ever since then it has been happening. It may just be because of the rotors somehow warping, but I want to check out the bearings. How can I check to see if they are set right?

I had this on my previous car and usually when it just pulls to one side, it is most likely alignment.

And I just came back from the Z shop to get a estimate for my rear drums but I asked the mechanic on duty about the wobbling at high speeds and he said that it could be possible that my suspension is set up with 0 toe in. He says that with 0 toe in the car just hunts for the grooves in the road, but he also mentioned that he believes it could be tie rods as well. He'll be doing a full car inspection by wednesday of next week, so I'll give you guys an update.

[ta240]

Yep, lack of front spoiler will cause this.

Having had a car with a front spoiler and one without it doesn't make That much of a difference. Not saying it doesn't make any difference but just not that much.

My current Z was plenty stable at 105 with well balanced wheels this morning. With the old wheels on it it would get squiggly at 75. And I still should get it aligned sometime as I haven't done that since replacing the steering rack (which it wasn't any more stable at speed with the new one)

The spoiler did seem to add stability in windy conditions but again it wasn't a fix for other suspension problems.

Edited June 10, 2009 by ta240