steering / tracking

[lwhssh]

Hi,
1990 56,000 Miles

I notice that when I get on the highway I am really influenced my slight ruts in the road. Rt 78 in NJ gets ruts in the right lane from alot of truck traffic. My car seems to dive into the ruts and I have to fight it to steer it out. It's actually scarey at 70+. Im talking tire depressions in the road that are barely visible, not real deep.
I have a newer pickup that I drive on the same road and with that I don't even notice the ruts.With the corvette I can hardly drive across them. When the car gets in those grooves it wants to stay there.
Any ideas? Could it be because the tires are much wider, or is it more than that?

 

[G Winter]

My 90 does the same thing. I believe it is the wide tires that cause it. I have checked everything in my front end and all seems tight. I have learned to not fight it.

 

[tnovot]

They decreased the front tire width - in 1993 I think. I think I remember reading that the reason was to eliminate some of the groove tracking.
This has been discussed here before. If you do a search, you could probably find more info.
Terry

 

[Chris Kennedy]

What I think you need to do is to have the caster of the front suspension adjusted. Caster is the most overlooked front end alignment setting! Everyone concentrates on camber and toe in/out, but forgets caster. Basically, caster is the angle (from 90 degrees vertical) that results if you were to draw an imaginary line through the lower and upper balljoints. Positive caster improves directional stability immensely at the expense of heavier steering, and our C4s were designed to have a lot of it. I think what you want is to have the suspension adjusted to between 5 to 7 degrees of positive caster. The adjustment is done by adding and subtracting shims to the control arms. Also, you will benefit from having a SLIGHT amount of positive camber dialed in at the front---but the main benefit comes from caster.

/s/ Chris Kennedy
Houston, Texas

 

[jsinga]

If alignment doesn't help look at tierod ends then wheel bearings. Before I replace all the wheel bearings on my 87 it was doing what you described. They were really out of tolerance. The spec is under .006" end play if I remember correctly. The shake test won't get it, use a dial indicator and check the bearings not all the suspension bushings, although they may be the cause to.

JS