Aftermarket Steering Rack?

[chikoo]

I have read that tramlining can be caused by weak or ineffective power steering.

The texture of a road surface is what determines if a car will tramline. Tramlining can be magnified by a car alignment and tires. Neutral toe will see more movement. Toe out and you'll fight to keep the car on the road. Triple so if the toe out's in the rear. Certain tire tread patterns and some tire compounds will want to tramline more than others.

Ineffective power steering doesn't cause it. But boy would you get a workout if you had to fight it without power assist.

I agree with what you are saying as things that will magnify tramlining. I can cite several car owners who said fixing their power steering cured their tramlining issues when they had tried everything else to solve it.

I came across this forum, and this post by Scargo when I was googling for tramlining and weak power steering.
Why was I googling this?

Well, it so happened that I have had been experiencing for the last 3 months or so a very bad case of tramlining, and the steering wheel being jerked from left to right as I go over the undulations on the back country road to my home. I had my alignment checked thrice, but it barely made any difference. As part of the alignment check, they even Ok'ed the control arms, bushings and tie rods. I also checked my tires which are bridgestone RE760 sports. They have 50% tread left. So I started thinking about changing my tires. Maybe the tires are just not keeping up as they get old. Then it so happened that I noticed a couple of spots of oil on the driveway. So I took my e46 330cic to my mechanic and he put it up on the rack, removed the belly cover, and found that the power steering hoses were weeping. So he goes ahead and replaces the hoses, and the belt.

Then as I drive back home, I notice none of the tramlining or the steering going left and right vigorously on the very same roads that I drive daily. Funny how it all disappeared right after fixing the power steering. This led me to arrive at a conclusion, as unbelievable as it sounds, and I had to google it to confirm if this is for real (or not).

so there you have it. Scargo, add me to your list of people who can confirm that a weak power steering does indeed lead to a bad case of tramlining. In other words, a good power steering fights the effects of tramlining for you, and keeping it from you having to fight it.