Drivers Side Tyre Smacks Underside On Big Bumps. Why?

[ausdrift]

Little puzzled about a suspension issue at the front. I bought coilovers about 25,000kms ago and about a year ago I changed the spring rates so that the ride is softer. While doing that I broke the damper adjustment dial thing, so I cant change the softness/hardness and don't know what is is. That's the passenger side one.

The real problem I have is that while I have the fronts wound up as high as I can, Im finding that on big bumps the drivers side one will bottom out and it appears that the tyre will smack the plastic guard about it in the wheel well. Ive change that adjustment from full hard to full soft, so that's not a factor.

Any ideas on what could cause this? And why it appears to just be on the drivers side?

[colourclassic]

Well there's an extra ~70kg placed in the driver seat when the car is moving so that could be a contributing factor. Does it do it when evenly loaded?

Are you sure it is hitting the guard and isn't another noise/suspension knock?

If the suspension is bottoming out so easily then that clearly points to a damper control issue, or incorrect spring rates.

[ausdrift]

With the Mrs in the passenger seat it still happens, so more like a 40kg increase, so I would assume, not enough to be a factor.

I'm quite sure it would be hitting the underside due to the sound it makes, plus there is a fair amount of rubbing marks and there is even a small hole worn there.

The spring rates were only 1 or 2 softer than what it came with, as I read that any more than that isn't gunna work. I don't want to change them back to the hard springs as Melbournes roads aren't really built for driving on. Anything I may have missed?

[colourclassic]

Pull the drivers side strut off, remove the spring and check the condition of the damper. If it blows through its travel that could be your problem.