hi, i have 18" on my is200SE n its a bouncy drive and you fee the road alot - im presuming the suspention & shocks r the same but not too sure -- what should i change to make the drive smooth again?


-Thanks

Shock + suspension are the same, sport lower by 10/15mm.

To get smooth drive you will have to go, 225/45/18 tyres on.
What you running at the min 225/40/18 tyres ?????

The 18's weight effects the un-sprung area of the suspension... If you find the ride now is very fluid then i suggest you change the dampers.

These will then reply to the coils sprung mass and stabilize the ride.

what do you mean by very fluid? how much do new dampers cost?

Anything from £500 uppppp + fitting

erm ill try new tyers first as thats a tad pricey

When the wheel hits a bump the energy is retained in the coil. As the coil unloads this energy the action of the damper controls the rate of release.

If the dampers are worn then they cannot control the release so the sprung area of the car rides like a row boat.

yea that could be my problem but would the geometery/tracking effect this caus when i hit bumps the the car kinda feels weird you could say row boat its not jus vibration -- like on the motor way it tends to drift abit aswell

Yes it would.... One function of the chassis Geometry is to ensure the tyre footprint is maintained during the suspensions transitions.

An image of the chassis combined with the owners complaint we can use the forces within the Geometry to address the handling.

Example
Assuming the car is adjustable we can ask the owner what they expect from the handling..... Albeit

Drifting
Tyre preservation
Time-trials
Track
Domestic

And so on.....