Corner Weights & Ride Height

[Richard Anderson]

Anybody (Peter :-)), want to give me a idea about how corner weights and ride height effect the handling?

 

When you are setting the corner weight, are you adjusting the stiffness of the damper, or the height, or both?

 

I take it that 'flat-bottoming' is just another way of saying that the corners of the car have been put under equal load? ..or not?

 

one, last question......before flat-bottoming, shouldn't you try to distribute the weight as evenly as possible around the car, so that one damper isn't stiffer than the rest? ....or am I getting the wrong end of the stick?

 

 

[Peter Carmichael]

When you set corner weights, you are setting the preload on the springs. If you remove preload from the front left hand corner:

 

The front left will "ride lower" as you would expect.

The front right will ride lower (by a smaller amount)

The rear left will ride lower (by a smaller amount)

The rear right will ride higher

 

The spring on the front right will be more compressed and have more load.

The spring on the rear left will be more compressed and have more load.

The spring on the rear right will be less compressed and have less load.

Because of the reduced preload:

The spring on the front left will be less compressed and have less load.

 

The car will tip towards the front left.

 

If you now slacken the rear right, the car will level up but will be lower.

 

If you now increase the preload on the front right and rear left, the car will stay level and you can bring it up to the original ride height.

 

The car is now at its original ride height and is level. You have achieved this by slackening the preload on the front left and rear right and by increasing the preload on the front right and rear left. The weight suported on the FL to RR diagonal is now much less than the weight supported on the FR to RL diagonal.

 

Flat flooring aims to get the car straight and level with an equal weight supported on each diagonal.

 

None of this is to do with the dampers or stiffness. The behaviour of dampers is related to speed of movement; the contribution of dampers to a static set up is immaterial. Stiffness is a measure of the spring behaviour, but you can't adjust the stiffness of even progressive springs using ride height. It is the equivalent of wedging a knife under the leg of a rocking restaurant table. You want the car to be evenly supported on its two diagonals and you want it to be level.

 

The average of a bumpy road is a flat road - any bump you hit with a front wheel hits the rear wheel an instant later. You want the car to respond evenly to bumps and corners whether they are to the left or right, so you set the car up relative to a flat floor.

[Richard Anderson]

Thanks Peter....I have suddendly become aware of how little I know about the mechanics which effect the handling of a car.

 

Can you recommend any good books? (I think I would be most interested in one which approaches the subject from a drivers perpective, rather than deeply technical)

 

One last question on the subject of flat-flooring, if I may : from a drivers perspective, flat-flooring would mean the car would exhibit more stability through a bumpy corner? ...anything more to it than that?