Those with ASTs - how much is the rear static drop? Looking for harder rear springs

[shiyan]

Static drop is the distance that your wheel moves when the suspension is unloaded, like when the car is on a lift, and when the car's sat on the ground.

Measuring the static drop will tell you the suspension frequency.

The static drop on the KW V2 seems to be around 6cm at the rear, which corresponds to a suspension frequency of 2.0Hz, which is somewhat lower than what it is at the front at the moment (2.2Hz with a 5cm static drop), and I need a higher frequency at the rear, so I need harder springs.

I'd be very grateful if someone with AST suspension wouldn't mind measuring the difference from wheel arch to bottom of the rim before and after jacking the rear of the car up.

 

[Daz Clio Cup]

Re: Those with ASTs - how much is the rear static drop? Looking for harder rear sprin

surely you cannot compare V2's to AST's? won't the frequency change depending on the stiffness of the damper? my cup is on 400lbs rear springs, but my car is totally stripped and the rear only weighs about 300 kgs and the static drop is about 2cm ( haven't measured it, but it really isn't a lot!)

 

[shiyan]

Re: Those with ASTs - how much is the rear static drop? Looking for harder rear sprin

surely you cannot compare V2's to AST's? won't the frequency change depending on the stiffness of the damper? my cup is on 400lbs rear springs, but my car is totally stripped and the rear only weighs about 300 kgs and the static drop is about 2cm ( haven't measured it, but it really isn't a lot!)

The natural oscillation frequency doesn't depend on the damping, only on the spring rate, mass, and suspension geometry.

So the weight is rather important for the static drop and natural frequency. My car is standard weight and weighs 400kgs at the rear, so if you were to measure the static drop on your car then I'd have to take the weight into account

But if your rear static drop is really just 2.0cm then your rear suspension's natural frequency would be 3.5Hz, those same springs mounted on my car would result in a natural frequency of 3Hz.

I'm targetting a natural frequency of 2.6Hz.

What springs are you using if I may ask? And an accurate measurement of your rear static drop is rather important to get a better estimate of the natural frequency

 

[Daz Clio Cup]

Re: Those with ASTs - how much is the rear static drop? Looking for harder rear sprin

400 lbs springs from AST. AST's are true coilover on the rear, are the V2's or are they separate spring and damper like OE?

 

[shiyan]

Re: Those with ASTs - how much is the rear static drop? Looking for harder rear sprin

400 lbs springs from AST. AST's are true coilover on the rear, are the V2's or are they separate spring and damper like OE?

Oh dear, V2s have a separate spring like OEM, damn :/
Plus I realised the method I described probably won't work for measuring static sag.

 

[Tony Hunter]

Re: Those with ASTs - how much is the rear static drop? Looking for harder rear sprin

I couldn't start to explain why,but it wouldn't.

 

[shiyan]

Re: Those with ASTs - how much is the rear static drop? Looking for harder rear sprin

Same result when I put the car up on a bridge. I'll try some more direct methods later.