Coilover springs Vs normal springs

[Mieran]

Can someone who knows about springs explain this to me.

I've recently bought GAZ rear coilovers and fitted them, back end was very stiff and the car was a bit tail happy.

They were 10" and 160lb.

I took the above springs off and ran the same GAZ shocks with custom rear springs which are 4" and 400lb.

But back end is much softer now and definitely not tail happy and understeers a bit more now.

How does that work out?

Does coilover springs rebound/compress differently to a normal spring?

[Stuart]

I would imagine the damper was set rock hard and as such on the soft spring it was terrible but on the stiff spring it's just right....

[autoworksnovasport]

do you mean when they were coilover they were harder and you sepertated them?? ie used the gaz as dampers and put some pig tails back on??

[Mieran]

damper is on the softest setting, car becomes like a rwd if I turn up the stiffness

Yes when they were a coilover they were harder even though the spring is softer than the pigtale that is on now

[autoworksnovasport]

whats the rebound set to???

[Mieran]

gaz gha is not rebound adjustable

[autoworksnovasport]

im lost then

[Stuart]

If the dampers were truly on soft and it was skittish then the springs weren't 160lb, and your pigtails aren't 400

[Mieran]

Springs have a gaz sticker with 160lb written on it.

A simple test is compressing by hand lol i can push the gaz spring and it would compress slightly but the pig tale spring is rock solid

[Lee H]

Coilovers wound too low so no damper travel and sat on bump stops?

[peester]

^ as above - im assuming the 10" coilover springs when running low ride height were just squished coil to coil, being a quite a tall spring with a soft/weedy 160lb; as soon as you put weight on them...
A 4" pigtail at 400lb would probably barely compress. Very stubby springs at only 4" must have a slammed stance.

[C612DNM]

What you have to consider is the coilover is on the beam just behind the wheel, so it's spring rate is a true "wheel rate", where the pigtail is at the front of the beam, and you have the crank/lever action of the beam to consider, which from memory is about 40% of spring rate = wheel rate.

I ran a 625lb pigtail spring on the back of my GSi racer to achieve a 325lb wheel rate. That doesn't move. (I ran 375's on the front - with Toyo road rubber - not 888's) They were used with race valved Koni's that were valved by Koni to match the spring rates & corner weights of the car.

The comments/questions about running it down on the bumps rubbers may also be spot on. You're probably running at the end of the shock travel, which will make it oversteer like a shopping trolley with wobbly wheels!

If you stiffen the back without altering the front in a similar amount (%), it will become tail happy due to the transfer of weight under braking and cornering. There comes a point where the suspension becomes too stiff for the rubber to be able to cope. Even a change of make/type of tyre can change the car's handling characteristics requiring a change in spring/damper settings.