changing coilover springs?

[emily_mx5]

Hi all, I have gotten my hands on a sexy set of HKS hipermax II coilovers, but alas they are for an NB
From what I have read I gather they will fit but not lower the car much if any.
So my question is would I be able to get some NA springs from another coilover like Teins or something, to bring them to the correct size?
Or are coilovers really specific and only HKS springs will fit?
Just because dealing with HKS would be really difficult and probably really expensive, whereas Tein make custom spring rates so I could easily order some of theirs.
Thanks

[plohl]

They probably run a 2.5" ID spring or the metric equivalent.

Springs have 3 measurements you need to worry about - Spring ID, Free length and Rate. You should be able to measure two of these.

I doubt that the spring is the issue, you'll probably fined the shock body to be longer. Do they have independent ride height adjustment? Or do you have to compress/un-capture the spring to change the ride height?

[Brainflex]

If I understand it correctly putting NB shocks on a NA lowers the NA due to the design of the tophat. Maybe best option would be to remove a rear shock and compare before spending any money.

[Charlie Brown]

A quick look at an HKS site shows the shock is only height adjustable by changing the preload.

You will need to fit the shocks to determine the lowest height the car can be set up to as there will be a different overall shock length and spring rate compared to your stock setup.

Before fitting check how much thread is left under the seat. Fit them and go for a drive and then measure your height. If it’s not low enough and you have thread under the spring seat you can wind down the seat to lower the car. You will need to determine how much lower one turn of the seat lowers the car.

If the spring seat is as low as it will go and the car is still too high, you will need to change the springs.

Somewhere on the springs will be the spring rate (you must match this with your new spring) and most probably the uncompressed length. If no length shown you will need to take the spring out and measure it. You also need to measure the internal diameter of the spring and the thread length the seat can be raised on the shock body.
Once armed with the correct figures of your old spring look at this table and determine if a new spring length 50mm shorter (keeping in mind the thread adjustment length) will work and get you high enough.
http://www.lovellsauto.com.au/docs/cat_xtreme11.pdf

I’m not sure what the current price per spring is but it’s probably around $150 each.

[emily_mx5]

awesome thanks heaps guys

[project.r.racing]

http://www.miataturbo.net/suspension-br ... -nb-63551/
something that might help:-

i wouldn't be changing the springs considering the old skool design of adjusting at the lower spring perch. unless only changing free length.