Harder spring rates, ride height and compressed rates.

[Breaka]

I'm after a little help here.

Basically I'm after harder rear springs but wanting to keep the existing ride height.

Is there an easy way to find out what free height measurements I need to give the spring manufacturer when wanting a harder spring (than ones in atm) whilst maintaining the same ride height?

Any help much appreciated.

Matt.

[Breaka]

Rates I'm unsure of and free height is yet to be measured.

Basically I made this thread to find out what I needed before I sent you an order :jdmsmile:

[blair]

Post up some pics of current height man :)

[Breaka]

Yeah, shouldn't have gone into this half arse and asked questions once I new current heights and what not.

Would get pics right now but I just had to drop the car off to the mechanics because the clutch isn't working (Hydraulics I'm pretty certain). Driving clutchless through traffic and intersections aint that fun!

[shift_rook]

should have fixed the problem yourself with the help of the dc crew haha, easy enough

[Breaka]

should have fixed the problem yourself with the help of the dc crew haha, easy enough

Yeah, should have. But I'm juggling three cars at the moment and I want the car fixed ASAP. Can't wait til I no longer have to pay some dude to fix my shit! :P

[RobertoX]

Hey if you want a formula you can use this:

L2 = L1 - m(1/k1 - 1/k2)

Where:
L2 = new spring open length (mm)
L1 = original spring open length (mm)
m = weight applied to the spring (kg) basically vehicle corner weight.
k1 = original spring rate (kg/mm)
k2 = new spring rate (kg/mm)

[Breaka]

Hey if you want a formula you can use this:

L2 = L1 - m(1/k1 - 1/k2)

Where:
L2 = new spring open length (mm)
L1 = original spring open length (mm)
m = weight applied to the spring (kg) basically vehicle corner weight.
k1 = original spring rate (kg/mm)
k2 = new spring rate (kg/mm)

Awesome, thanks dude!

[RobertoX]

No worries,

keep in mind though that it was worked out empirically based on a linear perfect spring.
So it'll give you an approximate only. It'll be a good starting point.
I take it you'll be getting some custom springs wound? Chat to the spring maker and see what they say before they make them. If what they say is very different then follow them up about it.
Don't specify an open length to them, just say you want standard height. That way if they mess it up then they have to fix it ;)

[boost+k]

i always just measure compressed height of spring, then goto spring manufacturer and say this spring compresses to this height in my car and i want a new one that will compress to the same height but in XXX rate, that way if its slighly off you can go back and get it adjusted to suit

[RobertoX]

That is the best way to do it, I agree. but I have had springs totally off on a couple of occasions so I reckon it's good to just check for yourself.

By the way, just to be a super nerd, the Above formula can be done using compressed height instead of mass also:

k1/k2(L1-LC)=L2

LC is the compressed height.