Spring rates

[BJL123]

Hi

i spoke with Enzo a couple of weeks ago and got some great help. if your able to help further I would be most grateful or if someone else can help I need the spring rates for the rear springs to a 2007 Quattrporte Sport GT duoselect.
I ordered a spare set of springs from the Main Maserati Dealer (which turned out to be Ebarch Springs) hoping I could have these altered but no-one seems happy to do this. I wish to lower the rear by 20mm and can get some made at Faulkener Springs in the UK who have asked for the spring rate, everything else they are able to deduce from my new springs. Their explanation is 'If i put a 20mm packer under the spring does it lift the car by 20mm ie a 1:1 spring rate'. the downside is the springs are on the car and are staying there until i get the replacements, so .............does anyone know for sure what the 'Spring Rate' is

Many thanks

 

[lozcb]

Could be worth having a chat with Andy at Millbrook Cars of sheffield , i know he has lowered many 4200 's and has a local chap who can either cut down the springs or make new to suit , he was charging around £225 a corner a couple of years ago



regards loz

 

[BJL123]

Thanks for that loz, I'll ring them in the morning.

 

[Emtee]

Hi BJL, This is going to sound glib, and I don't mean it to, but why don't they just put one of your spare standard rear springs in a spring rate tester?

 

[BJL123]

Hi Emtee

Apparently they can find out all they need to know from testing the new spring apart from the 'spring rate or ratio'. They say that with a double wishbone set up the manufacturer has springs made to a specific ratio or rate and this cannot be found out from the spring itself. I can however place a 20mm spacer under the spring and see by how much the ride height is increased but to do that is virtually impossible without nearly removing the spring, I think. Most springs are 1:1 ie 20mm spacer will lift the car 20mm but some are not.

Nothing is easy in this world, is it?

 

[Emtee]

Ah, I see BJL.

I'm no expert, but given the additional information in your post above, it doesn't sound like they're after the spring rate but rather the motion ratio? This would take into account wheel movement relative to spring compression and would therefore be dependent on suspension geometry / leverage? I know there is a formula for working this out, but I suspect you'd need engineering drawings for the rear suspension?

Best of luck!

 

[BJL123]

Thanks, I think I'm going to need it.