How to work out spring rates?

[stu21t]

I need to figure out what spring rates ive got on the front of the 5.

i think ive done it wrong working it out?

i did it by measuring the floor to wheel arch, then i stood on the turret and remeasured, it dropped 8mm.
to make the car drop 8mm with 80kg(my weight) = 10kg per mm
10kg/mm = 560 lbs/in

that seems very high to me so guess i did it wrong lol

any1 got any other ways of doing it?

I dont know if they are std or were supplied different.

[Scoff]

but some of your weight will have been distributed to the other wheels stu so your best measuing static deflection.

do your front springs become loose when you jack the front wheels ? IE do they get slack in the coilovers or maybe have helper springs which expand ? If so you can roughly measure the deflection quite easilly. You first need to know the total weight on your front wheels (corner scales come in handy here) . You then raise both front wheels off the ground then slowly lower them again until just before the spings start to compress. IE they've just sat tight in their seats. Measure the arch to the ground. Drop the car to the deck again. Check that handbrake is off, etc, and maybe give the front of the car a bump to settle the dampers. Measure the arch to the ground again.

If the front of the car was 200kg say then thats going to be roughly 100kg per side. If the springs compress 10mm then thats 100kg per 10mm, or 220lb/10mm, or 559lb/inch.

8mm sounds like not a lot of deflection so either those springs are very hard or the springs are loaded even with the wheels off the ground

[stu21t]

Nice 1 scoff. As i started reading i remember ive heard that way before.
But no, my springs dont go loose lol.
The front end has 227kgs drivers side and 234kgs pass. I corner weighted it at home, thats with my weight in the drivers seat.
So 460kgs total and 230 each wheel average.

Im gunna strip the suspension this weekend to get the unsprung weights and i will try to compress the spring alone to see the difference.
Will also try to measure the size as in thickness, length, coils of the spring too.
If they say similar amounts i gotta b close.

Unless theres another easier way some1 knows of?

Then just gotta decide on new rates lol.

[stu21t]

Just been told another way

Put the spring on some scales and the weight needed to compress it an inch is the lb/in

Gunna try that.

[Ricardo]

If you had the time/money to send them away

http://www.dfaulknersprings.com/spring_tester.htm

[stu21t]

Sod that, ive only just got the car back on the road lol.

[Andrew Cooke]

they quite possibly have the rate, length and ID engraved on the tail (if not printed on the side)- assuming that these are coilovers.

[Matt Cole]

[quote=Andrew Cooke; assuming that these are coilovers.[/quote]


What else would they be Andrew? Some really smart individuals put me right the other day.

https://www.rtoc.org/boards/showthread.php?t=25029

[stu21t]

Yes theyre coilovers, but nothing written/stamped/engraved.....
I checked that last time i had em apart lol.
Nothing on this car is that simple lol.