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Spring rates
Posted: Mon Jan 09, 2012 5:23 am
by marcjagman
Can anyone here give me a rough estimate of what springs I may need for my car? Got a RV8 and will weigh around 800kgs. Looking for a comfy ride. I was thinking of spring rates of about 250lb for the front and around 130lb for the rear, what do you chaps think?
Posted: Mon Jan 09, 2012 4:44 pm
by kiwicar
Hi
I have a few books with formulae in for calculating spring rates, but I will need alot more information. . . . Firstly what type of suspension set up is it front and rear. Actually lets start there and once I know I will ask you to make some measurments and we go from there.
Best regards
Mike
Posted: Mon Jan 09, 2012 6:38 pm
by marcjagman
kiwicar wrote:Hi
I have a few books with formulae in for calculating spring rates, but I will need alot more information. . . . Firstly what type of suspension set up is it front and rear. Actually lets start there and once I know I will ask you to make some measurments and we go from there.
Best regards
Mike
Coilovers on front, 9" free length springs 2.25 ID. Rears are coilovers, 14" long 2.25 ID.
Posted: Mon Jan 09, 2012 6:55 pm
by stevieturbo
marcjagman wrote:kiwicar wrote:Hi
I have a few books with formulae in for calculating spring rates, but I will need alot more information. . . . Firstly what type of suspension set up is it front and rear. Actually lets start there and once I know I will ask you to make some measurments and we go from there.
Best regards
Mike
Coilovers on front, 9" free length springs 2.25 ID. Rears are coilovers, 14" long 2.25 ID.
That isnt enough.
What type of suspension is it ?
Macpherson struts, double wishbone ? Where is the spring mounted ? What angle is it mounted ?
If wishbone, where on the bottom arm does the spring act ?
Leverage will have a huge impact on springs required as will overall suspension travel.
Corner weights at present would be a big help too or if you knew that and how far the current springs are compressed at normal ride height, and their poundage.
Posted: Mon Jan 09, 2012 7:13 pm
by marcjagman
stevieturbo wrote:marcjagman wrote:kiwicar wrote:Hi
I have a few books with formulae in for calculating spring rates, but I will need alot more information. . . . Firstly what type of suspension set up is it front and rear. Actually lets start there and once I know I will ask you to make some measurments and we go from there.
Best regards
Mike
Coilovers on front, 9" free length springs 2.25 ID. Rears are coilovers, 14" long 2.25 ID.
That isnt enough.
What type of suspension is it ?
Macpherson struts, double wishbone ? Where is the spring mounted ? What angle is it mounted ?
If wishbone, where on the bottom arm does the spring act ?
Leverage will have a huge impact on springs required as will overall suspension travel.
Corner weights at present would be a big help too or if you knew that and how far the current springs are compressed at normal ride height, and their poundage.
It's a coilover front and rear, front double wishbone (Triumph I think) mounted at the end close to the hub, 25 degrees from the vertical. No idea of corner weights. No suspension fittrd at the minute which is why I want to know what to fit.
Posted: Mon Jan 09, 2012 7:13 pm
by kiwicar
Yup
Pretty sure that was what I was asking. . . Are we talking coil overs on twin wishbone suspension up front?? If so as Stevie says we need the length of the wishbones, the mounting distance down the wishbone for the coil over and what angle to the verticle they are mounted, and finally the front scrub radius.
For the rear, a similar thing, distance out from the centre of the axel to the mounting point on the axel of the spring, the track of the rear wheels is there a anti roll bar? if the spring is not directly mounted on the axel, how is it mounted??
Sorry for all the questions, but is is all about leavers.
Best regards
Mike
Posted: Mon Jan 09, 2012 7:19 pm
by marcjagman
Think I'll just buy the ones DAX recommend, they seem to know. 300lb front, 140lb rear. Locost owners and phaeton owners all seem to use about the same. Too much faffing about taking measurements, just want a comfy ride not hurl it around a track at 120mph.
Posted: Mon Jan 09, 2012 7:26 pm
by stevieturbo
I came to the same conclusion about measurements for mine. Although I bought a pair of test springs up front.
At least then once it's back on its wheels I will know exactly how much load is on each spring in order to make changes