Thanks Andrew, you've done well. OK I can add a bit to this for coil overs but first you have to work out the spring rate. You can find calculators on the web but for the record here is the Spring Rate Formula:
K= (12,000,000*W^4) / (8*N*D^3) The 12,000,000 and 8 are constants. W= diameter of the spring in inches. (W is raised to the fourth power in the formula) N= number of active coils in the spring. (free coils plus 1/2 coil under load) D= diameter of the coil, measured from the centre of the wire to the centre of the wire. (D is raised to the third power in the formula) Coil overs on 240K/200B struts roughly work out to have a spring to corner ratio of 1.1, i.e. +10% of the in/lb rate for zero offset wheels. A typical front 200# lowered 1600 spring is: W 0.55" (14mm) N 6.5 D 5.12" (130mm) For rear coil overs an IRS rear are a bit tricker especially a 1600 so I'll stick to a solid axle. The spring mounting angle typically is 28-30 degrees and the SCR is around .75 regards Terry -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Andrew Greenbury Sent: Friday, 3 May 2002 11:49 AM To: [EMAIL PROTECTED] Subject: RE: question Hi Bob, Because of the strut suspension on the front, the "effective" spring rate at the wheels (or wheel rate) is roughly the poundage of the springs. But because the springs are inboard on the rear, their influence at the wheels is reduced, so stiffer springs are required on the rear to have the same effective rate at the wheels. Terry says this spring to corner (wheel) ratio is roughly .26 I may be wrong but I think he gets this from: Kw=Ks*(IR)^2 where Kw = effective rate at the wheels (wheel rate) Ks = spring rate IR = installation ratio, or motion ratio = y/x where y = the resulting spring compression from a wheel deflection x ie the spring to corner ratio is a measure of the spring position to the wheels. Terry is saying IR^2 =.26, because for a given deflection at the wheel, the 1600 rear springs compress roughly half that amount?? Im open to corrections, and sorry for the backwards explanation! Andrew > What is the spring to corner ratio a measure of? > > > Ben, > > > > It depends on the car i.e. IRS etc? On a 1600 most of the good > handling dirt > > versions have slightly softer springs in the rear. When you look at > the > > poundage rates on a 1600 allow for the spring to corner ratio on the > rears > > which as around .26:1 and on the front with stock struts the rate is > 1:1. > > i.e. 200# front springs are the same as ~800# rear springs. On a > 1600 RC a > > good starting rate is 175# front and 600# rear. > > > > regards > > Terry > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED]]On Behalf Of Ben > > Sent: Friday, 3 May 2002 12:05 PM > > To: [EMAIL PROTECTED] > > Subject: question > > > > > > bit of a strange question. my brother has sent me his RC car to > rebuild > > for him. im just setting up all the suspension at the moment. just > > wondering, with a normal car setup, are the rear springs stiffer > than the > > front, or is it the other way round?? > > > > > --membersozdat------------------------------------------------------- > > OZDAT Mailing List Please Note:- > > Send (un)subscribe requests to [EMAIL PROTECTED] > > Send submissions to [EMAIL PROTECTED] > > No unauthorised redistribution of this email > > http://www.ozdat.com/ozdatonline/index.htm > > http://www.ozdat.com/ozdatonline/listindex.html > > http://www.mail-archive.com/[email protected]/ > > > --------------------------------------------------------------------- > > > > > --membersozdat------------------------------------------------------- > > OZDAT Mailing List Please Note:- > > Send (un)subscribe requests to [EMAIL PROTECTED] > > Send submissions to [EMAIL PROTECTED] > > No unauthorised redistribution of this email > > http://www.ozdat.com/ozdatonline/index.htm > > http://www.ozdat.com/ozdatonline/listindex.html > > http://www.mail-archive.com/[email protected]/ > > > --------------------------------------------------------------------- > --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[email protected]/ ---------------------------------------------------------------------
