View Full Version : Mcpherson vs Double A arm spring rate

01-09-07, 12:55 PM
I came across this statement reading something somewhere.

Can anyone clarify why Double A arm suspension cars (Civic, Dc2r, Skyline) can handle with hander springrate but not Mcpherson strut equipped cars like Lancers, WRxs, Silvias?

eg. off the shelf coilovers for a integra can have a F12/R8kg springrate. At the same time the Integra is a light car so why the really heavy springrate off the shelf.
But mcPherson strut cars say a Lancer or Wrx are usually softer with F9/R8.

another eg.
Buddyclub N1 spec for All silvias are F8 R6
but for a lighter EG/EK civic they have F10 R6.
Add to that higher front spring rate generally civics more understeer on the track i still dont fully understand why some manufacturers make the front 2kg/mm stiffer.

I understand that Mcpherson strut is directly connected to the strut tower to the hub knuckle.

01-09-07, 01:13 PM
On a McStrut car, the spring tends to be a lot closer to the wheel. On a double wishbone setup it's usually further inboard, towards the strut tower. If you imagine yourself pushing upwards on a suspension arm, you have more leverage when the spring is further inboard.

Trolls Royce
02-09-07, 12:19 PM
Exactly what Babs said. The further inboard your spring is on your control arms, the higher the spring rate is going to be to achieve the same level of travel at the wheel for the same load.

Another good example is FD RX7's and most of the Toyota's that run wishbone setups. Spring rates are nearly always in the double figures, if not approaching the 20kg/mm mark.

The main point would be that spring rates for nearly every car are going to be different. If you want to know more about whether they are too stiff, best off asking someone who has tried similar spring rates. There is going to be little difference in mcpherson struts, but anything wishbone will most likely be unrelatable to any other car.