Spring rates, higher rate in the front?

[Frank818]

How about the S? I built to the manual: 350F, 275R. Don't tell me I need to swap them!

Yeah about the S?
Anyone called FFR yet?

[Boog]

I think I was under the naive understanding that you want spring stiffness to be linear with weight distribution.

Assuming the same control arm length from pivot to lower coilover mounts and the same angle spring angle on the front and rear of a vehicle, is there ever a case when you would want to run stiffer front springs on a rear biased car or stiffer rear springs on a front biased car?

[Ironhydroxide]

a while ago I read a thread on some MR2Spyder forums. from a guy who did AutoX pretty serious. his theory was that the end of the vehicle with the lesser weight, needed more spring rate so that while turning that "axle" would work as hard as the axle holding the weight. because the end holding the weight would want to "tilt" and the end with less weight would want to hold the chassis from tilting, therefore more force would be transmitted to the ground through those tires. Resulting in more even tire temperatures and more balance.


this said, I am NOT a Suspension Guru, though, the physics seem sound to me.

[Jim Schenck]

818 Springs rates that come in the kit:

818S 350# front, 275# rear
818R 300# front, 500# rear

If you are running an S with lots of aero (not the street splitter and spoiler but something more) then we can switch out springs, and same goes if you are running an R without aero. Comparing the rates to other cars won't work because there are so many other variables, motion ratio in particular being one of the biggest.

[metros]

A lot of us are building an s with r suspension and r aero. What are you recommending for spring rates in that scenario?

[Jim Schenck]

If it is the full R aero with the splitter, diffuser, and the rear wing then you can switch to the R rates (and I would switch the shocks to the mono-tubes from the R as well). But if it is still mainly a street car I would find a more middle of the road set-up. I would start with just flipping the front and rear springs on the stock shocks if you want to maintain the ride. I would only run it that way if I had the rear wing or possibly if it was an autocross only car. If it is a serious track car though I would up the rates to compensate for the downforce at higher speeds.

[metros]

Correct I'll be using all the r aero pieces and r monotube shocks. So flipping the springs front to rear would provide a more compliant ride for the street?

I think I'll start with the r recommendations and then switch if it's too much on the street.

[Jim Schenck]

Flipping the springs won't help with the ride but will help with the balance of the car. Having the wing in the back will make the car understeer so switching to higher rate rear than front will get the car back closer to neutral.

[D Clary]

At what speed do you think this aero stuff is going to make a difference? I don't know about all autocross but our course usually limits top speeds to under 60 mph. The large rear wing may do something if it is installed with a steeper angle but I don't see the splitter doing much going into a corner at 40mph.

[Frank818]

Joe @ FFR confirmed on the S it's 350 front and 275 rear.