Help me understand spring load

[rjs21]

I'm trying to wrap my head around how spring load works and how it affects the car. I'm in an IMCA modified but the late model forums have more activity. Basically what would be the difference in running a 450(currently) vs a 400 LF spring if you end up at the same compressed load? I assume the ride height would change, but would it cause other changes in how the car drives?

Thank you

[TheJet-09]

In your example, the ride height would not necessarily need to change. Meaning, the compression of the spring in meeting whatever your static load needs to be (to get your ride height) would be less for the stiffer spring than it would be for the softer spring. The difference in the two would remain from there on out. The stiffer spring in your example still needs 450# to compress one inch, and the softer spring would only need 400#.

[Jim11h]

The basics are still the same. Softer left front loosens entry. I prefer the simple approach of trying not to over think things

[Lizardracing]

Let me try to explain the theory.
Spring load and spring smashing(load check off the car)is a slightly more accurate way of setting up the car as if it were on the track under green flag conditions were old school scaling was a less accurate way of guessing what the car WOULD be at if it were on the track.
By concentrating on the car on the track, we know we can place less emphasis on Ride Heights and more on the ass up/nose down attitude and the loads placed on the car while on the track racing.
Load stick and smash loads do not assume engine torque, frame flexing, and bar angles and locations as a[art of the information however it is still a bit more accurate and more importantly repeatable than old school scaling on a flat surface, looking at just corner weights and Ride Heights.
One still adjusts the suspension the car the same as before, it's just measured differently these days.

If by example your 450 spring is compressed 3" the load stick would say 450*3/1350lbs at 3"
Install a 400 and it would say 1200@3",
If your car needed 1350lb of load to keep the frame off the track than you'll have to add more turns(about a half turn) to get back to 1350.
Stiffer or softer spring theory of handling doesn't change.
A softer spring will help loosen entry, off throttle and have little effect on the throttle.

[rjs21]

Thanks for the reply guys! Your explanation helps for sure. I kinda had the assumption that if you get the same 3" smashed load number that you would likely have a similar handling car.. I didn't know if the changing of ride heights would add another variable to the situation, since we aren't on coilovers on the front of our modifieds.

Basically what I am trying to achieve is a lower nose height at a dynamic state on the track without upsetting the handling of the car from where we are at. But also keeping the static ride height up so as to pass tech. In essence more travel on the LF from rideheight.

[MasterSbilt_Racer]

Thanks for the reply guys! Your explanation helps for sure. I kinda had the assumption that if you get the same 3" smashed load number that you would likely have a similar handling car.. I didn't know if the changing of ride heights would add another variable to the situation, since we aren't on coilovers on the front of our modifieds.

Basically what I am trying to achieve is a lower nose height at a dynamic state on the track without upsetting the handling of the car from where we are at. But also keeping the static ride height up so as to pass tech. In essence more travel on the LF from rideheight.

It will handle the same when the load is the same. So, at a particular smash number, it will be the same. When the car sees other travels, it will be effected according to the change in load. Like early entry off gas looser if less lf load.

[rjs21]

That makes perfect sense to me. I appreciate your input. And that is a change that I am after as well. The car is pretty regularly snug on entry, off throttle, not terrible, but I feel it could be better getting to the center. Plus I kinda wanted to try some different stuff for fun as the season winds down.