Shock Tuning Question for the Experts

[PushinTheLimit]

RacerX10, that is something that I've been wondering lately myself. I've been running mostly on a 375 RF spring and going to a 350 RF spring when it slicks off. Some of the local racers have told me to go down to a 325 RF spring and see how that feels in the slick. But then some I've talked to haven't went below a 450 RF spring (for a crate). I was following the Rocket book on what it said spring wise, but found that the setup for a Rocket with a crate was different.

[fastford]

To elaborate further the rebound sensitivity is where the action is. The spring only stores so much energy and no matter the rebound combination used if the spring doesn't have enough energy stored to create the speed allowable by the damper then you are just losing the ability to keep the contact patch planted. I like these type threads. We could dive into the details or proprietary information but that isn't really necessary because we are discussing principles. Think about what the stacked right front is placing on the demands of the shock? This is why it is so difficult for people to get it to work properly, along with utilizing the spring outside of its design limits. I'll quit there.

just curious, did you mean stacked right front or two stage right front?

[Matt49]

There isn’t any magic in a softer RF spring by itself. It complements the roll center migrations of many of the new front end designs but also needs to be complemented with other setup changes to make it work correctly.
Back to the “old logic” thing for a second. Old school thinking deduced that a stiffer RF spring would free the car on entry. But new front end design and LR spring behind setup dictates that we change our thinking. A softer RF spring is allowing for more RF suspension travel which does two things: 1) lowers the dynamic roll center and 2) allows the LR to decompress. Lowering the dynamic roll center increases the front end’s side bite which makes the car steer better. Allowing the LR to decompress induces rear steer which lets the car rotate better. So winner winner chicken dinner we’ve got a car that steers more positive on corner entry with a softer RF spring. But the problem with the softer RF spring is that it reduces dynamic wedge which has a negative impact on forward drive coming off the corner. So you have to do something (if not many things) to get drive back in the car or you’ll be slow in the slick coming off the corner. What those things are is beyond this discussion and more than I’m willing to disclose :-)
Dual stage RF spring setup and RF bump stops are another story and there is a lot more going on there from a shock perspective than meets the eye.

[let-r-eat]

stacked OR 2 stage.Sorry I wasn't more precise in clarification.

[hpmaster]

So to go off slightly on a tangent, is everybody running that soft RF spring setup these days ? I've never run under 450 on the RF.

RacerX10, running older shocks and set ups are not conducive to a softer RF spring alone, alone being the key as stated in the points outlined by matt above. Newer more adjustable shocks when added to a car with help of a competent shock guy will get you on a path that will have you seeing overall benefits that most likely also include your using lighter springs on the RF. As for everybody running a soft RF spring in a word NO. As stated by matt other changes to your car and set up will determine how soft of a RF spring you need and can effectively run for a positive overall performance benefit. With out these other set up and equipment changes it is safe to say if you were to simply add a 300 lb RF spring to your car today you would be completely dissatisfied with the cars performance, as I found out when I first tried a softer RF spring alone. JMHO

[RacerX10]

Those were some really helpful replies without giving up any trade secrets and I appreciate it very much.

I thinks for the time being I'll stick with my old school 450 RF setup and experiment with the soft configuration on a test and tune day.

With my known 450 setup, I'll play around a bit (one change at a time) and learn how these DA shocks affect he car.