Dual Stage Spring Setup ?

[let-r-eat]

The standard practice is length > 4x D is when buckling becomes a big problem. Giving that information for the record.

[let-r-eat]

Another thing I would like to state for the record is that springs are designed to work between 20% and 80% of their length.10" 400 pound spring should have 800 pounds of static weight to start with on it? What happens when we stack? Are we outside of those parameters?I'm sure you know when we check springs we compress them beyond and then back off to take readings. Yes, I'm taking you into the reason now for me saying that formulas don't solve all problems. They will when you are inside the box.............but how do we know we are inside that box?That is another point I'm making here.

[let-r-eat]

I would rather be helping people here determine what the proper combination may be and how they might find it. But to do that we must start by getting some things the books and magazines, chassis builders, etc don't teach into the limelight. You don't get faster on the racetrack without understanding what is really going on nor will you get faster without testing.That is the reason I'm conversing in this manner.

[Matt49]

We all have our own way of doing things, clearly yours is different from mine. I believe math gives us a very accurate model as long as we take as many variables into account as possible.
To dispute that, you have increased the number of variables thereby making the math more complex. Still doesn't mean it can't be "solved" with math but I have not the time nor the inclination to sit here and figure CoF constants for an Eibach spring rubbing against an Ohlins shock to see how that plays into my racing program just to prove a point. I'm done discussing whether or not math and physics are real things. And I’m not going to spend a bunch of time and energy figuring out how springs rubbing shocks are changing my spring rate when I could just avoid that situation altogether.
Springs bow for reasons that are well within our control.
1) Spring already bent or worn unevenly
2) Spring not flat on both ends (either ground that way or worn that way)
3) Spring damaged or deformed
4) Improperly installed coil-over hardware
5) Etc.
I don’t worry a lot about these things since checking all of this is on our weekly maintenance list for all springs that were raced any given weekend. So is checking our shocks for signs of shock interference from rubbing springs. It (interference) simply doesn't happen that much on our stuff but maybe I'm just getting lucky...or maybe it's because we configure and maintain our equipment to avoid it. Who knows.
Obviously spring interference is going to have an effect on spring rate (increasing it) but rather than spend a bunch of time figuring out how much, why not just do what can be done to avoid and potentially even eliminate it altogether. Works for me anyway and it's what I suggest to anybody that is willing to listen.
Softer springs are also more susceptible to bowing if they suffer from any of the ailments listed above which is why we combine two heavier springs to make a softer rate (stack) in the first place. You can also use shock savers to minimize the friction of a rubbing spring that might come unseated as is often the case on the LR. Or you can use a helper spring with a slider to do much the same. That's what we prefer on the LF.
To each their own.

[ALF401]

The Question Was................

The guy just wanted to know if a 4' top spring would work or should he go to a 6" spring. I have read thru 20 BS statements by you "Engineers" and not one comment even close to answering the guys question. Can someone answer the guy's question??? I really believe you guys should give up racing and get into politic's, you would fit nicely there!!!!!

[let-r-eat]

I see that Afco suggests starting off with their 400 lb secondary and 700 lb primary spring. It works out to being a 254 lb sping on entry and a 700 on exit for the right front setup.I have a 600lb secondary spring and was going to run it with a 10" 450 lb primary. The math works out to being a 250 lb spring on entry, but would this mean that it would only be a 450 lb spring on exit? This is also on a full cast motor car.

I would not run that light on the primary spring. What type of track? Big banking or flat? Smooth or rough?

[7uptruckracer]

To answer your question NO DO NOT RUN a 4" spring it will coil bind. I recommend the 700/400 Combo just don't run that 4" spring and run a sleeve on the shock so it can't hang up on the bottom of the shock body

[jrkracing54]

After reading all that I feel like I just gave birth. To a Physicist. Thanks for the input. My question is how does a 4" spring coil bind when both springs are active and the stop nut is only 1 1/4" from the slider? John 1*

[7uptruckracer]

Your 4" Tall spring has a 4" Free Height. Compress it to Ride Height, then see how much you have left to travel in racing conditions. Until you hit the lock out nut your one both springs which is the point, but you just simply run outta room because of how they have to design the coil and space the coils to get it to be 4" tall. I know this is cloudy but one day try on a corner of your care different spring heights but the same rate and you will see your coil spacing is different.

[MasterSbilt_Racer]

Depending on your wheel weights and setup, you MAY get away with a 600# 4 inch, but no way with a 400#

[7uptruckracer]

You don't wanna spend all that money to find out if it will work like I did just give yourself the extra room and you will have more gap to work with. When I talked to Josh when we were at Rocket he gave me the impression they run a 375 RF and NEVER change it, and he scales twice a year on some old grain scales. Take it for what its worth I guess they just play the shock game.

[let-r-eat]

Reading my information closely you will find why the 4" spring may bind. This is why I stated that keeping a system from being "out of bounds" was the reason for my comments. If you got a (not a nice word)(not a nice word)(not a nice word)(not a nice word) binding combination on there to start with, formulas and math ain't gonna do a (not a nice word)(not a nice word)(not a nice word)(not a nice word) thing especially if your running springs outside of their windows.A 4" 400# spring was in my comments. Is this a Rocket I assume? Blue front? I don't want to give out any secrets here but if you pm me I'll help you with what I know.

[jrkracing54]

Reading my information closely you will find why the 4" spring may bind. This is why I stated that keeping a system from being "out of bounds" was the reason for my comments. If you got a (not a nice word)(not a nice word)(not a nice word)(not a nice word) binding combination on there to start with, formulas and math ain't gonna do a (not a nice word)(not a nice word)(not a nice word)(not a nice word) thing especially if your running springs outside of their windows.A 4" 400# spring was in my comments. Is this a Rocket I assume? Blue front? I don't want to give out any secrets here but if you pm me I'll help you with what I know.

Says your box is full.

[let-r-eat]

Says your box is full.

Sorry about that..........I cleaned it up.