*CHANGED* the cut springs thread

[spitz7985]

Thread Subject Changed From "What SCCA Class Am I In" To "The Cut Springs Thread"

91 240sxaftermarket clutchunderdrive pulleyfalken azenis 205/15/50 (stock alloys)spl t/c rods

and i should have these before auto-x this season-1/2 coil cut off stock springsadjustable shocks

[Mr1der]

don't think I'd suggest cut springs for auto cross at all.

you might still be in stock, maybe street prepared due to the pulley, not too sure on that.

check the scca solo rules, there's a site that I can't remember off hand

[spitz7985]

Cut springs are better then stock in every way, except they have slightly less travel.

How many digits can my SCCA number be?

[IveBeenBad]

Cut springs are better then stock in every way, except they have slightly less travel

how do you figure?

[SeVa-S13]

Because it looks like tyte.

[crzycav86]

http://www.zilvia.net/faqs/archive/sccaclass.asp

[JDM]

All cut springs generally do is make your car ride terrible. I suggest you read up on the subject and buy some aftermarket springs instead.

[spitz7985]

I suggest you read up on the subject. Cutting a half a coil off the spring not only increases the rate, but also loweres the vehicle's CG. The same thing as aftermarket springs. Stiffer is not always better.

[spitz7985]

http://www.zilvia.net/faqs/archive/sccaclass.asp

thanks

[The Mic]

I suggest you read up on the subject. Cutting a half a coil off the spring not only increases the rate, but also loweres the vehicle's CG. The same thing as aftermarket springs. Stiffer is not always better.

lol.... So whose turn it is it this time?? i think Azhitman's due for one

[Onizuka]

I suggest you read up on the subject. Cutting a half a coil off the spring not only increases the rate, but also loweres the vehicle's CG. The same thing as aftermarket springs. Stiffer is not always better.

Im sorry buy you are dead wrong. Go research Hooke's law or Spring constants. Spring rate does NOT change by changing spring length. Yes your car will be lower, but it wont do jack shiat to your cornering ability and will make your car ride like crap. Lowing your center of gravity an inch does almost nothing.

F = Kx Force = (spring constant)(distance traveled)

By decresing the total distance the spring can compress you are lowering the amount of force it can absorb.

I doubt I'm wrong as I'm reading this right out of my Physics 211 text book.

[JDM]

:Werd

Maybe you should listen to my advice and do some research like I said before. Oh yeah, It might help to not to belive everything your ricer friends tell you!

Also, having a car that bounces like its on hydraulics on the highway sure helps corning... yeah.. right... :rolleyes

[The Mic]

and hes been a member for how long?:rolleyes

[spitz7985]

OK, you guys don't know me so don't me so quick to judge. Here is the formula for spring rate:

To calculate the rate of a linear spring-

Gd^4 8ND^3

whereG= 11.25 x 10^6 (11,250,000)d= thickness of wire in inchesN= number of active coilsD= mean spring diameter (inches)

To get the mean spring diameter, add the inside diameter and the outside diameter and divide by 2.

When the number of active coils is reduced, the spring rate is raised. Its simple mathematics.

Believe it or not, sometimes the popular belief is wrong. I'll be damned if I'm called a ricer. You guys need to back off. Apologies accepted.

[JDM]

That would be true if you were talking about linear spring rates, but the stock springs are progressive. I accept your appology.

[spitz7985]

It's the same principle. Then again I'm sure you're right over chassis designer & automotive engineer Herb Adams.

[masticatingcow]

LOL, these threads are great... no one learns anything and everyone gets pissed. Thank God for that.

From an outside perspective, I think that if Spitz wants to run auto-x on cut springs despite what the concensus says, that's fine. Innovation has always paved the way for improvement.

Then again, "innovation" has also done a lot to destroy A LOT of cars and, I think more importantly, PEOPLE.

Do what you like.

[rookiegtr]

hahah go spitz

http://forums.club4ag.com/topi...36764

the same exact argument with almost the same exact proofs but a bit more detailed.

[Onizuka]

Interesting, im actually very interested in figuring out the math of this. I wish I had a stock spring in front of me to measure, but even if i did it wouldnt help me find out the sheer modulus of the material (G).

This turns into an argument over weather or not force increases or decreses, and that is imposible to determine without exact measurements. You would also need to find out things like solid spring length and coil pitch.

Increased spring constant VS decreased availible compression, F could be lower, higher, or equal depending on the values you collect.

Also, I believe spring constants are usually not liniar with coil springs, im reading more into it. If it were just a bar fixed to a posision it would be liniar, I made a human weight scale on this principal last summer. One this is sure, progressive springs are BAD to cut.

Good discussion, no need to get heated

[spitz7985]

Well, since this thread has been hardcore jacked, I'll change the name of it.

[spitz7985]

sheer modulus of the material (G).

I don't have it in front of me, but G, I'm pretty sure, is the torsional stiffness for steel. I don't have units on that. I will double check when I get home.

[Onizuka]

It depends on the exact composition of the material. Getting the right aluminum plate last summer was a dizzying experence. There are tons of different types of steel from Alloy 625 Nickle Steel to 1095 Blue tempered and polished spring steel. The place I bought from offers 4 different types of carbon steel, I didnt even know there was more than one kind until I looked.

You would need a lab to calculate all of this correctly and precisely. Im sure you could get it close enough with educated estimates though :pface

[yellow_jacket]

I'm sure you can calculate it just fine, It would involve integration and I don't really feel like pulling out my old machine design book to get the formula.

You cannot use a linear equation on a progressive spring. It just doesn't work that way.

If you read the link to the other board they had some very valid points. By reducing the number of coils you are going to fatigue the spring more quickly. Depending on what factor of safety was used and how much spring you cut off will decide how long they endure. The main problem will be that you will lose a little load capacity. So you may have problems with the coil bottoming out. Just be careful how much you cut off. And if you can afford it, get properly designed suspension for your particular race application.

[spitz7985]

You cannot use a linear equation on a progressive spring. It just doesn't work that way.

I believe you are correct. I have researched further and read that it is impossible to calculate with a progressive spring. Although, I think an old fashion spring scale could give answers.Also, cutting off a coil or part of a coil would give unpredictable results with a progressive spring.

[marshun]

so wich part is the hard part? hehe. im just curious.

[Zydeco]

Well Im too lazy to read all this, so heres my 2 pennys. But sone Tein S-Type spring off of e-bay for 120 bucks and you'll be much happyer then if you cut your springs.

[offtheline]

So if the stock springs are progressive, why would you want unpredictable results?

[JDM]

You don't, that was the whole cause of the arguement.

[Dori Dori]

Read this old thread about cut springs.

http://www.nissaninfiniticlub....rings

[LiU]

the stock springs are linear