So I know what all the reaction is going to be, but here is what I am going to do.

I originally had Eibach springs, Then Got Tanabe Rears to have the perfect drop for my taste with going with just SPRINGS (I know you can do coils).

Now my issue is that tanabe rears handle like Sh*t.
I really want my Eibach rears back, but the issue is that with my offsets on my wheels any more positive camper than I have and it wont fit. I am really flush if you check my other Threats.

What to do:

1. I am looking into getting the Tanabe Sustec, so let me say that first.

2. before doing that I would like to just try cutting the Eibach rears and make them sit just as low as Tanabe rears. Maybe not the best Idea, but I want to try anyways. if it works it works.

3. where to cut from, so here is pop quiz for you all, Eibachs are Progressive springs, so if you were going to cut the coils which end would you do it from? (where its more spaced or less (dead coils) Why?

I already know this is not the best way to get what I want, but I know the best way to cut springs if you have to do it anyways.

This is just an experiment and I am going through with it in couple of weeks.

Please dont get into physics and math just give me your answer after you solve your equation or something, lol.

I was two classes away to get my minor in physics, so I know all about formulas.

Lets just see what kind of discussion we get.

 

Sounds like you already know the response you'll get, so what's the point here?

 

The stiffness "K" of a spring depends on many factors (cross sectional area, material's young modulus aka stiffness , the number of coils, distance between them etc..)

Cutting a spring = messing with it's stiffness as you'll have less number of coils, you know what that means?

From a dynamics perspective

You'll mess up K (spring stiffness) in this equation which models your suspension to an extent



Where m's your mass, c's your damping ratio and x's your distance and its derivatives

In other words, you'll mess up your rides dynamics and your ride will start reacting different to different road conditions and corners.

From a Mechanical Design perspective

There's less steel in the spring to support the weight of your car meaning you're approaching danger zone, I know it isn't THAT significant if you're just cutting a 0.1" off or so, but I honestly wouldn't even bother risking it

DONT do it, wait for your coils or just order Tanabe rears and call it a day, I'm sure you can find them for around 100 bux

 

^ Damn... Sam you actually sounded like you knew what you were talking about there. Lolz.

 

The point is I want short replies with answers not how you came up with your answer, I just wanna see how you would do it if you had to? I just wanna make sure I got all of it cover.

No disrespect, but I dont need responses like yours unless you are sharing knowledge gained through experience with something like this, not what you have heard.

 

I went through the experience, not cutting but designing from scratch and selecting the right spring stiffness and damping, on our senior design project which was an FSAE car

 

Thanks for all that, first the equation doesnt apply to progressive spring as cut as dry as you put it. you can cut progressive spring in a way that actually will decrease your overall spring rate and make your ride softer.

as far as mechanical stand point I can see how it might be risky.

and I already have tanabe rears, like I said they dont handle the same.

 

I have a Physics degree so I guess I could argue with you like Sam, but decided to ask Al for his opinion......he was not in favor.

 

Was it linear or progressive? most track springs are linear, so easier to design and come up with numbers.

 

Sam, do you know how much negative camber you can have with Eibach rears springs and stock suspension, (dont have camber kit)?

 

Ask Greg to help you.

 

And that was why I said "to an extent", I thought you said only a minor in physics so I thought I'd take it easy on you haha

In Progressive springs, F is not linearly proportional to x, meaning the more force you add the more "stiffness" you'll get i.e less travel. It all depends on where from the spring you cut, the ghetto shops cut the springs from the middle then re-weld, and you really don't want to be doing that:



The way to do it would be cutting from the dead edge of the progressive spring as those don't compress much with low road forces aka speeds, but I still wouldn't do that.

 

In short you'll be worst off! I wanted my car a tad lower than Eibach too. I'm ordering coilovers next month. Its not worth that experiment. Just wait and save and put on coilovers. Wish Id done it from the getgo there goes $750 down the drain!

 

Why not just do a Long Beach Lowering Job and put a blow tourch to it...but yeah, the cons of messing with springs will always out weigh the pros.

 

If you think the tanabe rears handle like ****, I cant wait to hear your opinion on how cut springs handle.

If you want the ride to be even, you are better off buying a bag of sand or 2 and putting it in your trunk.



Post of the year.

If you wanna "Greg-ify" your ride and you have to cut, like Sam said, cut from the dead side of the progressive springs that would only kick in under a lot of force. You wont be able to notice it driving in a straight line in normal driving. I wouldnt cut my springs, but if someone put a gun to my head and said make a cut, I wouldnt cut more than one complete coil off. This is a 40k car, not a Honda Civic.