How many coils to cut on Eibach springs?
 

I recently purchased a 71 240Z w/an L28ET turbo swap. The previous owner installed eibach coils with tokico struts. I want to lower the car so there is no gap between the wheels and fenders wells. Current wheels Sport Maxx 16 x 8 in the rear with 215/50/16 and 16 x 7 in the front with 205/50/16. How many coils should I cut? Thanks.

None, when the tire is no gap between the fender and fender wells, chances are you are already rubbing and you wouldn't be able to turn! How about learning what's happening when you lower a car in general and what happens when you cut a spring that is already WAY to soft.

get coilovers and sectioned struts, then lower your car moar.

Yeah, why would anybody want to cut lowering springs? Especially Eibachs? I know the one method which works on the 280zx. Is to get Mercedes 300 springs. And cut coils on them. It has been talked about quite a few times before. I don't know how different it would be between the 280zx and the 240z. But I would imagine, you could get it to work.

Alot of ways to get coilovers for the s30 it's your best choice but if you wanna be cheap cut the springs and see here it gets you

An effective way to lower it and still have spring travel is to shorten the strut tubes. Cut a section out equal to the desired amount of drop and weld a sleeve over the cut. The Tokicos have shorter shocks in front so you will need them for the rear also, maybe visaversa, don't remember for sure. The shorter shocks use a 2 inch long spacer so you need to shorten them as well. You might get by without the shorter shocks by using bump stop spacers. Fyi the Tokico springs are already 1 inch shorter than stock so cutting them would make the car bang when you hit a big bump. Also you don't need a spring compresser to change them.

I would never recommend cutting your springs as you end up with way too scarce suspension travel with oem length shocks, unknown spring rates and no spring preload. DON'T DO IT! Why don't you go get some AW11 strut inserts, section your strut casings and call it a day?

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cutting springs is so bad

That is a BAD idea on an S30...there are already suspension travel issues with the stock layout & aftermarket springs. You will not have any travel if you cut lowering springs & will be riding on your bumpstops & blow out your shocks with a quickness. Want no fendergap, buy a Civic...I'd suggest looking at hybridz.org for some real data on what the repercussions are for what you are looking to do, as well as some alternatives. Custom coilovers can get you the look, but will cost a pretty penny, as well as necessitate further mods (flares, cut fenders, etc.).

Cutting springs is fine, if you know how to calculate the spring rate, which is quite simple actually and can easily predict the resulting spring after the spring is cut, before you cut, by using the proper math.

I would not however cut a progressive spring, which I know my Eibachs are, I'm not sure if Eibach makes a non-progressive spring for the 240Z.

The springs between the 240Z and the 280ZX are quite different in mean diameter, so any direct or semi direct replacement for the S130 will not really apply to the S30.

I suggest that before people post about how bad something is because they've read it on the intarweebz, they should do some real research and not regurgitate what people keep posting on certain websites.

I do agree that to extremely lower an S30, there should be some investigation into possible strut body modifications. I've more than casually looked at the S30 suspension, and it seems that people might be doing way more work than they need to, because someone else has recommended that it should be done.
It seems that people think too linearly when they lower a car, and try to retain the same amount of strut/shock travel, but when you lower a car the amount of compression desired will actually be reduced, and stiffer springs will be fitted, so all of those modifications may not really be needed. ;)

[QUOTE=Six_Shooter;299871]Cutting springs is fine, if you know how to calculate the spring rate, which is quite simple actually and can easily predict the resulting spring after the spring is cut, before you cut, by using the proper math.
So can you please enlighten us on this proper math?

Yeah....

http://engineersedge.com/spring_comp_calc_k.htm

Put another way...

http://forums.focaljet.com/suspensio...ing-rates.html

http://lmgtfy.com/?q=Calculating+spring+rate

It's accurate, I've verified with some springs on known rates.

So after all that you would want to figure out what you have and then what you need in lbs of increased stiffness. My Tokicos ride perfect for me I just want to lower it more so that is easy too. Shortening the springs and further reducing the amount of travel is not really what I want for my car which will be for street use only. I want to incorporate small air bags or air shocks to give a little rise to get over driveways and speed bumps with just a flick of a switch.
BTW welcome to Zdriver.

See that's the problem that people don't realize is the wrong way to look at it.

When a car is lowered, you won't want the same amount of suspension travel, not the same amount of compression anyway. If you did, at some amount of lowering you would actually end up with enough suspension travel to bottom out the chassis of the car before bottoming out the suspension.

Auto manufacturers are pretty smart, when it comes to suspension travel (In most cases), where the tire contact patch will be kept at a height in relation to the the bottom of the chassis that would be below the chassis' lowest point under full suspension compression. It's safer to bottom out the suspension than to bottom out the chassis. This still allows steering and braking abilities, where as bottoming out the chassis doesn't allow either of those to happen, control-ably anyway.
This is where progressive springs and rubber (urethane) bumpstops help to reduce hard bottoming out, and maintain control.

To raise the car by a button there are a few different types of systems out there. Some use air, though that can use many components. There is a car that uses an electro-magnetic system, for speed bumps and driveways.

I've thought about many designs to do that, but have come to the conclusion that to lower a car that much, would make it difficult to drive on many roads