woodonastick

iTrader: (1)

i never planned on cutting springs. i just asked cuz i never knew how cutting springs acually helped performance.

trochoid

iTrader: (6)

Some springs have what are called dead coils. They don't really affect the spring rate or amount of travel, they do affect height. These coils can be cut, but how many of the dyi-er's out there actually know which is a dead coil and which is a live one? I sure as hell don't.

I know that a lot of guys who have cut springs on this forum feel they have a stiffer ride, but it is more than likely that the coils are collapsing onto themselves, along with hitting the bump stops. When I redid my suspension, and I mean every single component except the idler and pitman arms, (about 1200 in parts alone), the ride was much stiffer (can you say go-kart ) . I didn't trim the bump stops, and it didn't take much to hit them, they are now trimmed but the car isn't ready for the street yet.

I'm a firm believer in doing things right the first time. If you half *** the job, you get half assed results.

Glad to see you are going for the lowering springs. I suggest doing shocks at the same time. Old shocks and stiff springs can give that low-rider ride. Have you ever seen a 64 Impala going down the street on cut springs and wooden blocks for shocks? It's a bit bouncy.

RotaryAXer

iTrader: (4)

Did anyone actually read this.

This is the only person that has a good understanding of this here.

Look at the calculator and play with the number of free coils. Change it from 4.5 to 3 (as an example). The spring rate goes up. If you have fewer free coils you raise the spring rate. It can't be any simpler than that.

Dead coils are just that...not active. On many springs there are several coils at either end that are wound tightly with no gap between them. They do nothing but add height to the spring. Their sole purpose is to allow the end user adjustment of ride height. (of course you can only go down)

Cutting springs is not half assed and is for sure not a bad way to get the exact spring rate you need. Sure you need to understand what you are doing, doesn't mean it is a bad way to get the required results.

Oh, and in case you missed jgrewe's introduction on this forum....https://www.rx7club.com/race-car-tech-103/getting-back-racing-400085/ A racer through and through.

evil_motors

iTrader: (3)

i am pretty sure that the manufacturer made the springs as tall as they are and with that many coils for a reason.. if you change the spring height you also change the travel in the shock causing it to wear out quicker because it is not in its normal range of motion.. so like i said.. good luck replacing all your parts in a few months

Latin270

Whatever! I've always cut my springs and never had a problem. Maybe one day I'll buy springs and see if infact there is a diffrence but until then.......let me enjoy my ride!!

BMS2004

is that the only #'s ISC is giving out? they told us to run that on our EP car. to be fair though we're running a different setup than them. We now have 550/350.
You have coil overs? I have 350 and the 150 rear no longer on the car.

Wankelguy

So you're saying not to lower the car at all?

That in fact lowering the car by using shorter springs (whether they're cut or not) will cause undue wear on suspension components? Is that what you're saying?

EL5Letra

a car with cut springs cannot handle as well as a car with aftermarket springs. If u ever notice a car with cut springs they bounce all over the road. Aftermarket springs are made for reason. If u buy aftermarket springs and you cut them...what was the point? they are designed that way for a reason . Just buy springs....vipernicus42 is right.

797

agreed, the only time I saw someone cut aftermarket springs, was on the tv show called overhaulin, chip foose (hot rod genious) and the crew redid an entire car but he wanted it to sit just a tiny bit lower, so they took the springs off and cut them just a bit. He did this for looks though, not performance. All Im saying is its bad for your car to just cut the springs, when the time comes Im buying a set of eibachs or some aftermarket spring.

Hoodsy

If you want to improve your ride, seriously, go out and buy different springs. cutting them is just a backyard ghetto solution and is unsafe. yes you could cut them and then heat and bend the last coil so that they seat properly but unless you really know about metal properties and proper heating and cooling.. real bad idea. where I used to live we had yearly safety inspections on cars and no mechanic would ever pass a car that had springs cut or if they used one of these cheapo compress kitts. so if you want a better ride, buy springs.. less hassle and much safer.

Wankelguy

How do you know they are running cut springs as opposed to the "heat 'em with a torch until they sag" method favored by low-riders?

I've had a couple of different cars with PROPERLY cut springs and I can assure you they did not "bounce all over the road", but then in all fairness I had good shocks as well.

I'd like someone to explain how a properly cut spring is somehow more dangerous than an aftermarket lowering spring of the same height, especially since you really don't need to lower 1st Gens more than about an inch and a half. Personally, I think cut springs are a perfectly viable option if done right.

RotaryAXer

iTrader: (4)

^ exactly

Feds

Nope.

Lowering a car will increase the load that the suspension transmits to the mounting points. PERIOD. It does not matter whether the lowering is done with cut springs or "Proper" lowering springs.

How do I know this? I design suspensions for a living. One of my most recent projects involved designing the factory installed lowered suspension for an upcoming model. Our total lowering was limited by many things, one of them being the load on the chassis.

How ELSE do I know this? I've taken a LOT of math courses. The job of a suspension to absob the energy input from the bump to the vehicle. Ignoring the bumpstops, with a stock suspension, the spring and damper have X distance to absorb the bump energy, and thus must apply Y force to do it. Energy = force × distance. If you lower the suspension 1", the spring now has X-1 distance, but the energy is the same, so the force has to go up accordingly (XY = [X-1]Y', Y' = XY/[X-1], X/[X-1] >1, thus Y' > Y). Notice this has nothing to do with rates, valving, nothing, just pure free travel.

Also: Your suspension is designed to carry your vehicle's FULL load. So that is you, a passenger, your luggage, and a trailer, with all options and fluids to capacity. If you do not load your vehicle up to those levels, you do not need all of the suspension's free travel. Period, end of story.

The "horor stories" of cutting springs come from people who cut their springs in half, load up a cut-spring vehicle, or put 20's on it, or do some other foolish thing. This will easily overload chassis components, cause breakage, unseat the springs, etc.

What you have to keep in mind is that nay time you modify a vehicle, you change it's capabilities. You can't drive an F1 car to the grocery store, you'd tear up the suspension. So if you keep in mind that making a suspension stiffer reduces the carrying capacity of the vehicle, you'll be fine.

A last thought... To your chassis, shorter/stiffer springs "feel" the same as upsized wheels and low-pro tires. Yet no-one would come out and go crazy about someone putting 15" wheels on their car.

evil_motors

iTrader: (3)

i am saying if you use lower springs you need aftermarket shocks also

Kentetsu

Maybe I've had one beer too many, but I find the ideas presented here to be absolutely hilarious!!!

I'm not going to tell you I'm a famous racecar driver, or that I design suspensions for Porsche, but I do have more than enough experience to recognize a plethora of bullshit when I step in it!!

Anyway, with that out of the way, I will say again; take a walk down to the local damn library and check out a book on the subject! If you have money, then buy one so that you can refer back to it when needed.

So much of the info presented here appears to be "I heard this", or "they say that", and so on....

But anyway, I have raced and I have built up some cars in the past. But more importantly, I HAVE READ THE BOOKS!!! Do the homework if you want facts instead of everybody else's opinions.

And now, on to my opinion. There is nothing wrong with cutting springs as long as it is done properly. But that is the problem. It is not very hard to screw things up if you don't have either a good resource for information (like a book) or actual hands-on experience.

I have done it a few times myself. Twice badly (learning process), and twice correctly. If you can't afford to drop big $$$ on new springs, and you really need to stiffen things up a bit (insert Viagra joke here) then go ahead and try it. But get your information together first! Don't just blindly try something just to see what happens. Start small and increase as needed.

But again, my advice to Woodonastick is to go with aftermarket springs as long as he can afford them. Why argue with the experts who have already done the research and development part of figuring out what works best?

Oh, and as far as the question of whether cutting a spring makes it stiffer, think of it this way: If you were going to fall down flat on your back, would you rather land on a 3" thick piece of foam rubber or a piece that is 6" thick? The spring is a type of cushion, the more coils you have the softer it will be.

I hope I don't sound too obnoxious or arrogant here, but only a few of you have managed to touch on the truth of the matter. There is an amazing amount of knowledge to be had in this forum, and I have received plenty of help in the past. But I was seeing some posts by those I consider to be the "experts" that revealed a large gap in their knowledge.

But don't take my word for any of this, please! Just check it out for yourself. Spend an hour with a good book on the subject and you'll damn near be an "expert" yourself. Then after that, you can come back and tell me how right I was!

Feds

Hey! I never said I work for Porsche. It goes against my creedo:

There are only 2 things I hate: People who are intollerant of others, and the Germans.

woodonastick

iTrader: (1)

i believe i also saw 400# front. and that was it.

and no, i have stock set up right now, im still deciding on wat my set up will be. ive been searching for a long time into what i want. i will be doing a lot of road racing.

jgrewe

iTrader: (1)

This has gotten interesting! First, it appears that many have catalogitis. It's a disease that afflicts many in the racing world. The problem is these people can only buy parts out of a catalog, very similar symptoms show up in what we call checkbookracers. The result is they can only go so fast. The fast guys use computer modeling and other cool stuff and make their parts, sometimes from what is just laying around the shop.

Just because GroundControl or whoever says that "this is the spring you need" doesn't mean they know YOUR car. The fast guys figure it out for themselves for THEIR car.

Fortunately you have an FB, a fast guy has spent 1000's of hours figuring out every problem that you will come across and made his own catalog. The important thing to remember is you can't mix and match stuff. He's already thought about what your thinking, whatever it is, and has probably ruled it out with one of his modeling programs or his finite element analysis program.

If you don't know who I'm talking about yet, its Jim Susko at GForce Engineering. If you are going road racing you need his book.

Oh yea, the stock cut springs I talked about earlier... we were trying to get 300lb/in springs for the rear of an FB. We couldn't find them short enough to get the ride height we wanted so we made them... I keep using "we" because it was Susko And I setting up one of our cars to try his latest idea. That was oh, 10 years ago and he still probably wakes up at night with ideas on these cars.

But cutting springs is for country bumpkins... I know

Oh yea, those springs are still on a car somewhere in CENDIV, Cincinnati, Ohio I think

steve84GS TII

Man,you guys are considering 350-400lb springs on a streetcar?
I run 175lb RB springs with Tokiko blues and my ride is plenty firm and responsive.Putting 300-400lb'ers would jar my teeth out,but then again we do have some crappy roads in CA........

woodonastick

iTrader: (1)

well not really. i kno people who run stiffer with coilovers.

Kentetsu

Sorry Feds, this was not aimed @ you! Some good info in your post....I was tired (36 hours w/no sleep) and becoming a little tired of people stating opinions as if they were facts. Sorry if I was offensive to anyone...

jgrewe

iTrader: (1)

If your running 175's on the rear you probably have urethane bushings(or stock). These bushings become more a part of the anti-roll bar equation as the car squats. The rear upper links bind up if the car trys to roll and squat at the same time. Free these up and you can run higher rates in the rear without the ride getting to bad. Thats why you see huge front bars on cars and no rear bar. You have to make the front break away as much as the rear naturally does with things binding up.