sully91rs

As far as I know, there are stock RS springs in mr car. It is lower looking, from age. I want to keep the lower look but get new springs when I get new shocks/struts. I like the ride of my car.
Can I get Moog RS springs (rated at 424 lb/in) and cut them to get the lower look, or just go with the harsher ride of the Eibach Pros (rated at 714 lb/in) and they will come with the lower look.

techno101

I have a '89 RS, I had factory RS springs in front. Car sat low and moved like it was on the moon. Up and down, up and down. Made hard cornering very differcult. So, my solution was, I bought factory IROC front coils brand new. Installed them along with new struts. Car sat about 1 inch higher than before! Looked ok, but I ended up cutting half a coil off, and now the car sits where it orginally sat with the RS springs. Handles awesome now though, corners and tires beware! Oh one more thing, when I had the factory RS springs off standing next to the IROC springs, the RS springs are taller and A LOT smaller in diameter, the IROC springs were heavy, short and fat, but a 100% improvement over the RS springs I had. Best thing is, only cost about about $65 for springs and $80 for both struts.

sully91rs

I like that route. How is the ride feel? I drove a Z28 before, and it felt like there was no suspension, everything was absorbed by ur a$$. My RS has softer cornering, but the ride is very comfortable. Would you say ride comfort changed with the IROC springs?

Also, do you have pics of the fender gap?

CrazyHawaiian

Low ride height and soft spring rates is not a good combination in my opinion, especially if the struts/shocks are worn. By lowering the ride height you are limiting the ammount of suspension travel allowable before having tire contact and bottoming out. If you combine this with soft rate springs and/or blown struts/shocks then you might run into problems. So definately install those new struts. I'm sure there is a medium where you can get what you want, but be sure to keep this in mind. You dont want to go too low and too soft. Cutting the stock RS spring will raise the spring rate so you probably wouldnt end up with those advertised numbers. You also have the option of ordering custom springs at the rate and height you want.

techno101

The ride quality is very acceptable I'd say. With the brand new struts, and IROC coils, the car handles very well. I also have a 34mm front sway bar, Spohn 1 1/8 inch wonder bar, and a 3 point strut tower brace from Edelbrock. I'll tell you, I have never been on a real "track" but rural akansas there are sharps turns at every corner. I have never had a problem with tire clearance. I'll try to get a pic in the morning.

ShiftyCapone

iTrader: (7)

A set of lowering springs will give you the ride height you want without all the dangerous effects of cut coils. Lowering springs will not ride nearly as hard as cut stockers.

sully91rs

That's exactly what I needed to hear.

techno101

I like the way the IROC springs feel better than an aftermarket set. Like someone else said earlier the IROC spring is a little stiffer than an aftermarket set. But to me, a car that will turn on a dime and with almost NO body roll is what most of us are after. If you want heavy duty performance springs, get the factory IROCs. That whats they where egineered for right?

And as for being dangerous for cuttings coils? Maybe on the stock RS spring, because it looks like a progressive rate spring. But the IROC spring has the same coil gap all the way, so cutting half a coil is no problem. PLUS, you have a coil top insulator, or should have. I don't recommend discarding it, but you possibly could lower you car by 1/2 inch simply by removing the insulator.

sully91rs

This is my daily driver. I think the car handles nice right now. Body roll is slight. My favorite part is I do not feel any little ripples in the road, only significant divets or potholes or manhole covers. I would prefer to go to the aftermarket springs, if they are softer, and keep some comfort in the ride.

Also, when doing searches, I read that the IROC springs and WS6 springs were only ~500 lbs/in. These were posts dating back to 2001, but if thats true, wouldn't the IROCs be softer than the Eibachs (714 lbs/in)?

techno101

it all has to do with progressiveness too, don't know if thats a word, but some springs have a progressive rate. As they compress, they have a soft area of compression after they move past that zone they will become stiff. My RS springs were that way.

CrazyHawaiian

Both the Eibach spring sets are static rate in the front and progressive rate in the rear, and both are stiffer than IROC springs. As far as I know, no 3rd gens came with progressive rate springs stock, everything is static rate. I think the only danger of cutting springs is to cut them wrong and heat them up too much, then the metal might lose its temperment and thats when it goes soft so the spring rate goes down instead of up.

MikeH

iTrader: (10)

can you post a pic this is what i want to do. I want to keep my good ride but lower the front slightly. After installing lighter parts up front it sits a little high now. I want a slight rake towards the front. Not level like it is now.

Did the ride change much?

I dont see a reason why not to cut them. The coils are equaly spaced. Yes the rate will increase but its still goona be alot softer then any of the aftermarket stuff.

MikeH

iTrader: (10)

what dangerous effects? The front stockers arent progressive springs.

Taking an IROC spring with around 550lbs and cutting half a coil or so to get the same ride height as an aftermarket set. I cant see the spring rate increasing to anywhere near 700lbs + that the aftermarkets are running. I dont think it would take more then a 1/4 to 1/2 coil off a stock IROC spring to get it as low or lower then most aftermaket springs.

MikeH

iTrader: (10)

Ive had mine out several times. And wonder if the stock REARS arent progressive?

Mine are NNNs kinda rare. The IROCs ive seen most have NNLs. The NNLs had a harsher ride compared to the NNNs. having driven the same car with the two springs swapped out nothing else changed.

looking at them... They do seem to have tigher wound coils on top. At least the NNLs and NNNs that ive seen. Isnt that what makes them progressive?

techno101

Cutting coils can be difficult if you make it that way, or it can be a breeze. A sawzall (or reciprocating) is the safest way I know to cutting coils. It generates the least amount of heat. As opposed to a cutting disc or worse a cutting torch. A good sawzall and a new metal cutting blade will eat that coil in no time.

sully91rs

A sawzaw is what I would use.

CrazyHawaiian

Hmmm, well none of the stock springs or the replacements are advertised as progressive rate, they all provide a single rate so I assume they are all static. I guess the possibility is always there.

sully91rs

The more this goes, the more I feel I will just keep the stock springs in there and just get the kyb agx. I like the way the stockers feel and look.

MikeH

iTrader: (10)

IM wondering if its not just spring sag on the top few coils that make it kinda look like its progressive. The ones ive seen all had over 100,000 on them.

Norm Peterson

There are several Moog springs that will fit the front that are enough stiffer than 420-ish to be worth swapping in. Some trimming may be required, as not all of them are specifically F-body springs (all are S10/S15, which will physically interchange). Part numbers and rates to the nearest 5 lb/in are as follows.

5658 . . . 580 lb/in
5660 . . . 640 lb/in
5662 . . . 705 lb/in
5664 . . . 765 lb/in

I've got the 5660's in the front of the Malibu, (which is close enough to the weight and spring location of a 3rd gen F-body to make such a comparison valid) and it's legitimately a daily driver just about anywhere. Unless you're unusually sensitive to a firm ride (in which case I'd question the purchase of a sporty car in the first place).

Norm

83 Crossfire TA

iTrader: (2)

What dangerous effects? The fact that the car will sit lower with a stiffer spring rate so you might drive faster???

If you’re happy with your ride and ride height, why the hell do you want to change your springs?

yep, sometimes I’m not sure what people are smoking on this forum…

Yep and yep.

heh, springs might loose their _temperment_. I think that you meant temper, I have a bad temperament… steel is tempered to make it tough and have a specific stiffenss.

It’s pretty hard to heat a spring enough outside of where you’re cutting with a cutting torch to hurt it any. I’d be surprised if most people could actually do it if they tried to on purpose. For that matter, in most applications I prefer heating the last half coil of what is left of the spring after cutting it and bending it inward like the stock spring was, if it was possible to ruin a spring accidentally that would be where it would happen and it doesn’t.

Just use whatever you have/are comfortable with. I usually use an abrasive cutoff wheel in an angle grinder.

sully91rs

I'm investing in kyb agx all around, and I was under the impression that my springs now are too "saggy". At this point, I'm keeping my stock springs and just going to get the kyb agx. I've heard others with RS's upgrading just the shocks/struts and reporting a great ride. If I feel compelled to change the springs after that, I'll do it. I'm not worried about the extra work.

CrazyHawaiian

Heh sorry my engrish is so bad *hangs head in shame* but hey at least I can make better MS Paint diagrams than Dean!!

83 Crossfire TA

iTrader: (2)

that's kinda like saying that you can thumb wrestle better then a 3 toed sloth...

Sonix

iTrader: (1)

oh yea, so you're tough and stiff eh?

I'm pretty sure at least Moog 5660 and 5662 are both factory replacements for 3rd gens, so they DO have the *correct* height. Not sure about the other 2.

(ie, says it's the right height, but a new spring will make your
car taller then those worn out old ones of course.)

I bought moog 5664's, and i'm waiting to put them into the car for the spring. It's the factory spring for an s10 in '93 and a few other years.
The right stiffness in a moog spring will give you the same performance as an aftermarket "go fast" brand of spring, at a fraction of the cost IMHO.

sgt0704

from my understanding, it is not good to cut the springs, cause in acuality, you are weakening the spring. correct me if i'm wrong, but the drop coils, are wound tighter, but still maintain the same amount of coils. if that makes sence to you. so by removing one from the "stockers" you are weakening the spring and possibly lowering the load amount. i would just get the drop springs. i put 2" drop zone springs on mine. i got it off ebay for like 170 bucks or something around there. after upgrading the front end to poly bushings, with new balljoints, rods, struts, shocks, etc... (due for it any way), it rides like a champ.

83 Crossfire TA

iTrader: (2)

OK, you’re wrong.






Oh, you wanted more… well explain how you’re weakening the spring? If you look at the factory springs, count free coils… and aftermarket stuff you’ll see that just about anything that you can do to most of the springs still falls into a range of available free coils anyway. Secondly, the spring material used from the factory is probably better then all the aftermarket springs with the exception of maybe eibach.

MikeH

iTrader: (10)

Yeah that doesnt make sence to me either... I remember reading a book on thirdgens. Herb adams was suggesting to take a base set of camaro springs. And cut them to keep a good ride. While increasing spring rate some, and lowering the car for handling.

If it was so bad i dont think he would have suggested it as well.

I have a spare set of BZWs that im going to cut a 1/4 coil at a time till i get the front to drop like i want it.

ShiftyCapone

iTrader: (7)

It isn't that you are weakening the spring, but instead you are potentially creating spring surge. Changing the physical dimensions of a spring (from its design intent) can put the spring in an operating range that promotes resonance. This can result in damaging forces, since the internal dampening of the spring material is quite low, thus reducing the life (and creating possible sudden failure) of the spring. This is amplified even more if the wrong shock is paired with it. It may or may not happen for your application but it certainly can happen and has happened. Granted, as mentioned above, this isn't as severe with linear springs as it is with progressive springs. I agree with your thoughts on cutting practices and that there is minimal heat transferred into the entire spring. However, you create a local weak spot when cutting with heat at the end of the spring. This may not be a big deal but if the person cutting the springs spends a little too much time there (with the heat source) the same damaging effects will travel into the top half coil of the spring. That alone is enough to promote early spring failure. Will it happen on every car… Chances are low. However, it can happen and you will have to take some risk. FWIW.

Norm Peterson

I think spring surge is something that occurs at forcing frequencies that are much higher than anything a suspension spring would ever see with enough amplitude to get it going. At least in any streetable car. Granted, surge can be a problem with valve springs, but that's a rather different environment. As far as surge in F-body suspension springs is concerned, methinks one's fillings would be at risk first.

But - when you cut a spring you reduce its resilience, or the safe amount of work that can be done on the spring. Since this is tied to a safe level of stress, it's a fatigue thing, and adverse effects tend to be long-term in nature. In the absence of stress raisers such as nicks and scratches, or being REALLY clumsy with a torch, sag comes to mind.

Even the resilience issue is not all bad. Force limited loading, which includes the effects of lateral and longitudinal load transfer - incorrectly termed "weight transfer" by many - does not appear to be affected. The spring rate increases as fast as the volume of metal in the spring decreases, so at least in theory it's a wash ("real" cases should be close). It's the displacement caused loading, meaning all those bumps in the road (whose height didn't change just because you cut your springs), that increases the work per unit volume done on a shortened spring relative to its unmodified condition.

Fortunately, most OE springs have enough margin to permit some trimming, and hopefully there's a bump stop of some sort still in place to help with the really large events.

I've cut springs with the acetylene torch before, and this can be an acceptable method - as long as you use equipment with enough capacity to get the cut started right away. IOW, those little home torch kits need not apply. And laying the spring on its side in a shallow pan of water while cutting will tend to reduce the amount of heat transferred along the wire. A little heat travelling half a coil or so is not a deal-breaker, as that first half coil generally goes flat against the spring seat under the static load and hardly ever flexes anyway.

Norm

83 Crossfire TA

iTrader: (2)

Wow, the 2 of you have listened to dean or general ‘net misinformation for too long… well, more accurately, it’s more a misapplication of facts, they are facts, they are in fact (heh pun…) correct but they do not apply to what we’re doing.

First, once and for all the torch thing.

All the warnings about using a torch started some place totally different and somehow someone misapplied it to cutting springs. The old school way (and the way a lot of lowriders and imports originally did it) was to heat the spring, usually with a rosebud (which gets a lot of the spring hot at once, but you could start in one place and move on…) with the load of the car on it till it weakens and sags and keep heating more of it till you get a ride height that you want. Generally the end result is part of the coil weakened to the point where it is permanently stacked.

Outside of doing something like that, purposely messing up the spring, you’d have to be a retarded monkey (no offence to your avatar Shifty, hell, I use “Silverback” as my screen name on most forums, I’d love to change mine to that here), to put enough heat into a spring cutting it to hurt it.

Hell, even if you managed to do it to the last ½-2/3 coil left on the spring after you cut it you’d end up with EXACTLY what you want in a perfect world (if the end of the spring is compressed down in the pocket like the original you’ll get a more linear spring rate overall after cutting). Of course, I wouldn’t try to do it this way on purpose because you’re likely to get every spring slightly different. Real world I usually just cut them and leave them (seat the unstacked portion in a thick isolator or just deal with a little bit of progressiveness in the spring since it is only right where the spring is about to go totally free of the spring pocket, something you should never see driving) or if I’m being really **** retentive I use a hot flame at a spot exactly a set distance around the first coil, heat and bend.

”Spring Surge”

Harmonic/resonant rate of a spring is defined by a simple equation (search, I’ve posted it before). That harmonic depends on the rate of the spring and the load it is carrying. Nothing more, nothing less. ANY spring with the same rate in the same application will have the same “spring surge” whether it’s cut, aftermarket or OEM. If you don’t like your suspension resonating at a faster frequency don’t increase your spring rate and match your shock/strut dampening to your springs. Don’t blame it on cutting springs or whatever.

Resilliance, stress, fatigue…

This is about the only place where you guys do have a point. Yes, as you cut coils off a spring the stress placed in any part of that spring increases. A spring is just a long rod coiled into a coil so that 1- you don’t need as much force to bend it and 2- when you do bend it you only bend any particular part of it a little bit. When the spring gets shorter your total length gets shorter and you’ll have to bend each and every bit of that spring more to get it to compress the same amount. At some point you’ll reach it’s limit of elastic deformation, the metal will yield (damaging it) and it will not “spring back” all the way. So yes, your practical margin before you do damage to the spring has been lessened. But this is also a non issue WRT to this application. In most cases most coil springs can be compressed to coil bind without actually hitting their limit AND more importantly, in our specific application if you start measuring the total travel at the spring pocket, especially on lowered cars, tends to be much less then an inch before hitting the bump stops (or actually the frame even if you cut the bump stops).

Looking at this in the real world, most stock 3rd gen springs have between 5-1/3 and 8-2/3 coils. If you cut one off and by some miracle still have an inch of useful travel (the reason that I say by some miracle is that if you cut a full coil off of any of the shorter springs like the WS6 and Iroc springs you’ll be actually sitting on the bump stops and have no travel unless you use a thicker spring isolator…), making this totally a worst case scenario, you’re still only bending the equivalent of roughly an 81” (almost 7’) long piece of spring steel 1”, or slightly more then 1%. In other words, you’re worried about next to nothing.

All this being said, there is one, very specific danger with cutting springs, especially in some applications like an f-body. If you just start whacking coils till you have the ride height that you want I’ll guarantee that you’ll end up with too stiff a spring rate in the back and not enough to match it in the front, resulting in a car that wants to swap ends every time you look at it funny.

Every time I’ve cut springs I’ve gotten some rough idea of spring rates, cut the springs to get the spring rate that I wanted and then messed around with the isolators to get the right ride height. To simplify this for most people starting with one of the performance 3rd gen suspensions, to get them in a range that is reasonably close, just cut the springs somewhere in the ½-1 coil range and then use the thick, rear spring isolator in the front and the thin front one (actually, that one is a pita to keep seated right, I usually just use some heater hose on the last coil) in the back. That way you won’t kill yourself.

Norm Peterson

Pretty good analogy, but the actual description should refer to the amount of twist in a 7' long torsion bar. Even though coil springs don't look like torsion bars, they are stressed in in very much the same way. Not in bending (by way of comparative illustration, a leaf spring works primarily in bending). Anyway, the fact that coil springs see torsion rather than bending is why the coil spring formula for rate is normally written in terms of the shear modulus property (G) instead of using Young's modulus (E) that's applicable for tension and bending.

The correlation of unit end deflection to material deformation in a coil spring is linear, but would be in the ratio of

[length of wire cut off] / [7'], or something like 5% - 10%
not 1" vs 7'.

That's the way torsion works; a linear rate of angular deformation over the length of a bar of uniform cross section. If bending was in fact the mechanism involved, the correlation would be a [length]^3 function of some sort. Not linear.

Otherwise, I think we're in agreement.

Norm
civil structural engineer/stress analyst

83 Crossfire TA

iTrader: (2)

HUH… never thought about it like that, but I could see how that could be the case… Actually, I would really believe that there is some of each going on, and I’ve never really thought about it, just assumed that most if it is bending/deflection and not torsion. I wonder if anyone has actually done any analysis on this real world, for that matter, I don’t seem to remember a different equation for say coil springs vs leaf springs in mechanics class (thought that may be just a case of faulty memory), though I remember the equation using G and basically the diameter of the coil * free coils to work out the length of the piece of steel.

OTOH, not spending a lot of time working out the math, this should make my point even better, since it wouldn’t take much actual twist to get that much motion, and there should be more travel before you permanently yield the spring.

We’re comparing 2 different things, I was comparing how much the spring compression was affecting what was left of the spring, where you’re comparing how much cutting the coil off changes the affect on the spring. FWIW, that is more like 20% for one coil in that example.

ShiftyCapone

iTrader: (7)

Well said. Besides the analytical part of it this is really my only main concern when cutting springs. However, since TGO has people like you to teach those the correct way, a fist time TGO cutter won't do anything stupid.

super_kev

iTrader: (4)

I'm going to raise this thread from the dead.

I just finished transplanting an LS1 in my car, and I need to lower it because of the decreased weight of the front end, plus I want it about 1.5" lower on top of that; so make it a 2" drop. I have new Moog 5665's that were cut 1/3 coil, since I had installed new ones on another T/A and it raised the rear end a little. I just cut 3/4 coil off some new front Moog 5662's I had laying around, knowing that the spring rate would go up, but man, it really did go up. I am using the method where the strut is bolted in, and then the a-arm is jacked up with the spring to put the bolts in. As much as I try, I can't get the spring compressed enough to jack up the a-arm, because the a-arm was starting to bend under the stress, and it was still 2" away from the bolt holes.

So now for my question, should I buy 5660's and cut 1/2-3/4 coil off the front, or maybe some 5658's? Cutting will increase the spring rate, but I don't want to use lowering springs because of the lighter LS1 front end, and I still might have to cut those. I'm willing to learn how to do this right, so no yelling at me yet.

Edit: Added some pictures of as far as I wanted to jack the a-arm up. The strut is at least 1/2 compressed here, and there is a lot of stress pushing out, away from the car, probably do to the angle of the a-arm and of the strut. If I started jacking more, the car would get lighter on the jack stands, but not completely lift off yet. Plus I don't want to bent the top of the strut shaft from the spring pushing out.

Edit 2: Ok well I feel stupid. It turns out that if I had only had the jack in-line with the car vs. pointing out like I had it, I wouldn't have had this problem. The past few hours I spent installing everything; springs went in just fine. I'll find out how low it is and how it rides and report back.

sully91rs

Well, glad you could get it all back together. LS1 swap is a sweet deal.

Let us know how it rides.

Stephen

iTrader: (12)

On my wife's autocross 90 RS, we put in 86 IROC cut springs, the sway bars, the Wonder Bar, a 3pt STB, and went from the stock 15s, to GTA crosslace 16x8 street, 4 piece 16s for the track.

We never once regretted cutting the springs!

Check out the link to her 90 RS in my sig. The email links are no longer valid. That was my OLD page, and I don't have access to edit it, any more.

joecautela

iTrader: (1)

Hey Super Kev, I'd like to hear more. I recently finished the T5 swap on my Iroc. plus I put on headers and a flow thru cat. So the whole ride height has come up quite a bit, maybe 1 1/2-2". Plus the ride has softened up quite a bit, kinda floats over hard bumps now. I'm also getting ready to do the LS1 brake swap up front and figured I would just lop off 1 turn on the springs all way round to bring the height back down to where it was. Anyone have any idea what the weight diff is between the Auto and manual. I'm figuring I dropped almost 30lbs on the cast manifolds and cat but I don't know the weight difference in the trans? Thx