HD Shocks with Lowering Springs

[Backfire]

I have seen posted many times that lowering springs will wear out the stock deCarbon's and should be used with upgraded springs for best perfromance and shock life. What seems to get confused is the reason why. Is it the increased spring rates that the lowering springs generally have, or the ride height change? I have seen both reasons stated before, but have always thought that the greater spring rate was the cause of the problems. I could never figure out how lowering alone would cause the shocks to "work" any harder than before.

The reason for asking is I have been considering lowering my car slightly from its current height. The V8 spring swap dropped the rear about .5" (remember I have a 94 with the softer, but longer OEM rears than the V8), and left the front slightly lower as well. I would like to drop the front more to reduce the fender gap. I have been happy with ride quality of the V8 takeoff parts, so I would like to maintain that. I am considering cutting a coil off the front springs. Before you jump on me about cutting springs, many people have had success doing this, with no adverse affects to ride quality or performance. When linear rate springs are cut, the spring rate is unaffected, the length is simply reduced. I just wanted to verify that the spring rate was the issue when dealing with stock shocks, and not the lowering itself.

Thanks for any input.

[Dominic]

Stiffer springs pull/push harder on the shocks and are more difficult to control - therefore you need a stiffer shock to control the stiffer spring. Many people believe the stock shocks aren't even suitable for the stock springs since the stock suspension is nowhere even close to being critically damped - which is good for a nice ride, but can be bad for performance.

A good HD shock would seriously help control any spring upgrade you make. The only issue with a lowering spring is most are progressively wound, and shocks are not progressively "charged" - so you end up with a linear shock fighting a progressive spring, which is not necessarily bad but it can be.

With such a setup, using say eibach lowering springs and bilsten shocks, you will be critically damped or overdamped on the initial 1-2" of wheel travel, then you will have a critically damped oscillator, and then it will pass into an underdamped condition. This non linearity in the suspension can cause the vehicle to become more unpredictable.

However, most people like that setup and have no problems with it - so take your pick. I like the 0.75" drop less progressive SLP springs since they're not so low and not so stiff at the bottom. This combined with Bilsten HD shocks would be a fairly good setup since you'll end up with plenty of shock for the spring, but won't be quite so out of control [img]smile.gif[/img] .

[DominusEtDeusNatus]

Lowering springs are always stiffer. Why? Because they have to dampen the same amount but with less spring. Plus you don't want to scrape do you? Or have your wheel wells hit your tires. If you had soft and shorted springs then you would be bottoming out. I've always recommended stiff shocks with lowering springs cause if they are soft(aka stock V6 or stock V8) then they won't control the spring properly. It will be bouncy and wearing off the shock at the same time.

There are people on V8 boards running Pro kits with stock shocks. What can you do? Ride is OK at best. You will get by. It's just not optimal I guess. You could probably get the stiffest springs and the softest shocks and the car will "drive." People who never had a good setup argue all the time that it drives fine.

I just helped a kid put Sportlines on his 94LT1 that still had original shocks. Car also had ground effects. I couldn't fit a jack under it after I was done. I told him he'll need new shocks. He's not road racing or drag racing so I guess it's not a big deal for him. It's a show car I guess.

It's what you want out of the car that should make you decide on what shocks you want.

[Backfire]

Thanks for the info! That is about what I expected. Based on the spring rates of the factory springs, an impact that would compress the V6 spring 5" would compress the V8 spring less than 4". That is why I was considering losing a coil or so from the V8 springs. Even if sitting lower, it should absorb the same energy in less suspension movement. I may give it a try and see what it does to the ride. I still have the original springs and the V8 takeoffs are cheap to replace if it doesn't turn out well. We shall see :D

[Dominic]

Cutting coils on a stiff spring makes it weaker - it is not adviseable.

[Backfire]

How will it make it weaker? I will not be using a torch so heating will not be an issue. The spring rate will not change either. If the spring needed to be compressed 5", for example, to support the weight of the car when it had a 16" free length, it will still need to compress 5" to support the load. If I remove an inch of free length, it will now have a 10" compressed length instead of 11". Now, there will be an increase in stress on the spring, because the 5" of compression will be distributed through 1 less coil. But the spring is not "weaker", the rate is unchanged. Is this what you meant? I have heard of guys who have gone to extremes, and cut off numerous coils and had problems. But I haven't seen any spring failures from more moderate reductions, i.e. 1.x coils, before.

[CamaroBoy3800]

it's not a good idea to cut springs period, you make them less effective no matter what. They are designed by the manufacturer to be the way they are if you change that then you run the risk of doing damage to the car. Trust me I've heard of it happening. I know people may not agree with me but I'm sorry cars are not something that you should "go cheap" on, if you have to save money to buy a better and safer product rather than go the inexpensive route and make shortcuts. It will save you heartache and money in the long run. Pay a little now save a lot later. It's your car though I'm just trying to help you out

[V6Bob]

"Cutting coils on a stiff spring makes it weaker - it is not adviseable."

Actually, it's the other way around. Cutting coils on a spring (with a saw, not a torch) makes it stiffer. A coil spring is just a torsion bar wrapped in a spiral. Shorter is stiffer.

I'm staying out of the debate on whether cutting is a reasonable thing to do :D . Torching clearly is not, IMHO.

[Backfire]

V6Bob's thinking is along the lines of what I was thinking. When you cut a coil, you are now subjecting the spring to the same load only it is shorter/has fewer coils. This means that each coil will be under greater stress since its deflection is greater. To use the numbers I posted earlier. If the spring compresses 5in, and has say 10 coils originally, then each coil will deflect 0.50in. If you remove a coil, each of the nine remaining coils will deflect 0.56in. The spring rate shouldn't change for the remaining part of the spring.

Like I said in my first post, this purpose was to determine the reasons why lowering springs need improved shocks. People seem to think that lowering alone causes the problem, but it't the increased spring rates that are the real culprit.

[splifster]

I currently am running the Eibach Pro Kit. Havent replaced rear shocks because it is not giving me problems. I did however replace stock struts with Monroe's in the front. I did this after about a month of too much give with the stock struts. I have yet to have a problem. As you can see its pretty low though, have to drive carefully [img]smile.gif[/img]

Dont ever... ever cut the springs.