Z28avalanche

I need advice on the type of lowering springs to purchase. I want to lower my 95 Z about 1.5" front and back. I don't know what springs to get. I want a stiffer ride rather than a softer one. I really don't want to buy shocks unless absolutly necessary. Just wondering what the concensus is.
Thanks

JakeRobb

There are a few good options for springs. Check out our Supporting Vendor Index. J&M Products (hotpart.com) sells 4th gen shocks/springs. I'm not sure who else does.

You want a stiff ride? I can see preferring better handling, and being willing to give up some ride stiffness for that, but don't you want the nicest ride you can get at whatever level of handling performance you're targeting?

In general, you should match your shocks to your springs for best results. Unfortunately, the stock shocks and springs aren't very well matched to each other. If you upgrade the shocks and springs together, you can make your car handle better than it does today, while at the same time vastly improving the ride quality! As a secondary benefit, the improved ride quality will also postpone the onset of the interior rattles our cars are known for.

I'm not an expert on the matter -- give J&M a call and they'll fill you in on your options.

Z28avalanche

I guess I shouldn't say a stiffer ride, but not softer than stock. Just want better handling and to get rid of some of the fender gap.

JakeRobb

Still, why not softer than stock? The stock ride sucks.

Modern shock technology can give you better handling and better ride.

Z28avalanche

I just figured more body roll with a softer ride and won't handle as well.

JohnD

You want stiff, get subframe connectors. I was amazed at the difference it made. That and the 1LE springs I use, I have stock ride height, cornering like being on rails and a ride that rattles my passenger's teeth!

rexcellent

I have a Pro-Kit and it seems a little too soft too me. The car definitely handles better but I did several suspension upgrades at once so it is hard to determine what improvements were made from just the springs. It is a much rougher ride now but the springs just weren't quite as stiff as I was expecting them to be.

The car looks great with the Pro-Kit but it is pretty low. At first I was worried it wasn't going to be low enough for my liking but it sits real low in the front and it is hard to make it over most speed bumps. The rear is exactly how I like it but I think another 1/2"-3/4" up front would be nice.

9T8W66

For one thing the stock shocks are incapable of properly dampening the stock springs let alone a stiffer set with less travel so you really need to get a matched shock spring pkg.
I'm running Strano Springs with Koni S/A shocks along with Strano's 35/22 Hollow swaybar set and it is truly the best of both worlds in regards to ride and handling. The car is predictible and composed in almost all situations.
The ride is firm without being harsh and that's the best i can describe it.
Quality shocks are the key element here.

JakeRobb

You've oversimplified things too much, and as a result, you've come to the wrong conclusion. Allow me to explain (sorry, this is going to be long).

Body roll is primarily controlled by the anti-roll bars (aka sway bars). It has more of an effect on how confidence-inspiring the car is when cornering than it does on the actual handling limits. Spring rate contributes to body roll too, but the primary mechanism to dial in the desired amount of body roll is to adjust the stiffness of the sway bar(s).

There are two components to handling: maximum cornering grip (measured in G forces) and the car's ability to transition (generally evaluated based on the car's performance in a slalom, emergency lane change situation, or figure eight).

Maximum cornering grip is about two things: keeping the tires in contact with the road, and the amount of grip your tires are able to provide when they are in contact with the road.

Keeping the tires in contact with the road is all about shocks and springs. The stock shocks are too stiff, and this frequently allows the tires to lose contact with the road momentarily. No contact means no grip.

The amount of grip your tires provide when they're in contact with the road is a function of the width of the tire and the type of rubber used. In general, you get what you pay for. A $312 275/40R17 Michelin Pilot Sport PS2 is going to provide a lot more grip than a $156 BF Goodrich g-Force Super Sport in the same size (unless you're driving in the snow; the Michelin is a summer-only tire and the BFG is an all-season). Note that some 245/50R16 tires offer more traction than some 315/35R17 tires.

The car's ability to transition is defined by overall weight, center of gravity (including front/rear weight distribution), weight transfer, and chassis/suspension rigidity.

Overall weight is critical. More mass means more inertia to fight when changing directions (not to mention accelerating or braking). A 4th gen V8 Camaro (like yours or mine) weighs between 3300 and 3600 pounds, depending on options. My 2002 Z28 weighed in at 3400 even when I weighed it at the drag strip a couple years ago (~1/4 tank of gas; no idea how well calibrated the scale was). There are lots of ways to reduce weight. Most, but not all, of them involve sacrificing some creature comforts in the car (removing the air conditioning system, or the stereo and all of the speakers, for example).

When cornering, your car will tend to rotate around its center of gravity. Keeping front/rear weight distribution such that the center of gravity is near the middle of the car provides the most neutral cornering behavior. If the CoG is closer to the front of the car, the natural tendency is understeer. If it's closer to the rear, the natural tendency is oversteer. My car's weight distribution with me in it was 56% front, 44% rear. That's pretty good, but there's room for improvement. You can do things like relocate the battery to the rear or replace the front suspension components with lighter ones.

The height of the car's center of gravity is important too, but our cars start out pretty good in this regard, and lowering the car is pretty much the only way you can control this without significant modification. IMO, it's best to focus on the other factors.

Finally, weight transfer and chassis/suspension rigidity. For best turn-in response, you want weight transfer to occur as quickly as possible. When you're cruising in a straight line, the car's weight is pretty evenly distributed across all four tires. Turn the wheel to the left, and the tires start to generate some lateral acceleration forces. However, the body of the car still has that forward momentum. Basically, the tires get in a little fight against the car's momentum, and everything between the contact patch and the body has an opportunity to yield to the combined forces before the car changes direction. Tire sidewall, suspension bushings, springs, control arms, mount points -- everything. In an ideal handling situation, all of those things would be infinitely strong, and the cornering forces would be transferred to the body instantly. However, unless you're driving on the floor of a gymnasium or something similarly smooth, you need some flex in order to maintain good contact with the road. Without good contact, you can't generate those cornering forces in the first place! At the same time, an infinitely stiff suspension would provide the worst possible ride quality.

Still, some parts are supposed to flex, and some aren't. The factory stamped control arms are reasonably rigid, but they do flex under hard cornering and hard launches. You can replace them with stronger tubular components from companies like BMR or UMI. As an added benefit, those parts are generally lighter than the stamped parts you're replacing (and they look good too ).

Our cars use unibody construction, with separate front and rear subframes. The front subframe carries the engine and front suspension (including steering, etc), and bolts to the unibody. The rear subframe carries the axle and the rear suspension, and bolts to the unibody. The unibody itself is somewhat flexible, especially torsionally. This is just one more thing that can flex when you initiate a turn. Subframe connectors are long metal tubes (either rectangular or round, your choice) that bolt or weld to the front and rear subframe, connecting them more rigidly and reduce body flex.

So, if you want your car to handle well, do the following, in this order:

1. Pony up for a decent set of tires. Get larger wheels to accommodate them if necessary, but remember that wheels comparable in quality and durability to your factory wheels are extremely expensive ($500+ per wheel). Personally, I went with a set of wheels from a WS6 -- larger than my stockers, but still factory quality! I got them used, with tires, for $600. The tires were junky all-seasons, but the deal was unbeatable. When they wear out, I'll replacing them with something nice and sticky. I'll upgrade to a high-end forged wheel someday when I have more money.

2. Upgrade your shocks and get matched springs at your preferred ride height. Don't guess at what matches -- consult with a suspension expert or get a kit designed specifically for your car. Ideally, upgrade your swaybars at the same time. If you want to pay a little extra, you could get an adjustable shock, which lets you turn a dial to determine how stiff you want it to be. More stiffness for autocross days, less for road trips. The best of both worlds!

3. Subframe connectors. I prefer the weld-in variety, assuming you can weld (or that you're willing to pay someone to do it). Bolt-in is okay, but it's not quite as strong and they cost more. Note, however, that there's nothing stopping you from welding a subframe connector that was meant to be bolted.

4. Tubular lower control arms in the front and rear. Get rear LCA relocation brackets while you're at it -- this corrects the geometry that you will mess up when you lower the car. You can do the front separately from the rear -- it doesn't matter which you do first.

When you're done, your car will handle better than ever, and the ride will still be worlds better than it is today.

Z28avalanche

Right now I'm running 18x9.5 Z06 wheels all four corners wrapped in 275/35/18 BFG KDW2. That made a difference in handling. Looks like I'll be looking for some springs and shocks. Thanks for the help

JakeRobb

That's a nice tire.