Way back in our Aug. '11 issue, we ran an article titled "Coilovers for the Coppers," in which I gave you the lowdown on installing coilover shocks and an Addco sway bar on the front of my '03 Crown Victoria Police Interceptor. I also glossed over the installation of a pair of Eaton Detroit 1-inch lowering springs in the rear. At the time, my main goal was just to lower the car. It was too tall, even for a stock vehicle. I realize police cars are made to jump curbs in the pursuit of perps, but my car looked like it could leap small buildings. This time around, I had the time to finesse the setup, and in the process I learned some valuable lessons that apply to any car, not just late-model, fullsize Fords. So don't turn the page in disgust at the sight of a four-door sedan. There's good info here. Not Quite Right? Talk to different engineers and suspension builders and each one will have a preferred method of setting up a car. Generally, there are two camps: stiff springs/soft shocks/small sway bars versus soft springs/stiff shocks/big sway bars. If there is a universal constant, it is that the spring rate must increase, however slightly, when lowering a car, simply because the suspension physically has less room to pivot. Which theory is right? Neither. The answer partly depends on the handling characteristics you desire for your car. Dedicated autocross cars will generally have a stiffer spring rate than one destined for track-day driving, where a slightly softer spring rate will allow more weight transfer under cornering and braking loads. Performance street cars fall somewhere in between. Ultimately, the correct answer depends on what is most comfortable for your driving style. Before buying the Crown Victoria, I was used to driving a car more stiffly sprung. After installing the new springs, the car didn't feel right, not because the spring rates were necessarily wrong for the application but because the characteristics of the ride didn't change as much as I anticipated they would. Spring Rate Comparison '03 to '07 Crown Victoria Police Interceptor Stock Eaton Detroit 1-1/2-lower Naake/QA1 Front Rear Front Rear Front Rate (in/lb) 330 163 355 172 450 N/A What I Should Have Done I could have saved some of the hassle by following the guide outlined to me by QA1's tech support staff. This method works with any car and helps determine custom springs and shocks for custom applications, race cars, or cars that don't have broad aftermarket support. Also, don't take this as blatant QA1 product placement. This method will generate the measurements any suspension company will need to know before they can sell you anything. The Bottom Line I'd been hoping all this work would translate into better performance. The folks at our sister publication Motor Trend agreed to run my car through their standard battery of tests, and I was pleased to see how my car compared with a stock police package Crown Vic they tested two years ago. Stock '07 Crown Victoria Police Interceptor CC's '03 Project Panther 0-60 7.8 seconds 6.0 seconds Quarter-mile 15.9 at 88.1 mph 14.5 at 97.8 mph Braking 60-0 135 feet 126 feet Skidpad 0.80 g 0.86 g Figure-8 lap time 28.9 sec at 0.58 average g 26.6 sec at 0.68 average g Parts List Description Pn Source Price Double-adjustable front kit NA-MMFTDA Naake Suspension $795.00 Pro-Kit 1-inch lowering springs, front 3596120 Eibach $165.73 1-1/2-inch lowering springs, front, Police/Taxi MC5412-11/2 Eaton Detroit Spring $189.95 1-1/2-inch lowering springs, rear, Police/Taxi MC3895-11/2 Eaton Detroit Spring $189.95 12-inch heavy-duty combination square 67770 Harbor Freight Tools $7.99 Let’s recap first. The ’03-and-later Panther- platform cars have an interesting front spring and shock combo that looks similar to a coilover, though Ford calls it a strut. Let’s recap first. The ’03-and-later Panther- platform cars have an interesting front spri In the back is a traditional arrangement of shocks and coil springs, but the springs are pigtailed top and bottom, which poses one of the problems addressed in this article. In the back is a traditional arrangement of shocks and coil springs, but the springs are p To lower the car, I decided to replace the stock coilover with a kit assembled by Naake Suspension that is designed to fit ’03 to ’04 Mercury Marauders. The kit consists of QA1 450-lb/in springs and coilover shocks. Naake fits the shocks’ lower eyelet with bushings that fit the lower control arm. You can buy single- or double-adjustable shocks. I chose the double-adjustable and installed them two years ago. Admittedly, that was the most expensive route. Other options included cutting the stock springs (free) or buying 1-inch lower springs from Eibach. To lower the car, I decided to replace the stock coilover with a kit assembled by Naake Su With the front coilovers installed, the car had a severely raked appearance, which I obviously needed to fix by lowering the ride height in the rear somehow. Options for rear springs were limited, though, as both Naake and Eibach kits were intended for Mercury Marauders Those cars have air springs supporting the rear of the car, and adjusting the ride height is a simple matter of relocating a ride-height sensor, so neither company offered rear springs to match the ride height of their front springs. Cutting the stock springs was not an option because they have pigtail ends at the top and bottom. At the time, the correct way to lower a Crown Victoria was to order a pair of custom-wound springs from a company like Eaton Detroit Spring. With the front coilovers installed, the car had a severely raked appearance, which I obvio Ironically, when I contacted Eaton Detroit, I learned the company was about to make front and rear lowering springs for Panther-platform cars a permanent part number in its catalog, and I got an early set of 1-inch lower rear springs for my car. You can now buy 1- and 11⁄2-inch lowering springs, front and rear, for ’92 to ’07 Panther-platform cars. Ironically, when I contacted Eaton Detroit, I learned the company was about to make front Installing Eaton Detroit’s rear springs improved the stance somewhat, but the car didn’t feel quite right to me. Read on to find out why and what I should have done in the first place. Installing Eaton Detroit’s rear springs improved the stance somewhat, but the car didn’t f In the Aug. ’11 article, I alluded to possibly replacing the 450-rate front springs with QA1’s next highest 550-rate springs. Since that article was written, I’ve had several conversations with QA1’s tech support guys, and I switched to the 550-rate front springs. In the Aug. ’11 article, I alluded to possibly replacing the 450-rate front springs with Q While they sport a stiffer rate than stock, the 450-lb/inch front springs in Naake’s Marauder kit are shorter than stock (10 inches tall free height, probably 2 inches less than stock). For a cushy ride and reduced NVH, stock cars are usually equipped with soft springs with lots of travel. When you lower a car, you lose much of that travel, so spring rates need to increase to keep from bottoming the suspension. The QA1 tech guys recommend an installed height of 75 percent of free-standing height. In the case of my 10-inch-tall spring, they’d prefer it measure 7.5 inches in the car on level ground. The 450-rate springs were slightly less than that, so they supplied a pair of 550-lb/in springs that conform to their 75 percent guideline, as seen in the picture. While they sport a stiffer rate than stock, the 450-lb/inch front springs in Naake’s Marau Going down the road, the ride is what I had originally anticipated it would be: firm but not harsh. Over large bumps, the coils do not bind, and I haven’t bottomed the suspension out, at least judging by the crude (but effective) method of wrapping a zip tie around the shock piston. If the suspension were bottoming out, the zip tie would have been pushed up against the shock’s top mount or crushed and broken off. Going down the road, the ride is what I had originally anticipated it would be: firm but n Also since the Aug. ’11 article, I have replaced my car’s rolling stock with 17-inch wheels and new Kumho Ecsta ASX 245/45R17 front, and 285/40R17 tires, the diameter of which is nearly an inch less than my car’s stock 225/6016 Goodyear RSA’s, further exaggerating the wheel opening gap in the rear of the car. I attempted to fix that by replacing the 1-inch-drop rear springs with a pair of Eaton Detroit’s 1.5-inch lower springs. Also since the Aug. ’11 article, I have replaced my car’s rolling stock with 17-inch wheel Here’s the part where we explicitly instruct you not to follow our lead: Do not use the following procedure (hopefully that satisfies our company’s legal team). I cut two coils out of the 1-inch lower springs and reinstalled them. Here’s the part where we explicitly instruct you not to follow our lead: Do not use the fo That gave me the awesome stance seen in this picture here. Remember how I said these springs had pigtail ends and shouldn’t be cut? I made new pigtails by heating 3 inches of the cut ends to a bright cherry red with an oxyacetylene torch and then hammered that section into a pigtail shape with a 3-pound sledge. So far, so good. That gave me the awesome stance seen in this picture here. Remember how I said these sprin We present this information with a hint of sarcasm, but spring steel is hardened, heat-treated, high-carbon steel. Heating it with a torch changes the characteristics of the spring and could possibly create an area where cracks will develop over time. In my defense, the area heated was just enough to create a pigtail end. I did this outside of the car, so the springs weren’t loaded, and I let the them air cool rather than quenching them and possibly creating an area more brittle than the adjacent metal. I’ve put several thousand miles on the car since then as well as several laps at speed on the track at Willow Springs International Speedway, and they are fine. However, I will provide an update if things go south. We present this information with a hint of sarcasm, but spring steel is hardened, heat-tre Begin by setting the car to the stance you want to achieve. If you’re lowering the car, you’ll likely have to remove the springs and shocks to do this. Use floor jacks to raise or lower the body to achieve the desired visual relationship between wheel opening and tire, then measure the distance between the upper and lower shock mount attaching points for both the front and rear suspension. I parked my car on blocks of wood that gave just enough room for me to slide under. It’s good to have a helper when you do this. Begin by setting the car to the stance you want to achieve. If you’re lowering the car, yo For purposes of custom suspension building, these figures are referred to as ride height. They allow you to match springs and shocks to fit the space created when the body is set to the wheels where you want it to be. In my case, there are 14 inches between the front upper and lower shock mounts and 16 inches in the rear. Using these figures, select a shock from the manufacturer of your choice with the appropriate amount of travel to match these numbers. For purposes of custom suspension building, these figures are referred to as ride height. Spring selection is next. Generally, the spring manufacturers have a good idea which rate to recommend based on experience. If you have a custom application or want to be very precise, QA1 has a formula to measure the lever arm and shock angle that will determine an ideal spring rate. Be sure to take these measurements while the car is on level ground and set to the ride height you want. You’ll be measuring the distance between the lower control arm pivot and the lower shock mount. Then divide that number by the distance between the pivot and the ball joint. The result is the force ratio—the leverage the control arm puts on the spring and shock. Figures for my car are 10.5 inches to the shock mount and 15 inches to the ball joint, for a force ratio of 0.7:1. Spring selection is next. Generally, the spring manufacturers have a good idea which rate To continue, you’ll need to know the how much weight is on the front suspension. Not too long after I bought the car, I weighed it on our Longacre scales. Curb weight (without me in it) is a hefty 3,983 pounds. There’s a combined 2,282 pounds on the front axle and 1,701 on the rear. We realize most of our readers don’t own scales, but you can get an accurate enough number using a public scale. Dividing the weight supported by one front wheel (1,100 in my case) by the force ratio determines the spring force for that wheel (1,571 pounds for my car). To be very precise, I could weigh all the unsprung components (wheel/tire, brake components) and subtract that number from the total amount of weight on that wheel. To continue, you’ll need to know the how much weight is on the front suspension. Not too l One last factor to consider is the angle of the spring and shock relative to the control arm. Mine is 15 degrees from vertical, which calculates to a correction factor used by QA1 of 0.93. Divide the spring force (1,571) by that correction factor to determine the adjusted spring force (1,689 in my case). Based on that figure, QA1 could recommend a spring rate best suited for my car, which would be the 550-lb/in springs I already installed. See how sometimes it’s good just to trust what guys who do this for a living recommend? By the way, the process for determining the spring rate for the rear suspension would be the same. Instead of cutting the rear springs, I should have called Eaton Detroit Spring with specs for the rear suspension. Eaton can make custom springs, and the cost isn’t much more than buying a pair of off-the-shelf springs. One last factor to consider is the angle of the spring and shock relative to the control a SOURCES Naake Suspension Specialists Roseville CA 916-771-0109 www.naake.com Eaton Detroit Spring 313-963-3839 www.eatonsprings.com QA1 Motorsports 21730 Hanover Avenue Lakeville MN 55044 800-721-7761 www.qa1.net By John McGann Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!