How To Build A High Performance Suspension System - CHP Insider

Brian Entrot Of Performance Suspension Technology Explains How To Rebuild Your Suspension For Improved Safety And Performance

Stephen Kim Dec 1, 2009 0 Comment(s)

The only thing most hot rodders care about is going straight, and there's certainly nothing wrong with that. However, with 500hp street machines becoming the norm rather than the exception, those turns come up a lot quicker than they did just 10 years ago. Even for enthusiasts that aren't interested in road racing their muscle cars, the last thing you want when hammering through your favorite backwoods road is sloppy steering and a raggedy suspension. Rebuilding a car's underpinnings is just as much about safety as it is performance, so to find out how to do the job right we solicited the input of Brian Entrot of Performance Suspension Technology.

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For the last 25 years, the company has been providing top-notch suspension rebuild components for classic Detroit iron. Frustrated by the hassle of tracking down the dozens of components needed to rebuild their muscle cars' suspension from a dwindling list of suppliers, a group of car guys got together to fill the void in the mid '80s. As the OEs began discontinuing critical rebuild items such as idler arms and centerlinks, PST stepped up by manufacturing its own. Today, it offers a full line of suspension rebuild components, performance handling parts, and brake kits.

Company History
Performance Suspension Technology was started up by a group of enthusiasts in 1985 who wanted to make sourcing parts for suspension rebuilds easier. Prior to PST, customers pieced together steering and suspension components from a variety of sources across the country. This process became harder and harder as many idler arms and centerlinks were discontinued by the major manufacturers. PST began offering frontend kits that include all of the most commonly worn components in a frontend. We have reproduced many of the rare and discontinued components over the years to keep it easy and convenient for enthusiasts to get all the necessary parts from one source. With so many customers purchasing front suspension rebuild kits from us, we began to get a lot of requests for other components such as sway bars, shocks, springs, steering boxes, and brake kits. Today, we have an extensive catalog of suspension, steering, and brake components for muscle cars.

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Frontend Rebuild
Many muscle car enthusiasts aren't interested in road racing their cars, but know that they should rebuild their worn-out, 40-year-old suspension. Loose, sloppy steering makes for an uncomfortable and sometimes scary driving experience. Typical high-wear components that need to be replaced during a rebuild are the upper and lower ball joints, front control-arm bushings, sway-bar bushings, stabilizer links, outer tie-rod ends, and in some cases pitman arms and centerlinks. "We consider these components the bare essentials of a frontend rebuild since they see the most wear, which is why they're included in our standard Front End Kits," Brian explains. "For a complete rebuild, we recommend also replacing the inner tie-rod ends, adjusting sleeves, idler arm, and upper inner control-arm shafts, which are included in our Super Front End Kits. There's a good chance that these are worn, and it's still a good idea to replace them as preventive maintenance even if they're in fair shape. Replacing everything at once ends up saving you time and money down the road."

Polygraphite "One of the primary problem areas in classic muscle car suspensions is the use of rubber bushings. They are cheap to manufacture for mass production, and provide isolation from road noise and vibration. However, a significant tradeoff of rubber is its relatively soft durometer, which allows for significant deflection of chassis components under load. The rubber bushings twist and deform as the suspension components rotate, causing premature wear and unpredictable handling. Rubber eventually dry rots when exposed to the elements, and degrades in the presence of grease and oil. Enthusiasts quickly recognized the shortcomings of rubber bushings, and began replacing rubber bushings with custom-made solid steel or bronze inserts. Performance was great but the resulting harshness was unreal. Eventually, polyurethane was selected as a near-zero deflection alternative, but with one critical drawback. Regular polyurethane is too sticky, causing the suspension to squeak as the bushings rotated with suspension travel. Finally, PST perfected polyurethane with the introduction of Polygraphite, a special formula incorporating a low-friction graphite lubricant into the actual bushing material. With Polygraphite, you get the near-zero deflection performance of polyurethane with a quiet, self-lubricating bushing. As an added benefit, Polygraphite is impervious to grease, oil, weather, and other natural elements, and will never dry rot."

Street Car Handling
Not all hot rodders want to pound on their muscle cars on the autocross, but many still aspire to improve their car's handling for regular street driving. Fortunately, PST has the perfect solution. "One of our Polygraphite frontend rebuild kits is a great starting point, and is usually the first upgrade that an enthusiast will make," Brian explains. "To pump up handling and improve safety, a set of our KYB shocks, G-Max 1-inch lowering springs, and G-Max sway bars is a great three-pronged approach to tighten up steering and reduce body roll without breaking the bank. The combination of a firmer shock, higher-rate spring, and a lower center of gravity along with nice, tight steering from the rebuilt kit will really wake up your muscle car and provides performance capabilities far beyond that of a stock suspension."

Ball Joint Replacement
Removing and installing ball joints can be tricky, but Brian has some good advice to make sure you don't get stuck. "If your car has original bolt-in style ball joints, use a grinder to grind off the rivets. The ball joints should then come right out," Brian explains. "Press-in style ball joints can be a little more difficult. Many parts stores have a press that you can rent at little to no cost that really makes the job a breeze. If you're not comfortable doing any of this work yourself, we always recommend taking the control arms to a qualified mechanic for assembly. With Polygraphite bushings, always disassemble the bushings first and lubricate them liberally with the supplied grease. Along with the graphite-impregnated bushing formula, this will help cut down squeaks and creaks."

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Springs and Sway Bars
A question we get asked all the time is whether it's best to install lowering springs and stiffer sway bars as a pair, or install one or the other individually. In our opinion, although stiffer springs and sway bars work great as individual upgrades, it's best to install both at once to take full advantage of the performance benefits. We often design a sway bar specifically to work with a set of firm lowering springs, and the combination works together as a complete system. PST tries to stay away from very stiff springs or very stiff sway bars, as this can lead to a harsh ride. Instead, we use a midrange spring rate and a reasonably sized sway bar. When combined, this significantly reduces body roll without rattling your teeth loose when you go over a bump.

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Body Mounts
Fixated on replacing rusted up sheetmetal, enthusiasts sometimes overlook the body mounts during the restoration process. However, body mounts are a critical link in overall vehicle performance and should never be ignored. Essentially bushings sandwiched between the body and frame, body mounts maintain body-to-frame alignment and provide cushioning for a smoother ride. From the factory, body mount bushings were almost always made of rubber, and are susceptible to dry rot just like any other rubber bushing. "Combine this cracked, dry-rotted bushing with years of distortion and crushing, and you've got a bushing so deteriorated that they often fall off the vehicle altogether," says Brian. "Visually inspect your body mount bushings for cracking and deformation, and if either of these is present, the bushings should be replaced. Polygraphite body mount bushings provide a stronger link between your body and your frame, reducing chassis flex and improving handling. Most of our Polygraphite body mount bushings feature a strong, zinc-plated steel ring molded into the bushing for added durability and strength."

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Shock Selection
Factory shocks are a great example of where GM put the bean counters in charge. Factory installed shocks are often simply the least expensive units that were available at the time the car was built. The engineers could never have dreamed of the skidpad numbers that modern performance enthusiasts are able to achieve with today's tire and suspension technology, so to them their choice of a shock wasn't critical. On the other hand, our KYB shocks are a great upgrade from an OE twin-tube shock and are an ideal replacement for an OE monotube shock. For the vast majority of street driven cars, shocks like these are more than enough. For those customers who want a stiffer, more responsive shock, we are working on developing high-performance, non-adjustable shocks for Chevy muscle cars.

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Adjustable shocks can be a great upgrade for track cars because they allow compression and rebound to be changed separately. However, it requires expert knowledge to set up, and a lot of trial and error to dial them in correctly. Think about it like a stand-alone engine management system. You don't get a performance advantage just by installing it. The advantage comes from tuning for your specific vehicle. There isn't much of an advantage for a street-driven car because a street car sees such a wide range of operating conditions, requiring a shock that is valved to accommodate any scenario it might encounter, from potholes to perfectly smooth blacktop. You can reap the benefits of an adjustable shock when you're going to see a very narrow, specific set of track conditions. This is why race teams spend many hours setting up their suspensions for each different track. To put it succinctly, a budget, non-adjustable shock performs well in any scenario while an adjustable shock performs exceptionally in a controlled environment, like a race track.

Control Arm Shafts
Although they aren't typically associated as high-wear items, PST's front suspension rebuild kits include new upper control arm shafts for several reasons. According to Brian, some high-mileage cars have worn out the bushings to the point that they have cut into the shaft and make it impossible to get a perfect fit with a new bushing. Likewise, on many cars the front frame cradle has sagged from years of punishment and a heavy engine. "To correct this, our muscle car shafts are offset to allow additional camber adjustment," he explains. "The offset can be oriented on the wheel side for more positive camber, or on the inboard side for more negative camber. Lastly, when a shaft has been in place for 40 years, they can be a real pain to remove. It makes it easy when you can cut your old shaft in half, remove the two pieces, and install a brand-new unit."

Drop Spindles
Lowering springs and drop spindles are two effective options for lowering ride height, but each have their pros and cons. The advantage of drop spindles is that they retain stock suspension travel since they lower the car by moving the spindle upward in relation to the rest of the control arm. That's not the case with lowering springs. "Unlike newer cars, many muscle cars gained positive camber as the suspension was compressed. As a result, the top of the front tires will tilt outward as you lower a suspension with coil springs," says Brian. "You can generally lower a car up to 2 inches without causing any significant suspension or alignment problems. On the other hand, with drop spindles the major drawback is cost and a lack of space. Not only do they cost more than lowering springs, the maximum backspacing with drop spindles is usually limited to about 3.5 inches. Usually, someone will run either drop spindles or lowering springs, but guys who want a very low ride can run both."

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Stronger Trailing Arms
Tubular or boxed rear control arms are important for both drag racing and cornering. PST's Catapult trailing arms positively locate and control the rear axle. In drag racing, you'll notice faster 60-foot and quarter-mile times by simply eliminating wheelhop. Likewise, cornering and overall stability are dramatically improved through increased roll stiffness. One of the most important applications for a tubular or boxed trailing arm is when using a larger rear sway bar. The factory stamped steel trailing arms were engineered for a small rear sway bar. Many of our rear sway bars are several hundred percent stiffer than stock, transferring many times more load than the stamped steel arms were designed to accept. In some cases, a large rear sway bar can even snap the factory arms. In order to take full advantage of a stiffer rear sway bar, it's best to upgrade your trailing arms at the same time.

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Parts Catalog
PST is best known for its suspension products, but we also offer a full-line of non-suspension related components. Our second-biggest product line is our brakes. We have complete coverage of muscle car brakes, from stock-replacement rebuild kits to disc brake conversion kits, and all the way up to big brake kits with four-piston aluminum calipers. PST also carries engine overhaul kits and weatherstripping as well. Our mission has always been to provide the customer with a complete solution in one convenient package. It can be extremely frustrating to piece together a kit from various companies, so our frontend kits, brake kits, engine overhaul kits, and weatherstrip kits include everything you need to do the job.

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Disc Brake Conversions
Swapping from drum to disc brakes involves more than just bolting on a set of rotors and calipers. The procedure isn't difficult, but piecing together the necessary parts one item at a time is a painstaking chore. To simplify the task, PST's front disc brake conversion kits come with everything required for the swap including rotors, pads, a power booster (in power kits), wheel bearings, a master cylinder, splash shields, installation hardware, single-piston iron calipers, disc brake spindles, caliper mounting brackets, brake hoses, and an adjustable proportioning valve. "Our basic kits work great for many enthusiasts, but we also have more heavy-duty kits for those with greater performance demands," says Brian. "PST's Level 2 kits adds 2-inch drop spindles to our basic conversion kits, and our Level 3 setups include 11-inch slotted rotors and twin-piston aluminum calipers. Lastly, our top-of-the-line Level 4 kits have 12-inch slotted rotors and three-piston aluminum calipers. Regardless of your braking needs, PST probably has something that will work for your application."

Brake Clearance
There's no disputing the performance and safety advantages of swapping out those old brake drums for discs, but the potential headaches caused by wheel-to-caliper interference scare many people off. Fortunately, PST has taken the guesswork out of the equation, and unless you're running spare tires, it probably has a conversion kit that will fit behind your wheels. "We've done a lot of research on this, and our catalog lists the minimum wheel size for each kit. Our basic front disc brake conversion kits will fit most 14x7 and larger wheels," Brian explains. "The only time we seem to run into issues are with honeycomb-style wheels. As the kits get bigger and better with larger rotors and multiple piston calipers, the wheel size requirement goes up, but our basic conversion kits will fit behind most stock-style wheels. Your best bet is to check our catalog or website, and call us if you have any questions or concerns."

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Sagging Springs
The lower a car sits, the more spring rate it must have to prevent the suspension from bottoming out. Unfortunately, as a spring begins to sag, it loses its ability to support load but its rate remains the same. The result is treacherous handling and ride quality, which is why it's always a good idea to replace the springs in an old muscle car. "Even when these cars were brand new, spring rates from the factory were often too soft for high-performance driving," Brian opines. "Mileage, corrosion, age, and hard driving compound the drawbacks of being undersprung, resulting in worn, sagging, and weak springs. Replacement springs are a great way to restore factory ride height and bring your vehicle back to factory performance standards. For the more demanding driver, a stiffer lowering spring takes it to the next level by reducing body roll and lowering your center of gravity to keep your tires planted on the road."

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Sources

Performance Suspension Technology
Montville, NJ 07045
877-226-4101
www.p-s-t.com

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The only thing most hot rodders care about is going straight, and there's certainly nothing wrong with that.
Stephen Kim Dec 1, 2009

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