Raw, ugly steel tubing goes in one door,and race cars come out the other.Performing such a spectacular metamor-

phosis takes some serious talent, and ChrisAlston’s been doing just that for the better part offour decades. He started building race cars athome in his garage during the early ’70s to helpsupport his racing fix.

Always striving to improve his craft, his expand-ing collection of equipment necessitated rentingout a small shop. Over the years, Chris’ experiencebuilding turnkey race cars led to the developmentof off-the-shelf chassis components and innova-tions such as door-slammer chassis kits. Hisproduct line eventually expanded into the muscle-car market, and today Chassisworks is one of themost respected names in chassis and suspensioncomponents. From concept to production, Chas-sisworks incorporates an OE level of automationand sophistication that’s rare in the aftermarket.During a recent visit to his shop, we had a longchat with Chris—we covered everything, fromfabrication techniques and suspension design totips on real-world dragstrip tuning.

All About Chassisand SuspensionWith Chassisworks’Chris Alston

Most people think ofus as a builder of

drag-race parts, butthat’s only 35 percent

of our business.

INSIDER

Urethane bushings and spherical bearingsare arguably the two most popular types ofsuspension bushings for aftermarket appli-cations, so which is better? “Urethane isrevered but doesn’t deserve its reputation,”Chris opines. “The only reason to useurethane is that it’s a cheap way to do adifficult job. Urethane acts a little like ashock absorber, which is good for NVH[noise, vibration, and harshness] reduction,but that same compliance isn’t desirable foroptimal handling. Despite its higher cost, aspherical bearing is a better choice due toits higher load capacity, better suspensioncontrol, and greater range of movement.”

SUSPENSIONBUSHINGS

If you ask five people how to support avehicle while installing a ’cage or sub-frame connectors, you’ll probably get fivedifferent answers. Luckily for us, Chris hasthe right info. “On a stock-bodied streetcar, it needs to be sitting on the tiresbefore you start any welding,” says Chris.“Cars bend and flex so much that ifthey’re not resting on their tires, they’llsag. If using jacks, put them on the rear-end housing to support the back of thecar, and as close to the A-arm mounts aspossible on the front of the car.”

PROPER SUPPORT

Like trying to find a good machinist, tracking down aqualified chassis shop can be daunting. “The first thingyou have to deal with is that building cars is difficultbusiness,” explains Chris. “Very few people have the skillset needed to be good at it; customers sometimes havea very difficult time clearly defining what they want, andunfortunately customers let car builders lie to them. Toavoid this, ask for the names of three or four regularcustomers—not just a few guys the shop is buddieswith—whose cars he’s done in last year, and talk tothem. If you don’t have to wait to get into someone’sshop, that’s probably reason enough not to go to them.”

FAB SHOPS

MILD STEEL VS. CHROME-MOLY“Most people think chrome-moly is lighter than mild steel, but they actually weigh thesame. It’s a fallacy. Steel is steel and it weighs what it weighs. Since chrome-moly is an

alloy and stronger than mildsteel, you can use a thinnermaterial, which is where theweight savings comes from. Ina full rollcage, chrome-moly willweigh about 35 percent lessthan mild steel, which equatesto roughly 30 pounds. In atube-chassis car, the weightdifference is closer to 100pounds. The big disadvantageof chrome-moly is that it coststhree to four times as much asmild steel. Likewise, mild steelis easy to work with and canbe MIG-welded, while 4130chrome-moly has to be TIG-welded, which is a much more

labor-intensive process. Gaps between the tubing must be much tighter with chrome-moly, and it’s easier to overheat it while welding. So while chrome-moly is marginallylighter, it costs much more in terms of labor and the material itself.”

SPRING TUNING“A drag car should run the lightest frontspring rate possible without allowing theshocks to bottom out when making a pass.Generally, lighter springs allow the car toeasily transfer weight and settle faster downtrack. Changing spring rate affects rideheight and the rate at which weight is trans-ferred to the rear tires. A softer rate makesthe front easier to raise during acceleration,while a stiffer rate makes it harder. If you’rehaving trouble getting the front end to rise,you can soften shock rebound valving orchange to a softer spring. When usinglighter-rate springs, preload must be addedto achieve proper ride height. The worse acar hooks, the more shock extension travelit will need. If you need more extensiontravel, preload can be removed to lower rideheight. This method will cause the car tohave less ground clearance and reduce the

amount of compression travel. If you are going to operate the shock at a ride heightshorter than recommended, the upper chassis mounts must be relocated to correctany major vehicle ride-height issues.”

Drag-race sway bars and road-racesway bars are different animals, so don’texpect them to work effectively inapplications they weren’t designed for.A drag sway bar will result in far toomuch roll stiffness and oversteer for aroad-race car, and a road-race sway barwon’t adequately control body twistingat launch in a serious drag car. “In eitherapplication, the function of a sway bar isthe same, controlling weight transferfrom side to side,” explains Chris. “Thedifference is that a drag sway bar seesmuch more load, since it’s trying toprevent the rearend from twisting in thechassis due to the torque of the drive-shaft. Consequently, drag sway barscan’t have any flop, because that’s whatgets used up first and causes the car torotate before the bar can do its job.”

SWAY BARS

Obviously, the best mod for hooking up at the track is a fat set of meats. However, if class rules or wheel-well clearance limits tire size, good bushings and adjustable shocks are the most critical components inputting the power down. “To get a street car to work requires one thing first: The bushings must be ableto handle load without inducing wheelhop,” says Chris. “After that, you need a really good set of double-adjustable shocks to tune the car. There is a tremendous amount of traction to be gained from controllingthe compression and rebound of the shocks. It doesn’t matter if you can’t afford it; that’s what works.”

HOOKING UP

“When testing a freshly built car for the first time, verify that the vehicle tracks straight beforeaggressively launching from the line. Begin with light acceleration and low speeds. If thevehicle tracks and drives acceptably, make incremental increases in acceleration and speed.On vehicles not tracking straight, you should verify all chassis settings such as alignment,bumpsteer, and tire pres-sures. Once the vehicledrives safely at speed,move on to test launching.Test launches shouldconsist of only the initiallaunch, with no subsequentgear changes. Begin withlow-rpm launches andgradually increase rpm andseverity. At this time, we areonly determining that thecar launches in a controlledmanner to avoid damagingcomponents or the vehicle.The vehicle should leave ina straight line withoutextreme wheelstanding orharsh bounces. Sudden, uncontrollable front-end lift should be corrected by adjustinginstant center. More-gradual front-end lift can be corrected by adjusting the shock valving. Ifthe car gradually wheelstands or bounces violently, adjust front suspension first, then rear. Ifthere is rear tire shake, wheelhop, or excessive body separation, adjust rear suspension first,then front. After the car has been adjusted to launch straight, test-launch and include thefirst gear change. Repeat until the car can be launched straight and driven at speed safelyover an entire run. The car is now ready for fine-tuning.”

SHAKEDOWN TESTING

A four-link rear suspension is theultimate in traction, but it isn’t always themost practical for street or moderatedrag-race use. Unlike a factory-stylesuspension, a four-link’s adjustable pivotpoints allow dialing in more antisquat forimproved grip. There are two basicstyles of four-links, one for drag cars andone for street cars. “In a drag four-link,the intersect point is different and therearend can’t roll, while a street four-linkwill allow a bit of roll,” explains Chris. Forstreet use, Chris says a ladder bar maybe a better option. “Physically, a ladderbar has only one front pivot, as opposedto two pivots in a four-link. Although aladder bar is less adjustable, it’s easierto tune and make drivable. A four-linkcan be made to hook better, but since ittakes more work to set up, you’re betteroff with a ladder bar if you don’t havethe patience to tune it right.”

FOUR-LINKS VS.LADDER BARS

INSIDER

SHOCK TUNING“Front shock rebound determines howquickly a car’s front end rises at launchand during gear changes, while shockcompression determines how quickly itsettles. Too light of a rebound setting onthe front shocks allows excessive front-end chassis separation and may result inthe front wheels jerking violently off theground during launch. During gearchanges, too light of a setting allows thecar to bounce off its front rebound travel

limiter and then bottom out in an oscil-lating manner. Conversely, too firm of asetting will prevent the front end fromrising sufficiently, limiting the amount ofweight transferred to the rear tires. As forfront shock compression, a firm settingwill cause the chassis to bounce off thefront tire as the chassis settles down,while too light of a setting allows theshock to bottom out and bounce off thestop travel bumper. Adjustments should

be made in one-click increments. In therear, the suspension should be as firm aspossible before a loss of traction occurs.Changes to the vehicle, such as rideheight, tire size, weight distribution, orsuspension link adjustments, will alter theinstant-center location in relation to thevehicle’s center of gravity. Any shift ofeither the instant center or center ofgravity will usually require a shock-settingadjustment to optimize traction.”

As the rearend twists in one direction andthe engine twists in the other, the result isan out-of-shape launch that makes a cardifficult to drive. Tuning the suspension toalleviate this condition is only part of thesolution. By holding the engine and trans-mission securely in place with plates,chassis flex is greatly reduced. “A car withengine and trans plates is much easier to tune,” says Chris. “Without them, it’simpossible to get the tires to load evenly,since the chassis will twist. You might getone tire to hook up but not the other.”

MOTOR ANDTRANS PLATE

As a car gets faster, the basic ’cage doesn’tchange, but the protection surrounding

the driver gets more elaborate. If only prosbuilt ’cages, the rules would be more lax, but since they have to account for home

builders, rules have to be strict.

Rear wings are mainly for aesthetics in productioncars, but that’s hardly the case with race cars.“The speed at which you need a rear spoiler reallydepends on a car’s body style,” explains Chris.“Newer cars move through the air more cleanly,but the rear ends of older cars become very lightat 130 mph. The unfortunate thing is that cars areusually fastest without enough spoiler angle onthem, and the extra stability comes at the expenseof a few mph in trap speed.” Consequently, it’sbest to start off with an aggressive spoiler angle,then gradually back it down until reaching a trade-off between stability and speed that a driver iscomfortable with. That said, it’s possible to gooverboard with downforce. “If you get too muchdownforce, you can compress the springsenough to push the wheeltubs into the tires. I’veseen up to a 1.5-inch loss in ride height at speedbecause of downforce and tire growth.”

SPOILERS

In the old days, it didn’tmatter how much poweryou had, because youcouldn’t get the tires tohook up. That’s not thecase anymore.

CHRIS ALSTON’SCHASSISWORKSSacramento, CA916.388.0288 · cachassisworks.com

Chris doesn’t have the time to race thesedays, but he still has two shop cars that hisfamily campaigns within the West Coast’svarious 10-inch-tire classes. The lessonslearned while racing 7-second drag carsprovide real-world R&D for Chassisworks’product line. “Our tubular front clips wereoriginally designed for Pro Touring cars,but we modified them to work on dragcars as well,” explains Chris. “Whetheryou’re going straight or turning, the require-ments for good handling are the same.”Likewise, Chassisworks’ line of drag-racingbrakes was also developed on the com-pany’s race cars. “Cars are much heavier

these days than they used to be, whichrequires bigger brakes. Our 11.75-inchbrakes weigh the same as other brakes onthe market that are much smaller.” CHP

RACING

GET THE HOOKUP

INSIDER

Front-end rise without anyappreciable traction gain is

wasted energy that should beused to propel the vehicle

forward instead of up.

Dialing in a suspension for the dragstrip, road course, and street calls for trial and error, butChris has some tips to help you get started. Depending on the application, shock travel will bereserved in different percentages for compression and rebound. “Street vehicles require moreavailable compression travel for improved ride quality and unexpected road hazards,” explainsChris. “At baseline ride height, the shock and spring should collapse 40 percent from theirinstalled heights, resulting in 40 percent of travel available for extension and 60 percent forcompression. Since road-race vehicles are usually limited to smooth surfaces, less compres-sion travel is required and a 50/50 split will suffice.” Drag-race vehicles generally require morerebound travel to help weight transfer, and since the dragstrip is very flat, less compressiontravel is needed. The amount of rebound will drastically affect how the car works. “At baselineride height, the shock and spring should collapse 60 percent from their installed height,resulting in 60 percent of travel available for rebound and 40 percent for compression.”

SETUPS

When in doubt, back half. According to Chris, once youneed a tire that’s too big to fit your car, it’s considerablycheaper and easier to install a back-half kit than it is tomake the necessary suspension upgrades to makesmaller tires hook up. “People are intimidated by thethought of installing a back-half kit, because you have tocut the floor, but there’s such a wide knowledge basefrom backyard mechanics who have done it that it’s easyto install,” he explains. “If you’re in a class that allowsback-halved cars, it’s much easier to get a car to hookwith big tires, and it takes much less skill. Anyone with anaverage level of skill should be able to install one, and wehave detailed instructions and pictures on our Web site.”

BACK-HALF KITS

As one of the most automated aftermarketcompanies around, Chassisworks has been onthe cutting edge of computer-controlledmanufacturing for nearly two decades.Eliminating the potential for human errorimproves product quality, and streamlinedmanufacturing reduces operating costs, whichmeans less-expensive parts for consumers.“With our automated work cells, when we gohome at night and the lights are out in the shop,the parts are still getting made while we’resleeping,” says Chris. “A mandrel bender costs$250,000, so most shops can’t afford them.However, you can’t just mandrel-bend parts andcall it a day; the process must be preciselycontrolled with computers.” At Chassisworks,CNC machines load and unload themselvesand perform quality checks without any humanintervention. “Whether it’s our suspensionpieces or rollcages, we can ensure properfitment because of the extreme control we haveover our manufacturing process.”

AUTOMATED MANUFACTURING