Big B-Body Handling Upgrades - Rollin’ The Biscuit
Demonstrable Ride and Handling Upgrades for the Big B-Body
From the June, 2011 issue of Chevy High Performance
By Ro McGonegal
Photography by Ro McGonegal
Seconds before dissection,...
Seconds before dissection, the front end looked like this. Notice the (light-colored) PST 11/8-inch antisway bar. Directly below it, the strut rod attaches the lower control arm to the frame. Our ace-in-the-hole, Justin Brayman, began with disassembly of the upper arms.
When the Biscayne was conceived in the late ’50s, the notion of handling wasn’t even an afterthought. People wanted big and powerful, never mind your face grease getting smeared all over the side glass on a swoopy turn. Besides, that entire trick chassis stuff was for European twinks, right?
When I bought this car in 1997, Global West maestro Doug Norrdin said he would prototype everything that he’d developed for A-bodies on the Biscayne and if I’d be willing to leave it with him for six months he’d have it shipshape. I politely declined, under the illusion that the car would be finished and I’d be burning rubber by then. It took another eight years before it got to that stage.
My impetuosity ruled. I lost. Norrdin helped by inserting his inflexible sandwich of Del-a-lum (a billet aluminum core covered by a machined sleeve of Delrin) at either side of the front upper control arms and putting a spherical link on the frame end of the lower control arms. Rather than using two attachment points at the frame, the ’65-70 B-body lower control arms pivot on a single central locus. The front springs were unknown wire meant for a big-block application but with a coil hacked off the bottom to set the stance. Spring rate was anybody’s guess.
For the rear, Metco offered billet aluminum lower control arms that were originally meant for an A-body, adjustable (for pinion angle) on the top side and followed by more QA1s. I attached a PST bar to the lower links la the factory. Eaton supplied 2-inch drop (282 lb-in) lowering springs. Later, one end of the stock Panhard bar (keeps the axle housing centered beneath the car) was threaded for adjustment.
On the smooth expanse of the interstate, on the 800-mile shot from Memphis to my central Florida driveway, the car behaved normally, but on uneven secondary roads, the steering was so sensitive it was downright ugly. It trammed. It pulled. It took concentration to keep the car on the path over rough patches. At first I thought it a conspiracy of the 9-inch-wide Fikse wheels, grabby Goodyears, improper alignment, and quick 12:1 steering ratio. I didn’t discover until much later that the bar was actually riding against the frame (it passes through elongated oval openings), thus merrily steering the car quite independently of the driver.
Adhesion is good. Modern radial tires are so light-years better than the horrid bias-plies we used to suffer that they tend to turn an olden-day suspension into melted wax. The geometry, mainly caster angle, is all wrong. The object is to keep as much tread on the tarmac as possible at all times, and most modern performance road rubber has better tractive qualities than race tires used to have. To take full advantage of them requires a suspension system that responds in kind.
Norrdin emphasized that his B-body conversion is meant to remake the ride, handling, and steering for the street and not necessarily for autocross work. It’s for a purely fun ride: You can look down that flight deck of a hood and remember how horribly the original contraption worked. Before I ripped the wheels off it during the last century, I had driven the stock configuration less than 30 miles.
The Global fix begins with CTA-50A upper control arms that incorporate different geometry than the factory arm. To complement, the lower CTA-50L units are fitted with a rotating polyurethane cushion that allows the spring to index in the frame as well as the lower arm. B-bodies used strut rods attached to the lower control arm and the frame. Global’s ASR-50 adjustable strut rods eliminate fore-and-aft wheel movement (which directly changes the caster and toe) during braking, acceleration, and cornering and is accompanied by vague steering feedback.
At the rear, the TBC-51 upper control arm allows for the correct pinion angle without using shims. The spherical bearing on the frame side allows for the twisting action of the arm when the rear passes over bumps and as the body rolls. Companion to it, TBC-50 lower control arms provide smooth movement over bumps and reduce lift on the inside tire during cornering.
After inserting jackstands...
After inserting jackstands and supporting the lower arm with a floor jack, he pulled the caliper from the rotor and unbolted the shock absorber. Brayman used an “inside” coil compressor to mind the spring, a pickle fork and a heavy arm to separate the ball joint cleanly from the spindle. He lowered the jack to release tension on the spring and removed it. With castle nuts removed from either end of the control arm, he unbolted the crossbar that holds the arm to the frame.
Compared to the artifact,...
Compared to the artifact, the Global arm is hefty, streamlined, and beautifully drawn in all the right places. Note the Del-a-lum bushings at either end of the forged crossbars. The stock configuration posts a rubber bumpstop on the top of the framerail. For clearance, Global posts a polyurethane bumper on the underside of the arm instead.
The B-body is jinxed by brake...
The B-body is jinxed by brake reaction struts (stock one is at top) that affix one end to the lower control arm and the other to a forward portion of the frame so that the struts are in a V-formation. The stock rubber bushings are mushy at best and thus directly affect alignment, especially caster and toe-in, changing the calibrations and making the steering feel vague and the car to wander. Global addressed the shortcoming with rod ends that refuse deflection, a front perch in place of the rubber bushings, and the opportunity for fine adjustment.
Global’s lower arm versus...
Global’s lower arm versus the original has the same single frame attachment point, but that’s where the comparison ends. This hefty piece becomes the main suspension support and features a polyurethane seat that indexes the spring so that it will be loaded properly around the coil. An absence of the index will place too much load at the very end of the coil spring rather than on the full coil. Over time, this will fatigue the spring and make it sag. Global builds it from 15/8-inch rollcage tubing, gives it reinforced pickup points, and lower bumpstops. The plastic dowel eases bushing install and alignment, but is only that. Put it in the toolbox for next time.
Strut rods attach to the bracket...
Strut rods attach to the bracket at the front of the frame with a hefty rod end and nut assembly—no synthetics involved. Brayman torqued the bolt to 120 ft-lb. At the control arm, the bolts are tightened to 65 ft-lb.
The spring at the left was...
The spring at the left was a big-block application with one coil removed to set the stance. Though Global’s replacement is shorter, it has more rate, so it made the car sit an inch higher than before. As per Global’s wisdom, Brayman removed a full coil with a cutting wheel and dropped the front 2 inches. (Note: GW’s spring rates are proprietary.)
Ant’s eye view shows frame...
Ant’s eye view shows frame attachment point as well as the strut rod assembly. This design totally eliminates deflection so that the suspension no longer moves fore and aft. The vehicle now realizes a lower A-arm rather than a two-component system (strut rod and lower arm).
Adjustable VTC-50 antisquat brackets receive the leading end of the upper control arm. They change the geometry in the rear, increasing or decreasing the amount of downforce at the back tires. As part of the package, Global West built specific linear rate coil springs that lower the car 1 inch. Since the engine is all-aluminum, we opted for small-block S-68 at front and S-88 at the rear. Finally, the PHC-50K adjustable Panhard rod that centers and confirms lateral location of the axlehousing, has multihole brackets, and quells rearend instability around turns and over bumps. The relocation rod also imparts a high degree of torsional stability to the framerails.
We had neither space nor the proper telemetry equipment to produce any kind of empirical data, so this is a seat-of-your-jeans take, a report based on driving thousands of new and modified cars. Did it on the street. Did it on an unoccupied thoroughfare with a series of switchbacks, damn difficult to find in Florida. The ride is firm (QA1’s set at three front and rear) but fluid. I can actually feel the front tires through the steering, a facet that was vague at best prior to the changes.
Here’s everything back together...
Here’s everything back together and ready to rock.
Surprise. The Biscayne’s weight distribution is 49/51, undoubtedly a product of its enormous rear overhang, big glass, rear-mount battery, and all-aluminum engine up front that weighs less than an iron small-block. People kill for numbers like this and the car’s handling demeanor is quite neutral. No amount of tomfoolery would call the back end around; although, anything better than a 6/10s effort would probably pendulum the rear of the car easily. Although Global has a rear-mount antisway bar (not attached to the lower control arm) for this conversion, it was deemed unnecessary.
We made some very stupid maneuvers in an effort to upset the cart but got squat in return. Judging by the feel of the car, the bar would be superfluous. The biggest sensation is felt at the rearend. The adjustable Panhard brace and bar really tie the car together. Bumpsteer has been distilled down to nothing. The Biscayne now feels like a modern car, quite the equal of high-zoot, American, Euro, or Asian counterpart. As a matter of fact, BMW dudes despise our big, white junk. It floors them. It brow-beats them. It makes people stay up at night.
The stock antisquat bracket...
The stock antisquat bracket is shown on the right. It is the connection from frame to upper control arm and has no provision for tuning. Brayman replaced it with Global bits, which are adjustable and preclude the need for shims behind them (used to set pinion angle in the stock setup). Excessive squat during acceleration will cause the rear tires to spin. Adjusting the lower control arm down at the rearend will change the percent of antisquat, thus increasing the amount of traction. The antisquat kit will allow you to readjust the angle of the lower arm thereby increasing traction.
The original rear axle assembly...
The original rear axle assembly included Eaton 2-inch drop springs (left). Global’s spring dropped the rear of the car to the same height as did the Eaton coils.
Brayman measured eye to eye...
Brayman measured eye to eye on the upper arm ends and set them as per the length of the old upper control arm. He tightened the brackets with 65 ft-lb of torque. He set the 5/8-inch-diameter connecting hardware at 90 ft-lb.
One side of the Panhard rod...
One side of the Panhard rod attaches to the rearend while the other is joined at the frame. The stock Panhard rod is generally light duty and tends to deflect when the car is driven hard. Raising or lowering the ride height shifts the rearend laterally (no longer in the center of the car) and causes the rearend to be unstable around turns and over bumps, depending on the final angle of the Panhard rod (not parallel to the ground). When the car originally went together, the builder cut the stock rod, threaded either end, and machined a knurled adjuster from aluminum stock. While this is good for centering the axle, optimally the bar should be level with the ground. As you can see here, it isn’t.
Brayman prepped the ends of...
Brayman prepped the ends of the relocation bar and the inside of the framerails with an angle grinder and a sanding disc to remove powdercoating and paint to give the welding rod purchase.
Raising or lowering the car...
Raising or lowering the car requires readjustment of the length in order to center the rear axle under the car. One of the key features of Global’s collection is the track rod relocation kit, which includes an adjustable Panhard rod, a bearing rod end, and a greaseable urethane bushing, all designed to reduce lateral movement of the rear axle in the chassis. The relocation bar (top) also serves to strengthen the frame, and is welded to either side of the inner rails.
|Component Weight (In Pounds) |
| ||OEM ||Global West |
|Upper front control arm: ||9.5 ||9.5 |
|Lower front control arm: ||11.0 ||13.0 |
|Strut bar: ||5.5 ||5.5 |
|Coil spring: ||9.0 ||10.5 |
|Wheel Alignment Specs |
| ||OE ||Global West |
|Caster ||1/4 degree pos. ||Driver side: 4 degrees pos.; pass. side: 4.5 degrees pos. |
|Camber ||1/4 degree pos. ||Driver side: 0.5 degree neg.; pass. side: 0.5 degree neg. |
|Toe-In ||1/8 to 1/4 inch ||0.10 degree pos. |
For the install, he put the...
For the install, he put the car on his drive-on lift. He mock-fitted the relocation bar with clamps and used a level, tape measure, and angle finder to position the bar straight, parallel, and very close to the floorpan (less than an inch). His measuring pickup points were axletube to Panhard bar and Panhard bar to the front of fuel tank. The idea is to make the rod parallel to the ground, based off of the frame hole holding the stock track rod.
Brayman used a silver marker...
Brayman used a silver marker to outline the ends of the relocation bar for welding. He tacked the piece tentative and measured again. Then he welded the ends to the frame.
The last piece of the puzzle:...
The last piece of the puzzle: Rather than use the original passenger-side stud for the rod, Brayman substituted some Grade 8 goodies to complement the special semiconical-shaped Global spacers. He then eyeballed the fender lip-to-tire sidewall distance and centered the housing.
The bottom of the gusseted...
The bottom of the gusseted end of the relocation bar is completed with U-shaped bracket that bolts to the locator end on top and receives the Panhard rod end on the bottom. As per the schedule, Brayman welded the two together. Then he modified the Global gusset plate to the tire-facing end for increased strength. The driver-side tailpipe caught interference from the gusset and had to be removed for this step.
Garry Pulsifer at Ralph’s...
Garry Pulsifer at Ralph’s Auto Service in New Port Richey, Florida, did the alignment and also installed the Global tubular tie-rod sleeves (PN ADJ-2) in place of the factory junk. CHP