|
|
Kirban Performance GNX Suspension Kit - Traction To The XtremeKirban's GNX Suspension: Exclusivity, Driveability, And Neck-Snapping Acceleration All In One. From the March, 2002 issue of GM High-Tech Performance By Rick Jensen Photography by Evan J. Smith, Johnny Hunkins, Rick Jensen
|
|
There has been a lot of talk regarding the GNX suspension sold by Kirban Performance Products. From what we have seen, a love-it-or-hate-it attitude exists regarding this system. The hard-core racers scoff at the idea of spending so much money (A complete kit with an exhaust system is $2545.) for a reproduction suspension piece when a race rear swaybar or adjustable control arms would provide similar traction enhancements for less cash. The collectors are crazy about the idea of the GNX-like exclusivity and improved street performance from the ladder bar/torque arm setup. We at GMHTP like to ride the fence. We're always looking for a few extra tenths here and there, but our cars are our daily (and sometimes our only) transportation, so reliability and OEM-style engineering takes precedence over ET reduction. We hear pretty much what you hear, that this system is supposedly the real deal, so you can see why we've had our eyes on it ever since its introduction in 2000. After a few conversations with KPP owner Dennis Kirban, we learned that the gentleman who undertook this project (a fellow GN and GNX owner) spared no expense in accurately recreating the suspension responsible for the GNX's blistering 0-60 and quarter-mile times back in 1987. For people who try to put as many street miles on their cars as possible, we couldn't see a downside to this system--provided it lived up to its billing. Once we ordered it, we put in a call to Cotton's Performance Center regarding the installation. Jack Cotton is well-versed in turbo Buick restoration and performance, and has fabricated every square inch of his 9-second T-Type himself, so we knew we'd be in good hands. The reproduction GNX suspension... The reproduction GNX suspension includes (from top to bottom, left to right): panhard bar, stiffhard bar, machined aluminum differential cover with a magnetic drain plug, spring perch extensions, tube axle bracket with clamp, right frame bracket, left frame bracket, ladder bar, crossmember, and the required bolts, nuts, and washers. Our test mule was a daily-driven 152,000-mile Turbo-T. This old warhorse was basically stock until the fuel system took a dump at 100,000 miles. Now it sports a few minor modifications, such as green stripe injectors, an adjustable fuel pressure regulator, a Bosch inline fuel pump, a high-flow air filter, and a 3-inch downpipe/dump tube that we snagged for $100 off the Internet. With nothing more than a Red Armstrong 108 race chip, good gas and a cooled intake, it spun its way to a 12.94 ET on ET Streets and a Vericom-recorded 4.99-second 0-60 time on real radials at Englishtown, New Jersey's Raceway Park. Traction aids were ripped (read: uninflated) airbags, SouthSide Machine lift bars, a pinion snubber, and a flaring, downtrodden stock transmission. Our goals are simple: We're going to run this system over the coals and see how well it holds up. Launch it hard on slicks and street radials and compare the timeslips. Hang the tail out in fast corners and wait for it to break loose. Report any change to the car's ride characteristics, good or bad. And listen for the sounds that ill-fitting suspension parts and exhaust systems make. But first let's tackle the install, quoted by Kirban Performance Products to take four to five hours under normal conditions.  Kirban Performance Products...  Kirban Performance Products also included the fixtures needed to install the suspension. These are loosely based on the original factory steel components and are made from aluminum to save weight. Kirban charges a $500 fixture rental fee for the tool set which is completely refundable when returned.  Once in the capable hands...  Once in the capable hands of Jack Cotton and his staff in Agawam, Mass., our well-worn '87 T was raised and mechanic Charlie Robichaud removed the wheels. Dennis Kirban strongly suggests that you have rear seat bracing, GNX upper body bushings, and upgraded rear springs before installing this kit--GNX suspension tests on a stock GN proved unsuccessful because the car wasn't nearly stiff enough. In addition to those pieces, we have replaced several missing body bushings and added front frame braces to our hardtop.  A jack was used to take the...  A jack was used to take the load off of the shocks, and they were unbolted on the bottom. Charlie then used a prybar to pull one end of the axle down, and then pulled the spring out. If these had been the original springs, they could have been popped out with someone hanging on the axle. Our Kirban variable-rate replacement springs needed a little more encouragement.  Once the springs were out,...  Once the springs were out, we reconnected the lower shock mounts and turned our attention to disconnecting the factory upper control arms. Disposal of the flimsy stamped-steel uppers is another benefit of the GNX system.  We removed the rear end cover...  We removed the rear end cover and drained the funkdafied fluid. Charlie then cleaned the gasket mating surface with a cookie cutter tool using Scotchbrite abrasive. A flat mating surface for the GNX cover is imperative.  Here, the axle bracket locator...  Here, the axle bracket locator fixture was installed over the rear end so the tube bracket assembly could be properly positioned. The brake line clip can be undone so the bracket ears slip underneath the brake line. Once it was deemed to be in the right place, Charlie cleaned the rust from the frame and temporarily tack-welded the bracket, then torqued the tube clamp to 35 ft.-lbs.  The GNX differential cover...  The GNX differential cover doesn't use a gasket since the cover is now a load-bearing suspension component. Charlie applied a thin layer of OEM-quality gasket maker to the cover and torqued the 10 stainless Allen-head bolts to 30 ft.-lbs.  The axle-to-frame fixtures...  The axle-to-frame fixtures are clipped onto the frame, with the driver's side fixture holding the left frame bracket locator. The axle was raised with a jack until it met these spacers, leaving 4.2 inches between the axle and the frame rail. When it's time to weld, the perfect situation would have the rear axle 1/16-inch left of center while spaced at 4.2 inches, since with a panhard rod suspension the rear axle moves in a left-to-right arc as it goes up and down.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1999 Pontiac Firebird Trans Am - Street Heat
Almost no other GM model pulls off the aggressive look quite like the fourth-gen Trans Am, and when you modify one like Nathan Turjillo from Las Vegas has, well; you end up with a real showstopper....
more
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2011 Chevrolet Silverado LTZ LS9 Camshaft Swap
Seriously, the package we’re showing off here can be purchased for under 300-bucks if you shop smart (new parts, nothing used) and added 47-rwhp and 20 lb-ft of torque to our bolt-on equipped 2011...
more
|
|