Grassroots Motorsports
Issue link: http://grassrootsmotorsports.epubxp.com/i/397024
Grassroots Motorsports 118 PROJECT CAR: NISSAN 350Z tuning frustration. They deform and can allow your suspension to move under cornering loads. In many cases, this bushing deformation is simply a cost of doing business. In certain cases, though, it's a huge liability. For example, let's say we have a bushing that deforms under a cornering load. Think of that bushing as a tiny spring: Under load, it compresses; when the load is removed, it relaxes. But if the bushing deforms so far that it can no longer com- press, it effectively becomes solid. Imagine if your spring rates went from 500 lbs./in. to infnity in the middle of a corner. It's a frustrating situation to deal with, and it becomes more of an issue as cornering loads increase with the addition of wide, sticky tires and a more competent suspension. But there are times where compliance is a virtue. The front compression arm on the 350Z is a perfect example. The compression arm is the back half of the two-part lower control arm, which specializes in controlling front and rear movement of the hub. As such, it has a bushing oriented in so that the arm's pivot is perpendicular to the ground. But this arm also needs to move perpendicular to the ground, so the bushing is designed with lots of compliance to allow the joint to rotate vertically. It's a decent arrangement for a street car, but it becomes apparent pretty quickly that it's a compromise at best for real performance. If we replace the bushing with something stiffer to limit the fore and aft compression, we create vertical resistance that effectively adds to the spring rate in an unpredictable fashion. We made the decision to leave these bushings stock for now. We'll keep a close eye on them as we progress. We replaced many of our remaining suspension bushings with polyurethane units from Whiteline. We concentrated on swapping out the bad ones, obviously, but also the "high- impact" units. These are the ones we felt could allow the most mechanical displacement and thus cause the biggest upset if not properly controlled. Aftermarket Graphics: vinyl logos, aftermarketgraphics.com BFGoodrich: g-Force Rival tires, bfgoodrichtires.com, (877) 788-8899 Balanced Performance Motorsports: service, balancedperformance.com, (678) 546-3133 Exedy USA: clutch, exedyusa.com, (800) 346-6091 Hawk Performance: brake pads, hawkperformance.com, (800) 542-0972 ISC Suspension: suspension, iscsuspension-na.com, (603) 715-9078 Momo: seat, momousa.com, (800) 749-MOMO Ormond Auto Clinic: service, ormondbeachtuneup.com, (386) 675-6978 OS Giken: differential, osgiken.net, (310) 986-6620 Specialty Products Company: control arms, spcalignment.com, (800) 525-6505 TSW Wheels: wheels, tsw.com, (800) 479-9723 Whiteline: suspension bushings, whiteline.com.au, (909) 476-2860 SOURCES