Propickup Digital Magazine
Issue link: https://read.dmtmag.com/i/93737
SHOPTALK By Steve Temple SUSPENSION STABILITY The factory suspension on a pickup might not be stout enough to handle some of your more severe-duty jobs. Heavy loads which make your truck's rear end sag several inches can cause handling problems (along with pointing your headlights up in the air). Also, changing the center of gravity, such as with a large stack of material on a roof rack, creates excessive body roll, which can even occur with utility-bed trucks, especially once they're several years old and the suspension has taken a beating. For a few hands-on tips about evening out your suspension, we spoke with David Wheeler, engineer for Hellwig Products, which has been making helper springs since 1945. The company also off ers sway bars and air bags for a wide range of vehicles. The majority of its products go on pickups, for both con- sumers and tradesmen. Before adding anything, Wheeler's fi rst FYI ON EGT If you don't have an EGT (Exhaust Gas Temperature) gauge in your diesel pickup, get one. And if you already do, make sure you keep an eye on it, especially when handling heavy loads on steep climbs. An EGT gauge reacts more quickly than the water temperature gauge, so it allows you to spot an overheat prob- lem sooner and avoid engine damage. If the EGT climbs above 1,250 degrees F for even a short period of time, say, several seconds, you can cook your turbo, melting the square corners at the outer ends of the vanes where the material is thinnest on the turbine wheel. After the tips melt, the turbine wheel becomes imbalanced, wearing down the turbocharger bearings, which can also waste the shaft and eliminate both the turbine and compressor wheels. Those are very costly to replace in both parts and labor. a gauge for that as well) pushes out more heat, thus lowering the EGT. pyrometer (aka thermo- couple), the temperature sensor for the EGT gauge on your dash, is important as well. Typically the pyrom- Placement of the eter's sensing probe is mounted in the exhaust manifold or immediately 8 PROPICKUP October 2012 matter: either back off the throttle or downshift, which increases engine revs and thus the boost level. More boost (hopefully you have Reducing a high EGT is a simple after the turbine outlet of the turbo- charger. Placing the probe a few inches away from those ideal locations can result in markedly diff erent readouts. If the EGT is measured after the results from the heat energy expended to drive the turbocharger. the fl ow through the turbo. At part throttle, under light load, In addition, this drop depends on such as at cruise conditions, the turbine outlet EGT may be as much as 500 degrees F. lower than the turbine inlet temperature. Also, at high turbine speeds (under heavy load), the exhaust gases don't give up as much heat en- ergy as they speed through the turbine. This variance is why BD Power (bdpower.com) recommends install- ing a thermocouple in the exhaust manifold, where the measurement is more accurate. recommendation is to check the U-bolts on your spring packs. "Losing clamp load is the num- ber one cause of spring failure, points out. "You should regularly check and re-torque your bolts. " he " If snugging down your factory leaf springs doesn't work, you can level out the load of your pickup by either adding helper springs or an air bag system like we've done on our Big Red Sweepstakes project dually. "But not both," Wheeler points out, because you shouldn't ever exceed your pickups GVWR (Gross Vehicle Weight Rating). Each system has their advantages: "Helper springs are no- maintenance – just set 'em and forget 'em. Air bags have adjustability. " On the latter, he says it's important to keep the air-fi ll system separate for each bag (rather than using a T-fi tting to join them together). Otherwise the air will fl ow from one bag to the other as the vehicle leans, making body roll worse. Another tech tip is to keep the bags or springs far apart from each other. "The eff ect of distance between springs is actually squared," he explains. "So mount them as far outboard as possible. The wider the springs, the more roll stiff ness. " Thicker aftermarket sway bars can also re- duce body lean (without aff ecting ride quality), especially if your pickup is lifted and is being tasked to haul heavy loads or tow big equip- ment trailers. Hellwig off ers sway bars for those types of applications. turbine, the turbine outlet tempera- ture at full throttle or under a heavy load typically can be 200 to 300 degrees F lower than when measured in the ex- haust manifold. This temperature drop EGT gauges come in a wide variety of types and sizes. We have separate AEM gauges in Big Red to monitor EGT, boost and water-meth fl ow. The one on my work truck consists of a pair of needles combined in a single housing to display both EGT and boost so I can compare them at glance and estimate the most economical throttle setting.