In this picture you'll note...
In this picture you'll note a chain bolted to the rearend housing; the other end is bolted to the framerail. This is an important step when installing your rearend. Because of how these rearends sit in the car, when you jack the car up, you need something to keep the springs in place, prevent snapping brake lines, and worst of all, bending your driveshaft on the driveshaft loop.
DeMoss says that polished gears fall into the same category as gun-drilled axles if you're racing in a Street Stock/Sportsman level. The coefficient of friction is less than 10 percent, and that 10 percent isn't going to show up in your lap times, especially if you race on dirt. "We haven't seen polished gears improve the service life, either," DeMoss says.
However, the key to getting the most out of standard gears is to take the time to break them in properly. Quick Performance recommends two to three heat cycles in the rearend before racing. Understanding that takes time-time a lot of Saturday night racers don't have-DeMoss says he jacks the car up and runs it in forward and reverse with it sitting on jackstands, and then drives it around in the pits as much as possible.
Typically a rearend will run anywhere between 200 and 300 degrees, but the lower your gear ratio, the higher that temperature is going to climb. For example, a 7.00 gear is going to run a lot hotter than a 3.50 gear, which would usually run around the 250-degree range. If you run anything that's over 50 laps, you should seriously consider running a rearend cooler, especially if those 50-plus laps are on asphalt. However, in Frank's series the horsepower rating isn't high enough to warrant a rearend cooler. Adding a rearend cooler will, without a doubt, add cost that would be better spent elsewhere.
There is, however, something you can do to help keep your rear's temperature down without the added cost of a cooler, starting with the tube seals. "If you run them, don't," says DeMoss. "Tube seals prevent the oil from getting into the axle tubes which would actually help cool the oil, by keeping the oil out of the tubes the oil never cools and the rear's temperature can actually increase." DeMoss says just put four quarts of oil in there and go. By the way, go with mineral-based oil. According to DeMoss, the added cost of synthetics isn't worth it for this application, plus the mineral-based oils absorb heat better.
The chains have to be measured...
The chains have to be measured and bolted in at the proper length on both sides of the rear in order to ensure that everything stays in place and nothing is damaged when the car gets jacked up.
One Last Choice
Running a lightened ring gear can be equivalent to taking 10 to 30 pounds off the car, because it's rotating weight. Before you grab that gear and head over to the lathe, think again, you should leave ring gear lightening to the pros. DeMoss says, "There's no reduction in strength with a lightened ring gear as it comes out of the box. There is a reduction, however, when people lighten it themselves because they remove too much material and weaken the gear. There's a certain amount of material that can be removed before the safety factor comes into play, and we don't exceed that." The amount of material you can remove is directly related to the ratio of the gear. The lower the ratio, the more weight that can be safely taken off because the gear is thicker. Still, the safest way to gain the advantage is to leave the lightening to the pros.
Down To Business
When it comes time to order your new rearend it couldn't be simpler than picking up the phone. DeMoss and the boys at Quick Performance have been racing and building rearends for a long time. As such they have compiled a body of information from mounting locations, to pinion angles, to major sanction rules.
Basically before you get them on the phone you should know the make, model, and year of the frame of your race car, whether you're racing on asphalt or dirt, and whether you want a floater- or flange-style rear. In addition, you'll need to know the gear ratio and wheel width you want to run as well as whether you want a 28- or 31-spline axle. Take note here-a 31-spline axle is stronger and there is no reason not to go with that option unless you have 28 centers that you can't afford to or don't want to change