Q&A: Phil Mandella Of Pmr
CHP: What is the most common question you get when tuning small-tire cars?
Phil Mandella: That would be pinion-angle tuning. A positive pinion angle is upward, and that's the angle you want to stay away from. During launches, the pinion angle will move farther up, and it's hard on the U-joints and takes more power out of the drivetrain. A good place to start is with around 4- to 3-degree negative angle (pinion angle down) on the rearend and utilizing a 1-degree driveshaft angle.
CHP: Are there any tips you can share about burnouts?
PM: Don't get too excessive with burnouts. If you do you, you'll overheat the tires, causing them to blister, and reduce adhesion.
CHP: How much tire pressure would you recommend running in slicks?
PM: On a drag radial, I would recommend running between 13 and 20 psi. Bias-ply slicks usually work well from 6.5 to 12 psi. But the ultimate test is to check your 60-foot and 330-foot times to see what the car likes. Keep in mind, track temperatures will also play a role.
CHP: What are some ways racers can use technology to improve traction and lower their e.t.'s?
PM: One of the best ways is by gaining all the information you can. I recommend getting a data-acquisition recorder, like a Racepak system or something comparable. These systems allow you to check every parameter, including engine rpm, driveshaft rpm, engine versus driveshaft slip ratio, and g-forces with an accelerometer. The real challenge is being able to take that data and interpret the results.
Now unfold the newspaper, place in onto the rim, and mark all of the holes. Repeat the process on all four sides of the two rims. | 
Using a center punch on each felt-marked spot, tap a drilling starting point. Drill through all the holes with the 31/416 drill bit. Once the drag slicks are mounted, you can install the screws into the tire beads in a uniform manner. | 
Although this front suspension features lots of tubular arms and frame sections, its mounting points have retained the stock locations for class rules. The lighter tubular items serve to lighten the front end of the car and aid weight transfer to the rear, while adding rigidity. |
This stock rear Chevelle suspension is a factory-production four-link system. While they work reasonably well on the street, it's easy enough to bolt in a set of aftermarket control arms to reduce flex, and adjustable upper arms to improve the pinion angle. | 
This '70 Chevelle features lower control arms with a bracket that lowers the rear mounting position, which moves the instant center rearward for improved traction. | 
Figuring your corner weights is a vital step in performing a chassis setup. Many alignment shops can perform this task or recommend a shop that can. Once you've determined the weights, you can easily find out how much weight bias your car has. You'll first need to know how much your car weighs in total. For example, let's say our light car weighs 2,800 pounds with a driver and loaded with fuel. After having the car weighed, we found that the front tires each weighed 740 pounds and the rear tires each weighed 660 pounds. So if we add the front values together, we get 1,480 pounds (740 + 740 = 1,480), which divided by 2,800 is 0.5285, or 53 percent. For the rear, if we add up the values (660 + 660), we get 1,320, which divided by 2,800 equals 0.4714, or 47 percent. So our race car has a 53/47 weight split. |