Joliet, Ill. — NASCAR recently issued bulletins to the NEXTEL Cup teams notifying them of several changes that go into effect, starting here at the Chicagoland Speedway. The changes, all dealing with suspension related issues, were not unexpected and fall within the scope of what's been buzzing around the garage the past several weeks.
Tops on the change list are rules outlining rear shock management. Now, the teams will give their shocks to NASCAR after the final practice. The sanctioning body will hold the shocks until the following morning, then prior to the pre-race inspections release the shocks to the teams.
Pressurization charges of the shocks will be done with nitrogen, and the shock heads can only be charged to between 25 -175 psi — NASCAR will check these pressures prior to handing them back to the teams for race day installation.
According to engineers in the garage, the manufacturer’s minimum for these shocks is roughly 300 psi, about one-third of the maximum pressure the shock will take. One shock specialist told TFR that he's shop-tested shocks at 900 psi, without incident.
"And they'll go quite a bit higher than that," said the engineer. "In our destructive test we learned that upper limit is huge, which is understandable given that these shocks are built out of some awfully strong stuff."
However, some teams have been recently charging their shocks to 700 to 800 psi, which, after the shock warms while in use, raises the back of the car — raising the rear spoiler further into the air, giving the car more downforce. The cars employing such strategy would return to near normal ride height when the shocks cooled after an event, not exactly in the spirit of NASCAR's ride height rules.
To assure there is no trickery taking place under the car NASCAR has added a maximum height measurement for the rear quarters, which is 35.5-inches on the left and 36.5-inches on the right. Static ride height is 35.0-inches on the left and 36.0-inches on the right.
Also included in the bulletin is a specification for the inserts used on the front a-arms. Prior to this new specification the teams were left to their own devices to bolt the spring inserts, which are used to accommodate the various deviations in manufacture of springs. The new specification says that these inserts will be bolted to the a-frame using four 5/16-inch bolts.
Here at Chicagoland Speedway NASCAR has a room setup for team shock storage, where tables with holes drilled in them will hold the shocks. Some estimates are that this new process will add about 10 to 15 minutes to the pre-race inspection process.
