Q&A: Mark Tallent Of Calvert Racing
CHP: CalTracs bars have a reputation for tremendously increasing traction on leaf-spring cars. Just how do they work?
Mark Tallent: Each of the CalTracs bars uses a front pivot, a Force Transfer Link, and a rear mount. When the car accelerates, these components change the pushing point on the car by redirecting the turning action from spring wrap-up on the rearend, through the Force Transfer Link, and into the front pivot. As this happens, the front pivot-spring stop bolt holds back the turning motion and controls the bending of the leaf spring at its narrowest point. Consequently, the pushing force into the front pivot enables the car's weight to shift rearward because of the new directed angle of force moving to the front of the car. This causes the instant center to move farther forward and, in theory, it acts similar to a four-link system; plus it'll keep the pinion angle constant.
CHP: Are there any other modifications you recommend to aid the system?
MT: As with any improved rear traction system, we recommend installing a good double-acting shock absorber that is tunable. The dual settings allow you to tune the shock to react at different rates as the shock moves up and down. For these applications, we offer Rancho shocks.
CHP: Does Calvert Racing offer any other products to improve traction
MT: We just released a new split monoleaf spring (two-piece) that we custom-make to match a given car's ride height, power level, and use. These springs vary in thickness and arcs so that as the horsepower application goes up the spring thickness does too. The split monoleaf design emulates a parabolic shape so that it is thicker at the axle to negate torsional twist at the spot where the spring is prone to wrap up. The larger thickness at this spot counteracts this. Unlike a straight monoleaf spring that maintains the same relative rate throughout the length, this spring is designed to offer different rates at the axle mounting point and where the spring needs to move.
Tips & Tricks
* Keep your rear wheelwells clean. After several burnouts, it's common for small pieces of gravel to build up in the wheelwells. If these aren't removed periodically, they can fall onto your tire during launches and will contribute to a loss of traction.
* It's always a good idea to have a friend or teammate video your launches and follow it down the track. As good as you may think your eyes are, the camera doesn't lie, and will show you exactly how the chassis is reacting, helping you to make adjustments accordingly.
* Lakewood (Mr. Gasket) offers these No-Hop bars that mount between the rearend housing and upper control arms and changes the angle of intersection (instant center) of the factory four-link positions on Chevelles and G-body applications. This helps the car under hard acceleration force the rear wheels to the ground without wheelhop. For '64-72 Chevelles (PN 21609) and '78-88 A- and G-bodies (PN 21610).
This car features a complete 'cage made from chrome-moly tubing to make the car safer while adding structural rigidity to the chassis. The stiffer chassis serves to help allow the car's suspension to react in a predictable fashion. The massive rear wheeltubs allow the car to run monster rear slicks. | 
If you want to lower the overall effective gear ratio without swapping gears, you can always run a shorter tire diameter. Of course, this is assuming you can get away with a shorter sidewall and get the tires to stick. Then again, we've seen plenty of high-power cars running small 26x10.5 slicks and dipping well into the 10s. | 
The underside of this late-model Camaro wears BMR frame connectors to strengthen the frame from excessive flex, and a BMR torque arm constructed out of 1.25x0.120-inch tubing with heavy-duty 11/44-inch mounting plates. This version is equipped with a rear adjuster to move the pinion angle. CHP |