The NASCAR-sanctioned Late Model stock car we have been reporting on for some time is now finished. In the latter weeks of April, we completed assembly, aligned, and set up the car, and took it to Orlando Speedworld for a shakedown run. The car performed better than expected. Here is how we prepared the car for testing.
The very first thing we always tell you to do is to measure your moment center location and redesign it if needed. So that is exactly what we did with our LMSC. We ended up making minor changes to the arm angles by changing out the offset slugs in the upper mounts.
The upper control arm mounts from Hess Race Cars provided us with plenty of adjustment opportunities. The slugged mounting bracket allowed us to fine-tune the moment center location as well as set the antidive amounts.
After the changes, the MC was located at 2.636 inches high and 0.560 inch left of centerline at static, and moved to 1.710 inches high and 3.307 inches right of centerline. This location is good for this car with a higher center of gravity than the Late Model touring cars. The camber change on the right front was minimal, and we ended up with about 1 degree of positive camber at the left front after dive and roll. The actual tire temperatures will tell us if the cambers are correct.
We set up the centerline of the car using the framerails. This is a perimeter car, which means that the frame and suspension are equal on each side with no offsets allowed. We measured the distance from the bottom sidewall of each right-side tire to the centerline and adjusted the Panhard bar so that the right-side tire contact patches were lined up and parallel to the centerline. We did this before attempting to square the rear end because lateral movement of the rear end to line up the right sides will affect the rear alignment relative to the centerline.
We used the common 3-4-5 triangle method to create a line that was perpendicular to the centerline for rear square measurements. Once we had the marks on masking tape, we pulled a string over the marks and held the string with lead ballast.
Next, we dropped a plumb bob off the axle tube near the ends and measured back to a line that ran perpendicular to the centerline we had previously established. Project mechanics Kenny Hellyer (in hat) and Mark Jones take careful readings on tape. We adjusted the rear trailing arm (truck arms on this car) eccentric so that the rear end was exactly 90 degrees to the centerline.
Before we did our front-end adjustments, we locked the steering shaft with two vise-grip pliers (8th image). We centered the steering box, locked the shaft, and then did our bumpsteer check. Then we aligned the wheels to straight-ahead and set the toe. With this type of power steering, if the box is not centered, the power steering will always try to seek the center and pull on the wheel even when the wheels are pointed straight-ahead.
This adjustable, Coleman Racing-supplied front link replaces the shock for positioning the spindle for moment center measurements and bumpsteer checking. The rod is easily turned to adjust the height of the spindle to its relative position when at ride height (9th image). We need the spindle, along with the control arm angles, to be positioned correctly when the car is raised and supported on jackstands. In this case, for moment center measurements, the car was raised exactly 10 inches. This makes subtracting the height offset easy.
The next step was to adjust the front-end settings and check the bumpsteer. Kenny turns the adjuster while Mark reads the dials (page 2, 1st image). This Hess chassis was well designed, but we found that the slug in the right side of the drag link was installed upside down. Once we inverted that, the bumpsteer was perfect. The left side was installed correctly, and that, too, was perfect (within less than 10 thousandths of steering movement in 3 inches of travel).
We then checked Ackermann by stringing the tires out in front of the car 10 feet. We made a mark with the wheels straight-ahead and then a second mark for each wheel with the wheels turned about the same as they would be in the turns. We had less than 11/48 inch difference in the two sets of marks, which amounts to 0.029 inch, or about 11/432 inch, of added toe when the car is in the middle of the turns. That is minimal and acceptable for our purpose.
The right-rear fender posed a clearance problem when we moved the right-rear tire out to align it with the front tire. The body was hung with the rear end misaligned. So we had to use the common baseball bat method of creating a fender flare. It worked great. At the track, the tire never rubbed the fender.