HScott Motorsports

HScott Motorsports logo

After graduating from university, I went to work for Phoenix Racing, a NASCAR Sprint Cup team in Spartanburg, SC. Harry Scott, Jr. had just purchased the team and changed the name to HScott Motorsports shortly after I started. Much of the Phoenix Racing crew went on to other teams, and the new HSM crew chief hired mostly new guys. Because of this, I was the only engineer on the team for a few months and had to establish a new database and piece together many systems and processes from scratch.

HSM hired on a veteran Hendrick engineer as a consultant to get me up to speed during the first months. By the end of the season, I was able to take on lead-engineer duties and train new engineers for the next season when we fielded a second car.

As a race engineer, I traveled across the country to each of 36 race weekends  from February to November. With me was the rest of the road crew:

  • Crew chief
  • Race engineer (the other one)
  • Car chief (head mechanic)
  • Front-end mechanic
  • Rear-end mechanic (“underneath guy”)
  • Shock guy
  • Tire guy
  • Interior guy
  • Engine tuner
  • Car-hauler drivers
  • (the pit crew are not part of the standard road crew. They fly in only on race day and train the rest of the week.)

During the week, we worked in the shop preparing that weekend’s cars (primary and backup), as well as cars for future races. The organization has over a dozen cars and hundreds of parts, each chassis customized for different track types (short track, intermediate, speedway, road course, etc.). The engineers would develop a setup based on preliminary simulation runs and feedback from previous similar-track setups. As part of our “alliance” with Hendrick Motorsports, we used their vehicle-dynamics simulation program. Each track uses different Goodyear tire compounds, and we used the tire data supplied by Pratt & Miller along with Hendrick’s tire simulation program to determine optimal camber, toe, Ackermann, etc. for the weekend. (Tire temps and wear data during the race weekend helped us tune in the settings further.)

The car would be “set up” on a surface plate using a ROMER arm (a portable CMM) and PowerINSPECT software.

51 car ROMER setup
Setting up a car with fixtures and the ROMER arm.

The car’s setup involves all the selection of suspension parts, choosing from dozens of available A-arm, spindle, sway bar, sway-bar arm, truck-arm, and axle housing geometries. It also includes the infinite adjustability of each component on the chassis. Every alignment parameter is adjustable and carefully selected by the engineers for each track.

Before working in stock-car racing, I had assumed that “only turning left” eased some of the complication of car setup. Unfortunately, the opposite was true. In most road racing, the car is more-or-less symmetrical left to right, but stock cars use different suspension geometry at each corner, different springs, shocks, tire pressures, ride heights, camber, track width, toe, and more.

View from rear of 51 car at ground level showing difference in camber settings
Note the four different static wheel camber settings

The chassis and body are even built asymmetrically. Just about everything asymmetrical is that can be – sway-bar arms, side-skirt heights, track-bar heights…even the tire compounds are often different left-to-right.

Body asymmetry
Intermediate-track body asymmetry. Biased center of aerodynamic pressure promotes CCW yaw moment. Photo credit: Action Sports Photography

After the suspension geometry is finished, the car is put on the push-up rig, where the chassis is locked in place, and hydraulic pistons actuate the wheels to allow us to fine-tune wheel rates. I was in charge of the push-up rig from the first day I started. Since the springs are sandwiched in between the stationary upper spring perch and the lower control arm’s bucket which “levers” upward, wheel travel causes an uneven collapse of the spring, requiring the use of a “helix” and various spacers and angled shims to achieve the rate profile desired.

Speedway car on the push-up rig for rear truck-arm clearance check
Speedway car on the push-up rig, checking rear truck-arm clearance

Several odd effects could be obtained with careful helix configuration, such as dual rate, coil bind, and even a transition to negative wheel rate (try to figure that one out) which we even tested in the LF at Loudon once.

Spring inventory
Springs Phoenix Racing used before the 2014 ride-height rule change. We purchased and used just as many new springs.

After the car is set up and all our planned spring combinations are configured and documented with the push-up rig, other team members work on other parts of vehicle prep. The cars are loaded onto the Hauler for the race weekend, and they leave. For a typical Sunday race, the crew would fly out on Thursday.

On Friday, we would have practice 1 and qualifying. During practice, the crew chief and engineers worked together to try different prepared setups, or if the driver had good success with the first setup, we would just fine-tune that one. The driver would make a few laps and come back to the garage and give feedback. We would quickly make one or more setup changes and send the car back out, but not before I made the same change in the simulation and iterated a few times to determine the necessary shock-packer adjustment. During my time in Cup Racing, every car maintained front bump stop contact as much as possible. Track testing revealed the aero advantage of keeping the splitter as close to the track as possible (we targeted 0.010″ above) outweighed the negative grip effect of the stiff wheel rates. So in addition to the suspension springs, we ran a variety of different rubber and coil-spring bump stops (asymmetric, of course), with the shock gap precisely calculated to keep the splitter from crashing due to aero downforce (>3000 lb. at tracks like Michigan) and the effects of banking, braking, body roll, etc. Scraping the splitter on the ground more than a few times resulted in what we called “knife-edging” the splitter’s rear edge, and wind-tunnel data showed that was detrimental to front downforce. This sensitivity to ride height meant every adjustment had to be run through sim, and shock packer (thin, hard plastic spacers on the shock shaft) usually required adjusting.

Bump stop spring and shock packer
Hypercoil bump stop spring and shock packer used to fine-tune the gap


Comparison of bump-stop rate curves
Bump stop rate curves. The linear stops are Hypercoil springs. Note the significant hysteresis in the conventional polymer bump stops. Vertical axis is Load (lb).

My job was also to maintain the official documentation of the weekend in the form of run-by-run practice notes and a half dozen setup sheets, each one a snapshot of car setup at important milestones – pre-P1, Qual, Post-P3, Pre-Race, etc.

After practice is qualifying. Not many adjustments can be made – just tire pressures (and inner-tube pressures, if applicable) and right-side track bar height. We engineers mostly just watched the timing and scoring data.

Qualifying in Las Vegas
Qualifying in Las Vegas. Photo credit: Action Sports Photography

On Saturday, we typically had two practices, doing the same work as the first practice. Sometimes we had new setups to try based on what we learned from our first practice and what other teams were doing (many crew chiefs are surprisingly open with each other about such things). At the end of the day, race prep starts. Many parts on the car are replaced preemtively (like the rear-end gear), and other parts are exchanged for parts that impart more on-track advantage but are inconvenient to work on/around during practice when lots of setup changes are done. Some adjustment provisions are made, like adding packer pullers or rear-spring rubbers. Packer pullers are essentially a lanyard that a front tire changer can yank to lower the splitter if we got the adjustment wrong. They are not frequently used (or even installed) unless we make a big change between last practice and the race. Having the rear tire changer knock in or pull out a spring rubber allowed us to increase or decrease a rear-spring’s stiffness by changing the number of active coils. This is typically done to induce a crossweight change.

Rear knock-in spring rubbers to quickly modify spring rate
Rear knock-in spring rubbers. Different color foams indicate different hardness.

During Sunday’s race, engineers track fuel mileage and help formulate pit strategy with the crew chief. The cars don’t have fuel gauges, so engineers estimate fuel usage through precise fuel-cell capacity measurement, E15 temp-dependent density data, fuel-can weight measurements (before and after a pit stop), track-dependent adjustment factors for yellow-flag consumption, and many other considerations. We used an Excel-based program to make various predictions and war-game different scenarios (e.g. “we need three more yellow-flag laps if we want to get to the end of the race without needing to pit again.”) Running a car out of fuel on track happens, and it’s a big embarrassment that I’m happy I never experienced.

Fuel-mileage program

Fuel-mileage program
Some of our fuel-mileage program’s calculators

In addition to races, I traveled to each test. NASCAR does not allow data acquisition on cars during a typical race weekend, so we had to visit tracks specifically for tests. I was responsible for instrumenting the car and calibrating the independent data acquisition system before the test, and for maintaining it during the test. I had to offload data each run and overlay it with the sim data to dial in the grip factors and other things so they matched. Tests could be even more hectic than a race weekend since sensors sometimes go bad, and tiny LEMO and AutoSport connectors often broke after being handled roughly by mechanics who aren’t used to them being there.

Front-spring load cell
Front-spring load cell installed for a test in Texas


Going out for a test run in Texas. Note splitter lasers.


While getting up to speed on race engineering and developing new systems for the fledgling team, I managed to become the de facto IT guy too. I set up and tore down our timing-and-scoring radio equipment; hauler, toolbox, and pit-box computers; TV feed; NASCAR VLAN connections and config; maintaining ROMER-arm calibrations and writing custom measurment programs, and many more tech responsibilities. During the race weekend, there were always new challenges to keeping systems up and running. This is when I became obsessive about systems and automation. In keeping with the website’s theme, the systems and habits I developed for race-weekend preparation, execution, and documentation allowed me to keep learning, incrementally improve our processes, and maintain composure through a fast-paced and always-changing environment.

Eventually, the job’s luster wore away and revealed what felt like a hamster wheel of repeating the same efforts at the same tracks ad infinitum, all while working 60-70 hours each week with an inconsistent schedule. And the job didn’t give me much to show for my effort – I hadn’t really solved a problem or helped put a new product on the market. So after a few seasons, I was ready to get back to design engineering in an industry whose end product was more than just an advertising platform.