Picture this: a 410 sprint car on a glass-slick 3/8-mile late in a feature, driver rolls into the throttle off turn two, and the rear end just rotates — not because of tire grip, because the geometry is doing it. Two holes of pack down on the upper links, 0.625-inch bracket spacing, and that asymmetric instant center is doing work that tire compound alone never could. That's Column 26. You're listening to Hunter's Column Lab. I'm HUNTER, with Hast on the call. Tonight we go deep on the Black Book: four-link hole positions, pack down versus square, and the decision matrix for every track condition and class from 410 sprints down to Stallard SST micro sprints. We've also got Bobby Pierce stealing the $75,000 Show-Me 100 from twenty-back, and Michael Kofoid absolutely rolling through the World of Outlaws sprint car standings. This is Hunter's Column Lab. We read the column so you don't have to skim the data boxes.
HUNTER The big dirt late model story this week is Bobby Pierce at Wheatland. Starting twentieth, he caught Jonathan Davenport making a mistake on lap 61 and blew by to take his second straight Show-Me 100 — seventy-five grand to the winner, 1.296 seconds over Brandon Sheppard at the flag. Davenport had dominated both prelims, won the Gibson Tribute on Friday, so watching Pierce thread through a stacked field from that far back to steal the crown jewel is exactly the kind of story that tells you rear-geometry decisions late in a 100-lapper matter as much as anything on the car.
HAST Yeah and on the sprint car side, Michael Kofoid is just cooking right now — that's six wins on the World of Outlaws season, most recently at Huset's Speedway, and he heads into River Cities Speedway this weekend as the clear points leader and the heavy favorite at a track where he swept both events a year ago. Meanwhile over on the USAC side, Briggs Danner found something right at Circle City Raceway in Indianapolis — won the quarter-mile dirt oval event for ten thousand dollars after years of struggling to connect at that place. Hard to ignore that setup call when a driver suddenly clicks at a track that's been giving him fits.
HUNTER Wikipedia gives you 323 characters on multi-link suspension. Three hundred twenty-three — fewer than the average text message. It covers double wishbones, trailing arms, passenger car ride quality. It says nothing about four-link hole positions, nothing about pack-down geometry, nothing about left-rear angle separation on a dirt car that needs to rotate 180 degrees of attitude change between corner entry and corner exit. So we fix that. Permanently. A four-link rear suspension locates the rear axle housing relative to the chassis using four bars — two on the left side, two on the right. Upper bars. Lower bars. Each bar has a chassis-side mount and a housing-side mount. Each mount has multiple holes. The hole you choose determines the instant center of that link pair, and the instant center determines how the rear axle reacts to torque, braking, and lateral load. Every hole. Every time.
HAST And the hole-position conventions matter a lot here. Higher hole on the chassis bracket means shorter effective link angle, less anti-squat, the rear end is freer to rotate under power. Lower hole on the chassis bracket means steeper link angle, more anti-squat, the rear end plants harder. Higher hole on the housing bracket — the birdcage side — means the link slopes downward toward the chassis, more rear-steer potential, more lift on the left rear under torque. Lower hole on the housing bracket means flatter geometry, more stability, less rotation. And the Black Book is very clear: you evaluate upper and lower on the same side as a system, then you evaluate left versus right as a second system. That's four variables minimum before you even breathe on spring rates or birdcage float.
HUNTER Now here's where pack down versus square splits the room. Square means left-side upper and lower links are in the same relative holes as the right side — same angles, same anti-squat percentage, same instant center height. The rear end wants to go straight. Pack down means you've moved one or more links on the left side to a lower hole position relative to the right — asymmetric instant center, left side steeper, right side flatter. Under torque, the left side lifts or resists dropping, the right side accepts load. That creates rear steer to the left. On an oval, rear steer left is forward bite off the corner. The Black Book quote is blunt: one hole of pack down is the difference between a car that drives off the corner and a car that gets driven into the fence. Two degrees. Two degrees is an inch of rear steer over the length of the axle housing, and an inch is a whole car-width over fifty feet of acceleration zone.
HAST The decision matrix in the column is where this gets really practical. Heavy wet track — any size, any banking — run square. Let the tires work, because pack down on a gumbo track with maximum grip makes the car dangerously loose on exit, you've got mechanical rotation stacking on top of tire rotation. Dry-slick quarter- to 3/8-mile at moderate banking, six to ten degrees, that's one to two holes of pack down. Black-slick glass surface — that's aggressive pack down, two to three holes of upper-link separation. Half-mile tracks, square to mild regardless of condition, because the rear steer fights you down 800 feet of straight and costs you more time than you gain in the turns. And on the 410 sprint car specifically, the birdcage float variable adds a whole second layer — the static hole position is your starting point, but how tight or loose that clamp is determines how much the links actually move dynamically under load.
HUNTER Here's the take that I think trips up a lot of club-level crews: the instinct when a car feels tight on entry after you've packed down the links is to soften the left-rear spring or back off the torsion bar to compensate. The column calls this out directly — pack down creates rear steer, and some drivers feel pre-load on the left rear as tightness in corner entry. So the crew softens the LR bar, and now you've got geometric rotation plus a weak left rear all hitting at once. The car hooks violently on exit. The fix isn't the spring — it's recognizing that the geometry is doing its job and the driver needs to trust it.
HAST Okay but here's where I push back — the column says don't compound adjustments, and I get that philosophically, but on a track that's changing every ten laps through a 25-lap feature, you don't always have the luxury of single-variable discipline. If a driver is coming in hot every caution saying the car is hooked on exit, you have to do something right now, and the fastest tool in a crew chief's hands at that moment might actually be the LR torsion adjuster, not pulling a wrench on the link bracket in two minutes of pit time.
HUNTER Right but that's exactly the trap — you're solving a geometry problem with a spring tool and now you don't know what you have. The column's point is about diagnostic clarity. If you soften the torsion bar to mask the hook, next time you're at that track on a similar night you have a corrupt baseline. The correct in-race move is birdcage clamp adjustment — the column specifically says open the left birdcage clamp a quarter turn before you go to a second hole of pack down, because birdcage adjustment is finer resolution than a hole change. That's the real fast tool. The torsion bar is the last resort, not the first reach.
HUNTER Other dirt results from this week: Jonathan Davenport had dominated both Show-Me 100 prelims at Lucas Oil Speedway — he led all forty laps of the Gibson Tribute on Friday, which was his eleventh win at Wheatland since the spring of 2023 and his 96th career Lucas Oil Late Model Dirt Series victory — but Bobby Pierce came from twentieth to steal the hundred-lap main event on Sunday after Davenport miscued on lap 61. Brandon Sheppard ran second in the finale, with Hudson O'Neal, Brandon Sheppard, and Devin Moran all in the mix throughout the weekend.
HAST On the sprint side, Mat Williamson leads the Super DIRTcar Series points heading into the northern tour swing, and Aaron Reutzel has been Mr. May on the High Limit circuit — he's been on fire with wins at Grandview and elsewhere this month. Michael Kofoid is the one to beat in the World of Outlaws heading north to River Cities and Nodak Speedway this weekend, and Briggs Danner finally cracked Circle City Raceway for a ten-thousand-dollar USAC win — a track that had been giving him fits for years. Good week of results all over the map.
HUNTER Quick science note worth tagging from this week: Briggs Danner's quote about switching from sprint cars to late models is perfect four-link context — he said everything he knew about driving a race car in a sprint seat hurt him in a late model, that it was like learning all over again. That's a driver describing the same geometry shift we talk about in the column. Sprint car four-link behavior with floating birdcages is tactile and fast. Late model four-link on a longer wheelbase with 22-inch links is smoother and more gradual. The feel is completely different even though the underlying physics is identical.
HAST And the racer.wiki Black Book column specifically has the class breakdown table for this — 410 sprint upper links at 18 to 25 degrees from horizontal, 602 crate late model upper links at 12 to 18 degrees, super late model at 14 to 20. Shorter links, steeper angles, faster attitude change rate on the sprint car. Longer links, flatter geometry, more gradual response on the late model. If you're cross-shopping setups between classes, that table is the first thing you need to sit with before you touch a single hole position. That's Column 26 in the books — four-link hole positions, pack down versus square, and why two degrees of angular separation is worth more attention than any spring change you'll make at the track. Next column we're going into birdcage float and clamp science on the 410 sprint car — the dynamic second-order effects that make sprint four-link geometry the most complex in the sport. Stay with us. Hunter out. Read the full column at racer.wiki.