Towler's Martinsville Setup

October 28th 2011
Martinsville holds a special place in NASCAR as the oldest track on the schedule, it's also one of the most demanding tracks on both drivers and equipment with its unique paper-clip shaped surface. The track shape provides crew chiefs with a dilemma, you need the car to turn in, roll through the centre and have traction on exit but getting all three areas spot on is almost impossible with the current COT chassis so it’s up to driver preference were on the track you make the compromise in the setup.
 
This week’s topic is going to be ride height, this may seem like a minor adjustment but it has a huge impact on handling as it changes the centre of gravity on the car. A higher centre of gravity moves the weight of the car higher and increases body roll, while this can often be a negative for the handling, it’s not always that simple. Allowing the car to roll more can increase the load on the right side of the chassis, loading up the suspension and tires with more force compared to the left side. At a track like Martinsville were it’s all about mechanical grip having the body of the car roll isn't an aerodynamic disadvantage and allows you to maximize the potential of the chassis setup to your advantage.
 
We'll start this week’s guide by following on from the previous weeks, first on the list is an obvious adjustment for a short track brake bias. For a track were braking and more importantly braking while turning is the key you'll want to take it as low you can go, I found going down to 53% balanced the car just about on the limit before the rear tires started to lock up under braking.
 
The springs also needed a lot of adjustment for the direction we needed to go with the ride height and general chassis setup, going down to the minimal 350 lb/in front springs on both sides helped the mid corner grip. Adjusting the left rear to 300 lb/in and right rear to 600 lb/in helped the car turn on entry and mid corner, the car still felt it had some adjustment left in this area so I set the track bar to 8.50. This started to feel a little slippery on exit but produced the fastest lap times, all part of the compromise that is Martinsville.
 
At this point the balance of the car felt pretty good but still a little tight on entry and mid corner, downsizing the front sway bar to 2500 lb/in helped with this slightly on entry but the car still didn't feel like it was getting through the middle of the corner all that well. This meant moving onto the wedge and bias section of the setup, the front bias was moved to 50%, left bias to 51% and the wedge down to 50%. This moved most of the weight towards the centre and left side of the car, as we'll be using the ride height to shift some of the weight back on the right side to try and fully exploit the mechanical grip that the chassis can provide.
 
After several runs the rear ride height was moved to 9.5 inches, this really helped the car get into and through the corner, going much higher than this though really started to reduce the amount of lateral grip the car had which made the loose off condition even more of a problem. This is the same problem that the teams and drivers face in real life, I'm sure this weekend you'll be seeing the cars slide out of the corners, the key is just to be careful on the throttle minimizing the amount of wheel spin to reduce the heat that the rear tires generate if you want to achieve fast consistent lap times.
 
This setup should reduce your lap times from a low 19 second time to almost a mid 18 second lap on a solid hot lap, with average 10 lap runs under 19 seconds a lap too. That’s it for this week and remember rubbing is racing, just make sure you leave it to the last possible moment to avoid the payback! Next week we'll be heading to Texas and explaining the shocks on a stock car, but until than enjoy the race this weekend and don't damage too many body panels at Martinsville in NASCAR The Game.