MCG exclusive! 2013 NASCAR roll cage

Here’s the first public look at the NASCAR roll cage for 2013, built to comply with rules changes for next year intended to improve driver safety.

Mac’s Motor City Garage is indebted to ace fabricator Kevin Bryde of Earnhardt Ganassi Racing, who provided these photos and supplied the technical briefing.

First, in the photos above and below, note that the halo bar—the tube around the top of the cage that roughly describes the ¬†roof perimeter—has been doubled up with a second tube (yellow arrows) at the front along the top of the windshield. Now there are two full tubes, generously spaced, across the leading edge of the cage in front of the driver’s forehead.

Next, note another new tube (red arrow) that starts at the rear join of the Earnhardt bar and runs diagonally down to the right front (passenger) foot well area, adding an additional element of triangulation in the cage structure.

For the clarification of us non-NASCAR folk, the Earnhardt bar (white arrows below) is the vertical tube at the front center of the roll cage that runs down through the dash area just behind the windshield. This tube is named after Dale Earnhardt, Sr. and was inspired by a notorious 1996 crash at Talladega in which the nose of another race car penetrated Earnhardt’s windshield area.

Kevin explains that the new diagonal down tube has been carefully positioned so that the driver’s vision is in no way obstructed. Also, with the top six or so inches of the windshield blacked out, the new double halo bar will not be visible from outside the car.

In the most superficial way, the roll cage in a NASCAR race car hasn’t changed in decades. It’s still mild steel seamless DOM tubing, 1.75-inch diameter, .090-in. wall, MIG welded into a very familiar looking assembly. But over the past dozen years, nearly every detail has been agonized, sweated over, and optimized to produce the safest possible structure. In today’s NASCAR, safety is a total process.

For a story and video about the aerodynamic body design of the 2013 NASCAR Ford Fusion, including CFD studies, click here.

For a story on the most recent testing of the new-look 2013 cars at Talladega, including a large photo gallery of all the 2013 body designs, click here.

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31 thoughts on “MCG exclusive! 2013 NASCAR roll cage

  1. In photo 3, showing the Earnhardt bar, the rear ‘hoop’ doesn’t look symetrical, being lower on the right (left in the photo) and the right top rail looks different. Is there a reason for this, or is it just my eyesight?

    • The cage does indeed angle down more on the right side. It allows for clearance of the right side roof flap which is at about a 30 degree angle to the centerline of the chassis. The left roof flap is at a 90 degree angle to the centerline and sets back just behind that same bar behind the drivers head. Good eye!

      • Thanks Kevin, I’m not that familiar with these vehicles, but I know there are anti-flip flaps on the rear of the roof, it occured to me that this lack of symetry was to accomodate one of these.

  2. Unsurprisingly that cage would not be legal in a lot of Motorsport bodies. Eg the main hoop must go from left to right plus ofcourse the lack of space for a passenger, even if no passengers are carried!
    I do think though it is just a little over the top and decidedly heavy.

  3. I was just reading this article and found it interesting. Are NASCAR chassis really made with mild steel and mig welded? I am a drag racer, All of our cars we have worked on are chromemoly and tig welded. I have worked on drag cars ranging from top alcohol funny car’s and dragster’s clear down to Jr dragsters. Is there a reason mild steel is used over chromemoly. Also why wouldn’t they tig weld the mild steel? Just curious.. Marty

    • Many take the view that unless chrome-moly is normalized after welding, it is no stronger than mild steel and a hell of a lot more expensive. There’s nothing wrong with TIG welding mild steel except it’s far slower. Smaller, finer components generally are TIG welded in NASCAR.

      • I can’t see how chrome-moly is worth the extra expense in Sprint Cup. How many times do they actually run a chassis? It seems that teams are constantly bringing out new cars. I know that lower level racing series late model and dirt late model use chrome-moly, but they will run the same chassis for a year or two. I would also say that using mild steel has something to do with repairs (replacing front and rear clips). Chrome-molly could become too hard where it has been welded. I know on a dirt late model there is only so much you can do for chassis repairs (some of that is design). It would not be safe and welded joints can break.

        • Plus the “crushablity” of the mild steel is factored it to the design for controlled deformation to not transfer the G’s to the driver. If you hit hard on the RF, ideally you would want every joint all the way to the LR to deform a little. That’s distributing the load.

          • .090 wall cold rolled DOM seamless tubing is required by the rule book. It is generally ground in a centerless grinder to get consistency down to .090 the full length of the tube. I remember back in the day that sprint car guys were being killed/parylized by broken chromemolly cages because they weren’t normalized. 4130N needs to be used for that application if I remember correctly. I did work for a team in NASCAR that tig welded their chassis, but it was one guy, full time, for a small team that only needed a few chassis a year. Now a days it is an assymbly line that doesn’t stop because once the cars are bent it is so hard to get them to fit through inspection.

  4. Funny how different people use different names to refer to the same piece. The bar down the center of the windshield in my area was called a Valcke Bar. Ron Valcke was a driver in the SE Mich, NW Ohio area that ended up with a wheel and tire on his lap sometime in the early 80′s. I would say about 75% of us put that bar in even though we weren’t required to.

    And IDN, not that it matters because it’s NA$CAR rules for running NA$CAR races.

    First, the main halo bar does go continuously from left to right, it’s the ADDED bar that is in two pieces. Makes it easy to retro-fit the older cars.

    Second, car were never intended to carry a passenger, so it would seem that there would be no need for that archaic rule. Think of it as a big single-seater if you need justification.

    Third, as a former inspector in a series where cars also run at 200 mph at times, I can tell you from experience, there is NO such thing as over the top! And weight doesn’t mean anything when everyone runs the same weight.

    • The “Petty” bar is the one that goes from the center of the bar that runs across the car, just behind the seat at shoulder height, to the right side kick-up of the front stub through the floor, under the dash. The one that the left white arrow is on top of. In the last pic, you see the bar that goes from the floor near the shifter opening, and goes up to the halo bar. That’s new. The bar it connects to in the center of the pic, going horizontal across the center. That’s the “Petty” bar.

      • Forgot, the near vertical bar in the center of the last pic isn’t really “new”, but it does look like it’s position has changed slightly from what I’m used to.

  5. Great article, thanks.
    Curious, are the floor/main chassis box sections (RHS) seamless as well, or just the roll tubing?

    Chromoly is not used because of the cost and procedures involved with normalising it, like someone said. MIG welding is still used as a lot of chassis shops realise that TIG is too time consuming and doesn’t save much weight, strength is relatively the same between a good MIG and TIG weld.

  6. I was under the impression that the teams were TIG welding everything these days because it actually saves 30 or 40 pounds accross the whole car, which, even though they all run the same weight would mean quite a bit because that’s weight that they can add to other areas of the car to help it handle the way they want it.

    • I remeber Robert Yates Racing built a couple of tig welded chassis around 10 years ago. It saved 7 pounds on an entire chassis, and took two guys several weeks to build. Just not enough to gain, considering if it’s a favorite car it may run 5-10 races, and if it ends up being a least favorite, may run one race, or not at all.

  7. Appreciate the details and comments on the chassis and safety features. Could you illustrate the mounting points for suspension components and how the wrenches during the race change the suspension?

  8. While I can understand the need for tubes on the lower right of the structure for side impacts, I fail to see the benefit of extending the upper roll hoops to the right side of the chassis. There is nothing for this upper roll structure to protect on the right side of the chassis. If the upper roll hoop structures were limited to the left side around the driver, they would be stiffer and lighter.

  9. Slider, one reason to have a full-width cage is to not allow the roof to crush if that were the only means of escape, or for help to get in. Say, upside down, on fire, with the driver’s side against the wall. Plus the less tubing, the less the force on the impact can be absorbed by the chassis. Again, if everyone has to do it that way, there is no performance or safety advantage to it, stay with it what you know has proven to work.

  10. NASCAR cages are almost completely dependent on the bending strength of each tube as they bend and collapse in a crash. The design has very few diagonals that can distribute crash loads through out the chassis efficiently. The NASCAR approach, as shown by the addition of the new “brow bar” in front of the top halo’s front bar, is to add additional tubes that provide additional bending strength rather that attempt to transfer the crash loads to the rest of the chassis. It works for them and they know the car weights, and speeds and just add tubing until the cage can carry the crash loads. An FEA analysis of this chassis would be interesting. Lots of highly loaded weld joints and tubes in bending.

    • Clemson University sponsored some FEA studies in the late ’90s and reported the findings in SAE papers. I believe some are now posted online in various places.
      -MCG

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