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Racing the same car at different tracks – NASCAR Talk

Immediately after profitable last 7 days, Ross Chastain‘s crew main Phil Surgen noted that the car or truck sitting down in Talladega’s Victory Lane was the same motor vehicle they’d gained with at COTA.

“Really comes down to just the total Subsequent Gen platform,” Surgen said. “All the automobiles are the identical, have the identical range of changes, exact same group of parts. All the vehicles correct now are fundamentally common. We took that car soon after it was carried out at COTA, cleaned it up, established it up a minimal bit differently to come here.”

It turns out “cleaning up” a Upcoming Gen auto and setting it up “a little little bit differently” is a significant undertaking. So a lot of a person that you could problem no matter if it’s even fair to call it “the exact vehicle.”

Next Gen anatomy

Believe of a car’s chassis as its skeleton. In advance of the Upcoming Gen vehicle, teams designed their possess chassis by welding metal tubing to NASCAR’s specifications. Now groups purchase previously welded chassis items and bolt them together. The change is comparable to making a bespoke bookcase vs . shopping for a person from IKEA. Even though your strong, manufactured-from-scratch household furniture will never adjust, you can disassemble and re-assemble the IKEA bookcase. Of course NASCAR has tech inspections and IKEA does not.


A graphic showing the five parts of the Next Gen chassis.
Graphic credit score: NASCAR Rule E book

The key portion of the chassis arrives in 3 parts, as shown in the diagram previously mentioned. The centre portion protects the driver from impacts, warmth, flames and fumes. The front sub-body assembly supports the engine and entrance suspension (amid other points), and the rear sub-frame assembly does the exact for the fuel cell and rear suspension.

Almost everything on the motor vehicle, from suspension to system panels, attaches to the chassis. That means just about every part of the assembled car is dependent on precise chassis assembly.

A tolerance for units

NASCAR fabricators (and inspectors) discuss in thousandths of inches. In some cases, alternatively of indicating ‘thousandths’, they say ‘thou’. This confuses men and women because most of us believe ‘thou’ is thousands rather of thousandths. A thousand is 1,000 and a thousandth is .001. When I figured out machining in graduate college, we termed just one one particular-thousandth of an inch a mil. You’ve very likely observed that unit in advance of on trash-bag boxes. A standard kitchen trash bag is a minor much less than a mil thick. A fantastic outside trash bag is about a few mils.

But because NASCAR sticks with thousandths, so will I.

To give you an plan of the dimensions we’re discussing, here’s a photo of a ruler on to which I have superposed some values.

A photo of a ruler, with units shown in mils


As the graphic exhibits, 250 thousandths is 1/4 inch, 125 thousandths is 1/8 inch, and .160 inches is a small over 5/32 of an inch.

Why did I select .160 thousandths?

Because which is the greatest benefit of a minimal-talked-about component made use of in connecting chassis items. A component that provides teams the ability to introduce tiny amounts of asymmetry into the automobile.


Shims are parts of content normally made use of as fillers and spacers. You’ve most likely witnessed packs of wedge-shaped wooden shims in the house enhancement retail store. They taper from just about practically nothing to a quarter inch. You split off the dimension you have to have. People shims are very good for issues like leveling cabinets towards an uneven floor or wall.

Precision shims, these types of as those employed in manufacturing, can be created of any substance and typically come in increments of just one a single-thousandth of an inch (.001″).

NASCAR permits groups to put shims of up to 160 thousandths of an inch between the main section and just about every of the sub-assemblies. In the diagram below, the shims are in purple, the bolts used to attach them to the front sub-assembly are in dim blue, and the nuts are orange.

A graphic showing the shim placement between the center and front sub-assembly sections
Graphic credit: NASCAR Rule Book

Groups are not required to make all 4 shims the very same thickness — or even to use shims on all four attachment factors. Making use of different combinations of shims, they can change the entrance and rear of the motor vehicle a little up, down, proper or remaining. Simply because every thing attaches to the chassis, all those shifts finally impact everything from the suspension to the aerodynamics. The shim by itself isn’t pretty massive, but generating that tiny of a change at the sign up for with the heart area makes a bigger change by the time you get to the entrance or rear conclude of the auto.

Cleaning up

When a motor vehicle returns from the keep track of, most teams clear away every little thing from the door tops down. They eliminate the wrap and unbolt just about every composite system panel. They eliminate the engine, gas cell, suspension, transaxle, hoses… even the home windows.

Groups preserve specific notes on each car element. They know the place, when and how extensive every piece was used. The staff retires parts at the conclude of their reputable lifetimes. They cleanse and look at pieces that can be re-made use of.

If the motor vehicle will run at a observe related to the monitor it arrived from, the entrance and rear sub-assemblies might be remaining in position — in particular if the car or truck executed properly. Far more often than not, however, the front and rear sub-assemblies occur off, as well.

Location up the car or truck “a little differently”

Groups reattach the exact or different front and rear sub-assemblies with shimming specific to the monitor at which that car will race subsequent. Chassis positioning decides suspension geometry, which affects almost everything from skew to vacation. Diverse tracks contact for different springs and shocks, distinctive equipment ratios, and often, even various side home windows. Groups change entire body panels, then re-wrap the vehicle in the sponsor’s shades.

This is not a rapid process.

“It would be genuinely hard to switch (a car) around just about every week,” Surgen stated. “Every 3rd or fourth week, with the cleanup and the prep time that goes into it, you could use it each and every third or fourth week really quickly.”

What about tech?

NASCAR’s Following Gen chassis style and design offers groups a good total of adjustment space. But how a lot does that subject offered that each automobile must pass the Optical Screening Program (OSS) in tech inspection?

In accordance to the NASCAR rule reserve, the OSS will allow +/-150 thousandths tolerance on body panels. If a measurement is specified at 3.000 inches, the auto passes if the measurement is amongst 2.850 inches and 3.150 inches. That gives the crew just quick of a third of an inch from minimal to greatest price.

The OSS will allow tolerances of +/-200 thousandths on the windshields. Groups get .4 inches of leeway there. As we saw very last 7 days, they try to use each and every very last thousandth they can.

Is it the very same auto?

When a group talks about bringing ‘the same car’, that could signify only that they’re employing the exact centre part, or even the similar a few principal chassis sections. But most everything else on the car could be totally unique from what was on it at the past race.

Some people have suggested that the interchangeability of car or truck components suggests that any individual can put together a Upcoming Gen vehicle. Which is a big oversimplification. There is a even now a box inside of teams need to function. Placing collectively a car calls for higher precision instruments, expertise and plenty of understanding to make sure the auto delivers the biggest advantage attainable, but nevertheless passes inspection.

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