Blacktrax Performance S2000 Motorsport Makeover: Part 2 - Cage Fabrication

by Edward Hu

In the first part of our coverage on the rebuild of Irene, the Blacktrax Performance S2000, we saw how the car was stripped down and sent to CT Engineering to weld together all the metal to help prevent the car from flexing and twisting under cornering. During this time, the guys at CT Engineering also welded eight pads onto the chassis that their fully custom cage would ultimately be mounted to.

In part two of this Motorsport Makeover, the guys at CT Engineering are working with Blacktrax Performance and TunerPlayground with the goal of building a full cage for Irene.


Our completed cage, keep reading to learn the details that went into its construction.

Of course, the main function of a roll cage is to keep the driver and any passenger safe in the event of any incidents. In this case, the cage also serves to hold the entire chassis together to get the most out of the suspension by including anchoring points right in front of the rear shock mounts and just behind the front strut assembly.

In relation to the legality of this cage in different race series, this cage will be compliant with NASA, SCCA, Global Time Attack, Super Lap Battle, Redline Time Attack, and Pikes Peak International Hill Climb.

To start, the folks at CT Engineering in Rancho Cordova, CA picked up 51 feet of 1.500 x .095 DOM seamless steel tubing.


Just some of the larger pieces of tubing we started off with

For a cage of this complexity to fit, several measurements are needed for every bar and tube to ensure that they all fit in the cabin and fit together with the other bars and the pads on the chassis. For example, the A-pillar bars must fit perfectly onto both the main hoop and the pad welded in the chassis in the footwells on either side. The bar to which the harnesses mount must be exactly the same width as the main hoop, and so on. Additionally, the cage must provide sufficient clearance for the two seats, the hardtop, the steering system, and the driver with helmet (as well as any passengers). Many measurements must be taken before cutting, bending, or notching the expensive steel tubes.

The first bar that goes into the car is the main hoop, spanning from behind the driver’s left side to behind the passenger’s right side. Every other bar and tube (I use the terms interchangeably) will mount to this hoop.


Once the main hoop is put in, the rest of the cage is built using it as a reference point.
Another view of the main hoop.
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Tuesday, April 22, 2014 10:17 AM
I love seeing cage work being done. Maybe becuase it is the point of no return for being transformed into a racecar.

So the argument I alway hear is that you don't want to overdo your cage because it will add more weight than is necessary. While I get that you don't want to go overkill, wouldn't most small cars (like the S2k), when fully stripped, fall well under minimum weight requirements in many classes? I get that ballast can be added in a more advantageous place, but an extra 20% of cage in this build would only add 15lbs. I would happily take another 15 lbs of weight to ensure that my cage is extra beefy.

This question has nothing to do with the cage in this particular car. This cage looks great.
Tuesday, April 22, 2014 11:21 AM
How far is that diagonal from the upper corner?
Dan DeRosia
Dan DeRosialink
Tuesday, April 22, 2014 2:27 PM
Protodad: Well, and then there's classes that mandate fewer than X amount of ballast to meet minimum weight. No advantage whatsoever to not have some of the weight as cage.
Tuesday, April 22, 2014 8:32 PM
Looks great guys. One thing though... For pikes peak you need to add gussets on all 4 corners of the halo. Its a goofy rule with no specifics (I.e. you can use .0001 sheet if you wanted) but they are sticklers if you actually want to try the race :)
Wednesday, April 23, 2014 3:56 PM
honestly, there really is not enough triangulation in this build IMHO. I like to use WRC rally cars for reference because that is where i've seen the best cages, and their designs get regularly tested on the courses through the worst kinds crashes imaginable. i absolutely would not use NASCAR as an engineering reference for anything but iron block V8 engines.

some of the best cages i've seen look like small triangular mesh and absolutely every corner is triangulated.

you can also do some very easy structural simulations with ANSYS to test cages before they are built, by using your hard points as fixed reference points and trying different cage designs it's pretty easy when you're only using straight gauge tubing.

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