Once we made the decision to prep our free civic for endurance racing we immediately looked at the 2017 season calendar to schedule our first race. We decided on an 8-hour endurance race at Mid-Ohio Sports Car Course on Monday, April 24 2017, and we had our work cut out for us.
We were thrilled with the fact that we got a 5 year old engine running with little to no financial investment. We were ecstatic when it made it through its first track day at Waterford Hills Road Course without any issues. However, we weren’t foolish enough to bank on that engine lasting an 8 hour endurance race, let alone a whole season. So, several months prior to our first endurance race, the recently reassembled Honda D16 engine was removed from the Civic yet again, and received a full refresh, including new bearings, thrust washers, rings, seals, gaskets, and a general overall cleaning.
TIP: Remember to check your oil clearances versus spec to ensure you are putting in the correct bearings for the condition of your engine. Our favorite method is PlastiGauge due to its cost effectiveness and ease of use. It does take some time, but it is worth it to ensure the best outcome for your engine rebuild. EricTheCarGuy has a great video for measuring bearing clearances, which I’ve included below, incase you need any guidance on usage.
The next big ticket item on the list was to build the roll cage. The most important part about selecting your roll cage material is to check the requirements of the series you plan to race. The rules and regulations will have the required layout as well as minimum tube size based on the weight of the vehicle. We estimated that we would need about 75 feet of 1.5″ x 0.120″ DOM 1020 steel tube.
Note: The three main types of tubing that fabricators will use for their roll cage are listed below, from cheapest to most expensive.
ERW Steel: Electric resistance welding tube is made by rolling sheets of metal and then welding the joint to form the tubular shape.
DOM Steel: Drawn over mandrel tube is essentially ERW steel that is then pulled over a tapered steel shaft to smooth the inner surface from the weld seam. The outer circumference is also pulled through dyes to help shape the exterior of the tube. The end result is a more uniform product, typically with tighter tolerances. Note this process can be applied to many different alloys, such as SAE 1020, or 4130 chromoly.
Chromoly: Chromoly is a type of steel that gets it’s name from the materials its comprised of, specifically chromium and molybdenum. The addition of these specific materials yields a stronger end product that is slightly more resistant to corrosion than mild steel. Furthermore, the stronger product requires less material to achieve the same target strength, so look towards chromoly if weight savings is high on your priority list.
Once we had decided on the material type, dimensions, and quantity we called our local metal outlet to place an order. A few days later we went with a small army of ratchet straps to pick up the materials.
If you are new to building roll cages as we were at the time, one thing I cannot stress enough is planning. All welds need to be 360-degree, fully penetrating welds for tech inspection, and more importantly, YOUR safety. In order to achieve this without any body modifications the cage must be assembled in a certain order. The rough order we chose was:
1. Main hoop
2. Diagonal support
5. Door Bars
6. Rear Supports
7. Harness Bar
8. Dash Bar
A few issues we gave special consideration to are covered in detail below. It should be noted this entire cage was TIG welded. If you plan to use a MIG gun, as most do, some of these welds won’t be as difficult to reach.
Halo Bar to A-Pillar
Issue: Once the A-pillar and Halo are in place, the backside of the weld (as shown below) is inaccessible. Trapped between the cage and the roof.
Solution 1: Drill holes in the floor where the main hoop and A-pillar supports will be mounted. This allows the welder to drop the cage a few inches to reach the backside of the welds. The holes will then be covered up with the spreader plates for the cage. We found this method to be the simplest most discrete of the three solutions. We explain the other two options below.
Solution 2: Build the main hoop and A-pillar supports a few inches shorter than needed. The idea behind this is the same as in solution 1. The difference is that instead of taking away material from the floor, you add material in the form of welded boxes. We thought this method offered more room for error and would’ve taken longer to fabricate.
Solution 3: Cut holes in the roof, or better yet, cut it off entirely. This is the most intrusive method that people will use. Some use the holes in the roof as a last resort, others embrace their new one-off convertible.
Issue: The door bars are not as common of an issue, especially with a MIG gun, but the Civic was pretty cramped. Our issue arose due to a poor decision on assembly order which left the outer edge of the door bar to main hoop connection (backside of joint shown below) near impossible to TIG weld. Hassan was able to weld the passenger side using various techniques, but we didn’t feel comfortable using those same techniques for the driver’s side.
Solution 1: Weld the door bars to the main hoop before welding the A-pillar supports in place. This will allow the welder to slide the cage forward to access the outer edge of the main hoop. Then, using one of the methods above, the A-pillars can be attached.
Solution 2: Determine if there is enough room to rotate the cage in the car, even after the A-pillars are in. This usually works if the main hoop is close enough to the B-pillar/door, and it is done before the rear main supports are added to the main hoop. Our cage sat too far back in the car to rotate due to the instability of the floor in the B-pillar area.
Solution 3: Use a MIG gun and a mirror if room allows.
Solution 4: I call this solution the “Dude, don’t take a video. I don’t want to see this again.” I’ll let the video speak for itself.
That just about wraps up the Civic installment for this week. Enjoy the gallery below outlining the steps we took in building the roll cage in its entirety. Next week I’ll cover the remainder of the Civic’s race car conversion. As always, stay tuned.