How to install a bolt-in roll bar in 10 easy steps

By Per Schroeder
Mar 10, 2022 | DIY, roll bar, Safety, how-to | Posted in Shop Work , Safety | From the Dec. 2006 issue | Never miss an article

Photography by Per Schroeder

[Editor's Note: This article originally appeared in the December 2006 issue of Grassroots Motorsports.]

So, you’ve made the decision to start doing some more track events in your street car, but you’re not sure if you feel safe enough at speed. You might want to consider bolting in a roll bar before heading out to the track. A roll bar will give an added measure of safety in case the car flips; it will also provide some extra structural rigidity. Roll bars are required by some track event groups and can serve as the basis for a full roll cage later on. 

Early roll bars started out as simple U-shaped tubes welded to the floor of the car. A lot of times, these bars didn’t even extend the full width of the cockpit. 

Since then, roll bars have evolved to include extra bracing—tubes that run from the top of the main hoop to the rear of the car as well as a diagonal bar that strengthens the main hoop. This extra bracing gives a roll bar its strength, and we would recommend (as would most sanctioning groups) that you buy a roll bar with a diagonal brace. 

Roll bars can be welded or bolted into the car in a matter of hours. While we like the idea of a complete roll cage that is welded into a chassis, a bolt-in roll bar has high marks for ease of installation and the possibility of removal in the future. 

One caveat about installing a roll bar: They almost always prevent the use of the rear seat. You simply can’t put people back there without risking their lives. For this reason, most enthusiasts will yank the rear seat from the car when installing a bar. Once the bar is installed, the rear seat is basically dead weight. While most rear seats will weigh less than 20 pounds, removing it still helps a little toward offsetting the 60 or so pounds that a typical roll bar will add to the car’s total.

Practical Exercise

We ordered a bolt-in Race Roll Bar from Autopower Industries for our 1974 Alfa Romeo GTV. The bar is constructed from 1.75-inch DOM steel with a 0.120 -inch wall thickness. The harness mount crosses the entire width of the bar and will allow us to correctly attach our shoulder harnesses. 

Since a roll bar is often too large for typical shipping companies, it will need to be delivered via truck freight. If you can pick yours up from the builder or retailer, you’re ahead of the game. 

Our bar arrived about a week after it was shipped, and just a few scratches were visible on its gloss-black finish. Like other bar makers, Autopower cautions that there is no warranty on its paint finish. A quick shot of gloss-black spray paint covered up the largest scratches without a problem. That said, the finish on the bar is actually quite durable and attractive—despite the warning, we were impressed.

Step 1: Remove Seats

Installation starts off by removing the front and rear seats. Depending on the car, you may also have to remove portions of the rear carpet and the quarter panels. Since our Alfa was in the middle of a restoration, much of this had already been done. 

Step 2: Prep for Surgery

Once the interior is out, there is some preparation work needed to ensure a good job. Since we weren’t planning on reinstalling the rear seat, we painted the inner panels the body color. Then we made small aluminum panels to block off any holes that led to the trunk area. 

Another nice way to finish off the vacant area left by the removal of the rear seat is to lay down some felt-like trunk liner material. This lightweight carpet is much like the same Perlon felt that Porsche used to finish the interior of its uber-light early-’70s Carreras. The material conforms easily to compound curves and can be cut with household scissors. You can buy it at any decent upholstery or fabric store that carries automotive products. Pick up some aerosol contact adhesive while you’re there. 

Step 3: Clean Up

Before you slide the bar in the car, there’s some prep you should do. First, thoroughly clean the rear windows and vacuum the back seat area. Once the bar is installed, it’s kind of hard to get back there. 

Step 4: Protect the Paint

Next, you’ll want to lay some blankets or towels across the car’s door sills. It’s pretty darn easy to scratch the car while you’re wrestling a 60-pound roll bar into it. 

Step 5: Wrestle the Bar Into Place

Now you’re ready to take on the bar. With the help of a friend, maneuver the bar into the car. We’ve achieved our best results by tilting the top of the bar forward as we lifted it over the sills. As the bar goes in, slowly angle it backward. Ours had removable side braces that we fitted as we moved the bar into place.

Step 6: Properly Position

Once the bar is in roughly the correct place, start measuring its position on the floor. It’s important to get the bar centered in the car for the best fit. 

In our case, once the bar’s main tubes were correctly positioned, the left-rear brace was about a quarter of an inch off the inner fender. This gap proved to be inconsequential; as the bolts were tightened down, the gap disappeared. 

Step 7: Prepare to Drill

Before you break out the drill, check under the car for any brake or fuel lines. Also watch out for any wiring. It’s entirely too easy to forget this step and drill through a brake line—or three—while you’re installing a roll bar. That would be bad.

Step 8: Drill Away

Use the supplied backing plates as a guide in choosing a drill bit. We drilled one hole for each of the four mounting plates; we then tightened down those four bolts before we drilled the next hole for each plate. We then tightened each plate’s second bolt. We continued this sequence until all four holes had been drilled and the appropriate hardware fitted and tightened. This procedure minimizes misalignment and keeps the stress levels down. 

Step 9: Prevent Rust

Once the roll bar is bolted down, take some measures to keep the elements away from the backing plates. Rubberized undercoating or seam sealer works perfectly here. This step is especially important for a car that still sees regular street use. 

Step 10: Soften the Blow

Now that the bar is installed, you should go ahead and stick on some high-density roll bar padding. The soft padding that you can still readily find in local speed shops is no longer legal for many types of racing. The harder padding does a better job of protecting your melon in the case of a hard impact. Hopefully you’ll never personally test the padding—or the bar itself, for that matter.

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