Truck Topics
The Tool Box - Sun Visors and Bug Deflectors
Sun Visors and Bug Deflectors – they look good on the truck and do a good job at what they are designed to do. However, these two pieces of plastic, fiberglass, or stainless steel can cost you thousands of dollars each year in fuel. I heard a Peterbuilt engineer say once, “If it kills bugs it is bad for aerodynamicsâ€. Some things are unavoidable such as hoods, windshields, and grills but they are getting better.
Sun visors – these are designed to shade the drivers view on bright days. They are also, in most applications, an addition after the engineers have finished with their aerodynamic testing. With that said, I looked at my visor and the underside of it was covered with deceased flying creatures. I took a few steps back from the truck and looked at it from the side. I followed the slope of the hood, thinking of how the air would flow up the windshield and CRASH the air into the bottom of the visor. This, I determined, was a very bad thing, as the air had to fight to get around the visor and over the top of the cab and sleeper.
After talking to some Freightliner and Volvo engineers, I decided to remove the visor. Once this was done I saw 3/10 increase in my fuel mileage and more money in my pocket. We did not even notice the visor gone from the inside of the truck. If you need a visor the ones inside the truck work great, as they do not affect aerodynamics.
Some trucks visors are designed to not disrupt the airflow coming up the windshield and over the cab, like the Freightliner Century and some Volvo’s. In their most aerodynamic configuration, the new Cascadia and International Pro Star are both coming out without a visor installed.
Some trucks may not have the option of removing the visor, as they have marker lights built into them. For those that can remove theirs, the process is simple. If you take it off and it doesn’t help your fuel mileage you can always put it back on.
The project is simple. First you open hood and climb on top of motor, finding a good solid place to stand safely and without damaging anything. From there, figure out what tools you need to remove the visor. The M2 Freightliner is one of the worst offenders of visor aerodynamics. There are bolts using a torx (star) bit in each of the brackets. Once you know what tool is needed, simply remove the bolts and the visor will come off. Now we have a bunch of holes in the top of the cab.
I did not want a bunch of bolt heads sticking out of the top of the cab so I got some bathtub caulk (my truck is white), filled the holes and I was done. I saved the bolts and taped them to the visor, when we sell the truck we will have the visor with it. If your truck is not white you can get paintable caulk and touch up paint at a parts store.
Bug Deflectors – these are designed to change the air flow over the hood and off the windshield thus “deflecting†the bugs over the cab. However, this change in airflow will cost you in fuel. Just ask an engineer. But don’t ask a bug deflector engineer. Trucks are designed without bug deflectors for aerodynamic reasons. If they helped aerodynamics they would come from the factory with them on the really aerodynamic trucks.
Removing a bug deflector is easier then removing the visor as you can stay on the ground. Simply remove the screws or bolts fill the holes with caulk and paint if needed. You may need help if the bug deflector has nuts on the inside of the hood. Removing the bug deflector can save you a lot in fuel – more than enough to buy glass cleaner. They don’t really work that well anyway.
A friend went to a Freightliner shop to have his visor removed and they wanted $150.00 to remove the visor and plug the holes. This job should only take about 20 minutes and six dollars for caulk. The time spent and cost would be about the same for the bug deflector.
Until next time enjoy better aerodynamics!