February 23, 2023 2 min read
Few aftermarket suspension parts cause more heated discussion than the simple strut tower bar. Are they a dress up part that just makes you feel special? Or are they the first thing you should do to your suspension?
Every time a new platform is released, part of the hype is a more rigid chassis for improved ride, handling, and noise. The 2022 WRX and BRZ are 28% and 50% more rigid than earlier models, for example. Manufacturers try to optimize their chassis for the best combination of rigidity, weight, and cost.
But what’s the goal? Think about a very flexible chassis. Cornering loads will bend or twist the chassis itself instead of letting the suspension doing the work. Your carefully chosen spring rates and dampers aren’t doing as much and the car can be very unpredictable.
A stiffer chassis allows for better fine-tuning of the car’s suspension because the shocks and springs are doing the work instead of parts that aren’t meant to bend. In fact, a stiffer chassis requires a more carefully tuned suspension since the car is more sensitive to changes.
Notably, Subaru didn’t increase stiffness with a strut tower brace on the WRX or add one to the V bars on the BRZ. They used higher strength steels, adhesives, and a few key braces under the car.
This doesn’t mean all strut tower bars or aftermarket bracing is junk. But some… some is pretty clearly junk. Bracing the wrong points, too many bends, and bracing that just runs along existing sheet metal. Not worth the weight.
Why do brands sell them? Because people buy them.
There are also interesting designs with flexible braces -- Subaru offers some of these themselves -- bars with dampers built in, titanium, carbon fiber…you can spend quite a bit of money if you want.
And some braces do work. There are too many options to talk about here, but look for a simple brace across suspension mounting points, as straight as possible, ideally with triangles or Xs. In most cases, it’s a small change. But it’s not impossible to increase rigidity by 5% or more with a single brace. Multiple braces can make a real difference, especially on an older car.
Ultimately, cars are getting more rigid from the factory. But they’re also getting faster. Tires are stickier. Cornering speeds and lateral loads are increasing. Bracing has long been a smart idea on older cars and though it’s less effective, it can still be worthwhile on newer cars.
Does the STI strut bar on my BRZ make it faster in any significant way? Probably not. Maybe more responsive, maybe helps me dial in the car more easily.
But when I pop the hood, do I feel a bit more special? You bet your ass I do.