Installing a Strut Tower Brace
on Your BMW
Wayne R. Dempsey

Difficulty Level: 2
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

[click to enlarge]

     The BMW 3 Series cars are well known for their agility and superb handling. However, because of the chassis design, there is a weakness in the 3 Series cars. The front shock towers are not well supported in the 3 Series chassis. In fact, they are somewhat isolated and unsupported. As a result, the towers can bend and flex under heavy cornering. This flexing can cause detrimental changes in the handling of your car, because, in general, the stiffer the chassis, the better the handling of the car. Camber strut braces are designed to maintain the distance between the shocks under heavy cornering. A bar linking the top of the shock towers ensures the towers do not bend when the chassis is flexing.

     Well, that’s what the marketers say when selling these bars. The strut bars are yet another controversial product that many people feel the need to install on their BMWs. On some cars (the early Porsche 911s, for example), the installation of the strut bar is an important chassis stiffening device. Because of the Porsches’ rear-engine design, the front chassis can be decidedly weak, particularly when rust has started to affect chassis stiffness. But the BMW chassis is different. It’s supported by a much more rigid frame that includes a very strong engine mount bar that runs the width of the car under the engine.

     Which strut bars are most effective? I have little faith in the aluminum strut bars. Aluminum is not a very strong metal—you can often bend aluminum pipes with your hands. Add the fact that most strut bars are angled to fit neatly around the engine and under the hood, since there’s no straight shot across the engine bay. This combination creates a very weak support when you consider the forces you’re trying to counteract. In my opinion, an aluminum strut brace is merely window dressing for the engine compartment.

     I’m also not fond of bars with hinges built into the strut mounts. If they move at all, the shock towers are likely to see movement that would place the strut brace under compression and tension. A stiff connection between the strut towers is vital to proper strut bar operation. Any time you place a fastener in the assembly, you introduce backlash and slop in at least one direction (compression or tension). Thus, the bar becomes ineffective in at least one direction (compression or tension).

     The best strut tower braces are one-piece units manufactured out of thick, welded steel pipe. These braces offer the best protection against chassis flex when installed between the two strut towers. The strut braces manufactured by Ireland Engineering for the E30 cars fit this description perfectly. Their strut bars are some of the beefiest designs on the market.

      If you ask die-hard racers who drive their 3 Series cars on the track, most of them don’t run with a strut brace and can’t feel the difference even when pulling significant side loads (1.4 g’s) out of the corners. For dedicated track cars, the strut towers are often reinforced with steel pipe welded diagonally across the engine, connected to the front of the firewall.

     The bottom line? If you believe a strut bar will benefit you, or you are looking to spruce up the engine compartment, adding one to your car is a relatively simply task–simply bolt it on top of your strut towers. If your goal is increased performance, I recommend the bar only for a very stiffly sprung, dedicated track car. Make sure it’s a high-quality unit that’s designed properly: close-fitting on the struts, manufactured out of steel, a minimal amount of angles in the bar itself, and no hinges. A better upgrade, and one that should be installed first, is the BMW E36 convertible lower X-brace that stiffens the lower part of the chassis (see Project 66).

     If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.