Underpanel Goodness

Update by Joe Gearin to the BMW M3 project car
Sep 25, 2008

The old, worn-out undertray.
Naked underside is ready for new panels.
Here are the replacement JT-Designs panels ready for installation.
The newly installed panels are clean and sanitary.
The new assembly should protect the engine and aid airflow.

Although BMWs are known for their thoughtful engineering, occasionally a half-baked design element makes it through production. Case in point: the fragile interlocking plastic underpanels that protect the bottom of the engine and smooth airflow underneath the front end of the E36 cars.

These panels might have looked great on the drawing board, but in real life they’re a major pain in the rear. Even a minor encounter with a curb or driveway can cause one of these panels to break loose, compromising the strength of the other interlocked pieces of the assembly. Our M3 has lived a fairly sheltered life, but it has still gone through three sets of these panels! Clearly there has to be a better way.

Fortunately, a fix is available from JT-Designs. This firm, located just outside of San Diego, has been racing and improving BMWs for years now. They offer a three-piece aluminum undertray assembly that addresses the flaws of the stock component. Installing these pieces is a cakewalk, and the entire disassembly/assembly process takes only about an hour.

First, we lifted our M3 on the always handy Race Ramps (http://www.raceramps.com) provided by Brute Industries. These low-profile ramps are designed for cars with low ground clearance. As a bonus they are incredibly light, making them a pleasure to use.

The old plastic pieces were hanging on to our BMW by a thread—and some electrical tape! We removed the old, scratched pieces and cleaned the newly naked underside of the air dam. We made sure to save the old hardware for reassembly of the new panels.

Following the supplied directions, we laid out the JT-Designs underpanels and lined them up correctly. After a little adjustment, the panels fit perfectly and assembled very easily.

We are now left with a sanitary-looking undertray that should direct air at least as well as the stock pieces. This sturdy aluminum tray system should also be much more resistant to damage than the old plastic pieces. JT-Designs sells these panels for a very reasonable $149.95.

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