"In this Special Series, I document my experiences with the Lightweight Aluminum Skidplate. I have a feeling I know why you're here, your OEM plastic undertray has cracked and it's now hanging by threads.

In this entry, I document my unboxing impressions of the Lightweight Aluminum Skidplate, and go into details why I think it was the best option for my use."
- Matt

It's only a matter of time.

BMW M initially designed the E9x M3s undertray for aerodynamic, cooling and most likely crash test purposes.

Made out of thin ABS plastic covered with felt, the 3 components clip together and conform to the OEM stock bumper. This was a pretty common manufacturing and design approach to undertrays for BMW.  

See the undertray on the top right? That's the M5 V10 unit. It's flat. 

BMW didn't seem to account or core for the corners and middle section hanging lower than on the M5's design along with the lower ground clearance of the M3. 

I blew out my OEM undertray twice at stock ZCP height. Both events happened during the Winter. 

Aftermarket options weren't all that. 

I had been researching the aftermarket undertray options after the 1st failure. I ended up replacing the damage units with OEM parts as I wasn't satisfied with the options available back in 2018. 

Turner had a long lasting solution that required drilling into the chassis. It was also quite heavy and definitely seemed to be the most durable.

A few other shops had made their own in-house version, but they required cutting, drilling and moving hoses around.

I wanted an OEM+ solution: something that kept the original cooling and aerodynamic purposes of the undertray, while easily bolting on and off for service. 

 

K.I.S.S.

David, a forum acquaintance and fellow M owner, reached out about an undertray he had been testing.

His friend, an M3 owner, had designed a new take on an aluminum undertray after having experienced the same issues. He happened to be an aerospace engineer by trade. David and other Los Angeles owners had tested the undertray for months to account for slight design revisions and test durability.

I reached out to Winston and sourced a gloss version of his undertray. I wanted to review the product for myself and offer a group buy on M3 V8 communities for it. Those were pre-EuroConnex days. 

I received the unit a few days later and unboxed it. Below are my impressions and a review of the design features of his kit. 

The weight. 

The undertray weights less than the OEM unit: it's 3.7 lbs versus 3.9 lbs for the Genuine BMW plastic trays. 

The undertray is laser cut from a sheet of 5052 Mils spec aluminum. 

The OEM design integration. 

As an aerospace engineer, Winston understood he wasn't about to retro-engineer BMW's design in a wind tunnel. He opted to retain the integration of vents for along with a replica of the rubber add ons.

The design retains the OEM like cross sections in the middle of the opening. 

Winston designed small tabs on the corner sections to easily bolt into the fender liners for proper fitment. He also planned for 2x holes that attached the suspended wires that were put in to support the OEM plastic undertray. 

Proper hardware. 

Winston insisted on including every single piece of hardware to perform the installation. You do not need to re-use any OEM hardware for this. 

The skidplate mounting points have threaded inserts that greatly facilitate installation. 

The bolts are zinc coated. They will not rust over time. 

He also includes 2x zip ties for those that have hanging hydraulic lines from previous messy skidplate installations. 

Adjustability.  

Every bumper will fit different: it's the nature of a flexible composite and the different environment we put our M3s through. 

Winston understood this and designed slots into the 3x bolt holes that fit with the OEM oil pan skidplate. 

 

I was promised this would fit with the GTS' front lip chassis brackets or any GT4 lip with brake ducts.  

Up next: let's see how it fits.