"In this entry, I document the development process of the new 1:1 Carbon Mirror Replacement Caps made in Germany. We took notes of past errors and selected stringent development and production methods."
- Matt

The bind. 

With the previously discussed discontinuation of the Karbonius made carbon mirror caps, there were no quality options left on the market. Owners were left to the hooplas of Alibaba and its resellers - most often to their disappointments. 

Creating a new option would be challenging: we needed to original center caps. As now know, they've long been discontinued. In 2024, I was able to find a used passenger unit with flaking clear coat and worn brackets. 

Not ideal - but it'll work.

I briefly test fitted it to ensure it was straight. It was fine for photoshoot purposes. However the clips were worn and fitment was loose. I wouldn't have expected this cap to hold on to the housing in the wild. 

You'll see the worn plastic teeth on the clips below. This had a significant impact on fitment. 

P.S.: BMW Performance parts of the E9x generation were made in Europe, with most being made in Slovakia. 

The method.

Preliminarily, we discussed potential design and manufacturing choices in consideration of market expectations. The ultimate value of these mirror caps is aesthetic quality. Weight is far down the list - and this is obviously not a structural part. 

While mirror caps appear simple in nature, reality is a little different for the E9x M3. We  have expectations of perfection based on the original M Performance product - and we have Alibaba replicas to know what doesn't. 

We thus opted to use the highest level of development and manufacturing standards that would be commercially viable to create a true OEM quality product. 

The positive mold. 

In similar fashion to the 1:1 CSL carbon diffuser, we would machine a positive mold of the mirrors. This technique is expensive - but provides the most accurate and repeatable basis upon which to create and mass produce the mirror caps. 

The clips template. 

Next, we sought to solve the clips position problem of the previous version. 

Using the original M Performance caps, we created a digital and physical template to accurately design the clips. The clips kept the original position and style, but the bases and "teeth" were reinforced for durability. 

Lastly, we favoured the design of a production tool, it is essentially a jig that allows us to accurately position the clips for production runs. This step required months of variant testing to ensure accurate fitment with the E9x/E8x M3/1M mirror housing. 

The clips' material. 

While the position of the clips is the most obvious problem to manufacturing these caps. the 2nd is the material of the clips themselves.

We opted to re-use the original injection plastic process with improved carbon plastic material for improved durability. 

The originals are made from injection plastic while the previous Karbonius caps were 3D printed plastic. The clips on the mirror housing are made from metal and eat into the plastic over time. Both had durability issues as you install and uninstallation. 

The Karbonius 3D printed clips also suffered at the expense of the metal clips. These mirrors were installed and removed probably 4x times. 

The negative mold(s).

From the positive mold, we create the negative molds used for production.

This allows us to create multiple molds to increase capacity while retaining precision over time. Most carbon manufacturers will create negative molds from the original part, potentially leading to errors, and certainly will in the long run. 

The negative molds are created from pre-preg carbon as the manufactured components. The matching material ensures stability during the high temperatures exerted by the autoclave during its 4 to 6 hours curing process. 

Final QC. 

Lastly, we sourced original E9x/E8x M3/1M mirror bases and housings to test fit the caps for final quality control on fitment. 

Pictured below is the final pre-production unit for my car. It was created with 2x2 weave using the signature continuous style. They were finished in 2 component high gloss clear coat. Customization of weave and finishes will be available. 

Overall, we have used the method that would provide the most precise, repeatable product over time. 

While the development costs were high, we sought to create the highest quality option for carbon mirror caps for the foreseeable future. 

Up next: I provide my final impressions: I unbox, photoshoot and test fit the mirror caps in outmost details.