Meeting thresholds.
"In this Special Series, I'm taking another step towards the M5 CSL conversion. I document the development, features and conversion process of the E60 M5 CSL carbon roof panel.
In this entry, we get to work on the reconditioning processes of the slicktop headliner as part of the E60 M5 CSL carbon roof panel kit."
- Matt
Risk mitigation.
Sourcing a used headliner is always a risk, and a greater risk than most components out of part out car considering the nature of the remvoal process.
New headliners are installed at the factory with front and back windows fully removed. The way it went in should be the way it comes out.
Junkyard operators most often don't do that, they unclip, slightly bend and pull headliners through one of the doors, leading corners having seen better days and small folds.
As such, we needed to tackle repairs before the Alcantara recovering process.
Stripping & repairing.
The first step to reconditioning the headliner was to fully remove its cloth and foam. This headliner had been manufactured in 2006 using standard cloth backed with self adhesive foam. It made the removal process straight forward, although time consuming considering the size of the headliner.
It took roughly 10 hours to strip, sand and perform repairs.
The main area of concerns with this particular headliner was the receding front section. The side areas had slightly crumpled.
Repairs were performed to reshape, and solidify the areas, including to the metal brackets on the underside.
The black stripes that you see are the tell signs of foam repairs. New foam was shaped, glued and blended into the original headliner for a seamless finish.
Side edges of the headliner were also repaired in a similar process.
Corners are an obvious area to address. This is where folds are both most prevalent, and would be most obvious on a reconditioned headliner. Work is performed to ensure we achieve an OEM shape.
Further work is performed on the inner sections of the headliner. Most of these corrections are actually factory defects from the original mold.
The manufacturing processes create slight creases that may not exceed quality control thresholds set by BMW with its suppliers. We correct these areas to go beyond the original quality.
Re-foaming.
The next step is one up for debate and ultimately comes down to the quality targets.
Genuine Alcantara can be purchased with pre-applied self adhesive foam backing. It is cost effective in material costs, and reduced labor. However, it presents higher risks of folds and ungluing sections.
Our goal is to have OEM quality and beyond, as such we chose the more difficult, time intensive path forward on re-foaming, prior to recovering. It will the standard to all headliners sourced in the E60 M5 CSL carbon roof panel kits.
The foam backing of Alcantara is also slightly harder to the touch than the OEM foam we use.
The higher end process involves applying the foam to the headliner shell first with high adhesion dry glue. It is sprayed and left to dry prior to installation.
The foam is then carefully applied and shaped to all creases and edges of the headliner. This is critical for an OEM fit and finish later on.
With the foam applied, all cut outs are performed.
The excess material is cut to create straight edges across the outline,
Recovering.
The final step of the process is the actual recovering of the headliner with Alcantara. Even with impeccable preparation work, carefully applied foam, the final step ultimately dictates the final aesthetics. Most often conflated as the easiest step, this is where amateurs meet their doom.
Applying Alcantara has similar dynamics to paint protection film (PPF): there's a tact step, and lots of heat is required to stretch and contour the material to the surface's shape. The same challenges apply: complex shapes and sections require a specific process to conform without folds or lifting sections.
A similar gluing process to the previous foam application was used on the Alcantara.
A little over 2 meters long of Alcantara was used to provide the needed coverage.
Shaped plastic tools and lots of heat are our friends during this process. It's a tiresome, physically demanding process as Alcantara is a naturally stiff material.
Further glue is hand applied to the underside edges of the headliner.
The front and rear sections of the headliner have edges folded over to lock onto the headliner. They both make contact with windows, and require this folded edge to ensure proper fit and finish.
To achieve further elasticity, excess material is cut on all curved sections.
The front sections are cut out, and locked on the inside of the headliner like the original BMW process.
The cut out for the rear view mirrors is performed.
The side of the headliner are cut straight to the edges as on the original headliner. This is to ensure precise fit and finish with all pillars along with the weather seals.
The cut outs for accessories are performed and test fitted with original parts.
A careful eye will notice the sun-visors' cut outs were not performed. We will do this when the roof is installed as we want to validate the fold technique require.
At this stage, the process was 98% completed. The headliner would be steamed to remove any imperfections from the gluing and contour forming process .
With the headliner completed, we were ready to perform the conversion.
Up next: the M5 rolls into the paint & body shop for complete installation of the kit.
I'll chat best practices and the few while-you're-in-there that are worthwhile.
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