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How I fixed the sticky volume and tuner ***** on the PCM in my Cayman 981
I was curious why my PCM ***** were sticky and tacky to the touch. They weren't always this way, something had changed. So I did some googling.
Natural or synthetic rubber starts out as a very sticky substance. That’s because the molecules in the raw state are long chains of very weak links to each other. To turn that raw material into the rubber we all know and love, you have to put it through a process called vulcanisation. This involves heating the rubber with some other chemicals, which molecularly transforms the rubber from sticky to stretchy.
The vulcanised rubber though can revert back to it’s original state under certain conditions. It happens when the stronger polymer crosslinks get snipped and the molecules revert back into their original small chains. Once that happens you’re stuck with rubber that has become sticky and tacky.
So I decided to remove that mess from my *****, to reveal the cleaner plastic surface underneath. I used 1 part rubbing alcohol, 1 part water, and a few drops of dish soap to make the solution thinner. Microfiber cloths were not strong enough, and I didn't want to pick an abrasive cloth, for fear of scratching the plastic. Using an optical cloth (intended for cleaning eyeglasses) seemed to be the right fit. I held the **** steady with one hand, and used the other hand to press down and rub the sticky stuff off. It rolled up into sticky little chunks which adhered to the cloth.
Now the ***** feel clean to the touch you can see the sticky rubber peeling off after the initial pass with the optical cloth and the alcohol + water + soap solution getting a little cleaner finished, i could've been more thorough but it felt fine.
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Nice result, good to know that the buttons can be cleaned up/repaired!
Sunscreen and other lotions are often the cause of the break down. I would recommend wiping the touch surfaces of your hand or washing your hands after applying sunscreen or lotion.
Is there anything that can be done to keep the ***** from getting sticky?
I would probably just try not to touch them with greasy hands, and use a good quality interior plastics cleaner on occasion. Beyond that, there's probably not much you can do.
Nice post, thanks. Just curious, why did you remove the whole PCM radio head unit (vs. just popping off the *****)?
The PCM comes with a mechanical hard disk drive, this has moving parts and was showing signs of failure. I cloned the disk to a solid state drive by doing a sector-by-sector copy with Clonezilla on a computer, and upgraded the mechanical disk with a solid state one. I removed the sticky residue from the ***** while it was out, for that project.
Also installed a phone mount I ordered from rennlist while the panel for the PCM was off.
Is there anything that can be done to keep the ***** from getting sticky?
temperature and UV light are the 2 culprits. You could add a UV shield coating to your glass and make sure the inside of your car never gets hot. Despite parking in a closed deck (no outside light) the rubber on my volume and tuner ***** still succumbed. I never got a UV light blocking film added to any of my windows.
The PCM comes with a mechanical hard disk drive, this has moving parts and was showing signs of failure. I cloned the disk to a solid state drive by doing a sector-by-sector copy with Clonezilla on a computer, and upgraded the mechanical disk with a solid state one. I removed the sticky residue from the ***** while it was out, for that project.
Ah ok, that makes sense. What "signs of failure" did the old hard drive exhibit? Is the drive easy to access?
12-27-2020, 05:10 PM
How I fixed the sticky volume and tuner ***** on the PCM in my Cayman 981
