This may be an odd request, but I'm hoping to determine the size of the holes Porsche used for early 928 door speakers. Curious if they're the same as those used in the rear panels, as well.

It should be pretty easy to determine their diameter without damaging the interior via the smooth end of a drill bit if you've got a complete set, or a "bit sizer" if you have one. I'm sure there are more technical/impressive ways to go about this, but rudimentary is just fine!

 

Hi Pete- First issue is to define 'early'- For 78-79, it's not quite so straightforward to measure, as Porsche perforated the fiberboard panel with lots of holes. Here's the front door panel:




And here's a pic of the rear quarter underside, also from an early '78. The speakers are identical front to rear, and the mounting points are identical (they used these barbed M3 studs that break off easily)




I can pull dimensions off door panels and quarter panels at 928Intl, specify exactly which dimensions you want.

 

Rob, a peek "behind the music" is already invaluable. I am looking for the dimension(s) of the speaker holes seen on the passenger side of the door cards and, if different, the rear interior panels.

What I am trying to determine is what Porsche (or its suppliers) felt was sufficient to allow sound through the panels. Already I am seeing that it looks like some of the holes were far from perfect and were obscured by panel/upholstery shift. Wonder if they were that way new, or it's something that happens over time.

Fwiw, I'm considering trying to replicate the factory method in the dimples in basketweave. Not sure I can get away with it—and, if so, how "invisibly"—but an idea of the size of the holes used by the factory's interior designers would sure help me decide if it's a worthwhile experiment.

Many thanks for your help!

 

This calls for a field trip to 928 International. I'll grab my calipers and report back.

 

I'll check mine tomorrow. My recollection is that the actual hole diameter looks the same from the door panel to the rear quarter panel. Here's 2 pics that I have now, and you can blow them up and see better.

 

^ Ed: Just wanted to say…that is a fantastic interior.

 

Thanks Pete. I forgot to measure the holes - will get to them shortly (car is under cover in the garage)

 

No worries whatsoever, and keep that car cozy—Rob did some wonderful recon for me and provided some fabulous photos with and without calipers (thanks, Rob!).

I now better understand what's under a design element of the 928 (and other cars) that I often noticed but never thought about. Not sure I can apply the concept to vintage Porsche basketweave (the holes will likely be smaller, but there might be a way to do more of them, and eliminate the overlap). I've got some ideas, anyway—thanks to the 928.

 

I’m working on re-glueing my door panel right now, as well as trying to figure out how the heck I’m going to mount the new speakers. Here are some pictures of the openings. The holes appear to be 3 sizes. I’m afraid the PO amputated the rear quarter speaker openings.

 

Here is my replacement speakers, mounted, in my 82. Traced to old speaker housing and then Used cutting board type material. Worked perfectly, put a small piece of foam in the door indentation, did not hammer it in or make any other modification.

 

Ok Pete - I finally got around to measuring the holes. Had to unpack a bit to get in there, as Blumaxx is in deep slumber and all covered up with layers of protection

As suggested, I used the blunt end of drill bits to size them. The rear holes (see my pics above) are11/64 in diameter and the fronts on the doors are 5/32.