Like any other task during repairing/restoring a C3, we set out to do one thing and have to do 3 more to finish. I figured I would r&r my old cracked up dash(task 1). And since it is out I might as well replace the old 4 x 6 speakers(sort of unplanned task 2). New 4 x 6s don't just bolt up though. The speaker bracket has an 'X' brace across the front of it that interferes with the new tweeter and keeps the speaker from mounting flush(unplanned task 3). I tried cutting out the center of the 'x' but mounting the speaker was marginal at best. I felt like there would be vibration noise. After a bit of head scratching I came up with this solution and I wanted to share it should anyone else have the same issue.

Cost: speakers+plywood+silicone+screws=$110.00

Pictures to follow.

First I cut out the center of the bracket. Then using the bracket and the speaker I made a pattern in a piece of 1/4" plywood and cut it out. You will need a plunge router or jig saw for the middle. Using 100% black silicone (color doesn't matter) I attached the plywood to the bracket and the speaker to the plywood. I also screwed the speaker to the plywood. As well as an adhesive the silicone remains flexible and absorbs vibration so there won't be any unwanted noise.

Drawbacks: If you have to replace these again in the future, you will be able to remove the bracket from the dash the same old way but the speaker to bracket silicone bond could be difficult to undo. Also the 'x' we removed in the beginning may have offered some dash/speaker support from above the dash. If something were to damage you speaker from that side your dash is probably ruined also.

 

I used a piece of .060 aluminum cut to the size of the original bracket and tabs. I then cut out the oval opening, drilled speaker mounting holes, bolted the speaker in place and finally used the original screws to mount the speaker & plate to the dash pad. Only other step was a slight bending of the aluminum plate near the rear of the dash pad to follow the original's mounting profile.