I used some foam shelf liner from Lowes to make the gaskets outlining the woofer with a yellow colored pencil and marking the inner circumference 3/4" inward and tracing it by hand. Cut out with scissors, lay on the woofer and poke 8 holes with an awl and ready to go.
I drilled out my factory mounting holes to 1/4" and was surprised to find that I only had 4 factory holes for each woofer. I now have 8:) You'll need to pull the cross overs to hold the the flat T nuts as you tighten the bolts. Once you get enough tension, they won't spin and these are much better than conventional T nuts that may not be able to "bite" into the dense cabinet material. Place the gasket on the woofer and put all 8 bolts in place then put the woofer in the speaker hole. Get all 8 bolts in the holes and add the nuts by hand. Torque them down evenly like tightening lug nuts on a car wheel. I used my small torque wrench from my road bike tool kit here, don't recall how many newtons of torque I applied (probably the Smithwick's too)
Attach the wires (I plan to upgrade to 12G next time) and close up the crossover again. There were no gaskets here either so a little Permatex silicone was used with a small bead. Install the bases and put on your favorite tunes.
The bass sounds tighter now then without the gaskets and I wonder if I was getting some cabinet vibration with only 4 little wood screws holding each of the woofers? They are very heavy. Victor Wooten has never sounded so good! Looking forward to powering these with my new 4.0t and then the Sunfire 300~2/Tube preamp combo later on this week.
This site and the members are fantastic! Thanks for all the info and advice that made this upgrade easy and most enjoyable.
Speakers - Polk SRS 1.2TL; Carver ALiii; KEF 101, 104/2; Pioneer HPM150; JBL S7R Sovereign, L112, 4312, 43111
McIntosh - C28, C26, C24 preamps; MC30 monoblocks, MC2205, MC2120 amps
Carver - M4.0t amp; CT17 preamp; C9 Holography; Digital Time Lens; SDA360 CD
Sunfire 300~2 (2) & Dynaco ST-70 tube (2) amps
Jolida tube & Linn Karik CD; Rega P2 & Marantz 6300 Turntables