'66: Reinstalling underbody reinforcement brackets; caulking like material

[Gary B.]

I'm about to re-rivet the underbody seat belt brackets on my '66. When I removed the original brackets I found hardened caulking or dum dum like material between the brackets and the underbody fiberglass. I assume that material was used to prevent water from getting into the interior of the car where the seat belt anchor bolts pass thru the fiberglass. I found this material under all 4 of the seat belt underbody brackets. In the '66 AIM on page "1 BOLT WELD B2", there is no mention whatsoever of any type of dum dum or waterproofing material to be used when installing those brackets. But I have to believe it's a good idea to use something between the brackets and the fiberglass. I'm going to try and hide whatever material I use, but what do people suggest as a material and what color is best, if i wind up not hiding it perfectly? Black?

Thanks,

Gary

[Russ S.]

Re: '66: Reinstalling underbody reinforcement brackets; caulking like material

I would use windshield ribbon caulk. You can get it in different diameters or stretch it out to get a smaller diameter.

[Gary B.]

Re: '66: Reinstalling underbody reinforcement brackets; caulking like material

Russ,

Thanks. Corvette Central sells something I they call windshield seam sealer which looks like strips of caulking.

Gary

[Cecil L.]

Re: '66: Reinstalling underbody reinforcement brackets; caulking like material

3M Strip Caulk

[Gary B.]

Re: '66: Reinstalling underbody reinforcement brackets; caulking like material

Cecil,

I think that's what Corvette Central sells as seam sealer. I found it on Amazon as well. Thanks

Gary

[John H.]

Re: '66: Reinstalling underbody reinforcement brackets; caulking like material

I'm about to re-rivet the underbody seat belt brackets on my '66. When I removed the original brackets I found hardened caulking or dum dum like material between the brackets and the underbody fiberglass. I assume that material was used to prevent water from getting into the interior of the car where the seat belt anchor bolts pass thru the fiberglass. I found this material under all 4 of the seat belt underbody brackets. In the '66 AIM on page "1 BOLT WELD B2", there is no mention whatsoever of any type of dum dum or waterproofing material to be used when installing those brackets.

Gary -

On that sheet, you'll notice the "31d" flag symbol adjacent to the reinforcement in the illustration. If you'll then go to UPC 0, sheet D7, it tells you exactly what that "31d" material is, how much to use, and where it goes.

[Gary B.]

Re: '66: Reinstalling underbody reinforcement brackets; caulking like material

Gary -

On that sheet, you'll notice the "31d" flag symbol adjacent to the reinforcement in the illustration. If you'll then go to UPC 0, sheet D7, it tells you exactly what that "31d" material is, how much to use, and where it goes.

John,

I'll be darned. I never noticed that little flag symbol before. On UPC 0, sheet D&, item 31b is gm # 3851624 "Plastic Cement". Unless anyone suggests something better, I'm going to use 3M strip caulk, #08578.

Thanks for pointing out that flag, John.

Gary