May I recommend 3M strip caulk?

[Pierre B]

I built my MKII from 2004 to 2007. Since then, I have been in light rain a few times. Many of you will relate to the fine trickle of water that runs down the driver's left leg in those instances. In an open car, you are going to get wet anyway, but some of us might like a say in what part of us gets wet first.

I have had 3M strip caulk available for a long time now, but one of its important uses has escaped me till now. This stuff is dandy for sealing up the body holes at the base of the windshield posts. It's like a moldable black putty that can be shaped and pressed into place from under the body. It comes in 12-inch strips (about 1/4-inch wide and 1/8-inch thick), and each one looks a lot like a piece of licorice. A box of this material measures about 1x3x12-inches, and contains several dozen strips of caulk.

I installed my battery atop the passenger side footbox during the original build, using the Breeze Automotive pan intended for that purpose. Water trickling in at the base of the passenger side windshield post has collected in that battery pan over time, as I recently noticed. That water has no place to go, since there's no drain in that pan. This 3M putty should prevent that from happening again. Now it's time for me to have a look at the rollbar penetrations in the trunk: I think those could use some sealing as well.

[riptide motorsport]

One word.........THANKS!!!!!!!!!!

[Someday I Suppose]

Sounds like a great idea. Does it harden at all, or stay soft? I had planned to go at the windshield posts from the underside with RTV, but this might be a better solution.

_Scott

[AC Bill]

In my experience with using the product, the surface of it will harden after many, many, years. It still seems to seal well even then, and won't just simply crack and fall off. The trick is to tuck it in really well at places you want to seal, and leave it fairly thick. This way it won't dry out through and through.

[lbperry]

What is the product name and part # for it? Where is it typically available?
Thanks for the info,

[AC Bill]

Lawrence, many parts stores will carry it it as it is used in automotive/RV applications. You could ask for it by the name dum-dum, as it is also commonly referred to.

[Gumball]

A huge thumbs-up on 3M Strip-Caulk. I used it on a '65 Mustang I built a few years ago and had a bunch left-over that I'm using on my FFR build. It's available in the midwest at Farm & Fleet, as well as at just about any auto body supply house (and many auto parts stores). You can also get it from Eastwood.

[WAYNES WORLD]

Yes, good stuff!
Wayne

[Bob Cowan]

I installed my battery atop the passenger side footbox during the original build, using the Breeze Automotive pan intended for that purpose. Water trickling in at the base of the passenger side windshield post has collected in that battery pan over time, as I recently noticed. That water has no place to go, since there's no drain in that pan. This 3M putty should prevent that from happening again. Now it's time for me to have a look at the rollbar penetrations in the trunk: I think those could use some sealing as well.

I have the same battery mount, and that won't work. In the rain - or when washing the car - water gets in there anyway.

I drilled a hole towards the front of the box, and welded on a 3/8" steel tube bent at 90. I drilled a hole in the side of the foot box, and conneced clear plastic tube. Water drains easily, and you can't see it unless you really look for it.

[Pierre B]

The stuff is 3M Strip Calk, Part No. 051135-08578 (black). It comes 60 one-foot pieces to the box.
Bob: I found that, when I inserted the calk around the base of the windshield hole penetrations, I did use quite a bit and I packed it as tight as I could. I should think it would help keep out some of the water. I am going to space up my battery a hair to allow air to circulate under it. That should minimize problems with any water. Since my building process is complete, I cannot really weld in a tube like you did, but I will stay on the lookout for another way to penetrate the box floor, maybe with a grommet into which I can jam fit a plastic tube.

Also, I find that the steel tube sections that secure the base of the rollbar tubes probably fill with water in a similar way. Except, if that happens, it's a more serious problem, since there's no good way for the water to evaporate out of those tube bases. This same calk applied to the underside of the rollbar penetrations should prevent some water from finding its way into those rollbar cups as well. Again, though, the material needs to be packed generously and tightly.

[Bob Cowan]

The stuff is 3M Strip Calk, Part No. 051135-08578 (black). It comes 60 one-foot pieces to the box.
Bob: I found that, when I inserted the calk around the base of the windshield hole penetrations, I did use quite a bit and I packed it as tight as I could. I should think it would help keep out some of the water. I am going to space up my battery a hair to allow air to circulate under it. That should minimize problems with any water. Since my building process is complete, I cannot really weld in a tube like you did, but I will stay on the lookout for another way to penetrate the box floor, maybe with a grommet into which I can jam fit a plastic tube.


Drill a 3/8" hole near the front of the box, towards the center of the car. Use a ball peen hammer, and dimple the hole. Flare some 3/8" alum tubing, and drop it in the hole. The dimple and the flare should match up, so the drain is lower than the bottom of the battery holder. Use JB Weld, epoxy, or silicone to secure the tube in place. Easy to do, no welding.[/QUOTE]



Also, I find that the steel tube sections that secure the base of the rollbar tubes probably fill with water in a similar way. Except, if that happens, it's a more serious problem, since there's no good way for the water to evaporate out of those tube bases. This same calk applied to the underside of the rollbar penetrations should prevent some water from finding its way into those rollbar cups as well. Again, though, the material needs to be packed generously and tightly.

I noticed that during the initial build. The inside of the pipe was closed, and uncoated. I drilled a couple of drain holes, and then coated it well with Extend.

[gwnorth]

I am just finishing my Mk3 and after reading this post I rushed out and got some 3M Strip-Calk to plug up the windshield slots, especially on the driver's side near the fuse box. The stuff is amazingly sticky (to my fingers, rubber gloves, the box it came in, you name it) but it wouldn't adhere to the inside of the fibreglass body where the windshield posts are: the fibreglass is bare, rough and dry in there. I mixed up a little fibreglass resin and put a thin coat of resin on the area using a long paintbrush and that solved the problem. Thought this experience might be of use to someone doing the same thing. (The roll bar openings look like they'll need the same treatment).
Thanks Pierre for the tip.