shroud glue/sealer location

[Lin]

Picking up on Bob Claffie's questions: Does anyone (John Loftus comes to mind) have a digital image of the application of adhesive to the superstructure used to glue the shroud to prevent fumes etc into the cabin? Thanks.
Lin
1960 BT7 in restoration
1959 Bugeye

 

[John Loftus]

Hi Lin,

I don't have any process photos for that stage. My painter and I were rushing to install the front and rear shrouds, doors, and fenders in one session so there was no time for documentation. I'll mark up a picture for you later today showing the areas I sealed.

Cheers,
John

 

[John Loftus]

Lin,

I marked up a picture for you (this was pre-media blasting so you can see evidence of the sealer the PO had use). This picture was before spending about an hour with a heat gun and scraper getting all the old chaulk off (but at least it wasn't some silicon adhesive!). The red lines indicate where I used the strip-calk, basically around every opening. You also want to add some anywhere there is a possiblity of the shroud flexing and contacting the superstructure and causing vibration noises so I added some in the middle of any large surfaces (like dash top area).

It's also important to seal the vertical front edge where the shroud overlaps the engine compartment. I had trouble doing this during the shroud installation as it wanted to shear off so I worked additional chaulk up under the lip afterwards .. basically sealing the edge of the shroud that overlaps the firewall.

Cheers,
John

 

[Lin]

Thanks very much, John!

Lin
1960 BT7 in restoration
1959 Bugeye

 

[Keoke]

Hi John/Lin, I think the areas shown are excellent. However, I recommend that an adhesive type sealer be used at all the locations rather than just caulk. OTOH, One area that will require extensive caulking is the extreme outboard sections between the shroud and the scuttle as there is no over laping lip [sealing edge at the firewall] here to make the seal. Caulking is acceptable around the fresh air ducts though. -Fwiw---Keoke

 

[Dave Russell]

Keoke,
I heartily endorse the use of a good adhesive rather than a caulk which can squeeze out or lose it's bond or never had a bond. It does make later disassembly harder though. Hopefully it won't have to come apart very often!

I've wondered how 3M "Seam Sealer" might work. Mine is installed with a hard but very slightly flexible glue of some kind. Nothing worse than a shroud to scuttle leak or vibrating panel or a sealer that loses it's bond in a few years. It might even reduce scuttle shake a bit by stiffening the structure. I've never had the nerve to try "Fusor" panel bond in this location as it would be impossible to remove the shroud later if needed. I do believe that it would seriously increase structure rigidity though.

My original factory "stuff" had long since hardened, shrunk, & vibrated out of place. Same with the bonnet/hood support brace pads. Same thing here, a good bond reduces bonnet flex & vibration.

I have used "Scotch Caulk" in a few places but not here. It has no adhesive qualities to speak of, & can't take much heat.

I also agree that the front of the shroud can benefit from the same treatment.
D

 

[John Loftus]

I'm not worried about the 3M strip-calk working well for this type of application, especially since the shroud is fastened around the perimeter and also get fastened by the windshield wipers and center windshield hold down (at least on the BJ7-8). The data sheet states that it "remains permanently pliable, excellent high temperature resistance, capable of filling voids, non-shrinking, won't dry out and become brittle, remains at original size to retain sealing properties. Typical applications include engine compartment seams, firewall, and other non-visible automotive seams, gaps and joints." Good point about the firewall to shroud voids above the air duct areas .. the gaps here can be pretty large and the strip-calk worked well to fill these.

An adhesive sealer might be a good idea to adhere a few "inside" areas (again, not needed around the perimeter). If you decide to use some Lin, just don't go crazy or the next removal may really tweak the aluminum.

Cheers,
John

 

[Keoke]

Hi John/Dave Yes I think Fusor is a bit too much. However, it is imperative that the shroud be firmly attached to the scuttle rather than just sealed with caulk.3M might be OK I don't know having never used it in that application. OTOH, a product that will work is the product used by the Japanese car manufactures to assemble stiffeners to their car hoods and trunk lids.---Fwiw---Keoke
Don't worry about tweaking the Aluminum a very light treatment with heat breaks the bond.

 

[Dave Russell]

I give up, I guess. Strip caulk has no strength or bonding ability, gets softer than chewing gum when even mildly heated, has absolutely no resiliance or rebound ability, & no adhesive ability. You would be just as well off with modeling clay. The shroud, in this case forms part of a stressed skin application. If you are sure this is what you want to use go to it. The worst that can happen is more scuttle shake & body flex.
D

 

[Keoke]

Yep, we are on the same page Dave, it must use an adhesive type of sealer not just caulk. /ubbthreads/images/graemlins/nonod.gif---Keoke- /ubbthreads/images/graemlins/hammer.gif

 

[Lin]

John, Dave and Keoke
Thanks to all for comemnts and advice. I am going to do some checking around with body shops here and see what specific product is recommended.

Lin

 

[Michael Oritt]

3M makes a wonderful product called 5200--a polyurethane adhesive/sealant that remains strong and flexible FOREVER. It comes in white and black and cures in about 24 hours.

I have had occasion to remove fittings on my boat that I assembled using 5200 in 1977--almost thirty years later in a marine environment the stuff is like new. Until it catalyzes it can be cleaned up with water, though acetone is much easier. 3M also makes a product for chemically breaking the bond though I have never used it. It's widely available in marine stores in both small and caulking-gun sized tubes.

 

[Lin]

Thanks, Michael. I will check it out.
Lin

 

[shorn]

Lin,
I have an anti-corrosion joint strip that Moss sells (#858-205), pg 119 in 4/2006 cat. for $52.95, that I can't use. I don't know if it would suit your purpose, but I would let it go inexpensively since I now have no use for it.

 

[Lin]

Thanks Shorn, but I am going to go with a 3M product.
Lin