Bonded Smooth Hood

[Driver_WT]

Ok, so we are going to try the smooth hood on 53 AD by bonding with panel adhesive. Should we just bond the hood center flanges together or bond a strip of metal down the middle in the hollow that the chrome strip used to sit in? Also, should be put in a few tack welds to start? And finally, any recommendations on the best panel adhesive that is available to the general public (i.e. no special BMW adhesives that may not be available to me).

Thanks.

Wade

[joedoh]

you are I think confusing the attachment of the two sides together with closing the gap. fusor or another fusing adhesive will join the parts, assuming they are clean and you follow the instructions, but the body work you need to make the hood smooth in the center will still need doing. the adhesive wont fill the gap.

I wouldnt do the joining without welding a strip down the center to make it truly one piece, the using a filler to make it smooth. if you join the halves with adhesive and just try to use body filler in the gap, its going to come back 100%. 1000%

[Driver_WT]

Originally Posted by joedoh

you are I think confusing the attachment of the two sides together with closing the gap. fusor or another fusing adhesive will join the parts, assuming they are clean and you follow the instructions, but the body work you need to make the hood smooth in the center will still need doing. the adhesive wont fill the gap.

I wouldnt do the joining without welding a strip down the center to make it truly one piece, the using a filler to make it smooth. if you join the halves with adhesive and just try to use body filler in the gap, its going to come back 100%. 1000%

Thanks for the reply. We were thinking of gluing the two hood halves together and then gluing a metal strip down the center to fill the gap. Then finish with body fill.

[joedoh]

Originally Posted by Driver_WT

Thanks for the reply. We were thinking of gluing the two hood halves together and then gluing a metal strip down the center to fill the gap. Then finish with body fill.

I am not a body guy, so I am not the authority on it by any means. the body guys can maybe check in

[mongocanfly]

No way would I not weld it...I'm also not a body guy but I know how my luck usually goes...I know make some great bonding agents..... but....I wouldn't risk it...

[mr48chev]

I'd think doing it that way would lead to cracking out from flexing in a few months. You could possibly get away with bonding a 2 or so inch wide strip down the middle of the hood and blending it out but even that may fail after a while. From what I have seen bonded parts are parts that are in the main structure of the body of a vehicle and not in parts that flex some. Bonding a scoop to a wide hood works because the hood is rather stiff and one piece to begin with but I'm thinking that you will end up with stress cracks after a while.

[Driver_WT]

Thanks guys. I am waiting for Hogfarm to weigh in as I think he was the guy that said he would bond the hood if he did another one.

[mr48chev]

I don't know he did the hood on his 54 but that is probably the slickest filled hood I have ever laid eyes on. That whole 54 is just about flawless though. Very understated but flawless.

i don't think there is enough surface on the edges to be able to drill the rivets out and bond the pieces together. Nor enough surface to bond a strip down the line in the middle as that is 5/8 inch at most.

[1project2many]

Two part panel adhesive can be stronger and more reliable than welding. Some vehicles have far more adhesive than welds. Adhesive can be spread across a 1" wide area if desired while welds connect a narrower strip of metal. I trust the panel adhesives in many instances.

I will not speak to how the panel should be smoothed. But I would also want to reduce the chances of filler cracking in the hood. If you are going to add a strip of metal you will still want to flange the unions just as you would for a weld. I would create a frame to ensure the two halves are positioned correctly before cutting the strip out of the center. I would also add one or two flat braces across the hood which would support center area. I would additionally bond the center to the brace(s) to prevent flexing.

[Foot Stomper]

Originally Posted by 1project2many

Two part panel adhesive can be stronger and more reliable than welding. Some vehicles have far more adhesive than welds. Adhesive can be spread across a 1" wide area if desired while welds connect a narrower strip of metal. I trust the panel adhesives in many instances.

I will not speak to how the panel should be smoothed. But I would also want to reduce the chances of filler cracking in the hood. If you are going to add a strip of metal you will still want to flange the unions just as you would for a weld. I would create a frame to ensure the two halves are positioned correctly before cutting the strip out of the center. I would also add one or two flat braces across the hood which would support center area. I would additionally bond the center to the brace(s) to prevent flexing.

Totally agree that bonding is a very reliable method. If you don't know the value of bonding, you haven't researched it enough.

Perhaps it's not the appropriate method for the hood, but nontheless, is a proven method regardless.

[MARTINSR]

Originally Posted by Foot Stomper

Totally agree that bonding is a very reliable method. If you don't know the value of bonding, you haven't researched it enough.

Perhaps it's not the appropriate method for the hood, but nontheless, is a proven method regardless.

I totally agree, the one BIG issue I have with the hood (and I am working on mine right now in pieces, so I know exactly what we are talking about) the surface to bond is VERY small, that is my biggest concern.


Brian

[MARTINSR]

Originally Posted by 1project2many

Two part panel adhesive can be stronger and more reliable than welding. Some vehicles have far more adhesive than welds. Adhesive can be spread across a 1" wide area if desired while welds connect a narrower strip of metal. I trust the panel adhesives in many instances.

I will not speak to how the panel should be smoothed. But I would also want to reduce the chances of filler cracking in the hood. If you are going to add a strip of metal you will still want to flange the unions just as you would for a weld. I would create a frame to ensure the two halves are positioned correctly before cutting the strip out of the center. I would also add one or two flat braces across the hood which would support center area. I would additionally bond the center to the brace(s) to prevent flexing.

There is a recessed area the moulding sits in, so this is perfect to set a bonded in strip, adding strength to the bond too.

This would be a bit of a gamble any way you look at it being that flange is so thin, but adding the strip where the moulding went bonding that in, that would add a bunch of strength.

As far as finishing it off, if you bondo over that, you are GUARANTEED that you will have a "ghost line" there later when metal and filler expands and contracts at different rates.

On a BMW (we just put a quarter on a 2018) they have you bonding seams like that on the rocker, B and C pillar on a quarter, bonding, no welding. They then have you remove all the bonding out of the seams with a roloc disc so there is nothing but shinny metal exposed, then applying a metal filled "bondo" over it. That is how we did it as per BMW guidelines.

We will see how that works, it's been a few months and we haven't seen them back.

Brian

[hogfarm]

Originally Posted by Driver_WT

Thanks guys. I am waiting for Hogfarm to weigh in as I think he was the guy that said he would bond the hood if he did another one.

Well
if I did another hood,I would make sure the 2 halves were bonded together.Don't think I would use glue,bolts maybe then a weld every 6" or so on the inter lip.Then I would bond a filler strip on the out side using the glue.I often time go to the local scrap guy and he will give me a hood off imported car,I could cut the strips I need then give him the rest back.The steel from the imports is real easy to mold to any shape you want

[Driver_WT]

Originally Posted by hogfarm

Well
if I did another hood,I would make sure the 2 halves were bonded together.Don't think I would use glue,bolts maybe then a weld every 6" or so on the inter lip.Then I would bond a filler strip on the out side using the glue.I often time go to the local scrap guy and he will give me a hood off imported car,I could cut the strips I need then give him the rest back.The steel from the imports is real easy to mold to any shape you want

Thanks for the info.