Hood Flutter Investigated and Corrected

[nartmot]

Bill, what is the

Feed a heavy duty large trash bag between the inner and outer hood pieces with the opening of the bag near the front of the hood - higher up. Attach a clear plastic tube to the foam tip and put the other end in the bag. Push the push into the bag and let it expand into the bag. That seems like it could work without taking the hood off. And if the opening of the bag is collected at the opening you had your finger in in one of your pictures you should be able to zip-tie it close to make sure that even if the foam crumbles it won't come out.

Sorry, I am going to advise against that. Take the time to do things the right way and you will be far happier with the results.

@Bluegill I assume you mean you don't want to remove the trim piece that is in the way, and not the actual hood itself, which is not necessary. Its super easy to take the trim off, especially if you order replacement clips in advance like the ones OP suggested. For anyone looking to DIY, you will also need to order the applicator gun for this foam. Use the foam SPARINGLY as a reinforcement and check the results before adding more. A little goes a long way.

 

[Bluegill]

Well I am the OP and I have the trim pieces that I ordered! I also have removed the trim pieces as seen in my photos.

Ideally this expanding foam product would be applied with the hood removed and lying flat on a horizontal surface with the underside up. I'd be hesitant to inject the liquid product into the holes under the hood with the hood mounted in place...I'd think the product would run downslope a bit and drip out the holes below. That's what JPE was trying to avoid with the trash bag idea.

 

[nartmot]

Ah, I see. I would not expect gravity to have much of an impact as long as you dont go crazy. I would think a few quarter-sized dots placed sparingly around the panel would suffice.

 

[JPE]

Ah, I see. I would not expect gravity to have much of an impact as long as you dont go crazy. I would think a few quarter-sized dots placed sparingly around the panel would suffice.

I have no experience with the 3M foam product linked to in an earlier post. But I have used a two part racing foam to make a seat for my race car in the past and the foam I used took quite a while to expand. It was definitely affected by gravity. It started out the consistency of, say, a wood glue, and didn't expand to a point where it would stay in place for about a minute. Maybe the two part foam linked to above is different though.

 

[Bluegill]

You might be right, I don't know. Reading the reviews, once you get started oozing the stuff out of the 2-part container, you better be prepared to rock 'n roll until it's all gone. I'm not going to pony up $60 for a test run.

 

[Bluegill]

I have no experience with the 3M foam product linked to in an earlier post. But I have used a two part racing foam to make a seat for my race car in the past and the foam I used took quite a while to expand. It was definitely affected by gravity. It started out the consistency of, say, a wood glue, and didn't expand to a point where it would stay in place for about a minute. Maybe the two part foam linked to above is different though.

The reviews say it starts to set fast, one review said about 15 seconds but the product specs say it has a 5-minute working time and cures in an hour. Also says it expands to 10X original volume. Not sure how it flows or globs out of the container....can I accurately place a blob about a half inch in diameter and expect it to stay in place and expand to fill the gap in the place I want?

 

[JPE]

...can I accurately place a blob about a half inch in diameter and expect it to stay in place and expand to fill the gap in the place I want?

That's the million dollar question!

 

[JPE]

Bill, I assume the small holes on the bottom of the inner hood panel (not the ones with a flat area around them which I assume are used for the clips that hold the liner) are drain holes or something like that. Have you looked for a plastic or nylon nutsert that could be popped into a few of those holes? And then thread a nylon screw into the nutsert so it barely touches the upper hood? I imagine the support from a few of those nylon screws would prevent the hood flutter.

 

[TexLex]

So this morning, I followed an advice from one of the Facebook groups about raising the hood adjusters (rubber screws) and it worked. I did try this in the past and it didn't help. The reason was that I was a little gentle with the hood when trying to close. When it didn't fully latch, I would lower the screws more until it closes with a gentle/normal push. So the difference between the new height and original was not really that much, hence, it didn't make much difference with the fluttering. However, this time I closed the hood with more force so I was able to raise the screws higher.

Conclusion: Raising the rubber screws does help by allowing more air to escpace leading to less fluttering. I tested this driving at 75mph or so in opposite directions and the fluttering is definitelty less. I measured the new height for the screws, about 2cm from the top of the screw to the plastic frame around it. Hope this helps.

Can someone show a pic of these rubber feet? I can’t find them.

 

[Bluegill]

Can someone show a pic of these rubber feet? I can’t find them.

I'm pretty sure it's just these:

I just popped my hood up to let it cool down a bit and I'll mess with them in an hour or so.

 

[Bluegill]

Oops, just looked under the hood - the rubber feet are actually the yellow arrows below, looks like you can twist them to extend them up a bit more, the rubber twists into a slot.

 

[Pottsy]

Bill, what is the

Feed a heavy duty large trash bag between the inner and outer hood pieces with the opening of the bag near the front of the hood - higher up. Attach a clear plastic tube to the foam tip and put the other end in the bag. Push the push into the bag and let it expand into the bag. That seems like it could work without taking the hood off. And if the opening of the bag is collected at the opening you had your finger in in one of your pictures you should be able to zip-tie it close to make sure that even if the foam crumbles it won't come out.

but then the bag melts

 

[Bluegill]

I twisted out those rubber feet until I could barely get the hood closed. It did help with the flutter. It's more of a hood jitter now, it bounces up & down a bit across the middle. Before it was fluttering/rippling/waving like a flag in the breeze. Will be at the hardware store tomorrow for a few things and will also check out rubber spacers/plugs/etc.

 

[JPE]

but then the bag melts

That's a good point. Even with the hood insulation in place I bet it could get hot enough on a hot day during a long trip.

 

[YellowLab]

I have also looked at sound deadening pads that are adhesive you can put around the beams and hood.

Amazon

There are several styles and thicknesses. I assume a heavier pad you could adhere would work well.

I'm scared to try any spray foam. That stuff expands so fast - could you damage the thin Alluminum by the foam expanding? Plus it is beyond a messy version of hell to clean-up

 

[Mainelexus]

Any chance that if you reinstalled the oem pad with the spacers up the ripple would be further reduced?

 

[TexLex]

Oops, just looked under the hood - the rubber feet are actually the yellow arrows below, looks like you can twist them to extend them up a bit more, the rubber twists into a slot.

View attachment 2494

Thanks. I messed w those a bit but it didn’t seem like they were raising, that’s why I was wondering if it was somewhere else.

 

[Bluegill]

Thanks. I messed w those a bit but it didn’t seem like they were raising, that’s why I was wondering if it was somewhere else.

If you twist them counterclockwise they will rise up until they pop out.

 

[Bluegill]

 

[R!ck]

Also they have rubber sheeting that is magnetized for sign making. Could slip some of that in there.

Aluminum hood, mags won't stick but good thought.