Hood Flutter Investigated and Corrected

Guys this just has me baffled that Lexus puts out a beautiful designed SUV for $80,000 ish and you all got to come up with Jimmy Riged fixes. My 2015 F-150 is all aluminum and the only flexing I get is on the hood going through the car wash, and I can handle that. Oh once in a while meeting a semi on a two lane doing 70 plus. You can't tell me Lexus can't come up with something.
 
I'm not sure what engine compartment temps get up to but regarding any type of expanding foam idea - read the product info first. Flashpoints for the following......

  • Great Stuff Fireblock Insulating Spray Foam Sealant product brochure......"DuPont Polyurethane Foam Insulation and Sealants. CAUTION: When cured, these products are combustible and will burn if exposed to open flame or sparks from high-energy sources. Do not expose to temperatures above 240oF (116oC)."
  • 3M Fireblock Foam - Orange FB Foam...... Heat resistant up to 240°F (115°C)
  • 3M Flexible Foam #08463 (for autos)...... "Flashpoint >300'
Two other considerations, given how thin the top side is, there is a good chance something applied underneath will create a bump that will be visible to the driver's eye. Can you live with it? And what about any warranty fix? Some new trick today may void your warranty if Lexus decides to address the issue in the future. Just a thought.
 
I looked closer and there are actually little rubber spacers (or maybe it's injected expanding goo) in multiple locations between the inner structural panel and the outer skin. Whatever the factory did is clearly not doing the job. Yesterday I simply jammed some folded-over cardboard in the spaces and it made a huge difference. Didn't get to the hardware store yet but I will tomorrow to see about some rubber spacers.
 
Guys this just has me baffled that Lexus puts out a beautiful designed SUV for $80,000 ish and you all got to come up with Jimmy Riged fixes. My 2015 F-150 is all aluminum and the only flexing I get is on the hood going through the car wash, and I can handle that. Oh once in a while meeting a semi on a two lane doing 70 plus. You can't tell me Lexus can't come up with something.
You're correct! I hope Lexus does come up with something. In the meantime I'm thinking that wedging something in there in multiple locations is the temporary fix. I don't want to spray in an expanding foam and make a mess that can't be reversed. I'm also worried about the heat as many others have pointed out.
 
So the hood flutter is pretty much gone - the whole hood still shakes a bit up & down at around 80 mph but the waviness in the center panel is gone.
What I ended up doing is sliding in some long, thin, flat aluminum that I had sitting in the corner of the garage. I had a piece of 1/16" thick X 1-1/4" wide X 4' long stock and I slid it in behind the inner structural shell and the outer skin - the piece of aluminum makes a bow shape when the ends are wedged on either side of the structural panel. The bow shape gently pushes on the outer hood skin.

I went to the hardware store and picked up two more 4-foot lengths of thicker aluminum (1/8" thick) and less wide (1" wide) because I thought the 1/16" was a bit too weak and the 1/8" would press more firmly on the outer skin. When I tried to slide the 1/8" in the upper portion (see the photos) it was too stiff and you could see it pushing out the outer skin from above. I didn't want to crease or dent the outer skin so I didn't push it. I cut down the length of the 1/16" thick piece and slid it in the upper, shorter section and I used a 1/8" thick piece (full 4-ft length) in the longer middle section. The way the openings in the structural panel work, the longer run bows the piece of aluminum less, so the thicker piece works here. I also slid some cardboard between the ends of the longer run of aluminum because it was scratching the white paint. It's all covered so it really doesn't matter but I don't want to have the aluminum dig into the hood.

I'll let this ride for a while and see how it goes. Maybe another 1/16" piece slid in there through a set of openings might help.

aluminum1.jpgaluminum2.jpgaluminum3.jpgaluminum4.jpgaluminum5.jpg
 
Shoving pieces of metal and spraying foam into the hood is wild. If I never read this post, I would have never noticed any minor hood vibrations.
 
We've had our OT+ for a week and taken two short road trips and at 70+ hwy the hood flutter is pretty bad. I've had passengers notice it and say the same. Our 2014 4Runner is rock solid. I will be reporting it to the dealership and looking into some of the fixes. Will report back.
 
We've had our OT+ for a week and taken two short road trips and at 70+ hwy the hood flutter is pretty bad. I've had passengers notice it and say the same. Our 2014 4Runner is rock solid. I will be reporting it to the dealership and looking into some of the fixes. Will report back
We've had our OT+ for a week and taken two short road trips and at 70+ hwy the hood flutter is pretty bad. I've had passengers notice it and say the same. Our 2014 4Runner is rock solid. I will be reporting it to the dealership and looking into some of the fixes. Will report back.
Still love the vehicle though! Hood flutter is a very minor complaint. She's a beast.

1000009779.jpg
 
Oh yes, driving on the 130 tollway from Austin. 85mph it almost looked like the hood was unlatched. I pulled off the road to check. It was concerning for sure. By the way it’s an incognito Premium Plus, love the way it drives!

SS
 
Hi Folks. Got my wife a Land Cruiser First Edition in June and have driven it quite a bit (over her protests). Yesterday picked up my Overtrail at Lexus Latham, NY and drove it home to Vermont (around 200 miles). Mix of Interstate, state “highways”, and back roads. I am Type A (especially after following this and a couple other threads on the Forum!). Happy to say I noticed no discernible hood flutter, zero unusual vibration, and the ride is a little different but, in my view better, than the Cruiser. Hope this remains the case for many years to come.
PS. I deleted the factory roof rack based on the Forum comments about excessive wind noise. Since the LC has a factory rack, which is very quiet by the way, probably won’t add Westcott or other rack. Also deleted the factory rock rails (have them on the LC and they seem fine but will probably swap the “free” running boards for Dissent Offroad rock rails when they confirm they install on Overtrail without drilling.

Safe and happy travels all.
 

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OK, the little replacement clips for the black under-hood mouse fur "insulation layer" arrived so I popped out all the factory clips with a body panel clip pulling tool. They break upon removal, not the re-usable type. The black panel is just for show, paper-thin, backed with cheapo fiberboard about as thick as a human hair.

Here is the Amazon page for the clips - $10 for 25 pieces, you need 10...always good to get extras:

Amazon.com

So, the underside of the hood panel is actually highly-engineered. Lots of structural bends, air flow slots, etc. On the topside of the hood, the outer wheel-location humps over the fenders have bends that obviously define the fenders. These major bends on each side give it plenty of rigidity in this area. Furthermore, there are little rubbery plugs that wedge between the low sides of the fender bends and the inner hood structural panel, which supports this bend line from below. See the pics below.

The problem is apparent: the topside expanse in the middle of the hood appears to be completely unconnected to, and unsupported by, the underside structural panel. Coincidentally, this is the part that flutters at highway speeds. This topside expanse is about 40" wide across the hood.

It looks like sound deadening paneling (butyl or foam padding) is not going to work because you can't apply it directly to the underside of the topside, if you see what I mean. The inner underside structural panel is in the way.

I'm thinking that some rubber spacers stuck in there (like the factory rubbery plugs already installed under the bends) would do the trick to form a wedge between the inner structural panel and the topside expanse. Or, maybe even easier, would be to spray some heat-resistant expanding foam up in the little cutouts all across the expanse. I wonder if this would bulge the hood? Probably not if you let it just expand freely and ooze out the little cutouts and the sides, then trim it clean. Would really suck to bulge your hood trying to fix a flutter...LOL. Maybe just stuff some thermal batting up in there?

Opinions?
I got lost halfway through your explanation, I think you should do a YouTube vid to help us see how you have fixed this issue we all face! 😀👍
 
Upon doing some research, this is actually a pretty typical issue with many car manufacturers. The reason is that not enough adhesive is placed b/w the frame and hood skin, or the adhesive peel off and not provide enough adhesion, or the stopper is not adjusted properly. For the stoppers adjustment, you can do this yourself and hope the issue is fixed. However, if it doesn't, you'll have to add glue to your hood. There are several car manufacturers issued SB to address the adhesive issue. I don't think you can have Lexus doing anything about this. There are several that buy the adhesive and do this repair themselves. They don't recommend just adding any glue. It need to be flexible with temperatures to not create a dimple on your hood. I dont' think using expanding foam is a solution either, as this doesn't link your hood skin to frame for support and don't know how it will react with temperatures.

Btw, on waiting list for my GX Premium+.... Just doing research on issues to checkout once mine arrived.

Stopper Adjustment:

Adhesive:
 
I don't see the hood flutter, but I don't see the center of the hood while driving at speeds it would appear.

Curious about how tall people are. I'm 6'2" with a 34" inseam. When sitting in the GX and just driving around I don't see the middle of the hood at all, unless I try of course.
 

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