Hood flexing at 150 mph...

[markus]

So coming back from from LBI today the route is a long empty open one so I decided to see how hard I could push my 6.1 to. Once I got around 150-155 mph my hood started flexing and wobbling in the middle, as if it were just flapping in the breeze. Has anybody else experienced this problem before? Does this mean if I plan on taking it that fast again that I'll need to modify the hood somehow? If this car is designed to handle speeds up to 175-180, should the hood then not be slamming up and down seemingly about to rip from the car and smash the windshield???:doh:

[Super T]

it's aluminum, it'll probably flex. could you tell if the actual front edge was raising, at the latch? I'd expect the middle to flap around, but the latch should hold pretty damn solid.

[MikeEast]

Now -there- is a problem to have...

Mike

[lowriderman3]

I am sure that is normal at that speed anyhoo.

[GasGunR]

Ive been well past that speed and cruised at that speed quite a bit. Its NOT normal.

I'd check to see if all the underbody plastic panels are in place and the two panels that cover the top of the radiator support. It sounds like you are getting air under the hood that shouldn't be there.

Don

[Magnum375 Jr]

I know when my dad ran his magnum through the large auto car wash we have around here they have massive blowers that push wind around 200 mph and the flexed as well as the roof and the front fascia.........P.S....i thought this was gunna be another TORREDDAYTONA thread with that angry red face on it.

[GasGunR]

I'm guessing those fans are blowing pretty much straight down on the bodywork... something he shouldn't be experiencing unless he is doing endo's at 150... if he was, I doubt we'd be reading his post!

[Magnum375 Jr]

True....didnt think about that.

[MikeEast]

Good point with the underbody cover - that still on?

Mike

[cm2005300]

dont get caught man damn thats fast

[jizzajames]

i would expect that kind of movement at that speed.. GasGunR said that you are getting air under you hood which is not normal, but think of the pressure you are creating..

if not air under the hood, you could be creating a vacuum of sorts, which is pulling the hood up, instead of air pushing it up from the underside... only way to tell, put it in a wind tunnel.. as long as the latch isnt moving i wouldnt wory about a thing..

or... you should take it to you dealer and see if they can reproduce the problem and warranty it.. haha.. :racing:

[Bandit]

Same here... been much faster in mine and had no oddities similar to this.

[FloridaRT]

You should see my car bra dance around at speeds over 90 MPH, LOL.

My hood doesn't flex, but then, I have a shaker hood.

Bob

[roswald0511]

I only have an R/T, but I have been up to 152 mph (thanks to superchips, but that is all I will credit them for) and I did not notice any flexing at all. It was just nice and smooth. I would have gone faster but started to run out of road.

[markus]

hmmmmm. posted the same thing on 300cforums and got similar responses. im definately going to check and make sure all the plastics and underbody pieces are still there and in the proper place. there seemed to be no flexing or movement near the latch, just up towards the windshield, it was bouncing up and down like a porno.

[KWhale]

You should see my car bra dance around at speeds over 90 MPH, LOL.
Bob

Sorry, I mean this in the nicest way possible....you have a shaker hood, and all the cool mods listed in your signature AND one of those God awful bra's on your car? I know people put those on for protection, especially people who live in areas with a lot of bugs, or in my case, where the roads often have sand and gravel left over from the winter sanding but there is a much better alternative. The clear bra (it's basically 95% invisible) which is a thick clear plastic that you stick onto the nose and top part of your nose, and even on the front of the hood. Under most light conditions you really have to look to see it. It's also great for those low spots behind your tires that get hit by kicked up rocks. You can get it at most tint shops, or even on eBay if you're a do it yourselfer. Personally, I'd rather get rock chips than have one of those bras on the front of my car. And if they are not installed perfectly, you get dust and dirt under it, which is then grinding into your paint when it flaps in the wind, resulting in your paint being damaged anyways.

I had the clear bra on mine for a year, and while it had taken quite a few shots to it, the paint was still perfect. You can peal it off if it gets too many hits, and replace with fresh, if need be. Anyway, I just had to say this, because your car sounds great, and having that bra on there must just ruin the look...once again just my opinion, and just trying to be helpful, not insulting your ride (which has a ton of cool mods by the way).

[cbutler32]

markus,
check the set rubber mounts for your height on the hood.
front area above and behind headlights...
danrealtor and I had to "tighten" ours down when we made our runs...
we found out that the factory setting is a tad high for 150+ runs...:wink:

[cadzilla74]

cbutler32 makes a good point...I also like to drive out into the TX desert late at night and make high-speed runs as safely as I can muster (in other words, the only damage I will do is to myself in the event something goes wrong). I have found on my 05 Mag RT the hood is totally stable up to around 140 mph at which point it starts to do a little "NASCAR hood dance". Not enough to be alarming and certainly not what you describe happens on your car. It pretty much lifts as a whole unit and dances a bit. Not sure how else to describe it. It does not get worse as I go faster it actually stabilizes a bit above 150mph and flattens out.

I think what cbutler32 is describing is what my car experiences which is I could probably flatten out the aerodynamics on mine with a tweak to the hood snubbers. I probably am even getting a bit of excessive aero-drag at highway speeds because of this but it might let a little more air in there to cool it as well, that's just a guess and I may be WAY off in that assumption. I'm going to take the advice of cbutler32 and danrealtor and dial my rubber snubbers up or down until I find an optimum setting.

At the speeds we are discussing even a small adjustment will yield some fascinating results. Your mileage may vary.

[bigbore]

I'll put in my two cents... As I was trying to push the limit today I remembered this thread and took a few looks at my hood. My highest speed was 168 mph and I noticed very little flexing or movement on this run as well as the two 150 mph runs I made. I was hoping to see if I could pick up a little more speed but I started coming up on another car and didn't want to chance it.

[hemiwagn]

A couple of smart ass comments -- just for fun (I dont have the kahunas to drive that fast on a roadway)

1. At 150MPH, should you not be looking a bit farther down the road than the end of your hood?

2. You need one of these air extractor vent hoods:
http://i41.photobucket.com/albums/e287/hemiwagn/Zaino%20ROCKS/IMG_4943Large.jpg

Okay it is magnum hood, i just wanted to pat myself on the back...

Seriously though, anything is possible, it is not like they are going to get a lot of customer feedback for that issue. And cbutler fixed it anyway. I have heard of C6? vettes having the same problem.

[sixsicksheep]

^ that hood is SWEET!!! Where is it sold at? Who makes it? Is it functional?

[markus]

okay so heres what i think is what went wrong. its a sad story with a happy ending. as i was backing out from the grocery store the other day, i heard grinding. i got out of my car to see the left half of my front fascia hanging off my car. the whole time i had been dragging the plastic piece that goes under the car and connects to the front fascia. fortunately there was no damage done other then rivets being pulled out. went to pep boys, badda-bing like $5 later everything is back in place and no more hood flexing. nice hood by the way hemiwagon, im lookin.....and i'm likin'... also i wasnt exactly looking at my hood however it was hard to ignore the thump thump thump thump sound as i saw this piece of shiny black coming into my vision.

p.s.-she goes in to hhp today for p&p heads, a cam and an engine flash today so i'll have them take a looksie for anything i might have missed. im going to miss her while she's gone
=(...

[cbutler32]

A couple of smart ass comments -- just for fun (I dont have the kahunas to drive that fast on a roadway)
1. At 150MPH, should you not be looking a bit farther down the road than the end of your hood?
2. You need one of these air extractor vent hoods:
Okay it is magnum hood, i just wanted to pat myself on the back...
Seriously though, anything is possible, it is not like they are going to get a lot of customer feedback for that issue. And cbutler fixed it anyway. I have heard of C6? vettes having the same problem.

hemiwagn,
c'mon now...
you know we are looking down the road...
waaaaaayyyyy down the road...
or at least the back end of danrealtor's car the first 2 runs...:wink:
but while you are at this speed for 3-4 miles...
you do have some time to notice the hood issue, the windows and anything else you were not expecting or hearing at these speeds...:wink:
hehehe
not a smart arse comment at all...
good observation...
and the underhood bumpers were the trick we found...
I have not been up in this realm in quite a while...
no where out here to run without some type of traffic...
although, the other night I did take it up to 160 and spanked this heavily modded Mustang GT who was spraying at qualcomm...
poor little mustang got beat by a 4 door toaster...:mrgreen:
lates,
cb