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Hood pins... What are your thoughts?

TURBO2GO

TURBO2GO

Illustrious Member
Joined
8 March 2006
Messages
16,594
Location
Boston
I have noticed how much air pressure is under the hood at speed. I can see my carbon hood flutter ever so slightly at speeds around 80+. This has caused me some concern, and for a while I have been researching hood pins for extra safety. The issue is these things are butt ugly and kind of ricey. The best I have found are by a company called quick latch. They have a mini version that is only the size of a quarter, very flat, and can be painted. The problem is that it has a small footprint and I am wondering what happens if the factory latch fails, and these take the full force.

The main question is, how a I compromising the integrity of the carbon hood (downforce genII full carbon) drilling holes into it for this thing. Am I making it worse? It makes no sense to install a safety device that compromises the strength of the part that it is supposed to protect.

The company said I can use 4, spread the load very evenly, but I am not sure how that will look. Here is the latch:

http://www.quik-latch.com/quik-latch-mini-latch.html
 
I have seen those hood pins on a muscle car in person. IMO they are not necessarily stealth, they are better looking than the old fashion pins and loops but they are still noticeable and ugly IMO. The ones I saw were body painted, but they looked like two giant zits on the hood. :)

Will they prevent the hood blowing open in the event the latch attachment area fails? I don't know, probably, but only the company that sells them would be able to give you a real good answer. Tell them you road race your car ~ 130+ mph and the best you can hope for is an honest answer and not a sales answer.

I have never seen a CF hood blow open, I have never talked to someone who had FIRST HAND knowledge either. However, every manufacturer strongly recommends hood pins. I think if you did not want to put pins in then you should occasionally inspect the area where the latch attaches and check for any stress cracks or deformation. And if going to the track, include this as part of your "pre-flight" and "post-flight" inspection. Out of habit of my profession, I have a checklist that I check the day before and day after all track events. Inspection is not a guarantee, only hood pins are, but it's better than the alternative of blind faith.

Jim
 
Last edited:
^^ This.


I think Id rather chance my hood coming up than running hood pins. :eek:

In all seriousness... The majority of all aftermarket hoods do flutter some. Although I have never seen one come apart or come up unless it had previous damage etc. I've actually seen some kid driving around in a jetta with a carbon hood that is extra sketchy and it still hasn't come up.
 
Hugh has some really nice looking and functional flush mount latch assys. on his hood.
Maybe a p/m and he'll put up a picture.

Cheers
nigel
 
The hoods where the latch part is also made from fiberglass/carbon fiber, I would absolutely use hood pins. However, all of the NSX hoods I've seen require you to use your OEM latch and bolt that on in place. Since the connection is metal on metal, I feel confident that it will stay without any issue.

Keep in mind the hood you're running IS vented, so the pressure has a route to escape. I personally would NOT add hood pins.
 
I would not run an aftermarket CF or fiberglass hood on the track with just the OEM latch. I agree hood pins stick out unless it's on a dedicated race car (which yours is not).

The real Honda CF Type R hood doesn't need hood pins due to it's superior construction and Q/A. Either buy one of those, or buy a used 2002+ OEM aluminum hood and make a custom vent/duct. There's a lot of talented fabricators up in the New England area that could easily do this.

My $0.02.

Dave
 
HIJACKER said:
Since the connection is metal on metal, I feel confident that it will stay without any issue.

Keep in mind the hood you're running IS vented, so the pressure has a route to escape. I personally would NOT add hood pins.
Click to expand...

It's not the metal-metal connection that fails, it's the metal hood latch that is sandwiched between layers of CF that separates, and boom - hood blows back smashing your windshield and then may become a flying object for the people following you.

Also, if he can see the hood vibrating, then the air flow through the hood, over the hood, and under the car is fluctuating. It's not a smooth air stream - there are little Eddy currents being generated and shed that causes this for a bunch of reasons. It's a combination of frequency and amplitude that will cyclically load the hood attachment points and eventually cause failure.

We just don't know what those design limits are. I'm pretty sure none of the NSX hood vendors have ever tested one of their designs to failure, but I would love to be proven wrong. Worse yet is the role quality assurance (or lack of) plays in all of the aftermarket CF hoods.

Dave
 
Two things:

1) I never installed the gaskets that are around my OEM headlamp housings on the hood. It's a tight fit so I didn't think i would need to but perhaps air is getting in there.

2) I have a duct but not the R under-trays perhaps that's not helping either.

I will install those, but my question remains:

To what degree am I compromising the hood by drilling these holes? If I am introducing a spot for fractures to form, that's not worth it.

The mini's look very unobtrusive. You can barely see them on ponyboy's car. Painted, they may be pretty invisible. I just need an answer to the hole drilling question. I wish I could get a hold of peter at DF.
 
TURBO2GO said:
I have noticed how much air pressure is under the hood at speed. I can see my carbon hood flutter ever so slightly at speeds around 80+. This has caused me some concern, and for a while I have been researching hood pins for extra safety. The issue is these things are butt ugly and kind of ricey. The best I have found are by a company called quick latch. They have a mini version that is only the size of a quarter, very flat, and can be painted. The problem is that it has a small footprint and I am wondering what happens if the factory latch fails, and these take the full force.

The main question is, how a I compromising the integrity of the carbon hood (downforce genII full carbon) drilling holes into it for this thing. Am I making it worse? It makes no sense to install a safety device that compromises the strength of the part that it is supposed to protect.

The company said I can use 4, spread the load very evenly, but I am not sure how that will look. Here is the latch:

http://www.quik-latch.com/quik-latch-mini-latch.html
Click to expand...

I have these, smallest, great quality and stealthiest I found.
 
TURBO2GO said:
I have noticed how much air pressure is under the hood at speed. I can see my carbon hood flutter ever so slightly at speeds around 80+. This has caused me some concern, and for a while I have been researching hood pins for extra safety. The issue is these things are butt ugly and kind of ricey. The best I have found are by a company called quick latch. They have a mini version that is only the size of a quarter, very flat, and can be painted. The problem is that it has a small footprint and I am wondering what happens if the factory latch fails, and these take the full force.

The main question is, how a I compromising the integrity of the carbon hood (downforce genII full carbon) drilling holes into it for this thing. Am I making it worse? It makes no sense to install a safety device that compromises the strength of the part that it is supposed to protect.

The company said I can use 4, spread the load very evenly, but I am not sure how that will look. Here is the latch:

http://www.quik-latch.com/quik-latch-mini-latch.html
Click to expand...

I'm sorry - I don't have an answer for your question but rather a question of my own. You notice your DF hood fluttering at just 80? I have a Procar hood (with the under-aero pieces) and never noticed movement even at 100+. I am not saying it doesn't flutter, just that at 100+ I'm concentrating on the road ahead not looking for hood movement so I've never noticed my hood moving. At least it doesn't move so much that I notice it. Did you simply notice this, or did you watch your hood specifically to evaluate whether your hood does it or not?

I'll try to remember to watch my hood next time I'm going 80+

I'd try using the under-aero stuff before resorting to ugly hood pins.

J
 
You can use painters tape all around the perimeter of your hood before installing the weatherstripping to see if it will make a difference.

The underbody aero may screw you up on the track by limiting cooling more than help. When you use the car as it was designed, it all becomes a balancing act of drag, stability, and cooling... Things 90% of us don't experience just driving around on the street.

Have you searched? I know there have been other threads discussing this topic before.
 
Mac Attack said:
It's not the metal-metal connection that fails, it's the metal hood latch that is sandwiched between layers of CF that separates, and boom - hood blows back smashing your windshield and then may become a flying object for the people following you.

Also, if he can see the hood vibrating, then the air flow through the hood, over the hood, and under the car is fluctuating. It's not a smooth air stream - there are little Eddy currents being generated and shed that causes this for a bunch of reasons. It's a combination of frequency and amplitude that will cyclically load the hood attachment points and eventually cause failure.

We just don't know what those design limits are. I'm pretty sure none of the NSX hood vendors have ever tested one of their designs to failure, but I would love to be proven wrong. Worse yet is the role quality assurance (or lack of) plays in all of the aftermarket CF hoods.

Dave
Click to expand...

I have never heard of 1 case where a hood separated at the seam and allowed to blow open. Don't bother with hood pins. In the case of the flutter, try adjusting your hood latch on the support, adjust it down a few mm and pick up the slack, thus making the hood hold tighter to the body. The carbon fiber hood I had on my turbo s2000 held on at speeds upwards of 140mph on the highway, so I don't doubt their strength at high speeds...As long as it is a good name brand hood that is...not a chinese replica.
 
Last edited:
The flutter is extremely subtle. I notice this only as I watch the back edge, in relation to the wiper blade which seems to be steady in relation to the dash. You can see a slight vibration occurring between this line. The line of the blade and the back of the hood. I was much more suspicious of the blade, but after much close examination, I do in fact believe it to be the hood now. It may simply be flexing a bit behind the R vent as there is a shitload of air that passes through there. I never knew how much but it is A LOT. The air forced the nut that holds the under hood duct to the fan assembly come out of its sleeve on both ends.

Admittedly, this was more a function of glue used to install a nut inside a tube that then extended out and attached the back section of the duct to the car. I out JB weld on it and it's been solid. But still, there is more air pressure there than I expected.

The painters tape is a good idea. I am very suspicious that air is getting in around the headlamps under the hood. There is turbulence somewhere and I need to figure it out. I suspect many guys have this same issue but have never realized it. Do I feel unsafe? Not really. The flutter is minimal, and the latch seems very solid. But I am more concerned that over years this is adding stress to the one joint holding the hood front down. Long term that may crack, break, etc.

It just seems that one connection point is more "street" and less track oriented. Just like you add extra cooling to the car, better oiling systems, more safety precautions, this should also be on the agenda. These quarter coin sized latches are almost invisible, and they will hold the hood at two more points. Making it a total of 5. Just seems like a good idea.

I need to get a hold of peter at downforce somehow and ask him about the effects of drilling through the carbon for these. I will use some painters tape and some string and get the the bottom of the flutter. I didn't want to rip the gaskets off my OEM hood around the headlights, but now I think I will install them on the R hood.
 
I don't understand the counter argument on the safety issue. Stock hood latches fail on sports cars and the liklihood is greater on aftermarket hoods. To be sure, we're not talking about mass instances but the risk is enough for a tracked car to necessitate the extra precaution of whichever hood pin product.

IMHO, the last thing I want to worry about in the middle of a straight is whether or not my hood latch is going to fail.
 
I agree ponyboy, I think it's just an extra safety precaution that is worthwhile.

Anyone know what Hrant is talking about with a Z lock? Google came up empty.
 
Dave, I have a Procar hood and have posted before on the potential lift - with some weird solution idea that I finally gave up.

As others suggested, put a piece of masking tape 1" wide x 2" long max over the center edge the headlights/hood and the highest point of the side fender/hood. See if the tape lifts. I tried this and while I had some minor lift the tapes never came off at the track.
 
I'll deal with the minor uglyness of hood pins than the chance of my hood flying open at speed. Search around on youtube for unpinned hoods flying open, that's something I'd rather not experience.
 
TURBO2GO said:
These quarter coin sized latches are almost invisible, and they will hold the hood at two more points. Making it a total of 5. Just seems like a good idea.
Click to expand...

That's the problem. The smaller the aftermarket latch, the less area there is to distribute the forces acting on the hood. Granted, they will help, but if one latch (like the OEM front latch) is taking up most of the load and then fails, then these small pins will then be relied upon to hold down the hood and may immediately fail afterwards.

Who knows? Without knowing the actual differential pressure involved acting on a large surface area (basically the whole hood) at speed, we don't know what forces are involved and how large the hood pins or attachment points should be to evenly distribute those loads.

Pressure is force per area. So, if we could hook up a differential pressure transducer measuring these fluctuations at various points under the hood and outside, we can back-calculate the rough force involved by knowing the hood surface area.

Once you know the force involved, you decide how many latches you want to use. Using the preliminary latch attachment area and the shear strength of the hood material (aluminum or CF for example), you can determine if a larger latch is needed or you need more than what you originally assumed.



Not to be condescending, but I'm guessing most of the aftermarket hood companies put little thought into this. On my vented CF Seibon hood, I know the internal steel threaded area that the OEM latch and pivots bolt into is just a few square inches total. I'm going to enlarge my ducted hood vent area even more to get as close to the radiator inlet area as possible and come up with an efficient radiator duct up to it. No A/C, so those inlets are blocked off completely or go to brake ducts depending on street or track use. Next up is a custom splitter and partial undertray that will be balanced with handling and cooling requirements. I even have a custom sealed cowl area at the base of my windshield since that is a high pressure zone. The OEM hood fits that weatherstripping there - most aftermarket hoods don't :wink:

This stuff is pretty complicated, and is why I continually stress against piecemealing aero parts - it should be done as a complete package if possible. There's a reason these aftermarket companies label their stuff "to be used off-road only." It's to limit their liability when I'm driving down on the street and someone's "aero" piece falls off and impacts me. If it causes damage to me or my vehicle, you can bet I'm going after the person that was negligent putting that crap on their car.

But it's good you're thinking about this issue. The scary thing is, most people don't.

Once again, my $0.02.

Dave
 
Hrant said:
put a piece of masking tape 1" wide x 2" long max over the center edge the headlights/hood and the highest point of the side fender/hood. See if the tape lifts. I tried this and while I had some minor lift the tapes never came off at the track.
Click to expand...

The problem is, the fluctuating pressures are just acting on a small surface area of the tape then. A small pressure distributed over a large area (like a hood, underbody diffusor, or an airplane wing) can generate large loads. Maybe that's why the tape didn't lift. Also, once a part of the tape lifts, you've "relieved" that pressure so it is free to escape. At that point, no more tape is expected to lift off.

That's a reason why you should completely seal the hood with ~3/4" wide painters tape onto your bumper, headlights, and all down the sides. Cut it with scissors so you have clean edges and minimize the chances of an edge accidentally lifting off and peeling back. Go for a brief spirited drive and see if any part lifted off. If it did, then that's not good!

I'm guessing it won't though. It's a small surface area to act on (the gaps between the hood/fenders), and relatively sticky tape. I guess this test won't really prove anything other than to ensure the gaps aren't causing problems themselves :biggrin:
 
All I am saying is if there is enough pressure to have a presumed lift, the masking tape will lift/separate and that is what you want to know before assuming that this is a problem. In my case, while I believe there was enough to notice (subjective) the pressure was not enough to lift/separate the tape. So I gave up experimenting with pins, magnets etc. and focused on the duct.
 

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