[Z06] Cracking Hood
Thread Starter
Instructor
Joined: Oct 2007
Posts: 207
Likes: 0
Cracking Hood
My hood has cracked on the upper passenger side next to fender. Anyone else experience this? Also the drivers side also has the same cracks but they are only in the clear coat. This is the only defect to my car and I wonder has anyone else experienced this or knows what causes it. I do have a vararam installed and a K&N bridge (at least that is what is stamped on it.) Could this mod cause it? I look under the hood but cannot determine what has caused this.
Will this crack spread is there anyway to halt the spreading?
Will this crack spread is there anyway to halt the spreading?
Burning Brakes
Joined: Apr 2007
Posts: 1,030
Likes: 1
From: Douglasville Ga
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
How far from the rear corner of the hood are the cracks? Are they where the latches are, behind them, or in front of them?
Last edited by TEXHAWK0; Nov 26, 2007 at 12:09 PM.
Cruising
Joined: Oct 2007
Posts: 11
Likes: 0
I'm not 100% sure about this, cause I'm not with the car at this time, but if I recall correctly, the crack in on the very tip of the passenger side of the hood, right next to the fender. I believe that it is within about 1-2 inches from the very end of the tip, which would make it to the rear of the latch. The crack is approximately 1/2" long and goes from the outside in.
Please tell me that this is repairable and that I dont have to buy a whole new hood.
Please tell me that this is repairable and that I dont have to buy a whole new hood.
Drifting
Joined: Jul 2005
Posts: 1,484
Likes: 27
From: Torrance Calif
The flexing from closing this way is very minor compared to the shock from dropping or slamming the hood, especially at the points where the latches mount on the hood.
FYI Motor City Mold recommends that you not slam their hood closed either and it is CF. This is to keep the hood from flexing and contacting the S/C (if installed), however it's still a good idea.
Last edited by heavymetals; Nov 26, 2007 at 03:22 PM.
Le Mans Master
Joined: Aug 2005
Posts: 7,201
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From: DP(oh you know where) IL
St. Jude Donor '06
i heard the opposite about the stock hoods. That a drop is better than closing one end at a time. They say that pushing down on the hood creates stress on the hood. Just what ive heard here before when the topic has come up. I know that with teh CF hoods you have to close it one side at a time. 
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Pro
Joined: Jan 2005
Posts: 556
Likes: 0
From: Jacksonville FL
St. Jude Donor '06-'09
well, believe it or not I actually experimented one night with how high I needed to drop it for it to close all of the way. I was surprised to find that all I need is about 4-6 inches of drop.
And I try to remember to lower it from the center as not to flex.
But then again I have a black car so my hood is heavier than other colors...
And I try to remember to lower it from the center as not to flex.
But then again I have a black car so my hood is heavier than other colors...
Melting Slicks
Joined: Nov 1999
Posts: 2,460
Likes: 352
From: Madison Alabama
I'd like to see some pics of where you hood is cracking. I've seen photos of the CF hoods for the Z16 cracking at/near where the hood support rods are - underneath the hood...to date GM is not responding to the owner.
Also, FWIW, I also close the hood on my Z16 one side at a time rather than dropping it from 4 - 6 inches or higher as I've seen others do.
The whole "hood flex" thing will fall into the same body flex "Urban Myth" category as popping the T-Tops and opening the doors on my '82 prior to jacking her up. Some claim that if the body was going to flex that much when jacking I would break the tops simply driving over a speed bump...maybe, but I've never broke a top by not popping them loose prior to jacking up my car so I keep doing it...I'll also keep closing my CF hood one latch at a time.
Let's call Myth Busters!
Also, FWIW, I also close the hood on my Z16 one side at a time rather than dropping it from 4 - 6 inches or higher as I've seen others do.
The whole "hood flex" thing will fall into the same body flex "Urban Myth" category as popping the T-Tops and opening the doors on my '82 prior to jacking her up. Some claim that if the body was going to flex that much when jacking I would break the tops simply driving over a speed bump...maybe, but I've never broke a top by not popping them loose prior to jacking up my car so I keep doing it...I'll also keep closing my CF hood one latch at a time.
Let's call Myth Busters!
Race Director
Joined: Jun 2005
Posts: 17,640
Likes: 1
From: Lenoir City TN
St. Jude Donor '08-'09-'10-'11
I have an 02 with what I call stress lines (looks like very minor cracks or spider webbing) located along the hood edge directly over the front wheels, these lines radiate in wards about an inch or two and are really evident under florescent lighting. I used to close the hood by letting it drop but now I set it down and with a towel between my hand and the hood (over the latch) I press down, it does not take much at all to latch and a heck of lot less strain on other parts of the hood.
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
I'm not 100% sure about this, cause I'm not with the car at this time, but if I recall correctly, the crack in on the very tip of the passenger side of the hood, right next to the fender. I believe that it is within about 1-2 inches from the very end of the tip, which would make it to the rear of the latch. The crack is approximately 1/2" long and goes from the outside in.
Please tell me that this is repairable and that I dont have to buy a whole new hood.
Please tell me that this is repairable and that I dont have to buy a whole new hood.
The factory carbon fiber hoods I have seen are so light that you cannot drop them and get them to latch. You have to either push the hood down in the middle, or close one side at a time by pushing over the latches.
On CF hoods, I have seen a lot of people stand in front of the car and push down in the middle of the hood to minimize the flex at the hinge points.
Last edited by TEXHAWK0; Nov 26, 2007 at 08:28 PM.
Thread Starter
Instructor
Joined: Oct 2007
Posts: 207
Likes: 0
I will take pics of the crack tomorrow and post them. I can not see the underside of the hood due to the hood support construction. To the best of my knowledge the crack is behind the latch. I also has the spider cracks along the side of the edge of the hood.
Melting Slicks
Joined: Nov 1999
Posts: 2,460
Likes: 352
From: Madison Alabama
Here's the photo I was talking about on a Z16 factory CF hood. This is from the Z16 Forum. The owner had removed the hood liner and discovered the crack. Thought is that the supports are too strong for the lighter weight of the CF hood on the Z16 ~ they weigh about 10lbs less than other C5 hoods but the brackets/support rods are the same.
I'm scared to look at mine...
if I can't see it it didn't happen...
and I'll need a few of these 
and this 
if I find a crack!
I'm scared to look at mine...
if I can't see it it didn't happen... and I'll need a few of these and this if I find a crack!
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
Here's the photo I was talking about on a Z16 factory CF hood. This is from the Z16 Forum. The owner had removed the hood liner and discovered the crack. Thought is that the supports are too strong for the lighter weight of the CF hood on the Z16 ~ they weigh about 10lbs less than other C5 hoods but the brackets/support rods are the same.
I'm scared to look at mine... if I can't see it it didn't happen... and I'll need a few of these and this if I find a crack!
I'm scared to look at mine...
if I can't see it it didn't happen... and I'll need a few of these and this if I find a crack!
Is the reinforcement section carbon fiber too, or is it the same material as the regular C5 hoods?
Racer
Joined: Nov 2004
Posts: 448
Likes: 0
From: MCHENRY ILLINOIS
over extended
the crack looked to me like it came from opening to far like backing out of a garage with the hood open wasa there any over spray paint on the hood it might of been fixed and now re broken the crack is from going one way or the other the mods didnt do it unless someoone closed it on a blower hope you fuger it out 
try and open the hood from the middle and guide it up coming up easy to the top closing same hand close to center droping from about inches 7 say away fror the sides remember its plastic it does crack in cold weather alot more iv seen what happeded to yours before caused from over extending the hood comming up to fast and crack looks like when it was comming up some one caught it on the drivers side and flexed it more yet its not going to get better only worse depedding on how you open and cloe you hood get a new one and be gentle open and closen
try and open the hood from the middle and guide it up coming up easy to the top closing same hand close to center droping from about inches 7 say away fror the sides remember its plastic it does crack in cold weather alot more iv seen what happeded to yours before caused from over extending the hood comming up to fast and crack looks like when it was comming up some one caught it on the drivers side and flexed it more yet its not going to get better only worse depedding on how you open and cloe you hood get a new one and be gentle open and closen
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
When the crack originates from the bottom side, I would also think it is due to the hood flexing upward. The carbon fiber hoods are so flexible, if you push down quickly on one side instead of the center, the other side of the hood will actually flex upward. (whip action)Could also be pulling upward on the hood quickly on one side.
No matter what hood you have, I would think it is always better to lift or close the hood by pushing in the center and not on one corner or side.
Burning Brakes
Joined: Apr 2007
Posts: 1,030
Likes: 1
From: Douglasville Ga
the crack looked to me like it came from opening to far like backing out of a garage with the hood open wasa there any over spray paint on the hood it might of been fixed and now re broken the crack is from going one way or the other the mods didnt do it unless someoone closed it on a blower hope you fuger it out try and open the hood from the middle and guide it up coming up easy to the top closing same hand close to center droping from about inches 7 say away fror the sides remember its plastic it does crack in cold weather alot more iv seen what happeded to yours before caused from over extending the hood comming up to fast and crack looks like when it was comming up some one caught it on the drivers side and flexed it more yet its not going to get better only worse depedding on how you open and cloe you hood get a new one and be gentle open and closen
try and open the hood from the middle and guide it up coming up easy to the top closing same hand close to center droping from about inches 7 say away fror the sides remember its plastic it does crack in cold weather alot more iv seen what happeded to yours before caused from over extending the hood comming up to fast and crack looks like when it was comming up some one caught it on the drivers side and flexed it more yet its not going to get better only worse depedding on how you open and cloe you hood get a new one and be gentle open and closen 
Racer
Joined: Nov 2004
Posts: 448
Likes: 0
From: MCHENRY ILLINOIS
sorry im in a hurry ill do better next time
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I have been afraid this might happen to mine. I usually let mine all the way down and push it shut at the latches. The problem with this, on mine, is that it takes quite a bit more force on the passengers side to latch it. Here is where I am afraid I am going to hurt the car. I guess I need to raise the latch just a tad. Any ideas?