Hi, mates!

I've noticed some time ago that hood on my Firebird shakes between fenders while car is moving. Then, after engine swap I was riding my car without hood and discovered that front bumper cover is bouncing up and down...

I've inspected the whole front end of the car and everything is ok, all the reinforcement parts are there, no cracks on body, except front fenders...
You can see fender cracks encircled red on image attached (cracks on both sides). They have appeared because of bumper cover bouncing stress, if i'm not mistaken.

Now, I think problem solution is simple - just install brackets between bumper cover steel shock absorber and hood latch support panel, as shown on second image.

Have anybody faced with such a problem on front fenders?

 

It the hood latch plate missing the triangle reinforcement underneath?
If the latch is adjusted down far enough it should hold everything pretty tight.
Not sure what you mean by cracks in the fenders?

 

Triangle reinforcement is on it's place, neither of necessary parts are missing.
Cracks are vertical, on inner side of fender, you can see velded surface in the middle of encircled area on blue car - i tried to fix them, but problem lies somewhere else...

 

Do you mean there are cracks between the radiator support and the side rails?
That shouldn't have anything to do with supporting the front bumper cover but could be caused by hard cornering and flex in the front frame, same forces cause the main frame rails to crack at the steering box.
Do you have the cross braces in front of the radiator?

Was the egg crate crash pad firmly riveted on the bumper? It provides some support to the bumper cover.
Putting braces where you have indicated will firm up support, but shouldn't be necessary if the cover is attached properly everywhere else.

The cracks at the radiator support aren't caused by a floppy front bumper cover, it doesn't weigh that much. If you have cracks there, the front of the chassis is flexing too much for some reason. Could be from just pushing the car really hard.

The cracked area is just a couple of spot welds so it could easily be rewelded, but I would also check for frame fatigue in other areas like the k member and steering box area.

 

Just looking again at your pics, I think I can see the cross braces in front of the radiator but I don't see the triangle support under that big plate. It would support just the way you are suggesting with the braces.