what causes Stress cracks?
Thread Starter
Parrothead
Joined: May 2002
Posts: 48,231
Likes: 289
From: Margaritaville Embassy
St. Jude Donor '08-'09,'13, '14
what causes Stress cracks?
I noticed 2 new cracks today, both on the right front fender. the first is across the top of the fender, wehre a previous repair had been done. the second starts above the gills and meanders into the gill itself, running from 10 to 4 oclock. I'm assumming this is due to stress. i have ben doing the gofast thing lately. it's such a pleasure to drive a v8 instead of the miserable 4 the Saturn has.
so the real question is, if I repair, or more likely, replace, how do i avoid the repeat?
[Modified by Markm10431, 3:02 AM 7/19/2002]
so the real question is, if I repair, or more likely, replace, how do i avoid the repeat?
[Modified by Markm10431, 3:02 AM 7/19/2002]
Burning Brakes
Joined: Mar 2000
Posts: 1,092
Likes: 0
From: LIC NY USA
Re: what causes Stress cracks? (Markm10431)
i got stresscracks where the roof ends along the pillars above the rear wheels.i am not sure if it is from the "gofast thing" or from jacking the car up or what. :rolleyes:
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Re: what causes Stress cracks? (Markm10431)
I just had a crack develop same place as you first described, likely due to the front end being supported on jackstands for a prolonged period of time. It is just something we will have to live with, due to the nature of fiberglass. A car with a steel body-on-frame is subject to the same bending and twisting transfered through the body mounts. However, steel has a neat property of being very elastic. It will withstand repeated low stresses from driving, and moderate stresses from jacking your car, by always returning to its original shape. Beyond the elastic range, steel will plastically deform, such as a dent or crumple, where as fiberglass will just rip and crack.
[Modified by Turbo-Jet, 2:47 AM 7/19/2002]
[Modified by Turbo-Jet, 2:47 AM 7/19/2002]
Melting Slicks
Joined: Feb 2002
Posts: 2,625
Likes: 0
From: Cut n Shoot TX
Re: what causes Stress cracks? (Markm10431)
I noticed 2 new cracks today, both on the right front fender. the first is across the top of the fender, wehre a previous repair had been done. the second starts above the gills and meanders into the gill itself, running from 10 to 4 oclock. I'm assumming this is due to stress. i have ben doing the gofast thing lately. it's such a pleasure to drive a v8 instead of the miserable 4 the Saturn has.
so the real question is, if I repair, or more likely, replace, how do i avoid the repeat?
[Modified by Markm10431, 3:02 AM 7/19/2002]
so the real question is, if I repair, or more likely, replace, how do i avoid the repeat?
[Modified by Markm10431, 3:02 AM 7/19/2002]
Burning Brakes
Joined: Aug 1999
Posts: 774
Likes: 0
From: Palatine IL
Re: what causes Stress cracks? (Markm10431)
Jacking up one corner of the car at a time caused a few on my Vette. I now use ramps or try to jack under the rear diff or front cross member to lift both front or rear wheels at the same time so the frame does not flex/twist.
Another reason cracks happen is too much paint/clear in one area. When the fiberglass flexes the paint/clear can crack.
I have also heard driving in very very cold weather and hitting large bumps can cause them. I don't know if this is true but I didn't notice a small crack one after driving my Vette during one very cold Chicago winter season. They paint was also 22 years old.
Another reason cracks happen is too much paint/clear in one area. When the fiberglass flexes the paint/clear can crack.
I have also heard driving in very very cold weather and hitting large bumps can cause them. I don't know if this is true but I didn't notice a small crack one after driving my Vette during one very cold Chicago winter season. They paint was also 22 years old.
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Thread Starter
Parrothead
Joined: May 2002
Posts: 48,231
Likes: 289
From: Margaritaville Embassy
St. Jude Donor '08-'09,'13, '14
Re: what causes Stress cracks? (Markm10431)
so are stress cracks in the locations described common? I'll try to get some pics scanned asap
Burning Brakes
Joined: Jun 2000
Posts: 951
Likes: 0
From: NW Burbs IL
Re: what causes Stress cracks? (Markm10431)
Yes, they are pretty common. I have a couple. A small one near the top of the passenger front fender. I have another slightly larger one (about 3/4 of an inch) on the driver side extending horizontally from where the rear bumper meets the rear panel. Nothing major, but I plan to have them fixed as soon as I can. I hate the way they look.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: what causes Stress cracks? (Markm10431)
This type of fender stress crack is caused by jacking. You can relieve the stress by drilling a 1/8" hole at the end of the crack. This dissipates the stresses by cutting off the linear expansion: that fender will basically swivel a bit on the hole and the crack not move straight ahead. The screw serves no function; it just plugs the hole. This crack started about two years ago after a paint job and when I jacked up the front end. It has not progressed any further since I drilled the hole. Just a tip.
[Modified by paul79, 6:44 PM 7/19/2002]
[Modified by paul79, 6:44 PM 7/19/2002]
