billlee

I'm repairing the front of my 81 after a trip through a ditch, During final prep for a simple scuff and shoot for the front I've been finding fine spider cracks in the old paint, believe them to be from stress from the wreck. There does not appear to be damage to the glass under these scratches. Will I be ok just sanding the paint down to glass and re-primering these areas?

Thanks

Bill

wombvette

Usually the cracks are actually in the fiberglass. You should be able to tell by looking closely after stripping.

billlee

So far I'm unable to see any damage to the glass, but if there is any damage I'm assuming I'll have to grind it and re-lay a couple layers of glass?

DUB

SMC is pretty stout stuff. And if you got those fine stress cracks in the paint...I am pretty sure that some stress occurred to the SMC in some way. LOOK VERY CLOSELY. BUT this also depends on how many layers of paint the car had on it. A lot of times...there may be several layers of primer/paint/clear and what have you...and usually those layers were not prepped correctly for good adhesion...and can often times crack when stressed...but not to the point where the SMC got damaged. It also depends on where you have these fine stress cracks. Location will also better aid in determining if they are cracks in the SMC or not. Sometimes things appear to be one thing when actually they are not. Hard to actually say without seeing what your are seeing.

"DUB"

crossed

If you have stress spider cracks in the fiberglass itself, what's the best way to fix that? Would it be good enough to lay a couple layers of glass on the backside to make sure it still has strength and then just spray some 2k and sand it in good or does it need something more stout than that?

DUB

Applying fiberglass on the backside with aid in giving the repair area added strength. BUT that alone does not fix your problem. Sometimes adding fiberglass can not be applied to the underside of a damaged area.

Many issues come into play. Like...how badly stressed is the fiberglass/SMC. Also location of the stress cracks comes into play. Usually if you have acquired stres cracks for what ever reason...and they are visable when the paint/primer is removed....then it is wise to make sure that you grind at the stress cracks and attempt to get to the bottm of them ...if at all possible. Filling over stess cracks does nothing but POSSIBLY cause future problems. Moistue in the cracks and panel integrity are still a factor. And if these factors are not corrected...the percentage of failure in the future is increased.

Priming over stress cracks can be done ...BUT I do not advise it. I have known a few guys in the past who did not care and primed over everything and did not care if it came back....becasue they were only interested in making $$$$ and NOT doing quality repairs. As long as it made it out of their shop...they were happy. There is NO WAY that you can get the primer down into the deepest part of the crack...thus allowing for a problem to occur when the panel is subjected to heat, vibration and TIME.

"DUB"