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Shroud Fatigue Cracking

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Jedi Knight
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This is a known problem in big healeys, especially in the front shroud in the corners of the bonnet aperture, has anyone come across a good fix?
 
No solution but I have a similar problem (on a late 1967 BJ8 3000)

There are a number of cracks in the paint (not the best paint job in the first place) running back from the bonnet opening towards the screen in the area of the washer jets.

When I put my hand underneath in same area but on the otherside- up behind the dash,all seems fine. I thought it was just the paint cracking perhaps due to some sort of flexing.Is it more serious?
 
Believe me, I know what a pain removing either shroud is, but the best solution is to get someone who is a really good TIG welder to run a bead on both sides of the metal, so you can grind down the top side so it will not show when finished. Although it is a tough step to take, I would suggest finding the end of the crack and using a small drill bit, stop drill the end of the crack to keep it from spreading further (hopefully). It might be possible with some synthetic re-enforcment (i.e. fiberglass and some good quality resin on the under side to stabilize the crack after stop drilling, to the point where some polyester resin on top could be made to look OK. The latter is not a good solution, but perhaps the only way to avoid removing the shroud if you are not so inclined. I had cracks around the the top corner of my rear shroud and am very happy with the welded fix I described. I'm a fair welder and had access to TIG, but was not comfortable welding on such an expensive and multi-compound curved piece, so I had a friend who is a pro do it. I would be loathe to drill any holes other than one to stop drill it. I wouldn't want to rivet any kind of patch on the inside. Too many chances for further cracks.
 
Hello,
I have also the cracks in the shroud. Positioned at the corners of the bonnet. I see no chance to fix the cracks steady with two weld seams. If you would like to eliminate or reduce the root cause, you have to reduce the vibrations and torsion of the bonnet. I would like to fix it with WIG (Wolfram Inert Gas) welding. But I think ,to optimize this area you have also to patch from the underside a stiffener plate with good hole/- spot welding and very good weldseams around the patch.(no rivets!) To reduce the vibrations, I would like to dispense between the shroud and the chassis elastic material to absorb the mechanic forces.

By michel who is recently fix his frame bending...
 
Thanks for above but I am convinced my cracks are in the paint not the metal.

When I feel (and look up) from underneath - behind the dash - there are no cracks at all.

It seems to be flexing that is causing the problem.

I have had the car 3 or 4 years and they have only developded in the last 2 years. There were none evident when I bought it,and it most definatly was last repainted in 1990.

My driving is no doubt a bit more `spirited` than the old boy who had the car before me. So am I being overly optimistic? Is it not possible for just the paint not the metal to crack at these points?
 
Hi David,
I wonder if there is Bondo under the paint. Can you get a sense of how thick the shroud is at that point? A body shop put an inch of Bondo on the shroud under the grill of a friend's Healey. Only a matter of time before that starts cracking. :madder:
 
I found some filler in the area being discussed when I stripped the paint from my front shroud during restoration. I think the filler may have been applied at the factory since the welds were not ground smooth. Cracking later on may not have been a concern at the time.
 
When I was restoring my '63 BJ7 I was told that the paint used on the original was ' designed' to accommodate the flexing cars of that era experienced and to be sure not to use 'to-days paint' because it is ' designed ' for todays cars which of course do not flex as much. I was unable to confirm the above but used the original formula from a restoration book: 5yrs., 50,000 miles later no cracking is apparent.Hope I am not speaking too soon!!
 
John -

Whoever told you that is full of cr*p. Old lacquer paints are some of the hardest paints ever made for cars and they love to crack when flexed or with age.

New paints are typically polyurethanes and/or epoxy type paints and they are known for being exceptionally flexible and maintaining a seal to the underlying metal regardless of conditions.

My BJ8 is painted with a urethane (painted in 1986) at the actual finish looks as good as it did 20 years ago.

Alan
 
DavidThorn,
I think where your cracking is ocurring is probably due to something like a skim putty being put on too thick, it will skin and appear set, allowing you to sand it, however it will shrink over time as the remaining aromatics dissipate from below the hard skin
 
Hi Guys

Thanks for your thoughts - I have investigated further today and on scraping the cracks with a small screw driver have found that there is a small amount of filler on top of the metal.

There is no evidence of cracks in the metal at all so I think when the car was restored in 1990 (the boom years in car prices of course) it was skimmed over in places with filler to hide any imperfections in the finish.

It was a USA re import to the UK which some one probably decided they could make some quick cash on.

Anyway my plan is to chase out the filler where it has cracked re fill with a flexible filler and re spray when the weather gets warmer here in the UK.

My idea is it has lasted 18 years before cracking so hopefully it will do the same again.

Any thoughts?
 
Hi Gents, I've seen the cracks occur in quite a few big Healeys where you all discribe. And my car also has them, which I plan to fix soon. I believe it is typical stress cracks occurring mostly from scuttle shake or 'vibration'. You may have read in the past about one of our members who during restoration welded in 1" angle iron around the open transmission tunnel tostiffen up the cowl and firewall, (scuttle). I believe that was a good move and plan on doing it to my car. As far as fixing the existing cracks, If the aluminium is cracked the only way to fix it is obviously to weld it. But I do believe you can just weld it from the top side and it will hold. Providing you can do a good weld. I tig aluminium once in awhile, and a good weld will have pentitration all the way thru. It will be at least as strong as the original sheet. But that doesn't mean that It won't tear somewhere else. So try to reenforce the scuttle in some way to keep the stresses down.
Dave C.
 
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