Wish I took pics to post - you guys would have loved it...So I have been working with the greatest Automotive Electrician that has ever lived, John Schierloh in Oceano, Ca, over the last 2-3 years chasing down an electrical gremlin that would not allow the IROC to start (ended up being a loose connector at the fuel sender) - we are talking LED's on circuits to hunt it down, secondary starter switch to bypass, but we finally found it. Anyway, we have the tank out and John notices multiple cracks in the sheet metal panel behind the rear seats going out from the center where the hole is for the electrical connector!! We worked with another mechanic and ended up treating it like an airplane, making a panel of the same size and riveting it in with pop rivets and fender washers. I have had my Spohn SFC sitting in the corner for years and am having them welded on this next week! My wife cracked up when she saw it. I have been throwing it hard into corners for the last 20 years - thinking about a cage as well now. Have any of you heard of something like this? I have read about roof cracks (I have a small one of those starting). Bodies creaking (mine has a full blown conversation with me). And cracks up where the A arms attach. What else have you guys seen or heard of???

 

I've never seen that; but I have had the rear shock mounts pull out once on my old 3rd gen.

And thanks for not junking your car over those cracks. It's nice to see someone get it fixed instead of parting there car out and getting another one.

 

Nope, they'll bury me in our IROC! Ya, I can see how the rear shock mount could pull out. One of these days I have gotta stop getting sideways...Thanks for getting back to me. I am on a fact finding mission to deal with any other problems that might be lurking in the shadows. Anyone seen any others? We are hoping the Subframe connectors will solve the problems.

 

I have had my car in a body shop TWICE to fix stuff like that; cracks in the panels, spot welds cracked and no longer connected, etc. etc. etc. First time, the whole right quarter panel was waving in the breeze, you could grab it and pull it out a good half-inch above the wheel wells because all the welds that hold the inner well in were broken. Chassis has well over 300,000 miles on it. Needs it again but I'm getting to be afraid there's nothing left to weld together.

I no longer drive the car.

If you've got cracks like that, take out ALL the plastics and carpet and sound-deadening and whatnot under the back seat, on the sides, where the big L-shaped reinforcements that weld to the floor and the C-pillar are welded in. I bet you can almost lift those things right out of the car. Those were one of the things that had cracked welds both times I tore the interior out and had it gone over by a guy with sharp eyes, lots of time, and a wire welder.

 

WOW!!!!
Thanks bro, for this. This is the kind of stuff we were looking for. Just picked up a new hand held driver with all the attachments last night and a new led drop light - gonna get after it with help from friends and family this weekend. Stinkin love this car, we have had it in the family since new. Thanks again for the help.

 

I'm legitimately surprised! Over 300,000 miles is a lot; but that's a lot more chassis fatigue than I was expecting. My car has roughly 150,000 miles and all I have are the roof cracks which are fairly small. But Keep in mind I have not installed any chassis bracing other than the "wander bar".

Whats weired is I'm running gas charged shocks on my current 3rd gen and my rear shock mounts have not had any sign of failure. No stress cracks or anything has developed.
However, my old camaro had only a little over 50,000 miles when the rear shock mounts failed on it. I didn't drive that car hard at all; in fact I drive my current camaro wayyy harder. So what gives? Is there differing chassis strength from year to year? My old 3rd gen was an early 1983 year model; my current camaro is an 1989. Did they change building practices with later cars? (As far as I knew GM did not change a thing chassis wise.)

EDIT: At what miles on your car did you install strengthening braces? Do you feel it would have made a difference to your cars chassis if you had welded in extra bracing early on?

 

Starting in 1990 they began putting together/welding the chassis' better. Chevy realized in 89 there was a problem. Now the challenge for all of us now that our cars are 25+ yrs old is how to keep them together??? They just weren't designed to last this long...

 

Just had another thought...was watching "How its made" last year and on high end super cars they dont weld anything together, they use high strength industrial adhesives. Less weight, better bonding.

 

I had subframe connectors installed in about 1989 or so. HUUUUUUUJJJJJJJJE improvement. Prolly had a little over 150k at the time. Put a wonder bar in at about 250k or so; at the time, it made so little difference that if I didn't know I had done it, I prolly wouldn't be able to tell. Made the car feel just a bit "tighter", more "connected" if you will, going around bumpy curves.

It was around 300k that it started having stress crack problems: the first one was a strange ticking noise near the hood release assy, that turned out to be a whole string of welds popped around the cowl, and the sheets were vibrating.

Try this sometime: go get one of those curtain rods that you extend until it fits tight to the walls, and put it in your car across the back seat area, right behind the top of the doors. (or as close as you can get it behind the seats) Then go hit a few bumps. Watch it fall out as the sides of the car bulge out, as the floor pan bows. It's about like taking a shoe box or something, supporting it at the corners, and putting a weight in the center: the sides will all bulge out. Those reinforcements I spoke of earlier, are DIRECTLY stressed by that, which is no doubt why they're there in the first place, and of course, why they fail.

As far as I know also, nothing changed about how the cars were built, except that they filled some of the voids in the "frame"-like reinforcements of the unibody with foam, for noise reduction, in the last couple of years.

The welds on these cars weigh ABSOLUTELY NOTHING WHATSOEVER as far as I am aware. They are made by pinching the metal sheets together and passing electric current through them, causing them to melt together. Hard to imagine how any kind of adhesive could weigh any less than that.

 

The adhesive is more of a time saving feature. I don't think weight is a consideration.

In theory adhesive is stronger than spot welds as it is a continuous bond the full length of the panel. I just wonder if it could just pop apart in 1 sudden moment. I would view that as a catastrophic failure. Fatigue life of this method may not be any better... time will tell. Imagine if you were in an accident & it caused a bunch of body seams to separate... not an easy task to repair.

Mechanically spot welds are durable, but they can fatigue over time.
Nothing beats a continuous welded joint, but that's not typically possible due to accessibility or just the major labor needed to perform this task.