2004 Nissan. Have been feeling like the hood and front part of the body (i.e. fenders) really move around a lot when off pavement (washboard logging roads, etc). Feels like the whole truck was rattling loose; I know washboard feels/sounds like shit in general, but it was way worse compared to other SUVs/trucks I've driven!

Started investigating, took off the fender and bam! Check this out: enter image description here

The spot welds all around the fender support 'reinforcement box' let go so the thing was flexing like crazy. Also had cracks along the rad support, as well as around the hood hinges (where multiple body panels join).

For example: passenger side (rubber tube with anti-seize is the antenna mount). You can see cracks along the joint where the fender support joints the top of the body box where the window wiper motor sits: enter image description here

Was worried about fire risk with all the wiring harnesses behind it, so decided to rivet it all back together, along with some welding of the actual cracks:

enter image description here

Truck is body lifted (2") and has seen some off-road use, but nothing crazy - I'm not rock crawling! Only 180,000km on it, and most of it's life it was a stock city driver (I got it used a few years ago). Is this normal?? Is this something you would expect if a vehicle has been in an accident? Just seems crazy that so much is busted up :|

  • I thought I was the only one that had clothing hanging in my garage! – Moab Apr 18 '20 at 22:27

Likely the cracks started at the weld HAZ ( heat affected zone) , a common problem with steels. But auto sheet metal is normally low carbon so this should not be a problem. The fact that the cracks run through the base metal shows that there have been high stresses , likely higher than the design planned. Other than repair welding , apparently it needs all the screws and rivets there is room for.

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    Auto sheet metal is a lot harder and thinner than it was the 60's, therefore more prone to cracking over time. – Moab Apr 18 '20 at 17:26
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    Yes, much is age hardened with niobium/columbium ,has low C like 0.1% . It age hardens in the coil that comes off the mill at about 800 F and then slowly cools/hardens. This causes two conditions in this case ;the spot weld HAZ anneals the age hardening and the components are designed to higher strength levels to use the higher hardness. – blacksmith37 Apr 18 '20 at 19:26
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    Usually called "micro-alloyed" steels. The WIKIpedia enty is misleading ; Science direct has the correct description. The great majority is age/precipitation hardened by coiling the hot ( 800 F finish) steel and hardens while slowly cooling. Wiki is also in error on properties , these steels also have higher toughness than Q&T alloy steels.I have seen one of these steels "stop the hammer" on a Charpy machine. This is one of those events when everyone in the room stops what ever they are doing when they hear/feel the thump and asks, "what just happened"? – blacksmith37 Apr 18 '20 at 19:46

“Only city use”... and only used at weekends... never raced or rallied...

anyway, rivets won’t be good enough unless they are the old type that are inserted glowing red and hammered down.

You need to drill out the old spot welds then weld them together otherwise it will fail.

  • I was using stainless steel rivets. I know aluminum is weak and won't hold. Obviously inserting red-hot rivets isn't really an option, b/c of the electrical/fire risk - at that point I might as well spot weld! – wild coast Apr 20 '20 at 17:05
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    @wildcoast having been involved in rebuilding crash damaged vehicles, the point I made about drilling & welding the old spot welds was one that is used often and, done well, looks just like the original. BTW stainless is not the strongest steel... – Solar Mike Apr 20 '20 at 17:09

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