Cracked rear quarter from torque??

[Jonnybow]

I was doing some carburetor adjustments and took the car out to see how the acceleration was, did a slow speed rolling takeoff and the rear quarter panel on the driver's side just behind the door panel cracked.
Pretty sure there was a crack there before and wasn't fixed correctly, just painted over.
Anyone else with a non post car have this issue?

 

[JimKueneman]

Man are you sure that area has any metal? That looks like it was just filler. That should be solid welded in metal in that area.

 

[eldubb440]

very common on these cars...... but I'm not buying the "torque" explanation

 

[Jonnybow]

Man are you sure that area has any metal? That looks like it was just filler. That should be solid welded in metal in that area.

I haven't started digging in there yet, was mortified when I saw it. Just bought the car about a month ago, getting it up to my specs. Looks like it's going to be some work to make it right.

 

[snakeyes]

I was doing some carburetor adjustments and took the car out to see how the acceleration was, did a slow speed rolling takeoff and the rear quarter panel on the driver's side just behind the door panel cracked.
Pretty sure there was a crack there before and wasn't fixed correctly, just painted over.
Anyone else with a non post car have this issue?View attachment 1138598 View attachment 1138599

have seen many with this problem and other sheet metal cracks in other areas , have seen them re welded and down the road the cracks come back

 

[747mopar]

Unfortunately it's common. I put new AMD full quarters on mine and with 16,000 miles on it a crack has started in the exact same place. I do run the piss out of mine, hard acceleration, donuts, etc. I had a second gen Camaro, same thing after time they would crack where the roof met with the post. I honestly thought the subframe connectors would have helped but evidently they weren't enough, next time I'm adding bracing everywhere. I wouldn't consider mine to even be fast either, it's a stroked 400, 6 speed manual, 3:55 gears with 305 street tires.

I know that feeling, disgusting but at least it's in an area where the body and paint work can be kept local. It's just hard to commit to fixing it when you know it will eventually come back unless you baby it.

 

[Aarons Air]

There's old threads & pics on this. They also crack on the cowl, where the a pillars meet. Both my quarters cracked, and it was just a stock 318 then.

 

[zyzzyx]

This is very common, and the cause is from closing the door. The quarter window area has no support because
it's hanging in the breeze so it gets a stress crack. If you mig weld it up and repair it, make sure you weld up
all of the crack and then take it easy when you close the doors.

 

[RGAZ]

Is this just hardtops or post coupe as well? I am doing this steel work now and could easily reinforce that area from within but if its not a "post car" problem I won't bother. (My car is a post car)

RGAZ

 

[zyzzyx]

Not sure if post cars have the same problem but with the added support I would think it
would hold up longer.

 

[Tony Tee]

Maybe time for subframe connectors?

 

[zyzzyx]

They have nothing to do with the problem.

 

[747mopar]

They have nothing to do with the problem.

If I can get my hands on a GoPro that would be an interesting thing to put to the test, mount it right above the crack and go for romp. I'm not arguing that slamming the door doesn't contribute but when grabbing second on a hard pull I can feel the body moving. I personally think it's a contributing factor especially when the car hooks up.

 

[Lefty71]

A proper roll cage will help prevent those issues.

 

[Rjvb3]

Hey Jon,

Yep its from body flex. Either torsional stress or front to rear bending. Subframe connectors should prevent any repair from coming back.

I had it on both sides too, previously repaired at some point . Lucky for me I did not have nice paint to worry about!

-VB

 

[Dan64]

Either you or whoever welds it may want to drill a hole at the very end of the crack, as this can help with the crack not coming back. The hole is of course welded up along with the crack.

 

[fbs63]

The cracks in the upper door are from slamming the doors shut. Usually the hinges are shot and the door is sagging when open. Rebuild the hinges and CORRECTLY adjust the doors. Then repair the cracks.

 

[Jonnybow]

The cracks in the upper door are from slamming the doors shut. Usually the hinges are shot and the door is sagging when open. Rebuild the hinges and CORRECTLY adjust the doors. Then repair the cracks.

The specific crack on my car isn't in the door, it's the rear quarter. My doors don't sag, the gap is consistent top to bottom, see pictures in first post.

 

[chargervert]

My A12 Super Bee had it on both sides and I am sure that torque was the problem!

 

[RGAZ]

I just checked my 69 post car and there is no way this could happen. There is a substantial support piece behind that panel.

This appears to be a Hardtop-only problem and my vote is door slam related and not acceleration torque. Vote or die!

RGAZ