Inner Fender Crack

My 1964 Dodge 440 2 door hard top has a horizontal crack about 6 inches long on left front inner fender just above shock tower. Its even pulling spot welds loose from the gusset under the inner fender. I raced this car a good bit in the 80's & 90's but not a race car ran high 7's in 1/8th. Took it apart about 10yrs ago mini tubbed, moved springs to frame, tied frame rails, put 66 kframe in so had to modify trans tunnel. That's when I found crack. Shock didn't seem to be short but cant think of what else might have caused this. What would be a good fix? Started having a lot of back problems and left car on jack stands since but would like to ride in it one more time before I kick the bucket.

Thanks
Tim

There is a reinforcement bracket in behind the inner fender panel. I can't say what caused the crack but I have seen a few of them get thin in that area from sediment laying on the reinforcement behind it. I'd drill a couple holes thru the inner fender and one at each end of the crack and throw a small piece of plate in behind it. Plug weld a piece of 18ga metal in and grind it down and you should be good..

It's not uncommon for those stress cracks to occur when the front floor pans are rusty or other structural components like the frame or rockers start to fail. The result is that the middle of the car sags down and since the inner fenders are tied to the firewall they can't move. It places a stress on them and the thinnest part with the most weld stresses starts to crack. Right above the shock towers.

Check there first. IMHO.

The floors were a little rusty but have replaced them.
You can barely see on the pics that nearly all spot
welds around top of shock tower and on
top flat area of inner fender where brace/gusset
on back side are pulled nearly 1/8". It looks like shock
tower has pulled out and down. I think I'm going to make
a larger brace and box it in.