Classic Mustangs have always been cursed with rust and corrosionproblems. The most notorious are cowl-vent leaks that result in floorpanand kick-panel rust-out, and the inner-fender apron under the hood wherethe battery sits. Because lead acid batteries contain sulfuric acid andemit corrosive fumes, they are especially hard on sheetmetal body partslike the inner fender and battery tray. In the past, we've shown how toreplace the entire inner-fender assembly. But what if you don't want toreplace the inner fender? It's best to keep the serial number intact,which is stamped into the inner fender. And sometimes it's just too muchtrouble to pull the fender and drill out all of those spot welds.
We visited the Northwest Pony Shoppe in Snohomish, Washington, justoutside Seattle, to see how they correct battery-apron woes withoutmajor surgery. This is an easy fix for anyone who knows how to weld.And, if it's too much for your talents and abilities, this job can bedone by your favorite autobody shop.
We're going to show you how to patch the inner fender. It won't looklike a patch, and you'll save time and money in the process. For ourrepair, Mustangs Plus provided a new right-front inner fender, which ismade of the same heavy-gauge steel as original equipment.
1 Here's a '67 Mustang battery apron and inner fender. At firstglance, it doesn't look that bad.
2 First, remove the battery tray by extracting the four retainingbolts. Depending on how your Mustang was assembled, you may have toremove the front bumper bracket to get to the bolt heads.
3 With the battery tray removed, it's apparent this inner-fenderapron has been repaired before. Notice the sheetmetal patch that's beenwelded in place. This is not a solid repair. What's more, it looksawful.
4 We suggest removing all electrical components in this area. Noone wants to cut anything by mistake during inner-fender repair,especially the wiring harness. | 
5 Where you cut the inner-fender apron is a matter of preference.The Northwest Pony Shoppe cuts the battery apron only where necessary toeliminate the rust. The replacement patch from Mustangs Plus will fitthis area nicely. |
6 The corroded metal is removed as shown. | |