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Deadpan DIY: No laughing matter to replace front pan and inner fender

Tuesday, October 27, 2020

Above: Photo by Jessie Clewell

Kris Clewell owns a 1972 Porsche 911 that he drives everywhere at almost any time of the year. It’s seen what his home state of Minnesota has to offer plus several trips out to the West Coast over the years. That includes rain, salty air, snow, and snow treatment on the roads — a fast track to a rusty front pan. As he’s done with most of the work on his 911, he decided to get rid of the rust and replace the front pan himself, learning along the way and documenting the job in this blog series.

Read Deadpan DIY Part I: Rust has no humor for 1972 Porsche 911 front pan

Article by Kris Clewell
Photos by Kris Clewell unless noted.

I was crouched down inside the front trunk, leaning over with my head pushed up against the battery box. I shined a flashlight inside the driver’s side frame rail, or what was left of it anyways. Corrosion had crept far past the front pan. Sulfuric battery acid from the original wet cell battery (which Porsche Classic still sells to those who prefer originality over safer technology) had rusted the front pan and let moisture in. The rust had worked its way all the way back to the suspension crossmember mount, where the rear of the control arm attaches and the torsion bar is adjusted. I walked away, for weeks. Things had gone beyond a “simple” pan repair and ventured into boxed-in areas of the car, critical to how it would drive and be aligned.

Above, from left: Old crossmember mount. Rust inside the longitudinal. Rust inside the longitudinal and lower pinch weld.

Weeks later I slid back under the car on the creeper, wishing I had a hoist. Most welding, cutting, hammering, and prying were done on my back. I laid there thinking that there’s really nothing else to be done now than plow forward. With a third of the car cut away, I couldn't tow it anywhere, and pride was starting to elbow its way in.

Above: Drilling out spot welds and plug welds. (Photo on right by Jessie Clewell)

It's easy to get lost in what the car is and what it represents for you — and for everyone else. With Porsche especially, the labor and parts get put on a pedestal as untouchable by the average guy. With the rising tide of early 911 values pricing me out of not only the cars but also the labor market surrounding them, I had no choice but to go on. Like someone on a revolutionary mission, I drilled spot welds, ripped open seams with a seam splitter, cut out cancerous rust. Eventually I got to the point where I could start test fitting the new panels...

Above: Test fitting the pan and other parts.

I laid in the front pan and, at best, it was “alright.” That said, I was "alright" with things not being totally perfect, but none of the new parts from the inner fender to the front latch panel to the frame rails lined up. Not even close, and not even with each other. They were all made by the same company, but even spread out on the floor they didn’t match up properly. I’m told by multiple pros that it's “just the way it is.” I suppose I should be happy the parts even exist, but even in hindsight I find it difficult to understand why new parts can’t fit together with themselves. Everything needed hammers, magnets, pliers, and tack welds.

Clockwise from top left: Jig used to line up front pan and other panels. New front frame rail longitudintal meets front pan. Front latch panel welding to lower front pan, which is mounted on the jig.

With the jig bolted up, I could at least lay the pan in. I’d already made the cuts for the new pan before I found the rusty disaster in the frame rails. As a result, I had to puzzle together a few pieces of steel. I practiced on some of the parts I wouldn't need, new and old. When spot welding, temperature control is crucial. If a weld gets too hot, other welding locations won't line up farther down the seam because the repeated expansion and contraction causes the sheet metal to warp. Practicing on scrap metal was a good idea as I warped, blew out, and destroyed much of what I started with. Once the wire speed, heat, and spacing technique was dialed in, I started on the car.

Above, from left: Welding practice. Battery box about to be welded in. Sharpie outlines where cuts will be made for the new crossmember.

With the pan and inner fender tacked in, I took the jig off the car, grabbed a sharpie and the new mount for the rear crossmember, and drew out where I thought I could cut. I left extra to grind back for a perfect fit. Having a huge gap is a disaster and difficult to deal with, a lesson I learned on the battery box inner fender panel. Cutting a skinny piece to fit a gap, welding it in, and grinding it back is a pain. There’s nothing gentle about any of it. Once the mount was tacked in, my best friend was a hammer. I beat the sheet metal into place, as the profile and shape of the new part wasn’t even close to being accurately stamped.

Clockwise, from top left: Lower inner fender welded to front pan. Lower inner fender and crossmember mount being prepped for repair. Completed lower inner fender and crossmember mount with new undercoating.

The rest of the process was seam/butt welding and plug welding. Over and over again. I used a damp rag and copper spoon to leech the heat out of the welds. Holes for spot welds were drilled and filled. Where things got ugly, I ground the welds down. The passenger side of the car was untouched by the blind and careless previous repair guy, so I used it as a reference — and a reminder that these cars were built on an assembly line by regular guys. The factory spot welds were uneven and often haphazard. Porsche wasn’t building show cars. They were building machines. For me, spending $150,000 to restore something that was zapped together by someone named Hans as fast as possible so he could get back to his assembly line beer was impossible to conceive. There were no ruthless safety and process overlords. If they could do it quickly, I could do it taking as much time as I needed. And if I screwed it up, I could always do it again. And I did, a few times. It’s a good thing I work for free.

Above, from left: Factory welds on the untouched passenger side inner fender. Completed front end metal repair ready for primer.

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