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Panel Gapping Project Purple Pig - Mind The GapBefore Bodywork Comes Panel Gapping From the July, 2011 issue of Rod & Custom By Kev Elliott
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One of the seemingly little details that separates a really great-looking car from an average one is good panel fit, with uniform gaps between every panel. It’s a job that takes an inordinate amount of time and should be undertaken before any body or paintwork is tackled, as there’ll undoubtedly be some cutting and welding involved. This is especially true with an older car that isn’t using all its original panels. Modern cars will invariably have panel gaps of 1/8 to 3/16 inch, while those on cars such as our project ’49 Chevy will often be a little wider, at 3/16 to 1/4 inch. Here’s where we started, fitting... Here’s where we started, fitting the rubber lacing that screws in place across the top of the cowl. These support the hood at the correct height to align with the cowl. All rubbers were sourced from Chevs of the 40’s. If you want to bring those gaps up to modern specs, be prepared to add material to the edges of doors, fenders, and hoods, usually by welding lengths of welding rod or fabricated sheetmetal strips to the edges. We didn’t want to go that far, but did want uniform gaps throughout the vehicle. As we’d replaced the doors and hood on the ’49, we had to start our panel alignment from scratch, and there’s a definite order in which this has to be done, and I always start with aligning that gapwhich isn’t adjustable. On a car like our ’49, that non-adjustable gap is between the hood and cowl, meaning the first panel to be installed should be the hood. On a vehicle that has a removable cowl panel between the hood and windshield, the procedure is different. In that instance we’d usually start by installing the doors and working forward to align the fenders and hood. So, on the ’49, the hood went on first, and then was aligned on the hinges to be central, as well as vertically and front-to-rear to align with the cowl. We sourced a complete set of rubber components from Chevs of the 40’s to replace the worn-out originals, including the cowl seals and all the small rubber bumpers that help align the hood to the cowl and fenders. While the panels can be aligned without these, using them at this stage ensures everything will line up during final assembly after paint. You don’t want to be making adjustments at that stage! We’ll have all the panels... We’ll have all the panels blasted before we tackle the bodywork, but elected to align them first. We chased the threads in the hood with a thread restorer before bolting it to the hinges. Our front fenders, inner fenders, and radiator core support have been bolted together as a single unit since we replaced the driver side inner, repaired the other, and painted them. This assembly was installed next, without all the under-fender stone guards at this stage, as it made access to the door hinge bolts easier. On the Chevy, the fenders bolt to the cowl at the upper rear corner, bolt to brackets coming off the chassis at the lower rear, and the radiator core support bolts to a crossmember at the front of the chassis. Spacers between this crossmember and the core support provide vertical adjustment, which in turn aligns the panel gaps between the fenders and doors. With the fenders aligned to provide even gaps along both sides of the hood, once again aided by the small rubber bumpers along each side of the ladder, it was time to hang the doors. By adjusting the door hinges, front-to-rear and in-and-out alignment was possible, until we were happy with the door-to-fender and door-to-rocker panel gaps. What wasn’t so great was the door-to-rear quarter gap. There simply wasn’t one. The door shut OK, but we didn’t even have a 1/32-inch gap! Chevs of the 40’s also supplied... Chevs of the 40’s also supplied new stainless steel hood hinge bolts. These are vehicle-specific, and have a shoulder allowing them to locate in the hinge and be tightened, yet still allow the hinge to pivot. Yes, we’ll use washers on final assembly! Whether this was caused by the discrepancies between sizes of the replacement panels we’d fitted and the originals, we’re not sure, but this is exactly why panel alignment should be started at the cowl. If we’d fitted the doors first, then the fenders, we’d have had a 1/2-inch gap between the cowl and hood. Sure, we could have added material to the rear of the hood, but then the inner fenders, and likely the outer fenders wouldn’t have aligned with their mounting holes. We had two options to solve the door gap issue: grind the rear edge off the doorskin and inner frame and re-weld it, or cut the quarter-panel and move the door shut rearward. We elected for the latter, as it offered less opportunity for panel warpage and an easier repair. Aligning all the panels on any project is a time-consuming process, but take your time and you’ll be rewarded with a sharp-looking car in the end. Bear in mind two things: it’s only metal and can be cut and moved around to fit perfectly (unless it’s ’glass!) and never be tempted to use body filler to close up a gap. Plastic filler will crack or even fall out eventually. Get everything perfectly gapped before applying filler!  Once we’d bolted the hood...  Once we’d bolted the hood in place, the hinges themselves had to be moved down and rearward to acquire an even gap between the hood and cowl. Ensure the hood is also central on the car when you do this.  With a consistent gap across...  With a consistent gap across the cowl, we moved to the fenders. If you really want all gaps perfectly equal, use a paint mixing stick or similar to place in the gaps during adjustment. We used a steel ruler to measure them.  This rubber kit contains all...  This rubber kit contains all the hood bumpers for the sides of the hood, the rear corners, and the front, on top of the grille. Using these now will save a lot of frustration later as the fit you get at this stage will be the same once everything is assembled for the last time.  The rear corners of the Chevy...  The rear corners of the Chevy hood slide down and over these bumpers just in front of the doors on the cowl when the hood is closed, and prevent lateral movement. Note how the originals are excessively worn.  These stops push in place...  These stops push in place along the hood sides, and locate it snuggly between the fenders, again ensuring no sideways movement as well as keeping everything rattle-free.  While most cars don’t use...  While most cars don’t use rubber stops along the hood sides, on the Chevy they rest on these raised sections on the fender return lip.  Protecting paint may or may...  Protecting paint may or may not be an issue, but a couple of towels placed on the cowl corners are helpful when installing the hood if you’re alone. Though Project Purple Pig currently resides in our Tech Center, I usually work on it late at night when no help is around, just like most people at home!  With the hood in place, the...  With the hood in place, the fenders are next. Note this one needs to come up to align with the hood, and the door obviously needs to come out too.  Purpose-made body alignment...  Purpose-made body alignment shims are available, and are way quicker to use than washers. This selection of various thicknesses was sourced online.  The fenders on the ’49 bolt...  The fenders on the ’49 bolt to the cowl at their upper rear corners, and required a couple of shims to attain the correct gap against the hood sides. Shown are two different types of shims.  These Chevys use a bar across...  These Chevys use a bar across the top of the radiator core support to maintain the correct distance between the fenders, and it actually has the wiring harness running through it on stock applications. It won’t fit with our new radiator, but we used it during the alignment process and will fabricate a suitable one in due course.  The consistent gap between...  The consistent gap between the hood and passenger fender matched that at the cowl, once the core support brace had been fitted, and the shims added at the top rear fender mount.  Shims under the core support...  Shims under the core support allow the vertical door-to-fender gap to be adjusted.  The captive nuts inside the...  The captive nuts inside the door are often awkward to get the bolt started in. A screwdriver passed through the hinge helps with alignment. The door can be adjusted in and out to align with the fenders using these bolts.  The door hinges bolt to the...  The door hinges bolt to the inside of the A-pillar using these three bolts. They’re accessible without the stone guards in place, but photograph more easily with the fender pulled away from the body. The door can be adjusted fore and aft here.  [19] Compare this to caption...  [19] Compare this to caption 11 and you’ll see the door aligns much better now that it’s been adjusted out from the body as well as forward. The fender still needs to come up though.  Here are all the door, fender,...  Here are all the door, fender, and hood gaps aligned at just a shade under 1/4 inch. The discrepancy (arrow) on the rear of the fender will require a little material added to its rear edge.  Moving to the other side of...  Moving to the other side of the car, this section (arrow) marked at the corner of the hood required trimming and welding closed to achieve a perfect gap against the cowl. Remember, it’s only metal!  An hour with the welder, grinder,...  An hour with the welder, grinder, and file, and the cowl gap is perfect!  Both fenders should be gapped...  Both fenders should be gapped before moving to the doors, but here’s what we found on the driver side. We should have suspected something would be amiss when we discovered the ’49 had taken a hard whack on this corner sometime in its life, which is the reason we replaced the crumpled inner fender on this side. The fender is sorely out of shape, and seeing as it’s got some serious rust below the headlight and the rear return has been pie-cut and welded several times to align with the filler-laden original door, we’ll simply replace it when one becomes available. Anyone know of a good one locally?  Here’s the door-to-front fender...  Here’s the door-to-front fender gap on the passenger side.  The door-to-rocker and fender-to-rocker...  The door-to-rocker and fender-to-rocker gaps all look good too. Incidentally, those are MkI Ford Fiesta rockers, with one-and-a-half used on each side of the car!  The rear door gap, however,...  The rear door gap, however, was not looking so good, being almost non-existent.  Simply put, we moved the A-post...  Simply put, we moved the A-post rearward, and if it'd had to go further than the 3/16 inch we needed it to, we’d have cut the whole lower section out to make moving it easier. We got away with hammering the edge rearward using a block of wood.  We used some scrap steel and...  We used some scrap steel and aluminum to maintain a constant gap of 7/32 inch while we tack-welded the quarter-panel back together.  The solution? Cut the rear...  The solution? Cut the rear quarter just behind the door, move it back, and weld the gap closed. For once we didn’t use a thin cutting disc, as we wanted a large gap. Even 1/8 inch wasn’t wide enough.  The end result: a perfectly...  The end result: a perfectly gapped door that opens and closes with ease. Now it aligns with the front and rear fenders and it’ll make the body prep stage easier. There’s nothing worse than opening a door to see the edge is 1/4-inch thick with body filler as it wasn’t properly aligned in the first place.  Voíla! The door, fender, and...  Voíla! The door, fender, and hood are all gapped. Now to replace that driver side fender and repeat the process on that side. Onward …
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