Well maybe it’s not sexy, but how about non-rusty? While most rodders leave the unseen alone, this is one area that needs to be tended to. The core support doesn’t just hold the radiator; it is the entire basis of structure for the front of your ride. This is the part that holds the fenders square and keeps everything bolted to the frame, a pretty important job.
After decades of weather, road grime, leaky radiators and old batteries, the core support on most muscle cars has taken a lot of abuse. Eventually it needs some repair. One specific example is the front end of this 1971 Buick GS convertible. GM A-bodies are home to some of the worst core support rust. The battery was located directly over the passenger side frame mount, which leads to a loose front clip. The bolt was completely gone on the 71. While pulling the engine for a rebuild, it was noticed that the entire front clip could lift off the frame; this signaled it was time for some repairs.
Mr. Buick of Topeka, Kansas, manufactures a few repro parts for Buicks, one of which is a core support rebuild kit for either left or right hand sides. Both kits include lower core and side sections as well as a new bushing box. The new metal is thicker than stock, looks like factory, and comes complete with locating holes.
Each side takes about 3 hours to install, and requires precise cutting and welding. You will also need to cut quite a few spot welds.
$125 per kit per side
Body filler $9.85\quart
120-grit sand paper $0.50\sheet
PPG DP90 epoxy primer $34.95\quart
1. The original core support has faced over 30 years of metal-eating abuse. The frame bolts are gone and the battery box has fused to the inner fender and core support.
2. Several bolts required grinding out, as the heads had long been rounded off by rust. This is 3 layers of metal: the battery tray, core support and the inner fender.
3. Once the support is out of the car and pressure washed, the damage becomes apparent. A total replacement will be needed.
4. The repair kits from MrBuick.com come with the side and lower support metal and a new bushing box. The box metal is twice as thick as the original and should last a long time.
5. Using a straight edge and some chalk, Toby Ramsey, of Ramsey Auto Body, marks where the old metal gets sliced off.
6. A die grinder and cut-off wheel make quick work of the old rusted metal. The core is trimmed as little as possible.
7. The spot welds are punched drilled with a spot weld cutter. This special bit cuts the welds and leaves a hole so the new metal can be tacked on.
8. With the old metal removed, the new parts are clamped into place. The lower panel requires trimming, so the panel is marked and removed.
9. The new lower panel gets the same die-grinder treatment as it is prepared for fitting.
10. The bushing box and the other pieces are sprayed with a weld-thru primer. This keeps the parts from forming rust after they are welded.
11. The box is clamped and then welded in place on the lower support metal.
12. Next, the entire assembly is clamped in place to the core body. The new metal has alignment holes for correct placement on the core body.
13. The parts are now tack welded in place. Once they are tacked, a solid bead is run down the seam, being careful to let it cool every 1\2-3\4” so it doesn’t warp.
14. The old spot welds are tacked as well.
15. A right-angle grinder makes quick work of the new welds, smoothing them down.
16. A little body filler is wiped over the seam so the repair will be undetectable once installed.
17. A DA-sander levels the filler and feathers the edges; 120-grit is all that is needed for this project.
18. For the backside, a bead of seam-sealer fills the pinholes and keeps moisture out, preventing future problems.
19. A little PPG DP90 epoxy primer completes the repair with a smooth, flat finish that will look right at home in any musclecar.
A life-long gearhead, Street Tech Magazine founder and editor Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a shop manager, eventually working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin’, Mopar Muscle, and many more. Jefferson has also written 5 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced. You can follow Jefferson on Facebook (Jefferson Bryant), Twitter (71Buickfreak), and YouTube (RedDirtRodz).
Nice write up!