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Wilwood Brakes Aluminum Master Cylinder - What's Your Problem?

Will It Play In Peoria?
Pete Lassen, Peoria, AZ:
I was just reading the article on rust repair and had a question. If you cut the floorpans, left a flange for them to rest on, then welded them from the top side, wouldn't that leave a shelf on the bottom exposed to the elements where dirt can collect and start to rust? I know you are in SoCal where, except for the occasional flood, it never rains-but shouldn't you weld it from the bottom, too?

Jeff Smith: The short answer, Pete, is yes. The best plan for welding any two panels together is to butt-weld them, but that requires much greater fabrication skills. To address your question, there are several ways to eliminate this gap. Assuming you can access the backside of the panel, the best procedure would be to weld it closed. However, on a large panel, this would be a long process of a series of short welds to prevent putting excessive heat into the panel, which could easily cause distortion. Before the welding process begins, you should thoroughly clean both surfaces and spray them with a paintable zinc-based weld-through primer. Dupli-Color has a 12-ounce spray can (PN 108, $16.95, Summit Racing) that would work well, and we've also used the 3M primer with excellent results. There still will be some bare metal directly where the weld heat penetration is the highest, but the rest of the area will be protected.

A good alternative would be to use some type of high-quality seam sealer to fill the gap on the back side seam. We've used 3M's Heavy Drip Check with great results on our trunk floor installations. This stuff looks like a tube of silicone but in fact is much stronger and basically the same material used on older cars for panel installations with overlapping seams. If you are working on something like a quarter-panel on an El Camino where there is no easy access, it's possible to use a pressure gun with a long snout that can access the backside of the quarter-panel from the taillight opening. We found a rust-proofing kit from Eastwood (PN 50369ZP, $119.99) that includes the gun along with antirust and undercoating material. This gun has a long wand that will shoot undercoating or rust-proofing material into hard-to-access areas.

Finally, there is an alternative to welding. The 3M company makes a panel bond adhesive that allows even the backyard sheetmetal worker to adhere two nonstressed body panels together without a welder or heat. According to our sources, the OEs have been using this adhesive for several years on new cars. The idea is to overlap the pieces like in a quarter-panel, for example, and use this two-part adhesive to glue them together. We asked 3M about using this to glue the trunk floorpan on our '64 Olds, but because a potentially 120-pound gas tank hangs from these panels, it's probably not a good idea. But if you wanted to adhere a small repair to your door, this would be an excellent alternative to welding.

More Info
3M; St

Paul, MN
877/666-2277
3m.com/Automotive

CC Quickies
We're not sure what this is, but it has a '65 Chevelle front end and an LS swap.

Oil is Well
Unidentified CC reader, Somewhere in the Midwest: I spent last weekend at the World Series of Drag Racing in Cordova, Illinois. During a time out for cleanup, I engaged in an argument with another person who thought he knew it all. He voiced the old wives' tale about restricting oil to the heads so as not to fill the valve covers with oil. I countered that it was impossible to pump that much oil with large drain-back areas, and besides, lots of oil was required to cool the valve-springs. He says he reads all the magazines. How about it? Was I correct?

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