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Find someone that is comfortable welding aluminum. Grind and clean off the material on the back side and Prime and paint the backside after welding so you don't have moisture getting into the weld on the backside. Any high end body shop should be able to do this.
My body shop had to fill the hole on the door, the one furthest to the rear. They said it was inaccessible because of the vertical lip on the door. They welded the rest along with the 4 corners from the federalization lamps.
Really interested in this. The steel is easily welded, but the aluminum?? Lots of people have used fiberglass backing with a filler, but I don’t know if it’ll hold more than a few years before it’s noticeable
Take the fenders off for the work if you can. Makes it easier to clean all the coatings off the inside, plus full access in a horizontal position is a lot easier to weld correctly. Also a lot easier to manage heat migration. There are good welding guys here, like Ducman and Joe from Las Vegas, who will share guidance if asked.
I had a guy remove the rubbies, fill the holes, and paint to match on my '82. You can't even tell the rubbies were ever there. I believe he welded in plugs and smoothed it down.
Matt just put plastic plugs in when he did his 928RS, and they looked fine.
My research has turned to using 3M panel bond to adhere a 1 inch aluminum disk to the back of the hole properly prepared and sand and paint the epoxy.
I found aluminum disks on line to use. 1" diameter was easy. I was thinking about a smaller disk the thickness of the door and fender with a diameter small enough to slip into the hole. That has not been easy to find. Either too small or too big.
My body guy says all epoxies shrink. So, we are going ahead with the aluminum welding.
Epoxy’s shrink enough to be visible, especially along that body line. Some people let them cure for months in the summer sun before refinishing. That 3M adhesive looks really good though
Filling the holes in the aluminium--I went to an R/C expo one time and a guy there was selling 'Aluminium Brazing Rods': He punched a hole in the bottom of an aluminium can 1/4 inch wide and then used a MAP gas torch and one of his rods to fill it. He heated the can as he scrubbed the rod around the hole. As it melted he backed off the torch and continued to scrubbed the hole as it filled in. Then after it cooled, he tapped the plug, put a bolt in it and popped out the bottom of the can out before it let go..I bought a dozen and used them to: Move the exhaust ports on an 'In-Cowl' muffler, rebuild a broken muffler tab on an engine case, Make muffler extensions and tuned pipe header exhaust mounting flanges. "Worked great for me"...I wish I could remember the name of them. I could use some now...The PO of my 928 had the front cranked down so low (How low was it?) that the inside front fender lip was shaving the edge of the tire, So as a result, I have 2 cracks 3/4" long in the fender lip...The rods were 18" long about 3 mm dia. with no flux coating...I do remember the melting point was 780->820*F. Maybe a fellow R-Lister is also an R/C flyer and remember who made these rods, Seems like just the thing to fill the door & fender holes and the cracks in my front fender..
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
You guys are all missing the boat. I would use low temp aluminum solder,. Google Muggy Weld and check out his products. He has a very low temp (about 350 degrees F) that can be applied with a mapp gas torch.
Last edited by Jerry Feather; 04-14-2018 at 02:31 AM.
04-12-2018, 07:36 PM
Delete the rub strips - best practices for filling holes
